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| (R) HIP6021 Data Sheet March 8, 2005 FN4684.1 Advanced PWM and Triple Linear Power Controller The HIP6021 provides the power control and protection for four output voltages in high-performance, graphics intensive microprocessor and computer applications. The IC integrates a voltage-mode PWM controller and three linear controllers, as well as the monitoring and protection functions into a 28pin SOIC package. The PWM controller regulates the microprocessor core voltage with a synchronous-rectified buck converter. The linear controllers regulate the computer system's AGP 1.5V or 3.3V bus power, the 1.5V GTL bus power, and the 1.8V power for the North/South Bridge core voltage and/or cache memory circuits. The HIP6021 includes an Intel-compatible, TTL 5-input digital-to-analog converter (DAC) that adjusts the core PWM output voltage from 1.3VDC to 2.05VDC in 0.05V steps and from 2.1VDC to 3.5VDC in 0.1V increments. The precision reference and voltage-mode control provide 1% static regulation. The AGP bus power linear controller's output (VOUT2) is user-selectable, through a TTL-compatible signal applied at the SELECT pin, for levels of 1.5V or 3.3V with 3% accuracy. Based on the status of the FIX pin, the other two linear regulators provide either fixed output voltages of 1.5V3% (VOUT3) and 1.8V3% (VOUT4), or user-adjustable by means of an external resistor divider. All linear controllers can employ either N-channel MOSFETs or bipolar NPNs for the pass transistor. The HIP6021 monitors all the output voltages. A single Power Good signal is issued when the core is within 10% of the DAC setting and all other outputs are above their undervoltage levels. Additional built-in over-voltage protection for the core output uses the lower MOSFET to prevent output voltages above 115% of the DAC setting. The PWM controller's over-current function monitors the output current by using the voltage drop across the upper MOSFET's rDS(ON). Features * Provides 4 Regulated Voltages - Microprocessor Core, AGP Bus, Memory, and GTL Bus Power * Drives N-Channel MOSFETs * Linear Regulator Drives Compatible with both MOSFET and Bipolar Series Pass Transistors * Fixed or Externally Resistor-Adjustable Linear Outputs (FIX Pin) * Simple Single-Loop Control Design - Voltage-Mode PWM Control * Fast PWM Converter Transient Response - High-Bandwidth Error Amplifier - Full 0% to 100% Duty Ratio * Excellent Output Voltage Regulation - Core PWM Output: 1% Over Temperature - Other Outputs: 3% Over Temperature * TTL-Compatible 5-Bit DAC Microprocessor Core Output Voltage Selection - Wide Range . . . . . . . . . . . . . . . . . . . 1.3VDC to 3.5VDC * Power-Good Output Voltage Monitor * Over-Voltage and Over-Current Fault Monitors - Switching Regulator Does Not Require Extra Current Sensing Element, Uses MOSFET's rDS(ON) * Small Converter Size - Constant Frequency Operation - 200kHz Free-Running Oscillator; Programmable From 50kHz to Over 1MHz - Small External Component Count * Pb-Free Available (RoHS Compliant) Pinout HIP6021 (SOIC) TOP VIEW DRIVE2 1 28 VCC 27 UGATE 26 PHASE 25 LGATE 24 PGND 23 OCSET 22 VSEN1 21 FB 20 COMP 19 VSEN3 18 DRIVE3 17 GND 16 VAUX 15 DRIVE4 Ordering Information PART NUMBER HIP6021CB HIP6021CBZ (Note) HIP6021EVAL1 TEMP. RANGE (oC) 0 to 70 0 to 70 PACKAGE 28 Ld SOIC PKG. DWG. # M28.3 FIX 2 VID4 3 VID3 4 VID2 5 VID1 6 VID0 7 PGOOD 8 SD 9 VSEN2 10 SELECT 11 28 Ld SOIC (Pb-free) M28.3 Evaluation Board Add "-T" suffix for tape and reel. NOTE: Intersil Pb-free products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. Applications * Motherboard Power Regulation for Computers 1 SS 12 FAULT/RT 13 VSEN4 14 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a trademark of Intersil Americas Inc. Copyright (c) Intersil Americas Inc. 1999, 2005. All Rights Reserved Block Diagram VSEN3 FIX SD VSEN1 OCSET VCC VAUX POWER-ON x 1.10 RESET (POR) + 200A + DRIVE3 DRIVE4 + + + x 0.90 x 0.75 LUV x 1.15 + + 1.26V - VSEN4 HIP6021 VSEN2 + ERROR AMP1 x 0.75 OSCILLATOR + SELECT - 1.5V or 3.3V + - - DRIVE2 LINEAR UNDERVOLTAGE OV SOFTINHIBIT START AND FAULT FAULT LOGIC OC1 + + - VAUX + 2 + GATE CONTROL PGOOD VCC DRIVE1 UGATE PHASE - PWM COMP1 PWM1 VCC LGATE VCC 28A DACOUT SYNCH DRIVE TTL D/A CONVERTER (DAC) 4.5V PGND GND FAULT / RT SS FB COMP VID0 VID1 VID2 VID4 VID3 HIP6021 Simplified Power System Diagram +5VIN +3.3VIN LINEAR CONTROLLER Q3 VOUT2 PWM CONTROLLER Q2 Q1 VOUT1 HIP6021 VOUT3 Q4 LINEAR CONTROLLER LINEAR CONTROLLER Q5 VOUT4 Typical Application +12VIN +5VIN LIN CIN VCC OCSET +3.3VIN PGOOD Q3 DRIVE2 UGATE VSEN2 PHASE Q1 LOUT1 VOUT1 1.3V TO 3.5V POWERGOOD VOUT2 1.5V OR 3.3V COUT2 LGATE PGND TYPEDET SELECT VSEN1 VAUX Q2 COUT1 HIP6021 Q4 VOUT3 1.5V DRIVE3 VSEN3 FB COMP COUT3 FIX FAULT / RT VID0 Q5 VOUT4 1.8V DRIVE4 VSEN4 SS CSS GND VID1 VID2 VID3 COUT4 VID4 3 HIP6021 Absolute Maximum Ratings Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +15V PGOOD, RT/FAULT, DRIVE, PHASE, and GATE Voltage . . . . . . . . . . . . . . . GND - 0.3V to VCC + 0.3V Input, Output or I/O Voltage . . . . . . . . . . . . . . . . . . GND -0.3V to 7V ESD Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Class 1 Thermal Information Thermal Resistance (Typical, Note 1) JA (oC/W) SOIC Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Maximum Junction Temperature (Plastic Package) . . . . . . . 150oC Maximum Storage Temperature Range . . . . . . . . . . -65oC to 150oC Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300oC (SOIC - Lead Tips Only) Operating Conditions Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . +12V 10% Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . 0oC to 70oC Junction Temperature Range . . . . . . . . . . . . . . . . . . . 0oC to 125oC CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTE: 1. JA is measured with the component mounted on an evaluation PC board in free air. Electrical Specifications PARAMETER VCC SUPPLY CURRENT Nominal Supply Current POWER-ON RESET Rising VCC Threshold Falling VCC Threshold Rising VAUX Threshold VAUX Threshold Hysteresis Rising VOCSET Threshold OSCILLATOR Free Running Frequency Total Variation Ramp Amplitude Recommended Operating Conditions, Unless Otherwise Noted. Refer to Block and Simplified Power System Diagrams, and Typical Application Schematic SYMBOL TEST CONDITIONS MIN TYP MAX UNITS ICC UGATE, LGATE, DRIVE2, DRIVE3, and DRIVE4 Open - 9 - mA VOCSET = 4.5V VOCSET = 4.5V VOCSET = 4.5V VOCSET = 4.5V 8.2 - 2.5 0.5 1.26 10.4 - V V V V V FOSC RT = OPEN 6k < RT to GND < 200k 185 -15 - 200 1.9 215 +15 - kHz % VP-P VOSC RT = Open DAC AND BANDGAP REFERENCE DAC(VID0-VID4) Input Low Voltage DAC(VID0-VID4) Input High Voltage DACOUT Voltage Accuracy Bandgap Reference Voltage Bandgap Reference Tolerance LINEAR REGULATORS (OUT2, OUT3, AND OUT4) Regulation (All Linears) VSEN2 Regulation Voltage VSEN2 Regulation Voltage VSEN3 Regulation Voltage VSEN4 Regulation Voltage Under-Voltage Level (VSEN/VREG) Under-Voltage Hysteresis (VSEN/VREG) Output Drive Current (All Linears) VREG2 VREG2 VREG3 VREG4 VSENUV VSEN Rising VSEN Falling VAUX-VDRIVE > 0.6V SELECT < 0.8V SELECT > 2.0V 20 3 1.5 3.3 1.5 1.8 75 7 40 % V V V V % % mA VBG 2.0 -1.0 -2.5 1.265 0.8 +1.0 +2.5 V V % V % 4 HIP6021 Electrical Specifications PARAMETER Recommended Operating Conditions, Unless Otherwise Noted. Refer to Block and Simplified Power System Diagrams, and Typical Application Schematic (Continued) SYMBOL TEST CONDITIONS MIN TYP MAX UNITS SYNCHRONOUS PWM CONTROLLER ERROR AMPLIFIER DC Gain Gain-Bandwidth Product Slew Rate PWM CONTROLLER GATE DRIVER UGATE Source UGATE Sink LGATE Source LGATE Sink PROTECTION VSEN1 Over-Voltage (VSEN1/DACOUT) FAULT Sourcing Current OCSET1 Current Source Soft-Start Current POWER GOOD VSEN1 Upper Threshold (VSEN1/DACOUT) VSEN1 Under-Voltage (VSEN1/DACOUT) VSEN1 Hysteresis (VSEN1/DACOUT) PGOOD Voltage Low VPGOOD VSEN1 Rising VSEN1 Rising Upper/Lower Threshold IPGOOD = -4mA 108 92 2 110 94 0.8 % % % V IOVP IOCSET ISS VSEN1 Rising VFAULT/RT = 2.0V VOCSET = 4.5VDC 170 115 8.5 200 28 120 230 % mA A A IUGATE RUGATE ILGATE RLGATE VCC = 12V, VUGATE = 6V VGATE-PHASE = 1V VCC = 12V, VLGATE = 1V VLGATE = 1V 1 1.7 1 1.4 3.5 3.0 A A GBWP SR COMP = 10pF 88 15 6 dB MHz V/s Typical Performance Curves 100 CUGATE1 = CUGATE2 = CLGATE1 = C VIN = 5V 80 1000 RESISTANCE (k) RT PULLUP TO +12V ICC (mA) 60 C = 3600pF VCC = 12V C = 4800pF 100 40 C = 1500pF 10 RT PULLDOWN TO VSS 20 C = 660pF 0 100 10 100 SWITCHING FREQUENCY (kHz) 1000 200 300 400 500 600 700 800 SWITCHING FREQUENCY (kHz) 900 1000 FIGURE 1. RT RESISTANCE vs FREQUENCY FIGURE 2. BIAS SUPPLY CURRENT vs FREQUENCY 5 HIP6021 Functional Pin Descriptions VCC (Pin 28) Provide a 12V bias supply for the IC to this pin. This pin also provides the gate bias charge for all the MOSFETs controlled by the IC. The voltage at this pin is monitored for Power-On Reset (POR) purposes. the soft-start capacitor, disabling all the outputs. Dedicated internal circuitry insures the core output voltage does not go negative during this process. When re-enabled, the IC undergoes a new soft-start cycle. Left open, this pin is pulled low by an internal pull-down resistor, enabling operation. FIX (Pin 2) Grounding this pin bypasses the internal resistor dividers that set the output voltage of the 1.5V and 1.8V linear regulators. This way, the output voltage of the two regulators can be adjusted from 1.26V up to the input voltage (+3.3V or +5V) by way of an external resistor divider connected at the corresponding VSEN pin. The new output voltage set by the external resistor divider can be determined using the following formula: R OUT V OUT = 1.265V x 1 + ---------------- R GND GND (Pin 17) Signal ground for the IC. All voltage levels are measured with respect to this pin. PGND (Pin 24) This is the power ground connection. Tie the synchronous PWM converter's lower MOSFET source to this pin. VAUX (Pin 16) This pin provides boost current for the linear regulators' output drives in the event bipolar NPN transistors (instead of N-channel MOSFETs) are employed as pass elements. The voltage at this pin is monitored for power-on reset (POR) purposes. where ROUT is the resistor connected from VSEN to the output of the regulator, and RGND is the resistor connected from VSEN to ground. Left open, the FIX pin is pulled high, enabling fixed output voltage operation. SS (Pin 12) Connect a capacitor from this pin to ground. This capacitor, along with an internal 28A current source, sets the soft-start interval of the converter. VID0, VID1, VID2, VID3, VID4 (Pins 7, 6, 5, 4 and 3) VID0-4 are the TTL-compatible input pins to the 5-bit DAC. The logic states of these five pins program the internal voltage reference (DACOUT). The level of DACOUT sets the microprocessor core converter output voltage, as well as the coresponding PGOOD and OVP thresholds. FAULT / RT (Pin 13) This pin provides oscillator switching frequency adjustment. By placing a resistor (RT) from this pin to GND, the nominal 200kHz switching frequency is increased according to the following equation: 5 x 10 Fs 200KHz + -------------------R T ( k ) 6 OCSET (Pin 23) Connect a resistor from this pin to the drain of the respective upper MOSFET. This resistor, an internal 200A current source, and the upper MOSFET's on-resistance set the converter over-current trip point. An over-current trip cycles the soft-start function. The voltage at this pin is monitored for power-on reset (POR) purposes and pulling this pin low with an open drain device will shutdown the IC. (RT to GND) Conversely, connecting a resistor from this pin to VCC reduces the switching frequency according to the following equation: 4 x 10 Fs 200KHz - -------------------R T ( k ) 7 (RT to 12V) PHASE (Pin 26) Connect the PHASE pin to the PWM converter's upper MOSFET source. This pin represents the gate drive return current path and is used to monitor the voltage drop across the upper MOSFET for over-current protection. Nominally, the voltage at this pin is 1.26V. In the event of an over-voltage or over-current condition, this pin is internally pulled to VCC. PGOOD (Pin 8) PGOOD is an open collector output used to indicate the status of the output voltages. This pin is pulled low when the synchronous regulator output is not within 10% of the DACOUT reference voltage or when any of the other outputs are below their under-voltage thresholds. The PGOOD output is open for `11111' VID code. UGATE (Pin 27) Connect UGATE pin to the PWM converter's upper MOSFET gate. This pin provides the gate drive for the upper MOSFET. LGATE (Pin 25) Connect LGATE to the PWM converter's lower MOSFET gate. This pin provides the gate drive for the lower MOSFET. SD (Pin 9) This pin shuts down all the outputs. A TTL-compatible, logic level high signal applied at this pin immediately discharges COMP and FB (Pin 20, and 21) COMP and FB are the available external pins of the PWM converter error amplifier. The FB pin is the inverting input of the 6 HIP6021 error amplifier. Similarly, the COMP pin is the error amplifier output. These pins are used to compensate the voltage-mode control feedback loop of the synchronous PWM converter. either output voltage is achieved by applying the proper logic level at the SELECT pin. The remaining two linear controllers supply the 1.5V GTL bus power (VOUT3) and the 1.8V memory power (VOUT4). All linear controllers are designed to employ an external pass transistor. VSEN1 (Pin 22) This pin is connected to the PWM converter's output voltage. The PGOOD and OVP comparator circuits use this signal to report output voltage status and for over- voltage protection. Initialization The HIP6021 automatically initializes upon receipt of input power. Special sequencing of the input supplies is not necessary. The Power-On Reset (POR) function continually monitors the input supply voltages. The POR monitors the bias voltage (+12VIN) at the VCC pin, the 5V input voltage (+5VIN) on the OCSET pin, and the 3.3V input voltage (+3.3VIN) at the VAUX pin. The normal level on OCSET is equal to +5VIN less a fixed voltage drop (see over-current protection). The POR function initiates soft-start operation after all supply voltages exceed their POR thresholds. DRIVE2 (Pin 1) Connect this pin to the gate of an external MOSFET. This pin provides the drive for the AGP regulator's pass transistor. VSEN2 (Pin 10) Connect this pin to the output of the AGP linear regulator. The voltage at this pin is regulated to the level predetermined by the logic-level status of the SELECT pin. This pin is also monitored for under-voltage events. SELECT (Pin 11) This pin determines the output voltage of the AGP bus linear regulator. A low TTL input sets the output voltage to 1.5V, while a high input sets the output voltage to 3.3V. Soft-Start The POR function initiates the soft-start sequence. Initially, the voltage on the SS pin rapidly increases to approximately 1V (this minimizes the soft-start interval). Then an internal 28A current source charges an external capacitor (CSS) on the SS pin to 4.5V. The PWM error amplifier reference input (+ terminal) and output (COMP pin) are clamped to a level proportional to the SS pin voltage. As the SS pin voltage slews from 1V to 4V, the output clamp allows generation of PHASE pulses of increasing width that charge the output capacitor(s). After the output voltage increases to approximately 70% of the set value, the reference input clamp slows the output voltage rate-of-rise and provides a smooth transition to the final set voltage. Additionally, all linear regulators' reference inputs are clamped to a voltage proportional to the SS pin voltage. This method provides a rapid and controlled output voltage rise. Figure 3 shows the soft-start sequence for the typical application. At T0 the SS voltage rapidly increases to approximately 1V. At T1, the SS pin and error amplifier output voltage reach the valley of the oscillator's triangle wave. The oscillator's triangular wave form is compared to the clamped error amplifier output voltage. As the SS pin voltage increases, the pulse-width on the PHASE pin increases. The interval of increasing pulse-width continues until each output reaches sufficient voltage to transfer control to the input reference clamp. If we consider the 2.5V core output (VOUT1) in Figure 3, this time occurs at T2. During the interval between T2 and T3, the error amplifier reference ramps to the final value and the converter regulates the output a voltage proportional to the SS pin voltage. At T3 the input clamp voltage exceeds the reference voltage and the output voltage is in regulation. The remaining outputs are also programmed to follow the SS pin voltage. The PGOOD signal toggles `high' when all output voltage levels have exceeded their under-voltage levels. See the Soft-Start Interval section under DRIVE3 (Pin 18) Connect this pin to the gate of an external MOSFET. This pin provides the drive for the 1.5V regulator's pass transistor. VSEN3 (Pin 19) Connect this pin to the output of the 1.5V linear regulator. This pin is monitored for under-voltage events. DRIVE4 (Pin 15) Connect this pin to the gate of an external MOSFET. This pin provides the drive for the 1.8V regulator's pass transistor. VSEN4 (Pin 14) Connect this pin to the output of the linear 1.8V regulator. This pin is monitored for undervoltage events. Description Operation The HIP6021 monitors and precisely controls 4 output voltage levels (Refer to Block and Simplified Power System Diagrams, and Typical Application Schematic). It is designed for microprocessor computer applications with 3.3V, 5V, and 12V bias input from an ATX power supply. The IC has a synchronous PWM controller and three linear controllers. The PWM controller (PWM) is designed to regulate the microprocessor core voltage (VOUT1). PWM controller drives 2 MOSFETs (Q1 and Q2) in a synchronous-rectified buck converter configuration and regulates the microprocessor core voltage to a level programmed by the 5-bit digital-to-analog converter (DAC). One of the linear controllers is designed to regulate the advanced graphics port (AGP) bus voltage (VOUT2) to a digitally-programmable level of 1.5V or 3.3V. Selection of 7 HIP6021 fully charged to 4V (UP signal). An under-voltage on either linear output (VSEN2, VSEN3, or VSEN4) is ignored until after the soft-start interval (T4 in Figure 3). This allows VOUT2 , VOUT3 , and VOUT4 to increase without fault at startup. Cycling the bias input voltage (+12VIN on the VCC pin off then on) resets the counter and the fault latch. PGOOD 0V SOFT-START (1V/DIV) Over-Voltage Protection 0V VOUT2 ( = 3.3V) VOUT1 (DAC = 2.5V) VOUT4 ( = 1.8V) OUTPUT VOLTAGES (0.5V/DIV) During operation, a short on the upper MOSFET of the PWM regulator (Q1) causes VOUT1 to increase. When the output exceeds the over-voltage threshold of 115% of DACOUT, the over-voltage comparator trips to set the fault latch and turns Q2 on. This blows the input fuse and reduces VOUT1. The fault latch raises the FAULT/RT pin to VCC. A separate over-voltage circuit provides protection during the initial application of power. For voltages on the VCC pin below the power-on reset (and above ~4V), the output level is monitored for voltages above 1.3V. Should VSEN1 exceed this level, the lower MOSFET, Q2 is driven on. VOUT3 ( = 1.5V) 0V Over-Current Protection T0 T1 T2 TIME T3 T4 FIGURE 3. SOFT-START INTERVAL Applications Guidelines for a procedure to determine the soft-start interval. All outputs are protected against excessive over-currents. The PWM controller uses the upper MOSFET's on-resistance, rDS(ON) to monitor the current for protection against shorted output. All linear controllers monitor their respective VSEN pins for under-voltage events to protect against excessive currents. Figure 5 illustrates the over-current protection with an overload on OUT1. The overload is applied at T0 and the current increases through the inductor (LOUT1). At time T1, the OVER-CURRENT comparator trips when the voltage across Q1 (iD * rDS(ON)) exceeds the level programmed by ROCSET. This inhibits all outputs, discharges the soft-start capacitor (CSS) with a 10mA current sink, and increments the counter. CSS recharges at T2 and initiates a soft-start cycle with the error amplifiers clamped by soft-start. With OUT1 still overloaded, the inductor current increases to trip the over-current comparator. Again, this inhibits all outputs, but the soft-start voltage continues increasing to 4V before discharging. The counter increments to 2. The soft-start cycle repeats at T3 and trips the over-current comparator. The SS pin voltage increases to 4V at T4 and the counter increments to 3. This sets the fault latch to disable the converter. The fault is reported on the FAULT/RT pin. The linear controllers operate in the same way as the PWM in response to over-current faults. The differentiating factor for the linear controllers is that they monitor the VSEN pins for under-voltage events. Should excessive currents cause the voltage at the VSEN pins to fall below the linear undervoltage threshold, the LUV signal sets the over-current latch if CSS is fully charged. Blanking the LUV signal during the CSS charge interval allows the linear outputs to build above the under-voltage threshold during normal operation. Cycling the bias input power off then on resets the counter and the fault latch. Fault Protection All four outputs are monitored and protected against extreme overload. A sustained overload on any output or an overvoltage on VOUT1 output (VSEN1) disables all outputs and drives the FAULT/RT pin to VCC. LUV OVERCURRENT LATCH OC1 SQ R 0.15V + INHIBIT SS 4V + UP POR OV COUNTER R FAULT LATCH SQ R FAULT VCC - FIGURE 4. FAULT LOGIC - SIMPLIFIED SCHEMATIC Figure 4 shows a simplified schematic of the fault logic. An over-voltage detected on VSEN1 immediately sets the fault latch. A sequence of three over-current fault signals also sets the fault latch. The over-current latch is set dependent upon the states of the over-current (OC), linear undervoltage (LUV) and the soft-start signals. A window comparator monitors the SS pin and indicates when CSS is 8 HIP6021 FAULT REPORTED FAULT/RT 10V 0V COUNT =1 The OC trip point varies with MOSFET's rDS(ON) temperature variations. To avoid over-current tripping in the normal operating load range, determine the ROCSET resistor from the equation above with: COUNT =3 COUNT =2 1. The maximum rDS(ON) at the highest junction temperature. 2. The minimum IOCSET from the specification table. 3. Determine IPEAK for IPEAK > IOUT(MAX) + (I)/2, where I is the output inductor ripple current. SOFT-START 4V 2V 0V OVERLOAD APPLIED For an equation for the ripple current see the section under component guidelines titled `Output Inductor Selection'. INDUCTOR CURRENT OUT1 Voltage Program The output voltage of the PWM converter is programmed to discrete levels between 1.3VDC and 3.5VDC . This output (OUT1) is designed to supply the core voltage of Intel's advanced microprocessors. The voltage identification (VID) pins program an internal voltage reference (DACOUT) with a TTL-compatible 5-bit digital-to-analog converter. The level of DACOUT also sets the PGOOD and OVP thresholds. Table 1 specifies the DACOUT voltage for the different combinations of connections on the VID pins. The VID pins can be left open for a logic 1 input, because they are internally pulled up to an internal voltage of about 5V by a 10A current source. Changing the VID inputs during operation is not recommended and could toggle the PGOOD signal and exercise the over-voltage protection. `11111' VID pin combination disables the IC and opens the PGOOD pin. TABLE 1. OUT1 VOLTAGE PROGRAM PIN NAME VID4 0 0 OVER-CURRENT TRIP: V DS > V SET VIN = +5V 0A T0 T1 T2 TIME T3 T4 FIGURE 5. OVER-CURRENT OPERATION A resistor (ROCSET) programs the over-current trip level for the PWM converter. As shown in Figure 6, the internal 200A current sink, IOCSET develops a voltage across ROCSET (VSET) that is referenced to VIN . The DRIVE signal enables the over-current comparator (OVERCURRENT). When the voltage across the upper MOSFET (VDS) exceeds VSET, the over-current comparator trips to set the over-current latch. Both VSET and VDS are referenced to VIN and a small capacitor across ROCSET helps VOCSET track the variations of VIN due to MOSFET switching. The over-current function will trip at a peak inductor current (IPEAK) determined by: I OCSET x R OCSET I PEAK = --------------------------------------------------r DS ( ON ) VID3 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 VID2 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 VID1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 VID0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 NOMINAL DACOUT VOLTAGE 1.30 1.35 1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 2.05 0 0 0 i D x r DS ( ON ) > I OCSET x R OCSET OCSET IOCSET 200A ROCSET iD 0 0 VSET + VCC 0 0 0 0 0 0 0 0 OVERCURRENT OC + DRIVE UGATE PHASE + VDS - PWM GATE CONTROL V PHASE = V IN - V DS V OCSET = V IN - V SET FIGURE 6. OVER-CURRENT DETECTION 0 0 1 9 HIP6021 TABLE 1. OUT1 VOLTAGE PROGRAM (Continued) PIN NAME VID4 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 VID3 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 VID2 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 VID1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 VID0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 NOMINAL DACOUT VOLTAGE 2.1 2.2 2.3 2.4 2.5 Q5 DRIVE4 VSEN4 RS4 COUT4 RP4 FIX COUT3 VOUT3 RS3 RP3 VAUX +3.3VIN Q4 DRIVE3 VSEN3 HIP6021 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 FIGURE 7. ADJUSTING THE OUTPUT VOLTAGE OF OUTPUTS 3 AND 4 R S V OUT = V BG x 1 + ------- R P VOUT4 Application Guidelines Soft-Start Interval Initially, the soft-start function clamps the error amplifier's output of the PWM converter. This generates PHASE pulses of increasing width that charge the output capacitor(s). After the output voltage increases to approximately 70% of the set value, the reference input of the error amplifier is clamped to a voltage proportional to the SS pin voltage. The resulting output voltages start-up as shown in Figure 3. The soft-start function controls the output voltage rate of rise to limit the current surge at start-up. The soft-start interval and the surge current are programmed by the soft-start capacitor, CSS. Programming a faster soft-start interval increases the peak surge current. The peak surge current occurs during the initial output voltage rise to 70% of the set value. NOTE: 0 = connected to GND, 1 = open or connected to 5V through pull-up resistors OUT2 Voltage Selection The AGP regulator output voltage is internally set to one of two discrete levels, based on the status of the SELECT pin. SELECT pin is internally pulled `high', such that left open, the AGP output voltage is by default set to 3.3V. The other discrete setting available is 1.5V, which can be obtained by grounding the SELECT pin using a jumper or another suitable method capable of sinking a few tens of microamperes. The status of the SELECT pin cannot be changed during operation of the IC without immediately causing a fault condition. OUT3 and OUT4 Voltage Adjustability The GTL bus voltage (1.5V, OUT3) and the chip set and/or cache memory voltage (1.8V, OUT4) are internally set for simple, low-cost implementation in typical Intel motherboard architectures. However, if different voltage settings are desired for these two outputs, the FIX pin provides the necessary adaptability. Left open (NC), this pin sets the fixed output voltages described above. Grounding this pin allows both output voltages to be set by means of external resistor dividers as shown in Figure 7. Shutdown The HIP6021 features a dedicated shutdown pin (SD). A TTL-compatible, logic high signal applied to this pin shuts down (disables) all four outputs and discharges the soft-start capacitor. Following a shutdown, a logic low signal re-enables the outputs through initiation of a new soft-start cycle. Left open this pin will asses a logic low state, due to its internal pull-down resistor, thus enabling normal operation of all outputs. The PWM output does not switch until the soft-start voltage (VSS) exceeds the oscillator's valley voltage. The references on each linear's error amplifier are clamped to the soft-start voltage. Holding the SS pin low (with an open drain or collector signal) turns off all four regulators. The `11111' VID code also shuts down the IC. 10 HIP6021 Layout Considerations MOSFETs switch very fast and efficiently. The speed with which the current transitions from one device to another causes voltage spikes across the interconnecting impedances and parasitic circuit elements. The voltage spikes can degrade efficiency, radiate noise into the circuit, and lead to device over-voltage stress. Careful component layout and printed circuit design minimizes the voltage spikes in the converter. Consider, as an example, the turnoff transition of the upper PWM MOSFET. Prior to turn-off, the upper MOSFET was carrying the full load current. During the turn-off, current stops flowing in the upper MOSFET and is picked up by the lower MOSFET or Schottky diode. Any inductance in the switched current path generates a large voltage spike during the switching interval. Careful component selection, tight layout of the critical components, and short, wide circuit traces minimize the magnitude of voltage spikes. See the Application Note ANTBD for evaluation board drawings of the component placement and printed circuit board. There are two sets of critical components in a DC-DC converter using a HIP6020 controller. The switching power components are the most critical because they switch large amounts of energy, and as such, they tend to generate equally large amounts of noise. The critical small signal components are those connected to sensitive nodes or those supplying critical bypass current. The power components and the controller IC should be placed first. Locate the input capacitors, especially the highfrequency ceramic decoupling capacitors, close to the power switches. Locate the output inductor and output capacitors between the MOSFETs and the load. Locate the PWM controller close to the MOSFETs. The critical small signal components include the bypass capacitor for VCC and the soft-start capacitor, CSS . Locate these components close to their connecting pins on the control IC. Minimize any leakage current paths from SS node, since the internal current source is only 28A. A multi-layer printed circuit board is recommended. Figure 8shows the connections of the critical components in the converter. Note that the capacitors CIN and COUT each represent numerous physical capacitors. Dedicate one solid layer for a ground plane and make all critical component ground connections with vias to this layer. Dedicate another solid layer as a power plane and break this plane into smaller islands of common voltage levels. The power plane should support the input power and output power nodes. Use copper filled polygons on the top and bottom circuit layers for the PHASE nodes, but do not unnecessarily oversize these particular islands. Since the PHASE nodes are subjected to very high dV/dt voltages, the stray capacitor formed between these islands and the surrounding circuitry will tend to couple switching noise. Use the remaining printed circuit layers for small signal 11 wiring. The wiring traces from the control IC to the MOSFET gate and source should be sized to carry 2A peak currents. PWM Controller Feedback Compensation The PWM controller uses voltage-mode control for output regulation. This section highlights the design consideration for a PWM voltage-mode controller. Apply the methods and considerations only to the PWM controller. Figure 9 highlights the voltage-mode control loop for a synchronous-rectified buck converter. The output voltage (VOUT) is regulated to the Reference voltage level. The reference voltage level is the DAC output voltage (DACOUT). The error amplifier (Error Amp) output (VE/A) is compared with the oscillator (OSC) triangular wave to provide a pulsewidth modulated (PWM) wave with an amplitude of VIN at the PHASE node. The PWM wave is smoothed by the output filter (LO and CO). The modulator transfer function is the small-signal transfer function of VOUT/VE/A . This function is dominated by a DC Gain, given by VIN/VOSC , and shaped by the output filter, with a double pole break frequency at FLC and a zero at FESR . Modulator Break Frequency Equations 1 F LC = --------------------------------------2 x L O x C O 1 F ESR = ---------------------------------------2 x ESR x C O The compensation network consists of the error amplifier (internal to the HIP6021) and the impedance networks ZIN and ZFB . The goal of the compensation network is to provide a closed loop transfer function with high 0dB crossing frequency (f0dB) and adequate phase margin. Phase margin is the difference between the closed loop phase at f0dB and 180 degrees. The equations below relate the compensation network's poles, zeros and gain to the components (R1, R2, R3, C1, C2, and C3) in Figure 8. Use these guidelines for locating the poles and zeros of the compensation network: 1. Pick Gain (R2/R1) for desired converter bandwidth 2. Place 1ST Zero Below Filter's Double Pole (~75% FLC) 3. Place 2ND Zero at Filter's Double Pole 4. Place 1ST Pole at the ESR Zero 5. Place 2ND Pole at Half the Switching Frequency 6. Check Gain against Error Amplifier's Open-Loop Gain 7. Estimate Phase Margin - Repeat if Necessary HIP6021 +5VIN LIN CIN Compensation Break Frequency Equations +12V CVCC VCC GND OCSET1 Q3 DRIVE2 UGATE1 PHASE1 COCSET1 ROCSET1 Q1 LOUT1 1 F Z1 = ----------------------------------2 x R 2 x C1 1 F Z2 = -----------------------------------------------------2 x ( R1 + R3 ) x C3 1 F P1 = -----------------------------------------------------C1 x C2 2 x R 2 x --------------------- C1 + C2 1 F P2 = ----------------------------------2 x R 3 x C3 +3.3VIN VOUT2 VOUT1 LOAD COUT2 SS CSS LGATE1 HIP6021 Q2 COUT1 CR1 VOUT3 COUT3 Q4 +3.3VIN KEY VOUT4 DRIVE3 DRIVE4 PGND Q5 COUT4 Figure 10 shows an asymptotic plot of the DC-DC converter's gain vs. frequency. The actual Modulator Gain has a high gain peak dependent on the quality factor (Q) of the output filter, which is not shown in Figure 9. Using the above guidelines should yield a Compensation Gain similar to the curve plotted. The open loop error amplifier gain bounds the compensation gain. Check the compensation gain at FP2 with the capabilities of the error amplifier. The Closed Loop Gain is constructed on the log-log graph of Figure 10 by adding the Modulator Gain (in dB) to the Compensation Gain (in dB). This is equivalent to multiplying the modulator transfer function to the compensation transfer function and plotting the gain. The compensation gain uses external impedance networks ZFB and ZIN to provide a stable, high bandwidth (BW) overall loop. A stable control loop has a gain crossing with -20dB/decade slope and a phase margin greater than 45 degrees. Include worst case component variations when determining phase margin. FZ1 FZ2 FP1 FP2 OPEN LOOP ERROR AMP GAIN V IN 20 log ----------- V PP LOAD LOAD ISLAND ON POWER PLANE LAYER ISLAND ON CIRCUIT PLANE LAYER VIA CONNECTION TO GROUND PLANE FIGURE 8. PRINTED CIRCUIT BOARD POWER PLANES AND ISLANDS VIN OSC PWM COMP DRIVER LO DRIVER PHASE CO VOUT LOAD 100 80 60 GAIN (dB) 40 20 0 -20 R2 20 log ------- R1 MODULATOR GAIN VOSC - + COMPENSATION GAIN ESR (PARASITIC) ZFB VE/A + - ZIN REFERENCE -40 -60 ERROR AMP FLC 1K FESR 10K 100K 1M CLOSED LOOP GAIN 10 100 10M DETAILED COMPENSATION COMPONENTS ZFB ZIN C3 R1 R3 VOUT FREQUENCY (Hz) C2 C1 R2 FIGURE 10. ASYMPTOTIC BODE PLOT OF CONVERTER GAIN Component Selection Guidelines COMP Output Capacitor Selection + FB HIP6021 DACOUT FIGURE 9. VOLTAGE-MODE BUCK CONVERTER COMPENSATION DESIGN The output capacitors for each output have unique requirements. In general, the output capacitors should be selected to meet the dynamic regulation requirements. Additionally, the PWM converters require an output capacitor to filter the current ripple. The load transient for the microprocessor core requires high quality capacitors to supply the high slew rate (di/dt) current demands. 12 HIP6021 PWM Output Capacitors Modern microprocessors produce transient load rates above 1A/ns. High frequency capacitors initially supply the transient current and slow the load rate-of-change seen by the bulk capacitors. The bulk filter capacitor values are generally determined by the ESR (effective series resistance) and voltage rating requirements rather than actual capacitance requirements. High frequency decoupling capacitors should be placed as close to the power pins of the load as physically possible. Be careful not to add inductance in the circuit board wiring that could cancel the usefulness of these low inductance components. Consult with the manufacturer of the load on specific decoupling requirements. Use only specialized low-ESR capacitors intended for switching-regulator applications for the bulk capacitors. The bulk capacitor's ESR determines the output ripple voltage and the initial voltage drop following a high slew-rate transient's edge. An aluminum electrolytic capacitor's ESR value is related to the case size with lower ESR available in larger case sizes. However, the equivalent series inductance (ESL) of these capacitors increases with case size and can reduce the usefulness of the capacitor to high slew-rate transient loading. Unfortunately, ESL is not a specified parameter. Work with your capacitor supplier and measure the capacitor's impedance with frequency to select a suitable component. In most cases, multiple electrolytic capacitors of small case size perform better than a single large case capacitor. HIP6021 will provide either 0% or 100% duty cycle in response to a load transient. The response time is the time interval required to slew the inductor current from an initial current value to the post-transient current level. During this interval the difference between the inductor current and the transient current level must be supplied by the output capacitor(s). Minimizing the response time can minimize the output capacitance required. The response time to a transient is different for the application of load and the removal of load. The following equations give the approximate response time interval for application and removal of a transient load: L O x I TRAN t RISE = ------------------------------V IN - V OUT L O x I TRAN t FALL = -----------------------------V OUT where: ITRAN is the transient load current step, tRISE is the response time to the application of load, and tFALL is the response time to the removal of load. Be sure to check both of these equations at the minimum and maximum output levels for the worst case response time. Input Capacitor Selection The important parameters for the bulk input capacitors are the voltage rating and the RMS current rating. For reliable operation, select bulk input capacitors with voltage and current ratings above the maximum input voltage and largest RMS current required by the circuit. The capacitor voltage rating should be at least 1.25 times greater than the maximum input voltage and a voltage rating of 1.5 times is a conservative guideline. The RMS current rating requirement for the input capacitor of a buck regulator is approximately 1/2 of the summation of the DC load current. Use a mix of input bypass capacitors to control the voltage overshoot across the MOSFETs. Use ceramic capacitance for the high frequency decoupling and bulk capacitors to supply the RMS current. Small ceramic capacitors can be placed very close to the upper MOSFET to suppress the voltage induced in the parasitic circuit impedances. For a through-hole design, several electrolytic capacitors (Panasonic HFQ series or Nichicon PL series or Sanyo MV-GX or equivalent) may be needed. For surface mount designs, solid tantalum capacitors can be used, but caution must be exercised with regard to the capacitor surge current rating. These capacitors must be capable of handling the surge-current at power-up. The TPS series available from AVX, and the 593D series from Sprague are both surge current tested. Linear Output Capacitors The output capacitors for the linear regulators provide dynamic load current. The linear controllers use dominant pole compensation integrated into the error amplifier and are insensitive to output capacitor selection. Output capacitors should be selected for transient load regulation. PWM Output Inductor Selection The PWM converter requires an output inductor. The output inductor is selected to meet the output voltage ripple requirements and sets the converter's response time to a load transient. The inductor value determines the converter's ripple current and the ripple voltage is a function of the ripple current. The ripple voltage and current are approximated by the following equations: V IN - V OUT V OUT I = ------------------------------- x --------------FS x L V IN V OUT = I x ESR Increasing the value of inductance reduces the ripple current and voltage. However, the large inductance values increase the converter's response time to a load transient. One of the parameters limiting the converter's response to a load transient is the time required to change the inductor current. Given a sufficiently fast control loop design, the 13 MOSFET Selection/Considerations The HIP6021 requires 5 external transistors. Two N-channel MOSFETs are used in the synchronous-rectified buck topology of PWM1 converter. It is recommended that the AGP linear regulator pass element be a N-channel MOSFET as well. The GTL and memory linear controllers can also HIP6021 each drive a MOSFET or a NPN bipolar as a pass transistor. All these transistors should be selected based upon rDS(ON) , current gain, saturation voltages, gate supply requirements, and thermal management considerations. +5V OR LESS +12V VCC PWM MOSFET Selection and Considerations In high-current PWM applications, the MOSFET power dissipation, package selection and heatsink are the dominant design factors. The power dissipation includes two loss components; conduction loss and switching loss. These losses are distributed between the upper and lower MOSFETs according to duty factor (see the equations below). The conduction losses are the main component of power dissipation for the lower MOSFETs. Only the upper MOSFET has significant switching losses, since the lower device turns on and off into near zero voltage. The equations below assume linear voltage-current transitions and do not model power loss due to the reverserecovery of the lower MOSFET's body diode. The gatecharge losses are dissipated by the HIP6021 and don't heat the MOSFETs. However, large gate-charge increases the switching time, tSW which increases the upper MOSFET switching losses. Ensure that both MOSFETs are within their maximum junction temperature at high ambient temperature by calculating the temperature rise according to package thermal-resistance specifications. A separate heatsink may be necessary depending upon MOSFET power, package type, ambient temperature and air flow. HIP6021 UGATE PHASE Q1 NOTE: VGS VCC -5V Q2 CR1 NOTE: VGS VCC - LGATE PGND GND + FIGURE 11. UPPER GATE DRIVE - DIRECT VCC DRIVE OPTION MOSFET body diode from conducting. It is acceptable to omit the diode and let the body diode of the lower MOSFET clamp the negative inductor swing, but efficiency could drop one or two percent as a result. The diode's rated reverse breakdown voltage must be greater than the maximum input voltage. Linear Controller Transistor Selection The main criteria for selection of transistors for the linear regulators is package selection for efficient removal of heat. The power dissipated in a linear regulator is: P LINEAR = I O x ( V IN - V OUT ) I O x r DS ( ON ) x V OUT I O x V IN x t SW x F S P UPPER = ----------------------------------------------------------- + ---------------------------------------------------V IN 2 I O x r DS ( ON ) x ( V IN - V OUT ) P LOWER = -------------------------------------------------------------------------------V IN 2 2 Select a package and heatsink that maintains the junction temperature below the rating with a the maximum expected ambient temperature. When selecting bipolar NPN transistors for use with the linear controllers, insure the current gain at the given operating VCE is sufficiently large to provide the desired output load current when the base is fed with the minimum driver output current. The rDS(ON) is different for the two equations above even if the same device is used for both. This is because the gate drive applied to the upper MOSFET is different than the lower MOSFET. Figure 11 shows the gate drive where the upper MOSFET's gate-to-source voltage is approximately VCC less the input supply. For +5V main power and +12VDC for the bias, the gate-to-source voltage of Q1 is 7V. The lower gate drive voltage is +12VDC. A logic-level MOSFET is a good choice for Q1 and a logic-level MOSFET can be used for Q2 if its absolute gate-to-source voltage rating exceeds the maximum voltage applied to VCC. Rectifier CR1 is a clamp that catches the negative inductor swing during the dead time between the turn off of the lower MOSFET and the turn on of the upper MOSFET. The diode must be a Schottky type to prevent the lossy parasitic 14 HIP6021 HIP6021 DC-DC Converter Application Circuit Figure 12 shows an application circuit of a power supply for a microprocessor computer system. The power supply provides the microprocessor core voltage (VOUT1), the AGP bus voltage (VOUT2), the GTL bus voltage (VOUT3), and the memory +12VIN L1 +5VIN 1H C1-6 + 6x1000F C7 1F C8 1000pF voltage (VOUT4) from +3.3V, +5VDC, and +12VDC. For detailed information on the circuit, including a Bill-of-Materials and circuit board description, see Application Note AN9836. Also see Intersil's web page (http://www.intersil.com). GND C9 1F VCC 28 FAULT/RT +3.3VIN 13 16 8 R1 23 OCSET PGOOD 1.0K POWERGOOD VAUX DRIVE2 VOUT2 (3.3V or 1.5V) + VSEN2 Q3 HUF76121D3S 1 10 27 UGATE 26 PHASE Q1,2 2xHUF76143S3S L2 4.2H VOUT1 (1.3V-3.5V) C10,11 2x1000F 25 LGATE C12-19 + 8x1000F R2 10.2K 24 PGND TYPEDET SELECT 11 VSEN1 FB C21 10pF R3 1.62k 22 U1 21 HIP6021 Q4 HUF76107D3S VOUT3 (1.5V) DRIVE3 VSEN3 + C23,24 2x1000F 7 Q5 HUF76107D3S VOUT4 (1.8V) + C25,26 2x1000F DRIVE4 VSEN4 SD FIX VID0 6 VID1 VID2 5 4 VID3 3 VID4 18 19 C22 2.7nF R4 150K 20 COMP C20 0.22F R5 499K 15 14 9 2 17 GND 12 SS C27 0.1F FIGURE 12. POWER SUPPLY APPLICATION CIRCUIT FOR A MICROPROCESSOR COMPUTER SYSTEM All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation's quality certifications can be viewed at www.intersil.com/design/quality Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com 15 |
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