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| SMH4803 Distributed Power Hot-Swap Controller FEATURES * Supply Range 20VDC to >500VDC * Versatile Card Insertion Detection Supports Both - Multi-length Pin Systems - Card Injector Switch Sensing * Control Up to Four Loads or a Primary Load and 3 DC/DC Converters * Highly Programmable Host Voltage Monitoring - Programmable Under- and Over-voltage Detection * Programmable Power Good Delays for Sequencing DC/DC Converters * Programmable Circuit Breaker Function - Programmable Over-current Filter - Programmable Quick-TripTM Circuit Breaker Values - Programmable Circuit Breaker Mode * Duty-Cycle Mode * * Latched Mode 2.5V and 5.0V reference outputs - Easy Expansion of External Monitor Functions uri Fe a t Pr ng TM og Quick-Trip le ab eaker ra m m r it B Ci r c u ASSOCIATE MEMBER FUNCTIONAL BLOCK DIAGRAM ENPGB VDD 12V ref PG3# 50k EN/TS 50k PD1# + Programmable Delay ENPGA 50k Filter PG2# Programmable Delay PD2# UV + PG1# Drain Sense 12V + + OV 2.5V ref VSS 5V 2.5V 12V current limit 5.0V ref Vgate Sense CBMode CBReset# + 50 mV + Programmable Quick-Trip Ref Voltage Vgate Programmable Delay Fault Latch & Duty Cycle Timer CBSense (c) SUMMIT MICROELECTRONICS, Inc. 2000 * 300 Orchard City Drive, Suite 131 * Campbell, CA 95008 * Telephone 408-378-6461 * Fax 408-378-6586 * www.summitmicro.com Characteristics subject to change without notice 2041 8.4 6/15/00 - CBFault# 2041 BD 8.0 1 SMH4803 Symbol Drain Sense Vgate EN/TS PD1# PD2# CBFault# CBReset# CBMode CBSense Vss UV OV 5V 2.5V ENPGB ENPGA PG3# PG1# PG2# Vdd Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Description Drain sense input Output to MOSFET gate Enable/Temp Sense input Pin Detect 1 (active LO) Pin Detect 2 (active LO) Circuit Breaker Fault output Circuit Breaker Reset intput Circuit Breaker Mode control Cicruit Breaker Sense input Negative Supply Connection Under Voltage input Over Voltage input 5V reference output 2.5V reference output Enable input B Enable input A Power good output 3 Power good output 1 Power good output 2 Positive supply connection 2041 PGM T2.1 PIN CONFIGURATIONS Drain Sense Vgate EN/TS PD1# PD2# CBFault# CBReset# CBMode CBSense Vss 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 Vdd PG2# PG1# PG3# ENPGA ENPGB 2.5V 5V OV UV 2041 ILL10.1 RECOMMENDED OPERATING CONDITIONS Condition Temperature Min -40C Max +85C 2041 PGM T3.0 DESCRIPTION The SMH4803 is designed to control hot swapping of plug-in cards operating from a single supply ranging from 20V to 500V. The SMH4803 hot-swap controller provides under-voltage and over-voltage monitoring of the host power supply, it drives an external power MOSFET switch that connects the supply to the load, and also protects against over-current conditions that might disrupt the host supply. When the input and output voltages to the SMH4803 controller are within specification, the SMH4803 provides three "Power Good" logic outputs that may be used to turn ON the loads, e.g. isolated-output DCDC converters, or drive LED status lights. The SMH4803 provides three separate "Power Good" logic outputs that activate loads in a timed sequence. Additional features of the SMH4803 include: temperature sense or master enable input, 2.5V and 5V reference outputs for expanding monitor functions, two "Pin-Detect" enable inputs for fault protection, and duty-cycle or latched over-current protection modes. 2041 8.4 6/15/00 SUMMIT MICROELECTRONICS 2 SMH4803 ABSOLUTE MAXIMUM RATINGS Temperature Under Bias Storage Temperature Voltage on pins with respect to VSS Vdd UV, OV, CBSense, Drain Sense PD1#, PD2#, CBMode, CBReset# ENPGA, ENPGB, EN/TS CBFault#, PG1#, PG2#, PG3# Vgate Lead Solder Temperature (10 secs) -0.5V to Vdd -0.5V to Vdd +0.5V 10V -0.5V to Vdd +0.5V Vdd + 0.5V 300 C -55C to +125C -65C to +150C *COMMENT Stresses listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions outside those listed in the operational sections of this specification is not implied. Exposure to any absolute maximum rating for extended periods may affect device performance and reliability. DC OPERATING CHARACTERISTICS (Over Recommended Operating Conditions, Voltages are relative to VSS) Symbol VDD Vref5 ILOAD5 Vref2.5 Vref2.5 ILOAD2.5 IDD VUV VUV VUVHYS VOV VOV VOVHYS VVGATE IVGATE VSENSE VSENSE ISENSE VCB VQCB Parameter Supply Voltage 5Volt Reference Output 5Volt Reference Output Current 2.5 Volt Reference Output 2.5 Volt Reference Output 2.5 Volt Reference Output Current Power Supply Current Under voltage Threshold Under voltage Threshold Under voltage Hysteresis Over voltage Threshold Over voltage Threshold Over voltage Hysteresis Vgate Output Voltage Vgate Current Output Drain Sense threshold Drain Sense threshold Drain Sense Output Current Circuit Breaker Threshold Quick-Trip Circuit Breaker Threshold Notes IDD = 2mA IDD = 2mA IDD = 2mA TA = 25 C, IDD = 2mA IDD = 2mA IDD = 2mA Output Enabled TA = 25 C, IDD = 2mA IDD = 2mA IDD = 2mA TA = 25 C, IDD = 2mA IDD = 2mA IDD = 2mA Min. 11 4.75 -1 2.475 2.425 -0.2 2 2.475 2.425 2.475 2.425 Typ. 12 5 2.5 2.5 Max. Units 13 V 5.25 V 1 mA 2.525 V 2.575 V 1 mA 10 mA 2.525 V 2.575 V mV 2.525 V 2.575 V mV VDD V A 2.525 V 2.575 V 11 A 60 mV mV mV mV 2.575 2.525 15 Vref5 0.8 0.4 0.4 V V mV V V V V 2.5 2.5 10 2.5 2.5 10 100 2.5 2.5 10 50 200 100 50 OFF 2.5 2.5 10 VENTS VENTS VENTSHYS VIH VIL VOL VOL EN/TS Threshold EN/TS Threshold EN/TS Hysteresis Input High Voltage ENPGA/B, CBMode, CBReset# Input High Voltage ENPGA/B, CBMode, CBReset# CBFault# Output Low Voltage PG1#, PG2#, PG3# Output Low TA = 25 C, IDD = 2mA IDD = 2mA (Note 1) VSENSE = VSS IDD = 2mA Option E Option F Option H Option J TA = 25 C, IDD = 2mA IDD = 2mA IDD = 2mA 2.475 2.425 9 40 2.425 2.475 5 2 -0.1 IOL = 2mA ISINK = 2mA 0 0 2041 PGM T4.4 (Note 1) : TA = 25 C SUMMIT MICROELECTRONICS 2041 8.4 6/15/00 3 SMH4803 AC Timing Characteristics, -40oC to +85oC Symbol tPDD tCBD Description Pin Detect Delay to Vgate enable 50mv Circuit Breaker Delay (Filter) K L M N PGD Power Good Delay (PG1/PG2, PG2/PG3) A B C D tFSTSHTDN tCYC tVGD tCBRST Fast Shut Down Delay From Fault to Vgate Off Circuit Breaker Cycle Mode Cycle Time Delay from Release of Reset to Vgate on CBReset# Pulse Width 5 20 80 180 200 2.5 100 200 ms ms ms ms ns Sec. ns ns Min. Typ. 80 400 150 50 5 Max Unit ms s s s s 2041 8.4 6/15/00 SUMMIT MICROELECTRONICS 4 SMH4803 11V13V VDD 2.5V ref UV 2.5V ref OV tPDD PD1#/PD2# Vgate 2.5V ref Drain Sense 50mV ref CBSense PG1# ENPGB PG3# 2041 ILL18.0 Figure 1. Power Sequencing Timing Characteristics SUMMIT MICROELECTRONICS 2041 8.4 6/15/00 5 SMH4803 VIH CBMode 50mV tCBD tCBD CBSense tCYC Vgate VIH CBReset# 2041 ILL16.0 Figure 2. Circuit Breaker Timing - Cycle Mode, CBReset# Held High VIH CBMode tCBD 50mV CBSense Vgate tCYC CBReset# VIL 2041 ILL17.0 Figure 3. Circuit Breaker Timing - Cycle Mode, Used to Enable Vgate 2041 8.4 6/15/00 SUMMIT MICROELECTRONICS 6 SMH4803 CBMode VIL tCBD 50mV CBSense Vgate tVGD CBReset# tCBRST 2041 ILL14.0 Figure 4. Circuit Breaker Timing - Reset Mode QCBV 2041 ILL15.0 Figure 5. Circuit Breaker Timing - Quick-Trip SUMMIT MICROELECTRONICS 2041 8.4 6/15/00 7 SMH4803 SMH4803 Pin Descripiton PIN NAME (Pin #) Drain Sense (1) The Drain Sense input monitors the voltage at the drain of the external power MOSFET switch with respect to VSS. When the MOSFET is turned on, the Drain Sense input will be driven low and will be used as one of the enable conditions for the PG outputs. This will prevent any premature activation of the PG outputs. Vgate (2) The Vgate output activates an external power MOSFET switch. It is a constant current source (100A typical) allowing easy programming of the MOSFET turn on slew rate. EN/TS (3) The Enable/Temperature Sense input is the master enable input. When EN/TS is LOW, Vgate, and the PG outputs are off. As the name suggests, the EN/TS input may be used as a master enable by a host system or alternatively for circuit over-temperature protection using an external thermistor. PD1# and PD2# (4 & 5) The pin detect pins are active LOW inputs that are use to prevent any power sequence before the add-in card is properly seated. Both inputs must be at VSS before either Vgate or the PG outputs can be enabled. In applications where multi-length connector pins are use, the PD inputs should be tied to the short pins. On the mating connector side the pins opposite should be tied directly to VSS. Alternatively, either one or both of the PD inputs can be tied to card injector handle switches, insuring no power sequencing will occur until the card is properly seated. CBFault# (6) CBFault# is an open drain active low output, indicating the circuit breaker status. When an over current condition is detected CBFault# is driven low. CBReset# (7) CBReset# is the circuit breaker reset input. It can be actively controlled to reset a fault condition or it can be tied high or low to allow either timed restarts (duty cycle mode) or "latch-off" the Vgate output. Refer to the Circuit Breaker Operation and the associated timing diagrams for detailed characteristics. CBMode (8) The CBMode input selects one of two circuit breaker operational modes. When tied to VSS all fault conditions must be cleared by toggling the CBReset# input low then high. 2041 8.4 6/15/00 SUMMIT MICROELECTRONICS When CBMode is tied to 5V the circuit breaker will be placed in the self-restart or cycling mode. The state of CBReset# input will control the operation of the restart. If CBReset# is tied to 5V the Vgate output will automatically restart after tCYC has elapsed. If the fault condition still exists, the circuit breaker will trip once again. The cycling will continue until the fault clears or the circuit board is replaced. Alternatively the CBReset# input can be actively driven to VSS. If a fault occurs the Vgate and PG outputs will not be turned on again for tCYC after the CBReset# input is driven high. CBSense (9) The circuit breaker sense input is used to detect overcurrent conditions in the load connected to the power MOSFET. A low value sense resistor (RS) is tied in series with the MOSFET switch; one end tied to VSS and the other to the switch and the CBSense input. A voltage drop of greater than 50mV (for greater than tCBD) across the resistor will result in the circuit breaker tripping. A programmable "quick-trip" sense point is also available. If the CBSense input transitions above the threshold, the circuit breaker will immediately trip. VSS (10) VSS is connected to the negative side of the supply. UV and OV (11 & 12) The under-voltage (11) and over-voltage (12) input pins monitor the supply voltage for the SMH4803 and the downstream circuits. Both inputs have a 2.5V threshold on their respective comparators. If UV is less than 2.5V or if OV is greater than 2.5V, Vgate will be disabled. 5.0V (13) 5.0V is a precision 5 volt output reference voltage tha may be use to expand the logic-input funtions on the SMH4803. The reference output is with respect to VSS. 2.5V (14) 2.5V is a precision 2.5 volt output reference voltage tha may be use to expand the logic-input funtions on the SMH4803. The reference output is with respect to VSS. ENPGB (15) The ENPGB input may be used to independently switch off the PG3# output. When ENPGB is pulled low, the PG3# output is immediately placed in a high impedance state. If PG2# is active and ENPGB is driven high, then the PG3# output will immediately be driven low. 8 SMH4803 ENPGA (16) The ENPGA input controls the PG2# and PG3# outputs. When ENPGA is pulled low, the PG2# output is immediately placed in a high impedance state. If ENPGA is driven high, then the PG2# output will immediately be driven low, provided PG1# has been active for at least tPGD. PG3# (17) PG3# is an open drain active low output with no internal pull-up. PG3# is the last power good signal to be enabled after Vgate, PG1# and PG2# have been turned on. PG3# is delayed PGD after PG2# is active and 2xPGD after PG1# is active. PG3# can be used to switch a third load or a DC/DC converter. PG1# (18) PG1# is an open drain active low output with no internal pull-up. PG1# is enabled after Vgate is enabled and voltage across the load is within spec. PG1# can be used to switch a load or enable a DC/DC converter. PG2# (19) PG2# is an open drain active low output with no internal pull-up. PG2# is enabled after Vgate and PG1# have been turned on. PG2# is delayed PGD after PG1# is active. PG2# can be used to switch a second load or a DC/DC converter. VDD (20) VDD is the positive supply connection. An internal shunt regulator connected between VDD and VSS develops approximately 12 volts that supplies the SMH4803. A resistor must be placed in series with the VDD pin to limit the regulator current (RD in the application illustrations). PROGRAMMABLE FEATURES Because the SMH4803 is electrically programmable it can be fine-tuned for a wide variety of applications prior to shipment to the customer. Because of this a manufacturer can use a common part type across a wide range of boards that are used on a common host but have different electrical loads, power-on timing requirements, host voltage monitoring needs etc. This ability to use a common solution across many platforms shifts the focus of design away from designing a new power interface for each board to concentrating on the value added back-end logic. Because the programming of the features is done at final test all combinations (all 128 possibilities) are readily available as off the shelf stock items. Power Good Delay The PG delay timer that controls the delay from PG1# to PG2# and PG2# to PG3# being asserted can be set to typical values of 5ms, 20ms, 80ms or 160ms. Quick-Trip Circuit Breaker Threshold The Quick-Trip circuit breaker threshold can be set to 200mV, 100mV, 60mv or OFF. This is the threshold voltage drop across RS that is placed between VSS and CBSense. Circuit Breaker Delay The circuit breaker delay defines the period of time the voltage drop across RS is greater than 50mV but less than VQCB before the Vgate output will be shut down. This is effectively a filter to prevent spurious shutdowns of Vgate. The delays that can be programmed are 5s, 50s, 150s and 400s. Pin Detect The Pin Detect function can be enabled or disabled. SUMMIT MICROELECTRONICS 2041 8.4 6/15/00 9 SMH4803 DEVICE OPERATION Power-Up Sequence The SMH4803 is an integrated power controller for hot swappable add-in cards. The device operates from a single supply ranging from 20V to 500V and generates the signals necessary to drive isolated output DC/DC converters. The SMH4803 hot-swap controller provides under-voltage and over-voltage monitoring of the host power supply, it drives an external power MOSFET switch that connects the supply to the load. It also protects against over-current conditions that might disrupt the host supply. When the input and output voltages to the SMH4803 controller are within specification, the SMH4803 provides three "Power Good" logic outputs that may be used to turn ON loads or drive an LED status light. The SMH4803 provides three separate "Power Good" logic outputs that activate loads in a programmable timed sequence. There is a master enable/temperature sense input and 2.5V and 5V reference outputs for expanding monitor functions. There are two "Power Good" enable inputs that may be used to activate or deactivate output loads, and dutycycle or reset over-current protection modes to provide automatic or manual restart of the controller after overcurrent load conditions. Insertion Process As the add-in board is inserted into the backplane, physical connections must be made with the chassis to discharge any electrostatic voltage potentials. The board then contacts the long pins on the backplane that provide power and ground. As soon as power is applied the SMH4803 starts up but does not immediately apply power to the output load. Under-voltage and over-voltage circuits inside the controller check to see if the input voltage is within a user-specified range, and pin detection signals determine whether the card is seated properly. tPDD after these requirements are met, the hot-swap controller enables Vgate to turn on the power MOSFET switch. The Vgate output is current limited to IVGATE, allowing the slew rate to be easily modified using external passive components. During the controlled turn-on period, the Vds of the MOSFET is monitored by the drain sense input. When Vds drops below a user-specified voltage the power output is considered to be ON. The resistor and diode in series with the drain sense input determine Vds(ON). Provided there is no sustained over-current condition during start-up, the SMH4803 turns on the loads with the Power Good logic outputs. Three DC/DC converters can be connected to the outputs and their turn-on is 2041 8.4 6/15/00 sequenced by pre-programmed delays. If a sustained over-current condition occurs during or after the insertion process, then Vgate is shorted to Vss and the MOSFET switch is turned off to protect the host supply. Circuit Breaker Operation The SMH4803 provides a circuit breaker function to protect against over current conditions. A sustained overcurrent event could damage the host supply and/or the load circuitry. The board's load current passes through a series resistor connected between MOSFET source/ CBSense and Vss on the controller. The breaker will trip whenever the voltage drop across the series resistor is greater than 50mV for more than tCBD, and will trip instantaneously if the voltage drop exceeds VQCB. When the breaker trips, the Vgate output is turned off and CBFault# will be driven LO. The circuit breaker can be reset by taking CBReset# LO and then back HI when the circuit breaker is in the reset mode. In the duty-cycle mode, the circuit breaker resets automatically after a fixed time period. If the over current condition still exists after reset, the circuit will re-trip. In both operating modes of the circuit breaker, the MOSFET can be switched off by holding the CBReset input LO. The value of the over-current shunt resistor is determined by the following formula: Rs = 50mV/Ioc where Rs is the value of the shunt resistor and Ioc is the over current limit determined by the board's power requirement or the limit of the host supply. Current Sense Resistors Current sense resistors are available from a number of sources and come in two basic formats: open air sense resistors and current sense resistor chips. The open air resistors are metal strips that are available as both thru-hole and surface mount. The resistor chips are surface mount and offer excellent thermal characteristics. Both styles are available in resistance ranges from 3 milliohm to 1 ohm. IRC (www.irctt.com) is one source for these resistors. The open air sense resistors can be found in their OARS series, and the chip resistors are found in their LRC series. Load Control The SMH4803 is designed to control three or more DC/ DC converters, or other loads, which incorporate ON/OFF control. The Power Good outputs activate the loads when the following conditions have been met: the input voltage to the SMH4803 monitored by UV and OV is within userdefined limits and the external MOSFET is switched ON. The SMH4803 has three Power Good enable outputs, PG1#, PG2#, and PG3#, that turn on the DC/DC converter loads in sequence. Output PG1# is activated first, followed by PG2# after a delay of PGD, and finally PG3# SUMMIT MICROELECTRONICS 10 SMH4803 after another delay PGD. The delays built into the SMH4803 allow correct sequencing of power to the loads, e.g. +3V supply must come up before +5V supply. The delay times are factory programmed. PG2# and PG3# can be disabled using the ENPGA and ENPGB inputs. When these inputs are low they override the enable function produced when the SMH4803 sees a power good condition. The PG1#, PG2#, and PG3# outputs have a 12V withstand capability so high voltages must not be connected to these pins. Inexpensive bipolar transistors will boost the withstand voltage to that of the host supply, see figure 5 for connections. Output Slew-Rate Control The SMH4803 provides a current limited Vgate turn-on. A fast turn-off is performed by internally shorting Vgate to Vss. Changing the passive components around the power MOSFET switch will modify the turn-on slew-rate. Operating at High Voltages The breakdown voltage of the external active and passive components limits the maximum operating voltage of the SMH4803 hot-swap controller. Components that must be able to withstand the full supply voltage are: the input and output decoupling capacitors, the protection diode in series with DrainSense pin, the power MOSFET switch and capacitor connected between its drain and gate, the high-voltage transistors connected to the power good outputs, and the dropper resistor connected to the controller's Vdd pin. Over-Voltage and Under-Voltage Resistors In the following examples, the three resistors, R1, R2, and R3, connected to the OV and UV inputs must be capable of withstanding the maximum supply voltage which can be several hundred volts. The trip voltage of the UV and OV inputs is +2.5V relative to Vss. As the input resistances of UV and OV are very high, high value resistors can be used in the resistive divider. The divider resistors should be high stability, 1% metal-film resistors to keep the under-voltage and over-voltage trip points accurate. Telecom Design Example A hot-swap telecom application uses a 48V power supply with a -25% to +50% tolerance, i.e. the 48V supply can vary from 36V to 72V. The formulae for calculating R1, R2, and R3 are shown below. 1) First select the peak current, IDmax, allowed through the resistive divider, say 250A. The value of current is arbitrary; however, if the current is too high, selfheating in R3 may become a problem (especially in high voltage systems), and if the current is too low the value of R3 becomes very large and may be expensive at 1% tolerance. SUMMIT MICROELECTRONICS 2041 8.4 6/15/00 R1 is calculated from: Vov ID max VOV is the over-voltage trip point, i.e. 2.5V, therefore: R1 = 2.5V =10k 250 A 2) The minimum current that flows through the resistive divider, IDmin, is easily calculated from the ratio of maximum and minimum supply voltages: R1 = ID min = Therefore: ID max x VS min VS max 250 A x 36V = 125 A 72V 3) The value of R3 is now calculated using IDmin. ID min = R3 = (VS min - Vuv) ID min Where Vuv is the under-voltage trip point, also 2.5V, therefore: (36V - 2.5V) = 268k 125 A R3 = The closest standard 1% resistor value is 267k 4) R2 may be calculated using: (R1 + R2) = Vuv ID min R2 = Or Vuv ID min 2.5V 125A -R1 R2 = -10k = (20k - 10k) = 10k 11 SMH4803 Dropper Resistor Selection The SMH4803 is powered from the high-voltage supply via a dropper resistor, Rd. The dropper resistor must provide the SMH4803 (and its loads) with sufficient operating current under minimum supply voltage conditions, but must not allow the maximum supply current to be exceeded under maximum supply voltage conditions. The dropper resistor value is calculated from: (VS min - VDD max) (IDD + Iload) APPLICATIONS CIRCUITS Reversing Polarity of the Power Good Outputs The open-drain Power Good outputs on the SMH4803 are active LO. The output polarity may be changed to active HI, when required, with a minor circuit change around the high-voltage buffer transistor, see Figure 6. The 1N4148 blocking diode must be included to prevent high-voltage damage to the SMH4803. Expanding Enable/Monitoring on the SMH4803 The 2.5V reference and 5V outputs on the SMH4803 make it easy to expand the number of enable or monitoring inputs. The circuit in Figure 8 illustrates how a quad low-voltage comparator expands the EN/TS input to four enable inputs. The comparators draw power from the 5V output on the SMH4803 and use the 2.5V reference for the switching threshold. EN1 to EN4 inputs can accept either analog or CMOS logic level signals between Vss and +5V. The comparator outputs are ANDed together and drive the EN/TS input. A 1M resistor adds hysteresis around the comparators to prevent oscillation near the trip point. RD = Where Vsmin is the lowest operating supply voltage, Vddmax is the upper limit of the SMH4803 supply voltage, Idd is minimum current required for the SMH4803 to operate, and Iload is any additional load current from the 2.5V and 5V outputs and between Vdd and Vss. The min/max current limits are easily met using the dropper resistor except in circumstances where the input voltage may swing over a very wide range, e.g. input varies between 20V and 100V. In these circumstances it may be necessary to add an 11V zener diode between VDD and VSS to handle the wide current range. The zener voltage should be below the nominal regulation voltage of the SMH4803 so that it becomes the primary regulator. MOSFET VDS(ON) Threshold The drain sense input on the SMH4803 monitors the voltage at the drain of the external power MOSFET switch with respect to VSS. When the MOSFET's VDS is below the user-defined value the switch is considered to be ON. The VDS(ON) is adjusted using the resistor, RT, in series with the drain sense protection diode. This protection or blocking diode prevents high voltage breakdown of the drain sense input when the MOSFET switch is OFF. An inexpensive 1N4148 diode offers protection up to 100V. The VDS(ON) threshold is calculated from: VDS = VSENSE - (ISENSE x RT) - VDIODE - (IRS x RS) Where VDIODE is the forward voltage drop of the protection diode, and IRS is the current flowing through the circuit breaker sense resistor RS. The VDS(ON) threshold varies over temperature due to the temperature dependence of VDIODE and ISENSE. The calculation below gives the VDS(ON) threshold under the worst case condition of +85C ambient. Using a 68k resistor for RT gives: VDS(ON) threshold = 2.5V - (15A x 68k) - VDIODE = 2.5 - 1.0 - 0.5 = 1.0V 2041 8.4 6/15/00 SUMMIT MICROELECTRONICS 12 0V 0V SUMMIT MICROELECTRONICS VSS Rd = 10k MMBTA06LT1 100k 100k 100nF 15V Vdd 2.5V 47k PG2# 1N4148 -48V OUT 5V PG3# PG1 +12V Wrt VSS EN/TS ENPGB ENPGA 10k PD1# 10k PD2# OV CBFault# CBMode Vss CBSense Vgate 1k 100 nF 100nF 25V 20m Rs * 10 ohm resistor must be located as close as possible to the MOSFET. 2041 Was5.6 R3 PG3# PD1# PG2# EN/TS ENPGB ENPGA UV PG1# Drain Sense R2 Figure 6. Changing Polarity of Power Good Output PG1# 13 SMH4803 CBFault# CBMode CBReset# Rt 68k + 100F 100V 10 G 10 nF 100 V 1N4148 100nF 100V PD2# R1 * -48V S D SMH4803 2041 8.4 6/15/00 2041 8.4 6/15/00 0V 0V OUT +5V Wrt VSS VSS 1k R3 +2.5V Wrt VSS +12V Wrt VSS 100nF 15V ENPGB ENPGA 10k PD1# R2 PD2# OV CBFault# CBFault# CBMode Vss CBSense Vgate 1k 100nF R1 100nF 25V 20m Rs * 10 ohm resistor must be located as close as possible to the MOSFET. 2041 Was6.6 Rd = 10k MMBTA06LT1 100k 100k NTC 50k @TMAX 1M EN/TS ENPGB ENPGA UV Vdd 2.5V 5V PG3# PD1# PG3# PG2# LMV331 PG2# PG1# 100k -48V 50k 10k SMH4803 PG1# Drain Sense Figure 7. Overtemperature Shutdown on SMH4803 CBMode CBReset# PD2# Rt 68k 10 10nF 100V 14 + 100F 100V 100nF 100V * 1N4148 SMH4803 SUMMIT MICROELECTRONICS -48V LMV339 PD1# R2 10k OV CBFault# CBFault# CBMode Vss CBSense CBMode CBReset# PD2# 100nF R1 100nF 25V 20m Rs PD2# -48V - + Figure 8. Expanding Input Monitoring Capability EN/TS ENPGB ENPGA 10k UV PG2# Vdd 2.5V 5V PG3# 100nF 15V ENPGB 1M ENPGA EN4 - EN3 + - EN2 - + SUMMIT MICROELECTRONICS 0V 0V OUT +5V Wrt VSS VSS 1k +2.5V Wrt VSS PD1# EN/TS 100k 100k R3 Rd = 10k MMBTA06LT1 PG3# 10k PG2# EN1 PG1# 100k -48V + 15 SMH4803 PG1# Drain Sense Vgate 1k Rt 68k + 100F 100V 10 100nF 100V * 10nF 100V 1N4148 * 10 ohm resistor must be located as close as possible to the MOSFET. 2041 Was7.5 SMH4803 2041 8.4 6/15/00 2041 8.4 6/15/00 0V V3 + Rd = 10k -48V V2 R3 PD1# 10k +12V Isolated DC/DC #3 -48V ISOLATED DC OUTPUTS EN/TS EN/TS UV 5V PD1# PG3# PD2# OV PG2# Vgate PG1# Drain Sense 10 100k 3x MMBTA06LT1 100k Vdd ENPGB ENPGA Isolated DC/DC #2 V1 0V Figure 9. Typical Application Sequencing 3 DC/DC Converters 16 R2 100nF 25V SMH4803 100k Isolated DC/DC #1 -48V 10k PD2# Vss CBSense R1 * -48V Rs * 10 resistor must be located as close as possible to the MOSFET. 2041 Was12.3 SMH4803 SUMMIT MICROELECTRONICS +5V RESET2# RESET V3 V2 V1 0V SUMMIT MICROELECTRONICS RESET1# RESET ISOLATED DC OUTPUTS V1 + 0V + Rd -48V +12V R3 PD1# 10k Figure 10. Sequencing 3 DC/DC Converters with Output Voltage Feedback 17 Isolated DC/DC #3 Vdd EN/TS EN/TS UV 5V PD1# PG3# PD2# OV PG2# Vgate PG1# Drain Sense 10 ENPGB ENPGA Isolated DC/DC #2 -48V R2 100nF 25V SMH4803 Isolated DC/DC #1 -48V 10k CBSense PD2# Vss R1 * -48V Rs * 10 resistor must be located as close as possible to the MOSFET. 2041 IWas9.5 SMH4803 2041 8.4 6/15/00 V3 RESET2# RESET 2041 8.4 6/15/00 V2 V1 2x1N4148 2x MMBTA56LT1 RESET RESET1# 47 K 47 K OV 47 K 47 K OV + -48V R3 Rd PD1# 10 K Figure 11. Sequencing Converters with Common I/O Ground and Voltage Feedback 18 Isolated DC/DC #3 Vdd EN/TS -48V ENPGB ENPGA UV 5V PD1# R2 PG3# PD2# OV PG2# Vgate PG1# Drain Sense R1 Vss Isolated DC/DC #2 SMH4803 100nF 25V Isolated DC/DC #1 -48V PD2# CBSense 10 K * 10 Rs -48V SMH4803 SUMMIT MICROELECTRONICS * 10 ohm resistor must be located as close as possible to the MOSFET. 2041 Was11.3 SMH4803 20-Lead Small Outline Package (SOIC) 0.496 - 0.512 (12.598 - 13.005) 0.394 - 0.419 (10.007 - 10.643) 0.291 - 0.299 (7.391 - 7.595) 0.010 - 0.029 (0.254 - 0.737) 0 to 8 typ x45 0.093 - 0.104 (2.362 - 2.642) 0.037 - 0.045 (0.940 - 1.143 0.009 - 0.013 (0.229 - 0.330) 0.016 - 0.050 (0.406 - 1.270) 0.050 (1.270) 0.014 - 0.019 (0.356 - 0.482) 20pn SOIC ILL.1 0.004 - 0.012 (0.102 - 0.305) SUMMIT MICROELECTRONICS 2041 8.4 6/15/00 19 SMH4803 ORDERING INFORMATION SMH4803 A E K P Base Part Number Power Good Delay A = 5ms B = 20ms C = 80ms D = 160ms Pin Detect Function Blank = Enabled P = Disabled Circuit Breaker Delay K = 400s L = 150s M = 50s N = 5s Quick-Trip Threshold E = 200mV F = 100mV H = 60mV 2041 ILL8.3 J = OFF 2041 8.4 6/15/00 SUMMIT MICROELECTRONICS 20 SMH4803 Valid Part Number Combinations SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B E E E E E E E E F F F F F F F H H H H H H H H H J J J J J J J J E E E E E E E E F F F F F F F H H H H H H H H H J J J J J J J J K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 SMH4803 C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D E E E E E E E E F F F F F F F H H H H H H H H H J J J J J J J J E E E E E E E E F F F F F F F H H H H H H H H H J J J J J J J J K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N K L M N P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P P SUMMIT MICROELECTRONICS 2041 8.4 6/15/00 21 SMH4803 NOTICE SUMMIT Microelectronics, Inc. reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. SUMMIT Microelectronics, Inc. assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained herein reflect representative operating parameters, and may vary depending upon a user's specific application. While the information in this publication has been carefully checked, SUMMIT Microelectronics, Inc. shall not be liable for any damages arising as a result of any error or omission. SUMMIT Microelectronics, Inc. does not recommend the use of any of its products in life support or aviation applications where the failure or malfunction of the product can reasonably be expected to cause any failure of either system or to significantly affect their safety or effectiveness. Products are not authorized for use in such applications unless SUMMIT Microelectronics, Inc. receives written assurances, to its satisfaction, that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; and (c) potential liability of SUMMIT Microelectronics, Inc. is adequately protected under the circumstances. (c) Copyright 2000 SUMMIT Microelectronics, Inc. 2041 8.4 6/15/00 SUMMIT MICROELECTRONICS 22 |
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