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RT9224
5-Bit Programmable Synchronous PWM Buck Converter Controller and Output Voltage Monitor
General Description
The RT9224 is a high speed switching controller designed for use in synchronous DC/DC buck converter for modern CPUs. The regulated output voltage is digitally programmable from 1.3V to 3.5V by a 5-bit DAC which provides initial accuracy of 1%. The RT9224 drives two external N-Channel MOSFETs, providing high efficiency and eliminating the need for high cost P-Channel devices. It senses the output current across the on-resistance of the upper N-Channel MOSFET and provides an adjustable current limit without external sense resistor. RT9224 monitors the output voltage and provides the output signal for power-good and over-voltage protection. The switching controller drivers two N-MOSFETs at 200kHz frequency and provides an optimal solution for size, efficiency and cost in any application circuits. The high switching frequency cooperating with a high speed error amplifier maintains a fast response to the dynamic load of modern CPUs.
Features
Compatible with HIP6004B Simple Voltage-mode PWM Control with Buck Rectification 1% DAC Output Voltage Accuracy 5-Bit Digital-to-Analog Output Voltage Range from 1.3 V to 3.5V Fast Transient Response and Excellent Output Voltage Regulation Fault Protection for Over-voltage and Over- Current Power-Good Output Voltage Monitor Fixed 200kHz Switching Frequency
Applications
Power Supply for Pentium, Pentium ProTM, Pentium IITM, PowerPCTM, K6TM, 6x86TM, and AlphaTM Microprocessors Low-voltage Distributed Power Supplies High Power 5V to 1.3V~3.5V Switching Regulator
Ordering Information
RT9224 Package Type S : SOP-20 Operating Temperature Range C : Commercial Standard P : Pb Free with Commercial Standard
Pin Configurations
(TOP VIEW)
VSEN OCSET SS VID0 VID1 VID2 VID3 VID4 NC FB 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 NC OVP VCC LGATE PGND BOOT UGATE PHASE PGOOD GND
SOP-20
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RT9224
Typical Application Circuit
L1 1uH VIN = 5V F1
+
CIN
2N6394 2K
2 x1uF
5 x1000uF
+12V
10 0.1uF 15V VCC 18 SS 3 OVP 19 2 OCSET 1000pF 1K
0.1uF VSEN 1 OSC VID0 VID1 VID2 VID3 VID4 FB 4 5 6 7 8
Monitor and Protection
12 PGOOD
15 BOOT 14 UGATE 13 PHASE Q1 L2 3uH D2 Q2 COUT 9 x1000uF 4.99K 0.68uF +VO
+
D/A
10 + GND +
17 LGATE 16 PGND
750K
Component Selection Notes:
- Core: Micrometals T50-52B; Winding: 10 Turns of 16AWG. L1 - Core: Micrometals T50-52; Winding: 5 Turns of 18AWG. D2 - 3A, 40V Schottky, Motorola MBR340 or Equivalent. Q1, Q2 - PHB83N03LT; PHB95N03LT
L2
COUT, CIN - Each 1000F 6.3W VDC, Sanyo MV-GX or Equivalent.
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RT9224
Function Block Diagram
VCC
VSEN
110%
Power-On Reset (POR) + + PGOOD
90%
115% + + OCSET - Over Current Reference 200uA 4.5V Soft Start 10uA SS BOOT UGATE Inhibit Gate Control Logic PHASE Over Voltage OVP
VID0 VID1 VID2 VID3 VID4
TTL D/A Converter (DAC)
DACOUT Error Amplifier
+ -
PWM Comparator + Oscillator PWM
FB
LGATE PGND GND
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RT9224
Functional Pin Description
Pin No. Pin Name 1 VSEN Pin Function Output voltage monitoring input for OVP & PGOOD Over current set pin, sinks 200A through a resistor (ROCS) from this pin to upper N-MOSFET to set the trip point: 2 OCSET
IPEAK =
200uA x ROCS MOSFET - on resistance
An over-current trip cycles the soft-start function 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 SS VID0 VID1 VID2 VID3 VID4 NC FB GND PGOOD PHASE UGATE BOOT PGND LGATE VCC OVP NC Soft start speed is set by internal 10A current source and capacitor from this pin to GND Switching Regulator Output Voltage Setting Switching Regulator Output Voltage Setting Switching Regulator Output Voltage Setting Switching Regulator Output Voltage Setting Switching Regulator Output Voltage Setting No Connection Feedback input pin for the PWM Loop IC Signal Ground Open Drain Logic Output This pin is pulled low when the converter output is not within 10% of the DACOUT reference voltage Current Limit Sense Input High Side Driver Output Driver Power Low Side Driver GND Low Side Driver Output Power Supply Input Over Voltage Protection This pin is pulled high when the VSEN voltage is over 15% of the DACOUT reference voltage No Connection
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RT9224
Table 1 Output Voltage Program
Pin Name VID4 VID3 VID2 VID1 VID0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 Nominal Output Voltage DACOUT 1.30V 1.35V 1.40V 1.45V 1.50V 1.55V 1.60V 1.65V 1.70V 1.75V 1.80V 1.85V 1.90V 1.95V 2.00V 2.05V Pin Name VID4 VID3 VID2 VID1 VID0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 Nominal Output Voltage DACOUT 2.0V 2.1V 2.2V 2.3V 2.4V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V 3.4V 3.5V
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RT9224
Absolute Maximum Ratings
Supply Voltage ------------------------------------------------------------------------------------------------------- +15V Boot Voltage ---------------------------------------------------------------------------------------------------------- +15V Input, Output or I/O Voltage --------------------------------------------------------------------------------------- GND -0.3V to Vcc + 0.3V Storage Temperature Range --------------------------------------------------------------------------------------- -65C to 150 C Package Thermal Resistance SOP-20,JA ---------------------------------------------------------------------------------------------------------------------------------------------------------- 87 C/W
Recommended Operating Conditions
Supply Voltage, VCC ------------------------------------------------------------------------------------------------------------------------------------------ +12V 10% Ambient Temperature Range -------------------------------------------------------------------------------------- 0 C to 70C Junction Temperature Range -------------------------------------------------------------------------------------- 0 C to 125C
Electrical Characteristics
(TA = 25 C, recommended operating conditions, unless otherwise specified)
Parameter VCC Supply Current Nominal Supply Power-On Reset VCC Rising Threshold VCC Falling Threshold Rising VOCSET Threshold Oscillator Free Running Frequency Ramp Amplitude Reference and DAC DAC (VID0 - VID4) Input Low Voltage DAC (VID0 - VID4) Input High Voltage DACOUT Voltage Accuracy Error Amplifier DC Gain Gate Drivers UGATE Source UGATE Sink LGATE Source LGATE Sink
Symbol
Test Conditions UGATE and LGATE Open
Min ----170
Typ 3 9.5 7.5 1.6 200 1.9 ---65 8 5 500 5
Max ----230 -0.8 -+1.0 ------
Units mA V V V
ICC
VOCSET = 4.5V VOCSET = 4.5V
kHz VP-P V V % dB mA
VOSC
--2.0 -1.0 ------
RUGATE VBOOT - VPHASE = 12V RUGATE VUGATE - VPHASE = 1V ILGATE VCC = 12V, VLGATE = 6V RLGATE VLGATE = 1V
To be continued
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Parameter Protection Over-voltage Trip (VSEN/DACOUT) OCSET Current Source OVP Sourcing Current Soft-Start Current Power Good Upper Threshold (VSEN/DACOUT) Lower Threshold (VSEN/DACOUT) Hysteresis (VSEN/DACOUT) PGOOD Voltage Low VSEN Rising VSEN Falling Upper and Lower Threshold VPGOOD IPGOOD = -5mA 106 89 ----2 0.5 114 96 --% % % V IOCSET IOVP ISS VOCSET = 4.5V VSEN = 5.5V, VOVP = 0V VSS = 1.5V -167 60 -115 200 -10 120 233 --% A mA A Symbol Test Conditions Min Typ Max Units
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RT9224
Outline Dimension
A H M
J
B
F
C I D
Symbol A B C D F H I J M
Dimensions In Millimeters Min 12.598 7.391 2.362 0.330 1.194 0.229 0.102 10.008 0.381 Max 13.005 7.595 2.642 0.508 1.346 0.330 0.305 10.643 1.270
Dimensions In Inches Min 0.496 0.291 0.093 0.013 0.047 0.009 0.004 0.394 0.015 Max 0.512 0.299 0.104 0.020 0.053 0.013 0.012 0.419 0.050
20- Lead SOP Plastic Package
RICHTEK TECHNOLOGY CORP.
Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
RICHTEK TECHNOLOGY CORP.
Taipei Office (Marketing) 8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com
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