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Part: ISL6554
Category:
Power Management
-> Desktop
Description: 2 Phase Synchronous Buck Controllerpwm Buck VRM8.5
Company: Intersil Corporation
Datasheet: Download ISL6554 datasheet File size : 476 kB
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Datasheet text preview:
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ISL6554
TM
Da ta Sheet
Nov e m b e r 2001
Fi l e Number
9003.1
Microprocessor CORE Voltage Regulator Using Multi-Phase Buck PWM Control Without Programmable Droop
The ISL6554 is the first controller in the Intersil Multi-Phase family without the programmable droop feature. The ISL6554 in combination with the HIP6601A, HIP6602A or HIP6603A companion gate drivers and Intersil MOSFETs form a complete solution for high-current, high slew-rate applications. The ISL6554 regulates output voltage, balances load currents and provides protective functions for two to four synchronous-rectified buck-converter channels. A novel approach to current sensing is used to reduce overall solution cost. The voltage developed across the lower MOSFET's parasitic on-resistance during conduction is sampled and fed back to the controller. This lossless currentsensing approach allows the controller to maintain phasecurrent balance between the power channels and overcurrent protection. A 5-bit DAC allows digital programming of the output voltage in 25mV steps over a range from 0.95V to 1.70V with a system accuracy of 1%. Internal pull ups on each DAC input make external pull-up resistors unnecessary when interfacing with open-drain output signals. The PGOOD signal is held low during Soft-Start until the output voltage increases to within 4% of the programmed. When the CORE voltage falls 9% below the programmed VID level, an undervoltage condition is detected and results in PGOOD transitioning low. In the event of an overvoltage condition, The converter shuts down and turns ON the lower MOSFETs to clamp and protect the microprocessor. Overcurrent protection reduces the regulator RMS output current to 41% of the programmed overcurrent trip value. These features provide monitoring and protection for the microprocessor and power system.
Features
· Multi-Phase Power Conversion · Precision Channel Current Balance - Lossless Current Sampling - Uses rDS(ON) · Precision CORE Voltage Regulation - ±1% System Accuracy Over Temperature - No Programmable Droop · Microprocessor Voltage Identification Input - 5-Bit VID Decoder - 0.95V to 1.70V in 25mV Steps · Fast Transient Response · Over Current Protection · Selection of 2, 3, or 4 Phase Operation · High Ripple Frequency (80kHz to 2MHz)
Applications
· Power Supply Controller for Intel® ItaniumTM Processor Family · Voltage Regulator Modules · Servers and Workstations
Ordering Information
PART NUMBER ISL6554CB ISL6554CB-T TEMP. (oC) 0 to 70 PACKAGE 20 Ld SOIC PKG. NO. M20.3
20 Ld SOIC Tape and Reel
Pinout
ISL6554 (SOIC) TOP VIEW
VID4 1 VID3 2 VID2 3 VID1 4 VID0 5 COMP 6 FB 7 FS/DIS 8 GND 9 VSEN 10 20 VCC 19 PGOOD 18 PWM4 17 ISEN4 16 ISEN1 15 PWM1 14 PWM2 13 ISEN2 12 ISEN3 11 PWM3
IntelTM is a trademark of Intel Corporation. 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 © Intersil Americas Inc. 2001. All Rights Reserved Intel® is a registered trademark of Intel Corporation. ItaniumTM is a trademark of Intel Corporation
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ISL6554 Block Diagram
PGOOD VCC
POWER-ON RESET (POR) VSEN X 0.9 + UV OV LATCH S
-
THREE STATE CLOCK AND SAWTOOTH GENERATOR + PWM
FS/EN
OVP + X1.15
-
-
+
PWM1
-
SOFTSTART AND FAULT LOGIC
+
PWM
-
+
PWM2
-
COMP +
VID4 VID3 VID2 VID1 VID0 D/A + E/A
PWM
-
+
PWM3
-
+
PWM +
-
-
PWM4
-
FB
CURRENT CORRECTION I_TOT + + + +
PHASE NUMBER
CHANNEL DETECTOR
ISEN1 ISEN2 ISEN3 ISEN4
+ I_TRIP
-
OC
GND
ISL6554 Simplified Power System Diagram
VSEN PWM 1
SYNCHRONOUS RECTIFIED BUCK CHANNEL
PWM 2
SYNCHRONOUS RECTIFIED BUCK CHANNEL MICROPROCESSOR
ISL6554
PWM 3 PWM 4 SYNCHRONOUS RECTIFIED BUCK CHANNEL
VID
SYNCHRONOUS RECTIFIED BUCK CHANNEL
Functional Pin Description
VID4 1 VID3 2 VID2 3 VID1 4 VID0 5 COMP 6 FB 7 FS/DIS 8 GND 9 VSEN 10 20 VCC 19 PGOOD 18 PWM4 17 ISEN4 16 ISEN1 15 PWM1 14 PWM2 13 ISEN2 12 ISEN3 11 PWM3
converter. Pulling this pin to ground disables the converter and three states the PWM outputs. See Figure 10.
GND (Pin 9)
Bias and reference ground. All signals are referenced to this pin.
VSEN (Pin 10)
Power good monitor input. Connect to the microprocessorCORE voltage.
PWM1 (Pin 15), PWM2 (Pin 14), PWM3 (Pin 11) and PWM4 (Pin 18)
PWM outputs for each driven channel in use. Connect these pins to the PWM input of a HIP6601/2/3 driver. For systems which use 3 channels, connect PWM4 high. Two channel systems connect PWM3 and PWM4 high.
VID4 (Pin 1), VID3 (Pin 2), VID2 (Pin 3), VID1 (Pin 4) and VID0 (Pin 5)
Voltage Identification inputs from microprocessor. These pins respond to TTL and 3.3V logic signals. The ISL6554 decodes VID bits to establish the output voltage. See Table 1.
ISEN1 (Pin 16), ISEN2 (Pin 13), ISEN3 (Pin 12) and ISEN4 (Pin 17)
Current sense inputs from the individual converter channel's phase nodes. Unused sense lines MUST be left open.
COMP (Pin 6)
Output of the internal error amplifier. Connect this pin to the external feedback and compensation network.
PGOOD (Pin 19)
Power good. This pin provides a logic-high signal when the microprocessor CORE voltage is within specified limits and Soft-Start has timed out.
FB (Pin 7)
Inverting input of the internal error amplifier.
VCC (Pin 20)
Bias supply. Connect this pin to a 5V supply.
FS/DIS (Pin 8)
Channel frequency, FSW , select and disable. A resistor from this pin to ground sets the switching frequency of the 3
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