L6911B STMICROELECTRONICS | Alldatasheet
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Technical content
OPERATING SUPPLY VOLTAGE FROM 5V TO 12V TTL-COMPATIBLE 5BIT PROGRAMMABLE OUTPUT FROM: -1.3V TO 2.05V WITH 0.05V BINARY STEPS -2.1V TO 3.5V WITH 0.1V BINARY STEPS VOLTAGE MODE PWM CONTROL EXCELLENT OUTPUT ACCURACY +/-1% OVERLINE, AND TEMPERATURE VARIATIONS HIGH PRECISION INTERNAL REFERENCE DIGITALLY TRIMMED VERY FAST LOAD TRANSIENT 0% TO 100% DUTY CYCLE POWER GOOD OUTPUT OVERVOLTAGE PROTECTION OVERCURRENT PROTECTION REALISED USING THE MOSFET’s R DSon OPERATING FREQUENCY FROM 50KHz TO 1MHz MEETS INTEL PENTIUM II SPECIFICATION DISABLE FUNCTION
Applications
POWER SUPPLY FOR ADVANCED MICRO- PROCESSOR SUPPLIES POWER SUPPLY FOR PENTIUM II INTEL PROCESSORS
DESCRIPTION
The L6911B is a power supply controller specifi- cally designed to provide a high performance DC/DC conversion for Pentium II Microproces- sors. A precise 5 bit digital to analog converter April 1999 PGND PHASE GND VFB LGATE BOOT UGATE VCC OCSET V CC 5V/12V 18 2 Vin 5V/12V Vo 1.3V to 3.5V PGOOD 12 VD0 VD1 VD2 VD3 VD4 COMP VSEN SS OVP OSC D98IN956B APPLICATION CIRCUIT SO20 L6911B
5 BIT PROGRAMMABLE POWER SUPPLY
CONTROLLER FOR PENTIUM II PROCESSOR
(DAC) allows to adjust the output voltage from 1.3V to 2.05V with 0.05V binary steps and from 2.1V to 3.5V with 0.1V binary steps. The high pre- cision internal reference, digitally trimmed, as- sures the selected output voltage to within +/-1%. Thanks to the window comparator system, the de- vice provides excellent load transient perform- ance. The high peak current gate drive affords to have fast switching to the external power mos, performing an high efficiency. The L6911B as- sures a fast protection against load overvoltage and load overcurrent. An external SCR is trig- gered to crowbar the input supply in case of over- voltage. In case of output short circuit the soft start capacitor is discharged and the system works in hiccup mode. ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VCC VCC to PGND 15 V VBOOT -VPHASE Boot Voltage 15 V Input, Output or I/O Voltage -0.3 to V CC +0.3 V THERMAL DATA Symbol Parameter Value Unit R thj-amb Thermal Resistance Junction to Ambient 110 °C/W Tmax Maximum Junction Temperature 150 °C Tstg Storage Temperature Range -65 to 150 °C RECOMMENDED OPERATING CONDITION Symbol Parameter Value Unit VCC VCC to PGND 5V ±10%/12V ±10% V Tamb Ambient Temperature Range 0 to 70 °C TJ Junction Temperature Range 0 to 125 °C DESCRIPTION (continued) PGND PHASE GND VFB LGATE BOOT UGATE VCC OCSET V CC 12V Vin 5V Vo 1.8V to 3.5V PGOOD COMP VSEN SS OVP RT VD0 VD1 VD2 VD3 VD4 MONITOR and PROTECTION OSC D/A E/A PWM D98IN957A BLOCK DIAGRAM L6911B
N ° Name Description
1 VSEN Connected to the output voltage is able to manage overvoltage conditions and the PGOOD
signal. 2 OCSET A resistor connected from this pin and the upper Mos Drain sets the current limit protection. The internal 200µA current generator sinks a current from the drain through the external resistor. The overcurrent threshold is due to the following equation: IP = Iocs⋅R ocs Rdson 3 SS The soft start time is programmed connecting an external capacitor from this pin and GND. The internal current generator forces through the capacitor 10µA. This pin can be used to disable the device forcing a voltage lower than 0.4V. 4 - 8 VID0 - 4 Voltage Identification code pins. These input are open collector and TTL compatible. Are used to program the output voltage as specified in Table 1 and to set the overvoltage and powergood thresholds.
9 COMP This pin is connected to the error amplifier output and is used to compensate the voltage
control feedback loop.
10 FB This pin is connected to the error amplifier inverting input and is used to compensate the
voltage control feedback loop. 11 GND All internal voltage reference are referred to this pin.
12 PGOOD This pin is an open collector output and is pulled low if the output voltage is not within±10%
of the programmed voltage. This pin is forced high if the ”11111” VID is set.
13 PHASE This pin is connected to the source of the upper mosfet and provides the return path for the
high side driver. This pin monitors the drop across the upper mosfet for the current limit. 14 UGATE High side gate driver output. 15 BOOT Bootstrap capacitor pin. Through this pin is supplied the high side driver and the upper mosfet. 16 PGND Power ground pin. This pin has to be connected closely to the low side mosfet source in order to reduce the noise injection into the device. 17 LGATE This pin is the lower mosfet gate driver output. 18 VCC Device supply voltage. The operative supply voltage range is 4.5V to 12V. Do not connect V IN to 12V if VCC is 5V. 19 OVP Over voltage protection. If the output voltage reach the 15% above the programmed voltage this pin is driven high and can be used to drive an external SCR that crowbar the supply voltage. VSEN OCSET SS VID0 VID1 VID3 VID2 VID4 COMP PGOOD PHASE UGATE PGND BOOT LGATE VCC OVP RT1 FB GND D98IN958 PIN CONNECTION L6911B
ELECTRICAL CHARACTERISTICS
Symbol Parameter Test Condition Min. Typ. Max. Unit VCC SUPPLY CURRENT ICC Supply current UGATE and LGATE open - 5 - mA POWER-ON Rising VCC Threshold VOCSET = 4.5V - - 4.6 V Falling VCC Threshold VOCSET = 4.5V 3.6 - - V Rising VOCSET Threshold - 1.26 - V OSCILLATOR Free Running Frequency RT = open 185 200 215 kHz Total Variation R T to GND >6kΩ , R T to VCC = 12V > 200kΩ -15 - 15 % Δ Vosc Ramp Amplitude RT = open - 1.9 - V REFERENCE and DAC DACOUT voltage Accuracy VID0, VID1, VID2, VID3 see Table1 -1 - 1 % ERROR AMPLIFIER DC Gain - 88 - dB GBW Gain-Bandwidth Product - 15 - MHz SR Slew Rate COMP = 10pF - 10 - V/ µs GATE DRIVERS IUGATE Upper Gate Source V BOOT - Vphase = 12V, VUGATE =6 V 0.6 1 - A R UGATE Upper Gate Sink I LGATE = 0.3A - 1.5 3 Ω ILGATE Lower Gate Source V CC = 12V, VLGATE = 6V 1.2 2 - A R LGATE Lower Gate Sink I LGATE = 0.3A - 1 2 Ω PROTECTION Overvoltage Trip (VSEN /DACOUT) - 115 120 % IOCSET OCSET Current Source V OCSET = 4.5VDC 170 200 230 µA IOVP OVP Sourcing Current V SEN = 5.5V, VOVP =0 V 6 0 m A ISS Soft Start Current 10 µA N ° Name Description 20 RT Oscillator Switching frequency pin. Connecting an external resistor from this pin to ground the switching frequency is increased according to the equation: fS = 200kHz + 5 ⋅106 R T(KΩ) Connecting the resistor from this pin and the Vcc the Switching frequency is reduced according to the equation: fS = 200kHz − 4 ⋅107 R T(KΩ) If the pin is not connected the switching frequency is 200kHz. PIN FUNCTION (continued) L6911B
Symbol Parameter Test Condition Min. Typ. Max. Unit Upper Threshold (VSEN /DACOUT) VSEN Rising 106 - 111 % Upper Threshold (VSEN /DACOUT) VSEN Rising 89 - 94 % Hysteresis (VSEN /DACOUT) Upper and Lower Threshold - 2 - % VPGOOD PGOOD Voltage Low I PGOOD = -5mA - 0.5 - V ELECTRICAL CHARACTERISTICS (continued) Table 1. VID4 VID3 VID2 VID1 VID0 OUTPUT VOLTAGE (V) 01111 1 . 3 0 1 1 1 0 1.35 01101 1 . 4 0 1 1 0 0 1.45 01011 1 . 5 0 1 0 1 0 1.55 01001 1 . 6 0 1 0 0 0 1.65 00111 1 . 7 0 0 1 1 0 1.75 00101 1 . 8 0 0 1 0 0 1.85 00011 1 . 9 0 0 0 1 0 1.95 00001 2 0 0 0 0 0 2.05 11111 0 11110 2 . 1 11101 2 . 2 11100 2 . 3 11011 2 . 4 11010 2 . 5 11001 2 . 6 11000 2 . 7 10111 2 . 8 10110 2 . 9 10101 3 10100 3 . 1 10011 3 . 2 10010 3 . 3 10001 3 . 4 10000 3 . 5 L6911B
A eB D E L K H A1 C SO20MEC hx4 5° SO20 DIM. mm inch A 2.35 2.65 0.093 0.104 A1 0.1 0.3 0.004 0.012 B 0.33 0.51 0.013 0.020 C 0.23 0.32 0.009 0.013 D 12.6 13 0.496 0.512 E 7.4 7.6 0.291 0.299 e 1.27 0.050 H 10 10.65 0.394 0.419 h 0.25 0.75 0.010 0.030 L 0.4 1.27 0.016 0.050 K0 °(min.)8° (max.) OUTLINE AND MECHANICAL DATA L6911B
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