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US2076
PWM SWITCHER CONTROLLER & 7.5A ADJUSTABLE LOW DROPOUT REGULATOR COMBO FEATURES
The US2076 eliminates the need for a seperate switching controller IC Minimum part count allows lower system cost Adjustable 7.5A LDO on board 1.1V Dropout at 7.5A On board MOSFET driver Fastest transient response of any controller method. ( 0 to 100% Duty Cycle in 100 nS ) 1% internal voltage reference Internal Thermal shutdown Internal Under Voltage Lockout protects MOSFET during start-up
DESCRIPTION
PATENT PENDING PRELIMINARY DATASHEET
APPLICATIONS
Dual supply low voltage processor applications, such as: P55CTM,CYRIX M2TM, POWER PCTM and AMD K6TM
The US2076 is a dual function IC combining a switching controller and a 7.5A adjustable low dropout regulator all in a compact 7 pin TO220 and TO263 surface mount packages providing a total solution for dual supply processor applications such as an Intel P55C TM, AMD K6TM, as well as Cyrix 6X86LTM and the M2TMprocessors. Typically in these applications a dual supply regulator converts 5V to 3.3V for I/O supply and a jumper programmable supply of 1.25V to 3.5V for CORE supply.The linear regulator portion in the US2076 is an adjustable one that can be programmed to 3.30V output and has a minimum of 7.5A current capability designed to provide ample current for most applications. The US2076 uses an internal regulator generated from the 12V supply to power the switching controller as well as the 12V supply to drive the power MOSFET, allowing a low cost N channel MOSFET switch to be used. The IC also includes an error comparator for fast transient response, a precise voltage reference for setting the output voltage as well as a direct drive of the MOSFET for the minimum part count.
TYPICAL APPLICATION
L1
5V
C1 Vin Vout Vfb2 C6 R6 5V R7 D2 R8
I/O
US2076
Gnd Vfb1 V12 Drv
7 6 5 4 3 2 1
CPU
Vcc2 Det
L2 R1 Q2 R4 C2 C7 Core
2076app1-1.2
12V
C3
D1
R5
Typical application of US2076 in a flexible motherboard designed for Intel P55TM,P54TM, AMD K5 & K6TM as well as Cyrix M1TM and M2TM applications.
Notes: P54C,P55C are trade marks of Intel Corp. K5 & K6 are trade marks of AMD corp. Cyrix 6X86L,M1,M2 are trade marks of Cyrix Corp. Power PC is trade mark of IBM Corp.
PACKAGE ORDER INFORMATION
Tj (C) 0 TO 125
Rev. 1.3 4/26/98
7 PIN PLASTIC TO220 (T) US2076CT
7 PIN PLASTIC TO263 (M) US2076CM
4-1
US2076
ABSOLUTE MAXIMUM RATINGS
12V Supply Voltage ............................................................. 14V Vin Supply Voltage .............................................................. 7V LDO Power Dissipation .................................... Internally Limited FB Pin Voltage........................................................ -0.3V to 5V Storage Temperature Range ................................. -65 TO 150C Operating Junction Temperature ............................... 0 TO 150C
PACKAGE INFORMATION
7 PIN PLASTIC TO220 (T)
FRONT VIEW 7 6 5 4 3 2 1
7 PIN PLASTIC TO263 (M)
FRONT VIEW 7 6 5 4 3 2 1
Vin Vout Vfb2 Gnd Vfb1 V12 Drv
Vin Vout Vfb2 Gnd Vfb1 V12 Drv
JT=2.7C/W JA=60C/W
JA=35C/W for 1" Square pad
ELECTRICAL SPECIFICATIONS
Unless otherwise specified the following specification applies over,Vin=5V,V12=12V,and Tj=0 to 125C.Low duty cycle pulse testing are used which keeps junction and case temperatures equal to the ambient temperature. LDO Section PARAMETER SYM F.B Voltage Initial Accuracy Vfb2 F.B Voltage Total Variation Vfb2 F.B Input Bias Current Ifb2 Dropout Voltage (note 2) Line Regulation Load Regulation (note 1) Thermal Regulation Minimum Load Current (note 3) Ripple Rejection V12 Supply Current Icc2 Switching Controller Section PARAMETER F.B Voltage Initial Accuracy F.B Voltage Total Variation F.B Input Bias Current Min On Time Min Off Time V12 Supply Current Maximum Duty Cycle Minimum Duty Cycle Gate Drive Rise/Fall Time F.B Hysterises Icc1 Dmax Dmin Vgate TEST CONDITION Tj=25C Vfb2=1.25V Vout=1.25V, Io=7.5A Vout=1.25V,Io=10mA, 310
SYM Vfb1 Vfb1 Ifb1
TEST CONDITION Tj=25C Vfb1=1.25V Vfb1 is sq wave with 300 ns on time and 2 uS off time Vfb1 is sq wave with 300 ns off time and 2 uS on time Vfb1=1V, Vfb2=1.5V Vfb1=1V Vfb1=1.5V Load=IRL3303
MIN 1.237 1.225 -1
TYP 1.250 1.250 800 800 10
MAX 1.262 1.275 +1
UNITS V V uA nS nS mA % % nS mV
100 0 70 12
4-2
Rev. 1.3 4/26/98
US2076
Note 1 : Low duty cycle pulse testing with Kelvin connections are required in order to maintain accurate data. Note 2 : Drop-out voltage is defined as the minimum differential voltage between Vin and Vout required to maintain regulation at Vout. It is measured when the output voltage drops 1% below its nominal value. Note 3 : Minimum load current is defined as the minimum current required at the output in order for the output voltage to maintain regulation. Typically the resistor dividers are selected such that it automatically maintains this current.
PIN DESCRIPTIONS
PIN # 3 6 7 PIN SYMBOL Vfb1 Vout Vin PIN DESCRIPTION A resistor divider from this pin to the output of the switching regulator and ground sets the Core supply voltage. The output of the linear regulator. A minimum of a 100uF low ESR capacitor must be connected from this pin to ground to insure stability. The input pin of the linear regulator. Typically a large storage capacitor is connected from this pin to ground to insure that the input voltage does not sag below the minimum drop out voltage during the load transient response. This pin must always be higher than Vout plus the maximum dropout voltage in order for the device to regulate properly. This pin is connected to the IC substrate and must be connected to the lowest potential in the system. It is also connected to the Tab of the package. The PWM output of the switching controller. This pin is a totem pole drive that is connected to the gate of the power MOSFET. A resistor may be placed in series from this pin to the gate in order to reduce switching noise. A resistor divider from this pin to the output of the linear regulator and ground sets the I/O supply voltage. This pin is connected to the 12V supply voltage. A high frequency cap must be connected from this pin to the GND pin of the IC.
4 1
Gnd Drv
5 2
Vfb2 V12
BLOCK DIAGRAM
V12 2 Vfb 1 3 Vin 7 Vout 6
Drv 1
UVLO Vref PWM Control
5V Reg
Gnd 4
2076blk1-1.1
1.25V
Vfb2 5
Figure 1 - Simplified block diagram of the US2076
Rev. 1.3 4/26/98
4-3
US2076
TYPICAL APPLICATION
5V
C1 Vin Vout Vfb2 C6 R6 5V R7 D2 Vcc2 Det L2 R1 Q2 R4A R4B C2 C7 Core R8 L1 I/O
7 6
U1
5 Gnd 4 3 2 1
V12 Drv
CPU
Vfb1
2076app2-1.2
12V
C3 C4 R2 D1 R5A JP1 1 2 R5B 3 4 R5C 5 6 R5D 7 8 R5E
Figure2- Typical application of US2076 in a flexible motherboard with the 4 bit VID output voltage selection. This circuit uses a single jumper that programs the output voltage in 16 steps with 0.1V steps from 2V to 3.5V, designed for Intel P55TM,P54TM, AMD K5 & K6TM as well as Cyrix M1TM and M2TM applications. The Vcc2Det pin automatically shuts down the I/O when a single plane processor is dropped in the socket.
Ref Desig U1 Q1 D1 D2 L2 L1 R1 R2 R4A R4B R5A R5B R5C R5D R5E R6 R7 R8 C3 C1 C4 C2 C6 C7 HS1 HS2 HS3
Description LDO/Switcher IC MOSFET Schottky Diode Diode, GP Inductor Inductor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Heat Sink Heat Sink Heat Sink
Qty 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 4 1 1 1
Part # US2076CT (TO220) US2076CM (TO263) (note 1) IRL3303 (TO220) IRL3103S (TO263) (note 1) MBR1045CT (TO220) MBRB1545CT (TO263) (note1) 1N4148 Core:T50-18,L=4 uH Turns: 10T, 18 AWG L=2 uH 22 ohm,5%, SMT 1206 size 10 ohm, 5%, SMT 1206 size 806 ohm,1%, SMT 0805 size 90.9 kohm,1%, SMT 0805 size 1.24 kohm,1%, SMT 0805 size 2.49 kohm,1%, SMT 0805 size 4.99 kohm,1%, SMT 0805 size 10 kohm,1%, SMT 0805 size 1.30 kohm,1%, SMT 0805 size ohm,1%, SMT 0805 size ohm,1%, SMT 0805 size 10 kohm,5%, SMT 0805 size 1 uF,Ceramic, SMT 0805 size, Z5U EEUFA1A681L, 680uF,10V, Elect 470pF,Ceramic, SMT 0805 size 6MV1500GX, 1500uF,6.3V, Elect EEUFA1A681L, 680uF,10V, Elect 6MV1500GX, 1500uF,6.3V, Elect For MOSFET , 577002 For Schottky Diode , 577002 For US2076 , 507222 (I/O Load Current<5A) 576602 (I/O Load Current< 3.5A)
Manufacturer Unisem International Rectifier Motorola
Micro Metal (core)
Panasonic Sanyo Panasonic Sanyo Aavid Aavid Aavid
Note 1: For the applications where it is desirable to eliminate the heat sink, the US2076CM for U1 when load current is less than 1.5A, the IRL3103S for Q2 and MBR1545CT for D1 in TO263 packages with minimum of 1" square copper pad can be used.
4-4
Rev. 1.3 4/26/98

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