UNISEM US2076CT

US2076
PWM SWITCHER CONTROLLER & 7.5A
ADJUSTABLE LOW DROPOUT REGULATOR COMBO
FEATURES
PATENT PENDING
PRELIMINARY DATASHEET
DESCRIPTION
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
APPLICATIONS
Dual supply low voltage processor applications,
such as: P55C,CYRIX M2, POWER PC and
AMD K6
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 , AMD K6, as well as Cyrix 6X86L
and the M2processors. 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
I/O
C1
Vin
Vout
Vfb2
US2076
Gnd
Vfb1
V12
Drv
7
6
5
4
3
2
1
C6
R6
5V
R7
CPU
R8
D2
Vcc2 Det
L2
C2
R1
Core
Q2
C7
R4
2076app1-1.2
12V
D1
C3
R5
Typical application of US2076 in a flexible motherboard designed for Intel
P55,P54, AMD K5 & K6 as well as Cyrix M1 and M2 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 150°C
Operating Junction Temperature ............................... 0 TO 150°C
PACKAGE INFORMATION
7 PIN PLASTIC TO220 (T)
7 PIN PLASTIC TO263 (M)
FRONT VIEW
FRONT VIEW
7
6
5
4
3
2
1
Vin
7
6
5
4
3
2
1
Vout
Vfb2
Gnd
Vfb1
V12
Drv
θJT=2.7°C/W θJA=60°C/W
Vin
Vout
Vfb2
Gnd
Vfb1
V12
Drv
θJA=35°C/W for 1" Square pad
ELECTRICAL SPECIFICATIONS
Unless otherwise specified the following specification applies over,Vin=5V,V12=12V,and Tj=0 to 125°C.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
SYM
Vfb1
Vfb1
Ifb1
Min Off Time
V12 Supply Current
Maximum Duty Cycle
Minimum Duty Cycle
Gate Drive Rise/Fall Time
F.B Hysterises
4-2
Icc1
Dmax
Dmin
Vgate
TEST CONDITION
Tj=25°C
Vfb2=1.25V
Vout=1.25V, Io=7.5A
Vout=1.25V,Io=10mA, 3<Vin<6V
Vout=1.25V, 10mA<Io<7.5A
30 mS Pulse
MIN TYP
1.237 1.250
1.225 1.250
-1
1.1
0.2
0.5
0.01
MAX
1.262
1.275
+1
10
f=120HZ ,Co=25uF Tan,Io=1A
Vfb2=1V, Vfb1=1.5V, Io=7.5A
TEST CONDITION
Tj=25°C
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
70
75
MIN
1.237
1.225
-1
TYP
1.250
1.250
MAX
1.262
1.275
+1
UNITS
V
V
uA
V
%
%
%/W
mA
dB
mA
800
UNITS
V
V
uA
nS
800
nS
10
100
0
70
12
mA
%
%
nS
mV
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
PIN SYMBOL
Vfb1
6
Vout
7
Vin
4
Gnd
1
Drv
5
Vfb2
2
V12
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.
BLOCK DIAGRAM
V12
2
Drv
1
Vfb 1
3
Vin
7
UVLO
Vout
6
5V Reg
Vref
PWM Control
1.25V
Gnd
4
2076blk1-1.1
Vfb2
5
Figure 1 - Simplified block diagram of the US2076
Rev. 1.3
4/26/98
4-3
US2076
TYPICAL APPLICATION
L1
5V
I/O
C1
Vin
7
Vout
6
C6
R6
5V
R7
5
Gnd 4
Vfb2
U1
Vfb1
3
V12
2
Drv
1
CPU
R8
D2
Vcc2 Det
L2
C2
R1
Core
Q2
C7
R4A
2076app2-1.2
R4B
12V
C3
C4
R2
D1
R5A
JP1 1
2
R5B
3
4
R5C
5
6
R5D
R5E
7
8
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 P55,P54,
AMD K5 & K6 as well as Cyrix M1 and M2 applications. The Vcc2Det pin automatically shuts down the I/O when a single plane
processor is dropped in the socket.
Ref Desig
U1
Description
LDO/Switcher IC
Qty
1
Q1
MOSFET
1
D1
Schottky Diode
1
D2
L2
Diode, GP
Inductor
1
1
L1
R1
R2
R4A
R4B
R5A
R5B
R5C
R5D
R5E
R6
R7
R8
C3
C1
C4
C2
C6
C7
HS1
HS2
HS3
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
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