US2075
4-1
Rev. 1.2
4/26/98
PWM SWITCHER CONTROLLER & 7.5A
LOW DROPOUT REGULATOR COMBO
TYPICAL APPLICATION
TYPICAL APPLICATION
Typical application of US2075 in a flexible mother board designed for Intel P55
TM
,P54
TM
AMD K5,K6
TM
as well as Cyrix M1
TM
and M2
TM
applications.
PACKAGE ORDER INFORMATION
PACKAGE ORDER INFORMATION
Tj (
C) 7 PIN PLASTIC 7 PIN PLASTIC
TO220 (T) TO263 (M)
0 TO 125 US2075CT US2075CM
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.
DESCRIPTION
DESCRIPTION
The US2075 is a dual function IC combining a switching
controller and a 7.5A low dropout regulator all in a com-
pact 7 pin TO220 and TO263 surface mount pack-
ages providing a total solution for dual supply proces-
sor applications such as an Intel P55C
TM
, AMD K6
TM
,
as well as Cyrix 6X86L
TM
and the M2
TM
processors.
Typically in these applications a dual supply regulator
converts 5V to 3.3V for I/O supply and a jumper pro-
grammable supply of 2.8V to 3.5V for CORE supply .The
linear regulator portion in the US2075 is a fixed 3.30V
output and has a minimum of 7.5A current capability
designed to provide ample current for most applications
while the switching regulator controller uses the 5V sup-
ply to power the controller and the 12V supply to drive
the power MOSFET, allowing a low cost N- MOS switch
to be used. The IC also includes an error comparator for
fastest 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.
FEATURES
FEATURES
The US2075 eliminates the need for a
seperate switching controller IC
Minimum part count allows lower system cost
Fixed 3.30V/7.5A LDO on board
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
APPLICATIONS
Dual supply low voltage processor applications,
such as: P55C
TM
,CYRIX M2
TM
, POWER PC
TM
and
AMD
PATENT PENDING
5V
2.8V / 10A
12V
3.30V / 7.5A
2075ap1a-1.0
US2075
Drv
V12
Vfb
Gnd
Vhyst
Vout
V5
1
2
3
4
5
6
7
US2075
4-2
Rev. 1.2
4/26/98
ABSOLUTE MAXIMUM RATINGS
ABSOLUTE MAXIMUM RATINGS
12V Supply Voltage ............................................................. 14V
5V 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 ............................... O TO 150
C
PACKAGE INFORMATION
PACKAGE INFORMATION
7 PIN PLASTIC TO220 (T)
7 PIN PLASTIC TO263 (M)
JT
=2.7
C/W
JA
=60
C/W
JA
=35
C/W for 1" Square pad
LDO Section
PARAMETER
SYM
TEST CONDITION
MIN TYP MAX UNITS
Output Voltage V
OUT
Io=0mA
3.400
V
Line Regulation
Io=0mA, 4.75<V5<6V
0.2
%
Load Regulation (note 1)
0A<Io<7.5A
0.5
%
Maximum Output Current I
MAX
d
Vo
=0.995*V
OUT
7.5
A
Thermal Regulation
30 mS Pulse,V5=5V
0.01
0.02
%/W
Ripple Rejection
f=120HZ ,Co=25uF Tan 70 dB
Io=1A
Switching Controller Section
PARAMETER
SYM TEST CONDITION
MIN TYP MAX UNITS
F.B Voltage Initial Accuracy
Vfb
T
J
=25
C
1.237
1.250
1.262
V
F.B Voltage Total Variation
Vfb
Includes Temp & line,4.75 to 5.25V
1.225
1.250
1.275
V
F.B Input Bias Current
Ifb
Vfb=1.25V
-2
+2
uA
Min On Time
Vfb is sq wave with 300 ns on
400
600
800
nS
time and 2 uS off time
Min Off Time
Vfb is sq wave with 300 ns off
400
600
800
nS
time and 2 uS on time
Vhyst pin output-HI
Isource=500uA,Vfb=1.5V
11
V
Vhyst pin output-LO
Isink=500uA,Vfb=1V
1
V
Supply Current
Icc
Vfb=1V
10
mA
Maximum Duty Cycle
Dmax
Vfb=1V
100
%
Minimum Duty Cycle
Dmin
Vfb=1.5V
0
%
Gate Drive Rise/Fall Time
Vgate
Load=IRL3303
70
nS
FRONT VIEW
1
2
3
4
5
6
7
Drv
V12
Vfb
Gnd
Vhyst
Vout
V5
FRONT VIEW
1
2
3
4
5
6
7
Drv
V12
Vfb
Gnd
Vhyst
Vout
V5
ELECTRICAL SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
Unless otherwise specified the following specification applies over,V5=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.
US2075
4-3
Rev. 1.2
4/26/98
PIN DESCRIPTIONS
PIN DESCRIPTIONS
PIN # PIN SYMBOL
PIN DESCRIPTION
3
Vfb
A resistor divider from this pin to the output of the switching regulator and
ground sets the core supply voltage.
6
Vout
The output of the linear regulator. A minimum of a 10uF capacitor must be
connected from this pin to ground to insure stability. This voltage is set at 3.30V typ.
7
V5
The input pin of the 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 1.3V
higher than Vout in order for the device to regulate properly.
4
Gnd
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. A high
frequency capacitor must be connected from V12 to this pin to insure proper operation.
1
Drv
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 from this
pin to the gate in order to reduce switching noise.
5
Vhyst
A resistor is connected from this pin to the Vfb pin to set the output ripple voltage.
See application note for more details.
2
V12
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
BLOCK DIAGRAM
Figure 1 - Simplified block diagram of the US2075
Note 1 : Low duty cycle pulse testing with Kelvin con-
nections are required in order to maintain accurate data.
Vref
7.5A LDO
UVLO
1.25V
PWM Control
V12
Vhyst
V5
Drv
Gnd
Vfb
Vout
4
1
2
5
3
7
6
2075blk1-1.0
US2075
4-4
Rev. 1.2
4/26/98
TYPICAL APPLICATION
TYPICAL APPLICATION
Note 1: For the applications where it is desirable to eliminate the heat sink, the US2075CM 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.
Core Supply
Cache & Chip Set
U1
JP3
Drv
V12
Vfb
Gnd
Vhyst
Vo
V5
1
2
3
4
5
6
7
JP2
JP4
JP5
2050ta3d
12V
5V
JP7
CPU I / O
1
2
3
C7
L1
R3
Q2
D2
C1
R5
C3
C4
R7A
R7B
R7C
R7D
R7E
C6
L2
C5
R6A
C8
R8B
R8C
Ref Desig
Description Qty
Part #
Manufacturer
U1
LDO/Switcher IC
1
US2075CT (TO220)
Unisem
US2075CM (TO263) (note 1)
Q2
MOSFET
1
IRL3303 (TO220)
International
IRL3103S (TO263) (note 1)
Rectifier
D2
Schottky Diode
1
MBR1045CT (TO220)
Motorola
MBRB1545CT (TO263) (note1)
L2
Inductor
1
Core:T50-18,L=4 uH
Micro Metal
Turns: 10T, 18 AWG
(core)
L1
Inductor
1
L=2 uH
R3
Resistor
1
22 ohm,5%, SMT 1206 size
R5
Resistor
1
10 ohm, 5%, SMT 1206 size
R8C
Resistor
1
806 ohm,1%, SMT 0805 size
R8B
Resistor
1
90.9 kohm,1%, SMT 0805 size
R7A
Resistor
1
1.24 kohm,1%, SMT 0805 size
R7B
Resistor
1
2.49 kohm,1%, SMT 0805 size
R7C
Resistor
1
4.99 kohm,1%, SMT 0805 size
R7D
Resistor
1
10 kohm,1%, SMT 0805 size
R7E
Resistor
1
1.30 kohm,1%, SMT 0805 size
R6A
Resistor
1
324 kohm,1%, SMT 0805 size
C8
Resistor
1
10pF,Ceramic, SMT 0805 size
C1
Capacitor
1
1 uF,Ceramic, SMT 0805 size, Z5U
C7
Capacitor
1
EEUFA1A681L, 680uF,10V, Elect
Panasonic
C3
Capacitor
1
470pF,Ceramic, SMT 0805 size
C4
Capacitor
1
6MV1500GX, 1500uF,6.3V, Elect
Sanyo
C5
Capacitor
1
EEUFA1A681L, 680uF,10V, Elect
Panasonic
C6
Capacitor
4
6MV1500GX, 1500uF,6.3V, Elect
Sanyo
HS1
Heat Sink
1
For MOSFET , 577002
Aavid
HS2
Heat Sink
1
For Schottky Diode , 577002
Aavid
HS3
Heat Sink
1
For US2075 , 507222 (I/O Load Current<5A)
Aavid
576602 (I/O Load Current< 3.5A)
Figure2- Typical application of US2075 in a
flexible motherboard with the 4 bit VID output voltage selection.
This circuit uses a single jumper that programs the output volt-
age in 16 steps with 0.1V steps from 2V to 3.5V, designed for
Intel P55
TM
,P54
TM
, AMD K5 & K6
TM
as well as Cyrix M1
TM
and
M2
TM
applications. The jumper JP7 selects between single sup-
ply and dual supply processors.
JP2
JP3
JP4
JP5
Output
Voltage
0
0
0
0
3.5
0
0
0
1
3.4
0
0
1
0
3.3
0
0
1
1
3.2
0
1
0
0
3.1
0
1
0
1
3.0
0
1
1
0
2.9
0
1
1
1
2.8
1
0
0
0
2.7
1
0
0
1
2.6
1
0
1
0
2.5
1
0
1
1
2.4
1
1
0
0
2.3
1
1
0
1
2.2
1
1
1
0
2.1
1
1
1
1
2.0
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