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US2075
5V
PWM SWITCHER CONTROLLER & 7.5A
LOW DROPOUT REGULATOR COMBO
PATENT PENDING
FEATURESFEATURES
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
APPLICATIONSAPPLICATIONS
Dual supply low voltage processor applications,
such as: P55C,CYRIX M2, POWER PC and
AMD
TYPICAL APPLICATIONTYPICAL APPLICATION
DESCRIPTIONDESCRIPTION
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 packages providing a total solution for dual supply processor applications such as an Intel P55C , AMD K6,
as well as Cyrix 6X86L and the M2processors.
Typically in these applications a dual supply regulator
converts 5V to 3.3V for I/O supply and a jumper programmable 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 supply 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.
V5
7
2075ap1a-1.0
US2075
12V
Vout
Vhyst
Gnd
Vfb
V12
Drv
6
5
4
3
2
1
3.30V / 7.5A
2.8V / 10A
Typical application of US2075 in a flexible mother board 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 INFORMATIONPACKAGE ORDER INFORMATION
Tj (°C) 7 PIN PLASTIC 7 PIN PLASTIC
TO220 (T) TO263 (M)
0 TO 125 US2075CT US2075CM
Rev. 1.2
4/26/98
4-1
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US2075
ABSOLUTE MAXIMUM RATINGSABSOLUTE 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 INFORMATIONPACKAGE INFORMATION
7 PIN PLASTIC TO220 (T) 7 PIN PLASTIC TO263 (M)
FRONT VIEW
7
6
5
4
3
2
1
V5
Vhyst
Vfb
Drv
Vout
Gnd
V12
θJT=2.7°C/W θJA=60°C/W θJA=35°C/W for 1" Square pad
FRONT VIEW
7
V5
6
Vout
5
Vhyst
4
Gnd
3
Vfb
2
V12
1
Drv
ELECTRICAL SPECIFICATIONSELECTRICAL 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.
LDO Section
PARAMETER SYM TEST CONDITION MIN TYP MAX UNITS
Output Voltage VOUT 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 IMAX dVo=0.995*VOUT 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 TJ =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
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Rev. 1.2
4/26/98
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US2075
V12
Vhyst
V5
Vfb
Note 1 : Low duty cycle pulse testing with Kelvin connections are required in order to maintain accurate data.
PIN DESCRIPTIONSPIN 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 DIAGRAMBLOCK DIAGRAM
2 5 3 7
Drv
1
Gnd
4
Rev. 1.2
4/26/98
UVLO
Vref
PWM Control
2075blk1-1.0
Figure 1 - Simplified block diagram of the US2075
1.25V
Vout
6
7.5A LDO
4-3
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US2075
TYPICAL APPLICATIONTYPICAL APPLICATION
5V
V5
7
Vo
6
Vhyst
5
12V
Gnd
Vfb
V12
Drv
4
3
2
1
C1
U1
2050ta3d
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 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 jumper JP7 selects between single supply and dual supply processors.
L1
C7
Cache & Chip Set
1
C5
2
R6AC8
R3
C3
R5
C4
Q2
R7A R7B R7C R7D R7E
D2
JP3
JP2 JP4 JP5
L2
R8B R8C
JP7
JP2 JP3 JP4 JP5 Output
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
CPU I / O
3
Core Supply
C6
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)
Voltage
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.
4-4
Rev. 1.2
4/26/98
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