PT7771—5V
32 Amp “Sledge Hammer”
Programmable ISR
SLTS054A
(Revised 6/30/2000)
The output voltage is program-
mable from 1.3V to 3.5V via a 5-bit
input, compatible with Intel’s Pentiumâ
Pro Processor. A differential remote
sense is also provided to compensate
for voltage drop between the ISR and
load.
An output capacitance of 2400µF is
required for proper operation.
Note that this product does not
include short circuit protection.
The PT7771 is a high-output Inte-
grated Switching Regulator (ISR)
housed in a 27-pin SIP package. The
PT7771 operates off a standard 5V bus
to provide a 32 amp low-voltage power
source for the industry’s latest high-
speed µPs, ASICs, DSPs.
The PT7771 has been designed to
work in parallel with one or more of
the PT7746 -32A current boosters to
increase the load current capability in
increments of 32A.
Pin-Out Information
Pin Function
Pin Function
14 GND
15 GND
16 GND
17 GND
Standard Application
PROGRAMMING PINS
1
2
3
4
5
6
7
8
VID0
VID1
VID0
VID1
VID2
VID3
VID4
VID2
REMOTE SENSE (+)
VID3
6
4
3
2
1
26
STBY*- Stand-by
18 GND
19 GND
VID4
Vin
L1
VIN
VOUT
7 - 11
20 - 25
PT7770
1 H
20
21
22
23
24
25
V
out
V
out
V
out
V
out
V
out
V
out
Vin
27
13 - 19
5
12
+
+
9
Vin
CIN
COUT
LOAD
10 Vin
11 Vin
12 Remote Sense Gnd
SYNC OUT
GND
GND
STBY*
13 GND
26 Remote Sense V
REMOTE SENSE (-)
out
27 Sync Out
C
C
= Required 2400µF electrolytic
= Required 2400µF electrolytic
in
out
For STBY* pin; open = output enabled;
ground = output disabled.
L1 = Optional 1µH input choke
Specifications
PT7771
Characteristics
(T a = 25°C unless noted)
Symbols
Conditions
Min
Typ
Max
Units
(1)
(1)
Output Current
Io
Ta = +60°C, 200 LFM, pkg N
Ta = +25°C, natural convection
0.1
0.1
—
—
32
26
A
A
(2)
Input Voltage Range
Vin
0.1A ≤ Io ≤ 32A
4.5
—
5.5
V
Output Voltage Tolerance
∆Vo
Vin = +5V, Io = 32A
Vo-0.03
—
Vo+0.03
V
0°C ≤ Ta ≤ +55°C
Line Regulation
Regline
Regload
Vn
4.5V ≤ Vin ≤ 5.5V, Io = 32A
Vin = +5V, 0.1 ≤ Io ≤ 32A
Vin = +5V, Io = 32A
—
—
—
10
10
—
—
—
mV
mV
mV
Load Regulation
Vo Ripple/Noise pk-pk
50
Transient Response
with Cout = 2400µF
ttr
Vos
Io step between 16A and 32A
Vo over/undershoot
—
—
100
200
—
—
µSec
mV
Efficiency
η
Vin = +5V, Io = 20A, Vo = 3.3V
—
90
—
%
Switching Frequency
ƒo
4.5V ≤ Vin ≤ 5.5V
0.1A ≤ Io ≤ 32A
650
700
750
kHz
Absolute Maximum
Ta
Over Vin Range
0
—
+85 (3)
°C
Operating Temperature Range
Storage Temperature
Weight
Ts
—
—
-40
—
—
+125
—
°C
Vertical/Horizontal
53/66
grams
Notes: (1) ISR-will operate down to no load with reduced specifications. Please note that this product is not short-circuit protected.
(2) The minimum input voltage is 4.5V or Vout +1.2V, whichever is greater.
(3) Consult the SOA curves or contact the factory for the appropriate derating.
Output Capacitors: The PT7771 regulator requires a minimum output capacitance of 2400µF for proper operation. Do not use Oscon type capacitors.
The maximum allowable output capacitance is 30,000µF.
Input Filter: An input filter is optional for most applications. The input inductor must be sized to handle 32ADC with a typical value of 1µH.
The input capacitance must be rated for a minimum of 2.6Arms of ripple current. For transient or dynamic load applications, additional
capacitance may be required.
For technical support and more information, see inside back cover or visit www.ti.com/powertrends