Application Notes
Mechanical Outline
For assistance or to order, call (800) 531-5782
Product Selector Guide
S e r i e s
P T 7 7 7 0
32 AMP HIGH-PERFORMANCE
“SLEDGE HAMMER” PROGRAMMABLE ISR
Revised 5/15/98
The PT7770 is a new series of
from 1.3V to 3.5V with a 5 bit input
high-performance, 32 Amp Inte-
grated Switching Regulators (ISRs)
housed in a 27-pin SIP package.
The 32A capability allows easy
integration of the latest high-speed,
low-voltage µPs, ASICs, DSPs, and
bus drivers into existing 5V systems.
The output voltage of the
compatible with Intel’s Pentium
Pro Processor. A differential
remote sense is also provided
which automatically compensates
for any voltage drop from the ISR
to the load.
2400µF of output capacitance
are required for proper operation.
PT7770 can be easily programmed
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
L1
VID4
Vin
VIN
VOUT
7 - 11
20 - 25
PT7770
1µH
20
21
22
23
24
25
V
V
V
V
V
V
out
out
out
out
out
out
Vin
27
13 - 19
5
12
+
+
9
Vin
CIN
COUT
LOAD
10 Vin
11 Vin
12 Remote Sense Gnd
13 GND
SYNC OUT
GND
GND
STBY*
26 Remote Sense V
27 Sync Out
REMOTE SENSE (-)
out
C
C
L1
=
=
=
Required 2400µF electrolytic
Required 2400µF electrolytic
Optional 1µH input choke
in
out
For STBY* pin; open = output enabled;
ground = output disabled.
Specifications
PT7770 SERIES
Characteristics
(T a = 25°C unless noted)
Symbols
Conditions
Min
Typ
Max
Units
(1)
Output Current
Io
Ta = +60°C, 200 LFM, pkg N
Ta = +25°C, natural convection
0.1
0.1
—
—
32
26
A
A
(1)
(2)
Input Voltage Range
Vin
0.1A ≤ Io ≤ 32A
4.5
—
5.5
V
Output Voltage Tolerance
∆Vo
Vin = +5V, Io = 32A
0°C ≤ Ta ≤ +55°C
Vo-0.03
—
Vo+0.03
V
Line Regulation
Regline
Regload
Vn
4.5V ≤ Vin ≤ 5.5V, Io = 32A
Vin = +5V, 0.1 ≤ Io ≤ 32A
Vin = +5V, Io = 32A
—
—
—
±10
±10
50
—
—
—
mV
mV
mV
Load Regulation
Vo Ripple/Noise pk-pk
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
—
0
0
—
—
+85
+65
°C
°C
Operating Temperature Range
Recommended Operating
Temperature Range
Ta
Forced Air Flow = 200 LFM
Over Vin
—
Io Ranges
and
Storage Temperature
Weight
Ts
—
-40
—
—
+125
—
°C
Vertical/Horizontal
53/66
grams
(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.
Output Capacitors: The PT7770 series 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.
2
Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com