For assistance or to order, call (800) 531-5782
Revised 1/12/99
P T 7 7 5 0 S e r i e s
Application Notes
Mechanical Outline
Product Selector Guide
15 AMP 24V INPUT “BIG-HAMMER III”
PROGRAMMABLE ISR
The PT7750 series is a new +24V
input, 15 Amp output, high-perfor-
mance Integrated Switching Regulator
(ISR) housed in a 27-pin SIP package.
The 15A capability allows easy integra-
tion of the latest high-speed,
low-voltage µPs and bus drivers into
+24V distributed power systems.
The PT7750 series has been de-
signed to work in parallel with one or
more of the PT7747 current boosters for
increased I in increments of 15A.
out
The output voltage of the PT7750
series can be easily programmed over a
wide range with a 5-bit input. A differ-
ential remote sense is provided which
automatically compensates for any
voltage drop from the ISR to the load.
2000µF of output capacitance is
required for proper operation.
Pin-Out Information
Pin Function
Features
Pin Function
• +24V bus input
• High Efficiency
• Differential Remote
Sense
• 27-pin SIP Package
• Parallelable with
PT7747 15A current boosters
14 GND
15 GND
16 GND
17 GND
18 GND
19 GND
1
2
3
4
5
6
7
8
9
VID0
VID1
VID2
VID3
STBY* - Stand-by
VID4
Vin
Standard Application
PROGRAMMING PINS
VID0
VID1
VID2
VID3
VID4
REMOTE SENSE (+)
6
4
3
2
1
26
L1
VIN
VOUT
7
-
11
20 - 25
PT7750
1µH
27
13
-
19
5
12
20
21
22
23
24
25
26
V
V
V
V
V
V
+
+
out
out
out
out
out
out
CIN
COUT
LOAD
SYNC OUT
GND
Vin
Vin
GND
STBY*
REMOTE SENSE (-)
10 Vin
11 Vin
12 Remote Sense Gnd
13 GND
C
C
= Required 560µF electrolytic
(See input filter note)
= Required 2000µF electrolytic
in
out
L1 = Optional 1µH input choke
Remote Sense V
out
27 Sync Out
For STBY* pin:
open = output enabled
ground = output disabled.
Specifications
PT7750 SERIES
Characteristics
(Ta = 25°C unless noted)
Symbols
Conditions
Min
Typ
Max
Units
Output Current
Io
Ta = +60°C, 200 LFM
0.1*
0.1*
—
—
15**
15**
A
A
Ta = +25°C, natural convection
Input Voltage Range
Vin
0.1A ≤ Io ≤ Io max
0.1A ≤ Io ≤ Io max
Vin = +24V, Io = 15A PT7751
0°C ≤ Ta ≤ +55°C
20.0
—
—
28.0
—
V
V
Undervoltage Lockout Threshold
Output Voltage Tolerance
Vuvl
∆Vo
18.7
—
—
—
—
±80
±160
mV
mV
PT7756
Line Regulation
Load Regulation
Vo Ripple/Noise
Regline
Regload
Vn
20V ≤ Vin ≤ 28V, Io = Io max (w/remote sense)
Vin = +24V, 0.1 ≤ Io ≤ Io max (w/remote sense)
Vin = +24V, Io = Io max
—
—
—
±15
±10
75
—
—
—
mV
mV
mV
Transient Response
with Cout = 2000µF
ttr
Vos
Io step between 7.5A and 15A
Vo over/undershoot
—
—
100
200
—
—
µSec
mV
Efficiency
η
Vin = +24V, Io = 10A
Vo = 5.0V
Vo = 3.3V
Vo = 2.5V
—
—
—
88
84
80
—
—
—
%
%
%
Switching Frequency
ƒo
20V ≤ Vin ≤ 28V
0.1A ≤ Io ≤ 15A
300
0
350
—
400
+85
kHz
°C
Absolute Maximum
Operating Temperature Range
Ta
Ta
Recommended Operating
Temperature Range
Forced Air Flow = 200 LFM
At Vin = +24V, Io = 12A
0
—
+65***
°C
Storage Temperature
Weight
Ts
—
—
-40
—
—
+125
—
°C
Vertical/Horizontal
53/66
grams
* ISR-will operate down to no load with reduced specifications. Please note that this product is not short-circuit protected.
** The PT7750 series can be easily paralleled with one or more of the PT7747 Current Boosters to provide increased output current in increments of 15A.
*** See safe operating area chart.
Output Capacitors: The PT7750 series requires a minimum output capacitance of 2000µF for proper operation. Do not use Oscon type capacitors. The maximum allowable
output capacitance is (42,000 ÷ Vout)µF for the PT7751, (96,000 ÷ Vout)µF for the PT7756, or 15,000µF, whichever is less.
Input Filter: An input inductor is optional for most applications. The input inductor must be sized to handle 9ADC with a typical value of 1µH. The input capacitance
must be rated for a minimum of 8.0 Arms of ripple current when operated at maximum output current and maximum output voltage. Contact an applications engi-
neer for input capacitor selection for applications at other output voltages and output currents.
56
Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com