Application Notes
Mechanical Outline
For assistance or to order, call (800) 531-5782
Product Selector Guide
P T 7 9 S R 1 0 0 S e r i e s
-1.5 AMP NEGATIVE STEP-DOWN
INTEGRATED SWITCHING REGULATOR
Revised 5/15/98
• High Efficiency > 85%
Regulators (ISRs). These ISRs have a
maximum output current of -1.5 Amps
and an output voltage that is laser
trimmed to most industry standard volt-
ages. They have excellent line and load
regulation, and are ideal for applications,
such as RS232 and Ethernet communica-
tions, ECL logic, and op-amp circuitry.
• Self-Contained Inductor
• Short Circuit Protection
• Over-Temperature Protection
The PT79SR100 Series is a new
line of Negative Input/Negative Out-
put 3-terminal Integrated Switching
Pin-Out Information
Ordering Information
PT79SR1
XX
Y
Pin Function
1
2
3
GND
-Vin
Output Voltage
Package Suffix
Standard Application
-Vout
05 = -5.0 Volts
52 = -5.2 Volts
08 = -8.0 Volts
09 = -9.0 Volts
12 = -12.0 Volts
15 = -15.0 Volts
V = Vertical Mount
S = Surface Mount
H = Horizontal
Mount
COM
COM
-Vout
C1
D1
C2
1
-Vin
2
3
PT79SR1
C1 = Optional ceramic (1µF)
C2 = Optional ceramic (1-5µF)
D1 = Zener diode required to clamp
turn-on overshoot
(See Application Note)
Pkg Style 500
Specifications
PT79SR100 SERIES
Characteristics
(Ta = 25°C unless noted)
Symbols
Io
Conditions
Min
-0.1*
—
Typ
—
Max
-1.5
Units
A
Output Current
Over Vin range
Vin=Vo-4V
Short Circuit Current
Input Voltage Range
Isc
-3.5
—
Apk
Vin
Io=-0.1 to -1.5 A
-0.1 ≥ Io ≥ -1.5 A
Vo=-5V
Vo=-15V
-9
-19
—
—
-30
-30
V
V
Output Voltage Tolerance
∆Vo
Over Vin range, Io=-1.5 A
Ta=-20°C to shutdown
—
±1.0
±3.0
%Vo
Line Regulation
Load Regulation
Vo Ripple/Noise
Transient Response
Regline
Regload
Vn
Over Vin range
—
—
—
±1.0
±0.5
35
±2.0
±1.0
—
%Vo
%Vo
mVpp
-0.1 ≤ Io ≤ -1.5 A
Vin=-15V, Io=-1.0 A,Vo=-5V
ttr
50% load change
—
—
100
30
—
—
µSec
%Vo
Vo=overshoot/undershoot
Efficiency
η
Vin=-10V, Io=-1.0A, Vo=-5V
Over Vin and Io ranges
—
85
—
%
Switching Frequency
ƒo
Ta
0.95
1.0
1.05
MHz
Absolute Maximum
Operating Temperature Range
-40
-40
—
—
+85
°C
°C
Recommended Operating
Temperature Range
Ta
Free Air Convection, (40-60LFM)
Over Vin and Io ranges
+60**
Thermal Resistance
Temperature Coefficient
Storage Temperature
Mechanical Shock
θja
Tc
Ts
—
—
Free Air Convection, (40-60LFM)
Over Vin and Io ranges
—
—
45
—
°C/W
mV/°C
°C
—
±0.5
—
±1.5
+125
—
-40
—
Per Mil-STD-883D, Method 2002.3
500
G’s
Mechanical Vibration
Per Mil-STD-883D,Method 2007.2,
20-2000 Hz, soldered in a PC board
—
—
—
5
G’s
Weight
—
—
7.0
—
Grams
* ISR will operate down to no load with reduced specifications.
** See Thermal Derating chart.
22
Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com