UA78S40
Universal Switching
Regulator Subsystem
The mA78S40 is a switching regulator subsystem, consisting of a
temperature compensated voltage reference, controlled−duty cycle
oscillator with an active current limit circuit, comparator, high−current
and high−voltage output switch, capable of 1.5 A and 40 V, pinned−out
power diode and an uncommitted operational amplifier, which can be
powered up or down independent of the IC supply. The switching
output can drive external NPN or PNP transistors when voltages
greater the 40 V, or currents in excess of 1.5 A, are required. Some of
the features are wide−supply voltage range, low standby current, high
efficiency and low drift. The mA78S40 is available in commercial
(0° to + 70°C), and automotive (−40° to + 85°C) temperature ranges.
Some of the applications include use in step−up, step−down, and
inverting regulators, with extremely good results obtained in battery−
operated systems.
• Output Adjustable from 1.25 V to 40 V
• Peak Output Current of 1.5 A Without External Transistor
• 80 dB Line and Load Regulation
• Operation from 2.5 V to 40 V Supply
• Low Standby Current Drain
• High Gain, High Output Current, Uncommitted Op Amp
http://onsemi.com
MARKING
DIAGRAM
16
PDIP−16
P SUFFIX
CASE 648
16
UA78S40Px
AWLYYWW
1
1
x
A
WL
YY
WW
= C or V
= Assembly Location
= Wafer Lot
= Year
= Work Week
PIN CONNECTIONS
Diode Cathode 1
16 Switch Collector
Diode Anode 2
15 Driver Collector
14 Ipk Sense
Switch Emitter 3
13 VCC
Op Amp Output 4
Noninv.
Input
Inv.
Input
Gnd
Timing
Capacitor
VCC
Ipk
Sense
Driver
Collector
Switch
Collector
9
10
11
12
13
14
15
16
12 Timing Capacitor
VCC Op Amp 5
Op
Amp
11 Ground
Comparator
10 Inv. Input
9 Comparator
Noninv. Input
Noninv. 6
Inv. Input 7
Reference 8
(Top View)
CT
Ipk
Oscillator
S
Q
ORDERING INFORMATION
−
Comp.
+
1.25V
Reference
Device
− Op
Amp
+
D1
8
7
6
5
4
3
2
Inv
Input
Noninv
Input
VCC
Op Amp
Output
Switch
Emitter
Diode
Anode
PDIP−16
25 Units/Rail
PDIP−16
25 Units/Rail
1
Ref
Output
Shipping
mA78S40PV
170
Package
mA78S40PC
R
Diode
Cathode
(Bottom View)
NOTE:
This device contains 84 active
transistors.
Figure 1. Simplified Block Diagram
© Semiconductor Components Industries, LLC, 2006
July, 2006 − Rev. 3
1
Publication Order Number:
UA78S40/D