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Электронный компонент: uA78S40C

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Semiconductor Components Industries, LLC, 2001
February, 2001 Rev. 2
1
Publication Order Number:
A78S40/D
A78S40
Universal Switching
Regulator Subsystem
The
A78S40 is a switching regulator subsystem, consisting of a
temperature compensated voltage reference, controlledduty cycle
oscillator with an active current limit circuit, comparator, highcurrent
and highvoltage output switch, capable of 1.5 A and 40 V, pinnedout
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 widesupply voltage range, low standby current, high
efficiency and low drift. The
A78S40 is available in commercial
(0
to + 70
C), and automotive (40
to + 85
C) temperature ranges.
Some of the applications include use in stepup, stepdown, 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
Figure 1. Simplified Block Diagram
C
T
I
pk
Oscillator
-
+
Comp.
-
+
Op
1.25V
Reference
S
R
Q
170
8
(Bottom View)
Ref
Output
Output
9
D1
Inv
Input
Noninv
Input
V
CC
Op Amp
Switch
Emitter
Diode
Anode
Diode
Cathode
Noninv.
Input
Inv.
Input
Gnd
Timing
Capacitor
V
CC
I
pk
Sense
Driver
Collector
Switch
Collector
7
6
5
4
3
2
1
10
11
12
13
14
15
16
Amp
This device contains 84 active transistors.
Device
Package
Shipping
ORDERING INFORMATION
A78S40PC
PDIP16
25 Units/Rail
PDIP16
P SUFFIX
CASE 648
16
http://onsemi.com
A78S40PV
PDIP16
25 Units/Rail
MARKING
DIAGRAM
x
= C or V
A
= Assembly Location
WL = Wafer Lot
YY = Year
WW = Work Week
1
PIN CONNECTIONS
11
5
2
1
9
10
12
13
14
15
16
8
7
6
4
3
(Top View)
Diode Anode
Reference
Inv. Input
Noninv.
V
CC
Op Amp
Op Amp Output
Switch Emitter
Diode Cathode
Op
Amp
Comparator
Noninv. Input
Comparator
Inv. Input
Ground
Timing Capacitor
V
CC
I
pk
Sense
Driver Collector
Switch Collector
1
16
UA78S40Px
AWLYYWW
A78S40
http://onsemi.com
2
MAXIMUM RATINGS
Rating
Symbol
Value
Unit
Power Supply Voltage
V
CC
40
V
Op Amp Power Supply Voltage
V
CC
(Op Amp)
40
V
Common Mode Input Range
(Comparator and Op Amp)
V
ICR
0.3 to V
CC
V
Differential Input Voltage (Note 2.)
V
ID
30
V
Output Short Circuit Duration (Op Amp)
Continuous
Reference Output Current
I
ref
10
mA
Voltage from Switch Collectors to Gnd
40
V
Voltage from Switch Emitters to Gnd
40
V
Voltage from Switch Collectors to Emitter
40
V
Voltage from Power Diode to Gnd
40
V
ReversePower Diode Voltage
V
DR
40
V
Current through Power Switch
I
SW
1.5
A
Current through Power Diode
I
D
1.5
A
Power Dissipation and Thermal Characteristics:
Plastic Package (T
A
= + 25
C)
Derate above + 25
C (Note 1.)
P
D
1/R
JA
1500
14
mW
mW/
C
Storage Temperature Range
T
stg
65 to + 150
C
Operating Temperature Range
A78S40V
A78S40C
T
A
40 to +85
0 to +70
C
ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC
(Op Amp) 5.0 V, T
A
= T
low
to T
high
, unless otherwise noted.)
Characteristic
Symbol
Min
Typ
Max
Unit
GENERAL
Supply Voltage
V
CC
2.5
40
V
Supply Current (Op Amp V
CC
, disconnected)
(V
CC
= 5.0 V)
(V
CC
= 40 V)
I
CC

1.8
2.3
3.5
5.0
mA
Supply Current (Op Amp V
CC
, connected)
(V
CC
= 5.0 V)
(V
CC
= 40 V)
I
CC


4.0
5.5
mA
REFERENCE
Reference Voltage
(I
ref
= 1.0 mA)
V
ref
1.180
1.245
1.310
V
Reference Voltage Line Regulation
(3.0 V
V
CC
40 V, I
ref
= 1.0 mA, T
A
= 25
C)
Reg
line
0.04
0.2
mV/V
Reference Voltage Load Regulation
(1.0 mA
I
ref
10 mA, T
A
= 25
C)
Reg
load
0.2
0.5
mV/mA
1. T
low
= 40
for
A78S40PV
T
high
= +85
for
A78S40PV
= 0
for
A78S40PC
= +70
for
A78S40PC
2. For supply voltages less than 30 V the maximum differential input voltage (Error Amp and Op Amp) is equal to the supply voltage.
A78S40
http://onsemi.com
3
ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC
(Op Amp) 5.0 V, T
A
= T
low
to T
high
, unless otherwise noted.)
Characteristic
Symbol
Min
Typ
Max
Unit
OSCILLATOR
Charging Current (T
A
= 25
C)
(V
CC
= 5.0 V)
(V
CC
= 40 V)
I
chg
20
20

50
70
A
Discharging Current (T
A
= 25
C)
(V
CC
= 5.0 V)
(V
CC
= 40 V)
I
dis
150
150

250
350
A
Oscillator Voltage Swing (T
A
= 25
C)
(V
CC
= 5.0 V)
V
osc
0.5
V
Ratio of Charge/Discharge Time
t
chg
/t
dis
6.0
CURRENT LIMIT
CurrentLimit Sense Voltage (T
A
= 25
C)
(V
CC
V
lpk
Sense)
V
CLS
250
350
mV
OUTPUT SWITCH
Output Saturation Voltage 1
(I
SW
= 1.0 A, Pin 15 tied to Pin 16)
V
sat1
0.93
1.3
V
Output Saturation Voltage 2
(I
SW
= 1.0 A, I
15
= 50 mA)
V
sat2
0.5
0.7
V
Output Transistor Current Gain (T
A
= 25
C)
(I
C
= 1.0 A, V
CE
= 5.0 V)
h
FE
70
Output Leakage Current (T
A
= 25
C)
(V
CE
= 40 V)
I
C(off)
10
nA
POWER DIODE
Forward Voltage Drop (I
D
= 1.0 A)
V
D
1.25
1.5
V
Diode Leakage Current (T
A
= 25
C) (V
DR
= 40 V)
I
DR
10
nA
COMPARATOR
Input Offset Voltage (V
CM
= V
ref
)
V
IO
1.5
15
mV
Input Bias Current (V
CM
= V
ref
)
I
IB
35
200
nA
Input Offset Current (V
CM
= V
ref
)
I
IO
5.0
75
nA
Common Mode Voltage Range (T
A
= 25
C)
V
ICR
0
V
CC
2.0
V
PowerSupply Rejection Ratio (T
A
= 25
C)
(3.0
V
CC
40 V)
PSRR
70
96
dB
OUTPUT OPERATION AMPLIFIER
Input Offset Voltage (V
CM
= 2.5 V)
V
IO
4.0
15
mV
Input Bias Current (V
CM
= 2.5 V)
I
IB
30
200
nA
Input Offset Current (V
CM
= 2.5 V)
I
IO
5.0
75
nA
Voltage Gain + (T
A
= 25
C)
(R
L
= 2.0 k
to Gnd, 1.0 V
V
O
2.5 V)
A
VOL
+
25
250
V/mV
Voltage Gain (T
A
= 25
C)
(R
L
= 2.0 k
to V
CC
(Op Amp), 1.0 V
V
O
2.5 V)
A
VOL
25
250
V/mV
Common Mode Voltage Range (T
A
= 25
C)
V
ICR
0
V
CC
2.0
V
Common Mode Rejection Ratio (T
A
= 25
C)
(V
CM
= 0 V to 3.0 V)
CMRR
76
100
dB
PowerSupply Rejection Ratio (T
A
= 25
C)
(3.0 V
V
CC
(Op Amp)
40 V)
PSRR
76
100
dB
Output Source Current (T
A
= 25
C)
I
Source
75
150
mA
Output Sink Current (T
A
= 25
C)
I
Sink
10
35
mA
Slew Rate (T
A
= 25
C)
SR
0.6
V/
s
Output Low Voltage (T
A
= 25
C, I
L
= 5.0 mA)
V
OL
1.0
V
Output High Voltage (T
A
= 25
C, I
L
= 50 mA)
V
OH
V
CC
(Op Amp)
3.0
V
A78S40
http://onsemi.com
4
Figure 2. Output Switch On/Off Time
versus Oscillator Timing Capacitor
Figure 3. Standby Supply Current
versus Supply Voltage
Figure 4. EmitterFollower Configuration
Output Switch Saturation Voltage
versus Emitter Current
C
T
, OSCILLATOR TIMING CAPACITOR (nF)
0.1
1.0
10
100
, OUTPUT
SWITCH ONOFF
TIME (s)
onof
f
t
V
CC
= 5.0 V
I
pk(sense)
= V
CC
Pin 10 = Gnd
Pin 9 = V
ref
t
on
t
off
V
CC
, SUPPLY VOLTAGE (V)
0
5.0
10
15
20
25
30
35
40
, SUPPL
Y
CURRENT
(mA)
CCI
C
T
= 0.001
F
I
pk(sense)
= V
CC
Pin 3 = Gnd
I
E
, EMITTER CURRENT (A)
, SA
TURA
TION VOL
T
AGE (V)
CE(sat)
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
V
V
CC
= 5.0 V
Pins 14, 15, 16 = V
CC
Pins 10, 12 = Gnd
Pin 9 = V
ref
I
C
, COLLECTOR CURRENT (A)
, SA
TURA
TION VOL
T
AGE (V)
CE(sat)
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
V
V
CC
= 5.0 V
Pin 14 = V
CC
Pins 3, 10, 12 = Gnd
Pin 9 = V
ref
Darlington Connection
Figure 5. CommonEmitter Configuration
Output Switch Saturation Voltage
versus Collector Current
1000
100
1
0
1.0
3.2
2.4
1.6
0.8
0
1.6
1.5
1.4
1.3
1.2
1.1
1.0
1.2
1.0
0.8
0.6
0.4
0.2
0
Forced Beta = 20
A78S40
http://onsemi.com
5
C
T
I
pk
Oscillator
-
+
Comp.
-
+
Op
Amp
1.25V
Reference
S
R
Q
170
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
D1
V
out
5.0V/500mA
*
L
470
+
C
O
R2
3.6k
R1
1N5822
+
100
C
T
*Use external rectifier to increase circuit efficiency
1.2k
V
in
25V
470
pF
R
SC
0.33
220
H
V
CC
Figure 6. StepDown Converter
C
T
I
pk
Oscillator
-
+
Comp.
-
+
Op
Amp
1.25V
Reference
S
R
Q
170
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
D1
V
out
28V/175mA
*
150
+
C
O
R2
47k
R1
1N5822
+
100
C
T
*Use external rectifier to increase circuit efficiency
22k
V
in
12V
1500
pF
R
SC
0.22
V
CC
Figure 7. StepUp Converter
170
H
L
180