Universal Switching
Regulator Subsystem
The μA78S40 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 μA78S40 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
Order this document μA78S40/D
μA78S40
UNIVERSAL
SWITCHING REGULATOR
SUBSYSTEM
SEMICONDUCTOR
TECHNICAL DATA
P SUFFIX
PLASTIC PACKAGE
CASE 648
Simplified Block Diagram
Noninv. |
Inv. |
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Timing |
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Ipk |
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Driver |
Switch |
Input |
Input |
Gnd |
Capacitor |
VCC |
Sense |
Collector |
Collector |
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9 |
10 |
11 |
12 |
13 |
14 |
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15 |
16 |
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CT |
Ipk |
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Oscilator |
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S |
Q |
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± |
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+Comp. |
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R |
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170 |
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1.25V |
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± Op |
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Reference |
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Amp |
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D1 |
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+ |
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8 |
7 |
6 |
5 |
4 |
3 |
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2 |
1 |
Ref |
Inv |
Noninv |
VCC |
Output |
Switch |
Diode |
Diode |
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Output |
Input |
Input |
Op Amp |
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Emitter |
Anode |
Cathode |
(Bottom View)
PIN CONNECTIONS
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Switch Collector |
Diode Cathode |
1 |
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16 |
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Driver Collector |
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Diode Anode |
2 |
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15 |
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Switch Emitter |
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Ipk Sense |
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3 |
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14 |
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Op Amp Output |
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VCC |
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4 |
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13 |
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VCC Op Amp |
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Timing Capacitor |
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5 |
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12 |
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Op |
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Noninv. |
6 |
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11 |
Ground |
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Comparator |
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Amp |
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Inv. Input |
7 |
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10 |
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Inv. Input |
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Comparator |
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Reference |
8 |
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9 |
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Noninv. Input |
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(Top View) |
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ORDERING INFORMATION
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Temperature |
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Device |
Range |
Package |
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μA78S40PC |
TA = 0° to +70°C |
Plastic |
μA78S40PV |
TA = ± 40° to +85°C |
Plastic |
Motorola, Inc. 1996 |
Rev 1 |
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μA78S40 |
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MAXIMUM RATINGS |
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Rating |
Symbol |
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Value |
Unit |
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Power Supply Voltage |
VCC |
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40 |
V |
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Op Amp Power Supply Voltage |
VCC (Op Amp) |
40 |
V |
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Common Mode Input Range |
VICR |
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±0.3 to VCC |
V |
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(Comparator and Op Amp) |
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Differential Input Voltage (Note 2) |
VID |
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± 30 |
V |
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Output Short Circuit Duration (Op Amp) |
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Continuous |
± |
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Reference Output Current |
Iref |
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10 |
mA |
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Voltage from Switch Collectors to Gnd |
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40 |
V |
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Voltage from Switch Emitters to Gnd |
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40 |
V |
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Voltage from Switch Collectors to Emitter |
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40 |
V |
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Voltage from Power Diode to Gnd |
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40 |
V |
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Reverse±Power Diode Voltage |
VDR |
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40 |
V |
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Current through Power Switch |
ISW |
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1.5 |
A |
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Current through Power Diode |
ID |
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1.5 |
A |
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Power Dissipation and Thermal Characteristics: |
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Plastic Package (TA = + 25°C) |
PD |
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1500 |
mW |
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Derate above + 25°C (Note 1) |
1/RθJA |
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14 |
mW/°C |
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Storage Temperature Range |
Tstg |
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±65 to + 150 |
°C |
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Operating Temperature Range |
TA |
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°C |
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μA78S40V |
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±40 to +85 |
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μA78S40C |
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0 to +70 |
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NOTES: 1. Tlow = |
±40° for μA78S40PV |
Thigh = |
+85° for μA78S40PV |
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= |
0° for μA78S40PC |
= |
+70° for μA78S40PC |
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2.For supply voltages less than 30 V the maximum differential input voltage (Error Amp and Op Amp) is equal to the supply voltage.
ELECTRICAL CHARACTERISTICS (VCC = VCC (Op Amp) 5.0 V, TA = Tlow to Thigh, unless otherwise noted.)
Characteristic |
Symbol |
Min |
Typ |
Max |
Unit |
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GENERAL |
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Supply Voltage |
VCC |
2.5 |
± |
40 |
V |
Supply Current (Op Amp VCC, disconnected) |
ICC |
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mA |
(VCC = 5.0 V) |
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± |
1.8 |
3.5 |
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(VCC = 40 V) |
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2.3 |
5.0 |
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Supply Current (Op Amp VCC, connected) |
ICC |
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mA |
(VCC = 5.0 V) |
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± |
4.0 |
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(VCC = 40 V) |
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± |
± |
5.5 |
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REFERENCE |
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Reference Voltage |
Vref |
1.180 |
1.245 |
1.310 |
V |
(Iref = 1.0 mA) |
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Reference Voltage Line Regulation |
Regline |
± |
0.04 |
0.2 |
mV/V |
(3.0 V ≤ VCC ≤ 40 V, Iref = 1.0 mA, TA = 25°C) |
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Reference Voltage Load Regulation |
Regload |
± |
0.2 |
0.5 |
mV/mA |
(1.0 mA ≤ Iref ≤ 10 mA, TA = 25°C) |
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2 |
MOTOROLA ANALOG IC DEVICE DATA |
μA78S40
ELECTRICAL CHARACTERISTICS (VCC = VCC (Op Amp) 5.0 V, TA = Tlow to Thigh, unless otherwise noted.)
Characteristic |
Symbol |
Min |
Typ |
Max |
Unit |
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OSCILLATOR |
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Charging Current (TA = 25°C) |
Ichg |
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μA |
(VCC = 5.0 V) |
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20 |
± |
50 |
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(VCC = 40 V) |
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20 |
± |
70 |
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Discharging Current (TA = 25°C) |
Idis |
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μA |
(VCC = 5.0 V) |
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150 |
± |
250 |
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(VCC = 40 V) |
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150 |
± |
350 |
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Oscillator Voltage Swing (TA = 25°C) |
Vosc |
± |
0.5 |
± |
V |
(VCC = 5.0 V) |
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Ratio of Charge/Discharge Time |
tchg/tdis |
± |
6.0 |
± |
± |
CURRENT LIMIT |
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Current±Limit Sense Voltage (TA = 25°C) |
VCLS |
250 |
± |
350 |
mV |
(VCC ± Vlpk Sense) |
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OUTPUT SWITCH |
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Output Saturation Voltage 1 |
Vsat1 |
± |
0.93 |
1.3 |
V |
(ISW = 1.0 A, Pin 15 tied to Pin 16) |
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Output Saturation Voltage 2 |
Vsat2 |
± |
0.5 |
0.7 |
V |
(ISW = 1.0 A, I15 = 50 mA) |
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Output Transistor Current Gain (TA = 25°C) |
hFE |
± |
70 |
± |
± |
(IC = 1.0 A, VCE = 5.0 V) |
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Output Leakage Current (TA = 25°C) |
IC(off) |
± |
10 |
± |
nA |
(VCE = 40 V) |
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POWER DIODE |
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Forward Voltage Drop (ID = 1.0 A) |
VD |
± |
1.25 |
1.5 |
V |
Diode Leakage Current (TA = 25°C) (VDR = 40 V) |
IDR |
± |
10 |
± |
nA |
COMPARATOR |
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Input Offset Voltage (VCM = Vref) |
VIO |
± |
1.5 |
15 |
mV |
Input Bias Current (VCM = Vref) |
IIB |
± |
35 |
200 |
nA |
Input Offset Current (VCM = Vref) |
IIO |
± |
5.0 |
75 |
nA |
Common Mode Voltage Range (TA = 25°C) |
VICR |
0 |
± |
VCC ± 2.0 |
V |
Power±Supply Rejection Ratio (TA = 25°C) |
PSRR |
70 |
96 |
± |
dB |
(3.0 ≤ VCC ≤ 40 V) |
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OUTPUT OPERATION AMPLIFIER |
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Input Offset Voltage (VCM = 2.5 V) |
VIO |
± |
4.0 |
15 |
mV |
Input Bias Current (VCM = 2.5 V) |
IIB |
± |
30 |
200 |
nA |
Input Offset Current (VCM = 2.5 V) |
IIO |
± |
5.0 |
75 |
nA |
Voltage Gain + (TA = 25°C) |
AVOL+ |
25 |
250 |
± |
V/mV |
(RL = 2.0 kΩ to Gnd, 1.0 V ≤ VO ≤ 2.5 V) |
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Voltage Gain ± (TA = 25°C) |
AVOL± |
25 |
250 |
± |
V/mV |
(RL = 2.0 kΩ to VCC (Op Amp), 1.0 V ≤ VO ≤ 2.5 V) |
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Common Mode Voltage Range (TA = 25°C) |
VICR |
0 |
± |
VCC ± 2.0 |
V |
Common Mode Rejection Ratio (TA = 25°C) |
CMRR |
76 |
100 |
± |
dB |
(VCM = 0 V to 3.0 V) |
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Power±Supply Rejection Ratio (TA = 25°C) |
PSRR |
76 |
100 |
± |
dB |
(3.0 V ≤ VCC (Op Amp) ≤ 40 V) |
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Output Source Current (TA = 25°C) |
ISource |
75 |
150 |
± |
mA |
Output Sink Current (TA = 25°C) |
ISink |
10 |
35 |
± |
mA |
Slew Rate (TA = 25°C) |
SR |
± |
0.6 |
± |
V/μs |
Output Low Voltage (TA = 25°C, IL = ±5.0 mA) |
VOL |
± |
± |
1.0 |
V |
Output High Voltage (TA = 25°C, IL = 50 mA) |
VOH |
VCC(Op Amp) |
± |
± |
V |
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± 3.0 |
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MOTOROLA ANALOG IC DEVICE DATA |
3 |
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