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L78S00 SERIES
2A POSITIVE VOLTAGE REGULATORS

. . . . .

OUTPUT CURRENT TO 2A OUTPUT VOLTAGES OF 5 ; 7.5 ; 9 ; 10 ; 12 ; 15 ; 18 ; 24V THERMAL OVERLOAD PROTECTION SHORT CIRCUIT PROTECTION OUTPUT TRANSISTOR SOA PROTECTION

DESCRIPTION The L78S00 series of three-terminal positive regulators is available in TO-220 and TO-3 packages and with several fixed output voltages, making it useful in a wide range of applications. These regulators can provide local on-card regulation, eliminating the distribution problems associated with single point regulation. Each type employs internal current limiting, thermal shut-down and safe area protection, making it essentially indestructible. If adequate heat sinking is provided, they can deliver over 2A output current. Although designed primarily as fixed voltage regulators, these devices can be used with external components to obtain adjustable voltages and currents. BLOCK DIAGRAM

TO-3

TO-220

January 1993

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L78S00 SERIES
ABSOLUTE MAXIMUM RATINGS
Symbol Vi Io Pt o t T stg To p Parameter DC Input Voltage (for V o = 5 to 18V) (for V o = 24V) Output Current Power Dissipation Storage Temperature Operating Junction Temperature (for L78S00 ) (for L78S00C ) Value 35 40 Internally limited Internally limited 65 to + 150 55 to + 150 0 to + 150 °C °C °C Unit V V

THERMAL DATA
TO-220 R t h j- cas e Thermal Resistance Junction-case R t h j -amb Thermal Resistance Junction-ambient Max Max 3 50 TO-3 4 35 °C/W °C/W

CONNECTION DIAGRAMS AND ORDERING NUMBERS (top views)

Type L78S05 L78S05C L78S75 L78S75C L78S09 L78S09C L78S10 L78S10C L78S12 L78S12C L78S15 L78S15C L78S18 L78S18C L78S24 L78S24C

T O- 22 0 L78S05CV L78S75CV L78S09CV L78S10CV L78S12CV L78S15CV L78S18CV L78S24CV

TO-3 L78S05T L78S05CT L78S75T L78S75CT L78S09T L78S09CT L78S10T L78S10CT L78S12T L78S12CT L78S15T L78S15CT L78S18T L78S18CT L78S24T L78S24CT

Output Voltage 5V 5V 7.5V 7.5V 9V 9V 10V 10V 12V 12V 15V 15V 18V 18V 24V 24V

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L78S00 SERIES
APPLICATION CIRCUIT

SCHEMATIC DIAGRAM

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L78S00 SERIES
TEST CIRCUITS Figure 1 : DC Parameters. Figure 2 : Load Regulation.

Figure 3 : Ripple Rejection.

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L78S00 SERIES
ELECTRICAL CHARACTERISTICS FOR L78S05 (refer to the test circuits, Tj = 25 oC, Vi = 10V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 7 to 25 V Io = 5 mA Tj = -55 to 150 oC -1.1 40 60 8 17 500 3
o

Test Conditions Io = 1 A Vi = 7 to 25 V Vi = 8 to 25 V Io = 20 mA to 2 A Vi = 7 V

Min. 4.8 4.75

Typ. 5 5

Max. 5.2 5.25 100 50 100 8 0.5 1.3

Unit V V mV mV mV mA mA mA mV/oC µV dB V m mA A

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

ELECTRICAL CHARACTERISTICS FOR L78S75 (refer to the test circuits, Tj = 25 C, Vi = 12.5V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 9.5 to 25 V Io = 5 mA Tj = -55 to 150 oC -0.8 52 54 10.5 16 500 3 Io = 1 A Vi = 9.5 V Vi = 9.5 to 25 V Vi = 10.5 to 20 V Io = 20 mA to 2 A Test Conditions Min. 7.15 7.1 Typ. 7.5 7.5 Max. 7.9 7.95 120 60 120 8 0.5 1.3 Unit V V mV mV mV mA mA mA mV/oC µV dB V m mA A

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

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L78S00 SERIES
ELECTRICAL CHARACTERISTICS FOR L78S09 (refer to the test circuits, Tj = 25 oC, Vi = 14V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 11 to 25 V Io = 5 mA Tj = -55 to 150 oC -1 60 53 12 17 500 3
o

Test Conditions Io = 1 A Vi = 11 V

Min. 8.65 8.6

Typ. 9 9

Max. 9.35 9.4 130 65 130 8 0.5 1.3

Unit V V mV mV mV mA mA mA mV/oC µV dB V m mA A

Vi = 11 to 25 V Vi = 11 to 20 V Io = 20 mA to 2 A

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

ELECTRICAL CHARACTERISTICS FOR L78S10 (refer to the test circuits, Tj = 25 C, Vi = 15V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 12.5 to 30 V Io = 5 mA Tj = -55 to 150 oC -1 65 53 13 17 500 3 Io = 1 A Vi = 12.5 V Vi = 12.5 to 30 V Vi = 14 to 22 V Io = 20 mA to 2 A Test Conditions Min. 9.5 9.4 Typ. 10 10 Max. 10.5 10.6 200 100 150 8 0.5 1 Unit V V mV mV mV mA mA mA mV/oC µV dB V m mA A

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

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L78S00 SERIES
ELECTRICAL CHARACTERISTICS FOR L78S12 (refer to the test circuits, Tj = 25 oC, Vi = 19V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 14.5 to 30 V Io = 5 mA Tj = -55 to 150 oC -1 75 53 15 18 500 3
o

Test Conditions Io = 1 A Vi = 14.5 V

Min. 11.5 11.4

Typ. 12 12

Max. 12.5 12.6 240 120 160 8 0.5 1

Unit V V mV mV mV mA mA mA mV/oC µV dB V m mA A

Vi = 14.5 to 30 V Vi = 16 to 22 V Io = 20 mA to 2 A

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

ELECTRICAL CHARACTERISTICS FOR L78S15 (refer to the test circuits, Tj = 25 C, Vi = 23V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 17.5 to 30 V Io = 5 mA Tj = -55 to 150 oC -1 90 52 18 19 500 3 Io = 1 A Vi = 17.5 V Vi = 17.5 to 30 V Vi = 20 to 26 V Io = 20 mA to 2 A Test Conditions Min. 14.4 14.25 Typ. 15 15 Max. 15.6 15.75 300 150 180 8 0.5 1 Unit V V mV mV mV mA mA mA mV/oC µV dB V m mA A

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

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L78S00 SERIES
ELECTRICAL CHARACTERISTICS FOR L78S18 (refer to the test circuits, Tj = 25 oC, Vi = 26V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 22 to 33 V Io = 5 mA Tj = -55 to 150 oC -1 110 49 21 22 500 3
o

Test Conditions Io = 1 A Vi = 20.5 V

Min. 17.1 17

Typ. 18 18

Max. 18.9 19 360 180 200 8 0.5 1

Unit V V mV mV mV mA mA mA mV/oC µV dB V m mA A

Vi = 20.5 to 30 V Vi = 22 to 28 V Io = 20 mA to 2 A

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

ELECTRICAL CHARACTERISTICS FOR L78S24 (refer to the test circuits, Tj = 25 C, Vi = 33V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 8 to 25 V Io = 5 mA Tj = -55 to 150 oC -1.5 170 48 27 23 500 3 Io = 1 A Vi = 27 V Vi = 27 to 38 V Vi = 30 to 36 V Io = 20 mA to 2 A Test Conditions Min. 23 22.8 Typ. 24 24 Max. 25 25.2 480 240 250 8 0.5 1 Unit V V mV mV mV mA mA mA mV/oC µV dB V m mA A

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

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L78S00 SERIES
ELECTRICAL CHARACTERISTICS FOR L78S05C (refer to the test circuits, Tj = 25 oC, Vi = 10V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 7 to 25 V Io = 5 mA Tj = 0 to 70 C
o

Test Conditions Io = 1 A Vi = 7 to 25 V Vi = 8 to 12 V Io = 20 mA to 1.5 A Io = 2 A Vi = 7 V

Min. 4.8 4.75

Typ. 5 5

Max. 5.2 5.25 100 50 100

Unit V V mV mV mV mA mA mA mV/oC µV dB V

80 8 0.5 1.3 -1.1 40 54 8 17 500 3
o

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

m mA A

ELECTRICAL CHARACTERISTICS FOR L78S75C (refer to the test circuits, Tj = 25 C, Vi = 12.5V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 9.5 to 25 V Io = 5 mA Tj = 0 to 70 C
o

Test Conditions Io = 1 A Vi = 9.5 V

Min. 7.15 7.1

Typ. 7.5 7.5

Max. 7.9 7.95 120 60 140

Unit V V mV mV mV mA mA mA mV/oC µV dB V

Vi = 9.5 to 25 V Vi = 10.5 to 20 V Io = 20 mA to 1.5 A Io = 2 A 100

8 0.5 1.3 -0.8 52 48 10.5 16 500 3

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

m mA A

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L78S00 SERIES
ELECTRICAL CHARACTERISTICS FOR L78S09C (refer to the test circuits, Tj = 25 oC, Vi = 14V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 11 to 25 V Io = 5 mA Tj = 0 to 70 C
o

Test Conditions Io = 1 A Vi = 11 V

Min. 8.65 8.6

Typ. 9 9

Max. 9.35 9.4 130 65 170

Unit V V mV mV mV mA mA mA mV/oC µV dB V

Vi = 11 to 25 V Vi = 11 to 20 V Io = 20 mA to 1.5 A Io = 2 A 100

8 0.5 1.3 -1 60 47 12 17 500 3
o

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

m mA A

ELECTRICAL CHARACTERISTICS FOR L78S10C (refer to the test circuits, Tj = 25 C, Vi = 15V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 12.5 to 30 V Io = 5 mA Tj = 0 to 70 C
o

Test Conditions Io = 1 A Vi = 12.5 V

Min. 9.5 9.4

Typ. 10 10

Max. 10.5 10.6 200 100 240

Unit V V mV mV mV mA mA mA mV/oC µV dB V

Vi = 12.5 to 30 V Vi = 14 to 22 V Io = 20 mA to 1.5 A Io = 2 A 150

8 0.5 1 -1 65 47 13 17 500 3

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

m mA A

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L78S00 SERIES
ELECTRICAL CHARACTERISTICS FOR L78S12C (refer to the test circuits, Tj = 25 oC, Vi = 19V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 14.5 to 30 V Io = 5 mA Tj = 0 to 70 C
o

Test Conditions Io = 1 A Vi = 14.5 V

Min. 11.5 11.4

Typ. 12 12

Max. 12.5 12.6 240 120 240

Unit V V mV mV mV mA mA mA mV/oC µV dB V

Vi = 14.5 to 30 V Vi = 16 to 22 V Io = 20 mA to 1.5 A Io = 2 A 150

8 0.5 1 -1 75 47 15 18 500 3
o

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

m mA A

ELECTRICAL CHARACTERISTICS FOR L78S15C (refer to the test circuits, Tj = 25 C, Vi = 23V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 17.5 to 30 V Io = 5 mA Tj = 0 to 70 C
o

Test Conditions Io = 1 A Vi = 17.5 V

Min. 14.4 14.25

Typ. 15 15

Max. 15.6 15.75 300 150 300

Unit V V mV mV mV mA mA mA mV/oC µV dB V

Vi = 17.5 to 30 V Vi = 20 to 26 V Io = 20 mA to 1.5 A Io = 2 A 150

8 0.5 1 -1 90 46 18 19 500 3

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

m mA A

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L78S00 SERIES
ELECTRICAL CHARACTERISTICS FOR L78S18C (refer to the test circuits, Tj = 25 oC, Vi = 26V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 20.5 to 30 V Io = 5 mA Tj = 0 to 70 C
o

Test Conditions Io = 1 A Vi = 20.5 V

Min. 17.1 17

Typ. 18 18

Max. 18.9 19 360 180 360

Unit V V mV mV mV mA mA mA mV/oC µV dB V

Vi = 20.5 to 30 V Vi = 22 to 28 V Io = 20 mA to 1.5 A Io = 2 A 200

8 0.5 1 -1 110 43 21 22 500 3
o

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

m mA A

ELECTRICAL CHARACTERISTICS FOR L78S24C (refer to the test circuits, Tj = 25 C, Vi = 33V, Io = 500 mA unless otherwise specified)
Symbol Vo Vo Vo Vo Id Id Id Vo T eN SVR Vi Ro Isc Iscp Parameter Output Voltage Output Voltage Line Regulation Load Regulation Quiescent Current Quiescent Current Change Quiescent Current Change Output Voltage Drift Output Noise Voltage Supply Voltage Rejection Operating Input Voltage Output Resistance Short Circuit Current Short Circuit Peack Current Io = 20 mA to 1A Io = 20 mA Vi = 27 to 38 V Io = 5 mA Tj = 0 to 70 C
o

Test Conditions Io = 1 A Vi = 27 V

Min. 23 22.8

Typ. 24 24

Max. 25 25.2 480 240 480

Unit V V mV mV mV mA mA mA mV/oC µV dB V

Vi = 27 to 38 V Vi = 30 to 36 V Io = 20 mA to 1.5 A Io = 2 A 300

8 0.5 1 -1.5 170 42 27 28 500 3

B = 10Hz to 100KHz f = 120 Hz Io 1.5 A f = 1KHz Vi = 27 V

m mA A

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L78S00 SERIES
Figure 4 : Dropout Voltage vs. Junction Temperature. Figure 5 : Peak Output Current vs. Input/Output Differential Voltage.

Figure 6 : Supply Voltage Rejection vs. Frequency.

Figure 7 : Output Voltage vs. Junction Temperature.

Figure 8 : Output Impedance vs. Frequency.

Figure 9 : Quiescent Current vs. Junction Temperature.

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L78S00 SERIES
Figure 10 : Load Transient Response. Figure 11 : Line Transient Response.

Figure 12 : Quiescent Current vs. Input Voltage.

Figure 13 : Fixed Output Regulator.

Figure 14 : Constant Current Regulator.

IO =
Notes : 1. 2. 3. To specify an output voltage, substitute voltage value for "XX". Although no output capacitor is needed for stabili ty, it does improve transient response. Required if regulator is located an appreciable dis-tance from power supply filter.

VXX R1

+ Id

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L78S00 SERIES
Figure 15 : Circuit for Increasing Output Voltage. Figure 16 : Adjustable Output Regulator (7 to 30V).

IR1 5 Id V0 = VXX (1 + R2 R1 ) + Id R2 Figure 18 : High Current Voltage Regulator.

Figure 17 : 0.5 to 10V Regulator.

R1 = IREQ VO = VXX R4 R1

VBEQ1 IQ1 Q1 VBEQ1 R1 ]

IO = IREG + Q1 [IREG

Figure 19 : High Output Current with Short Circuit Protection.

Figure 20 : Tracking Voltage Regulator.

RSC =

VBEQ2 ISC

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L78S00 SERIES
Figure 21 : Positive and Negative Regulator. Figure 22 : Negative Output Voltage Circuit.

(*) D1 and D 2 are necessary if the load is connected between + V0 and V0.

Figure 23 : Switching Regulator.

Figure 24 : High Input Voltage Circuit.

VIN = Vi (VZ + VBE) Figure 25 : High Input Voltage Circuit. Figure 26 : High Output VoltageRegulator.

VIN = VZ - VBE

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L78S00 SERIES
Figure 27 : High Input and Output Voltage. Figure 28 : Reducing Power Dissipation with Dropping Resistor.

VO = VXX + VZ1

R=

Vi(min) VXX VDROP(max) IO(max) + Id(max)

Figure 29 : Remote Shuntdown.

Figure 30 : Power AM Modulator (unity voltage gain, Io 1A).

Note : The circuit performs well up to 100KHz.

Figure 31 : Adjustable Output Voltage with Temperature Compensation.

VO = VXX (1 +

R2 ) + VBE R1

Note :Q 2 is connected as a diode in order to compensat e the vari ati on of the Q 1 VBE wi th the temperature. C all ows a slow rise-t ime of the V O

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L78S00 SERIES
Figure 32 : Light Controllers (Vo min = Vxx + VBE).

VO falls when the light goes up Figure 33 : Protection against Input Short-circuit with High Capacitance Loads.

VO rises when the light goes up

Applications with high capacitance loads and an output voltage greater than 6 volts need an external diode (see fig. 33) to protect the device against input short circuit. In this case the input voltage falls rapidly while the output voltage decreases showly. The capacitance discharges by means of the BaseEmitter junction of the series pass transistor in the regulator. If the energy is sufficiently high, the transistor may be destroyed. The external diode bypasses the current from the IC to ground.

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L78S00 SERIES

TO-3 MECHANICAL DATA
mm MIN. A B C D E G N P R U V 11.00 0.97 1.50 8.32 19.00 10.70 16.50 25.00 4.00 38.50 30.00 TYP. MAX. 13.10 1.15 1.65 8.92 20.00 11.10 17.20 26.00 4.09 39.30 30.30 MIN. 0.433 0.038 0.059 0.327 0.748 0.421 0.649 0.984 0.157 1.515 1.187 inch TYP. MAX. 0.516 0.045 0.065 0.351 0.787 0.437 0.677 1.023 0.161 1.547 1.193

DIM.

P G

A

D

C

U

V

O

N

R

B

P003F
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E

L78S00 SERIES

TO-220 MECHANICAL DATA
DIM. MIN. A C D D1 E F F1 F2 G G1 H2 L2 L4 L5 L6 L7 L9 DIA. 13.0 2.65 15.2 6.2 3.5 3.75 0.49 0.61 1.14 1.14 4.95 2.4 10.0 16.4 14.0 2.95 15.9 6.6 4.2 3.85 0.511 0.104 0.598 0.244 0.137 0.147 4.40 1.23 2.40 1.27 0.70 0.88 1.70 1.70 5.15 2.7 10.40 0.019 0.024 0.044 0.044 0.194 0.094 0.393 0.645 0.551 0.116 0.625 0.260 0.165 0.151 mm TYP. MAX. 4.60 1.32 2.72 MIN. 0.173 0.048 0.094 0.050 0.027 0.034 0.067 0.067 0.203 0.106 0.409 inch TYP. MAX. 0.181 0.051 0.107

A

C

D1

L2 F1

D

G1

E

Dia. F2 F

L5 L7 L6

L9

L4

G

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H2

P011C

L78S00 SERIES

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsability for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may results from its use. No license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use ascritical components in life support devices or systems without express written approval of SGS-THOMSON Microelectonics. © 1994 SGS-THOMSON Microelectronics - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A

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