The L7900 series of three-terminal negative
regulators is available in TO-220, ISOWATT220
TO-3 and D
2
PAK packages and several fixed
output voltages, making it useful in a wide range
of applications.Theseregulators can providelocal
on-card regulation, eliminating the distribution
problems associated with single point regulation;
furthermore, having the same voltage option as
the L7800 positive standard series, they are
particularly suited for split power supplies. In
addition, the -5.2V is also available for ECL
system.If adequate heat sinking is provided,
they can deliver over 1.5A output current.
Although designed primarily as fixed voltage
regulators, these devices can be used with
externalcomponentstoobtainadjustable
voltagesand currents.
SCHEMATICDIAGRAM
1
2
TO-3
TO-220ISOWATT220
D2PAK
3
1
3
2
1
April 1997
1/13
Page 2
L7900
ABSOLUTE MAXIMUMRATINGS
SymbolParameterValueUnit
DC Input Voltage (forVO=5 to 18V)
V
i
OutputCurrentInternally limited
I
o
P
Power DissipationInternally limited
tot
Operating Junction Temperature Range0 to 150
T
op
StorageTemperatureRange- 65 to 150
T
stg
(forV
= 20, 24V)
O
THERMAL DATA
SymbolParameterD2PAKTO-220ISOWATT220TO-3Unit
R
thj-case
R
thj-amb
Thermal Resistance Junction-caseMax
Thermal Resistance Junction-ambient Max
OutputNoise VoltageB = 10Hz to 100KHz Tj=25oC125µ V
e
N
SVRSupply Voltage Rejection∆V
V
Dropout VoltageIo=1ATj=25oC
d
ShortCircuit Current2A
I
sc
I
ShortCircuit Peak CurrentTj=25oC2.5A
scp
* Load and line regulation are specified at constant junction temperature. Changes in Vodue to heating effects must be taken into account
separately. Pulce testing with low duty cycle is used.
=-9 to -21 V
V
i
=-9 to -12 V Tj=25oC
V
i
= 250 to 750mATj=25oC
I
o
=10Vf=120Hz5460dB
i
=100mV
∆V
O
-4. 95-5. 2-5. 45V
105
52
105
52
mV
mV
mV
mV
1.4V
3/13
Page 4
L7900
ELECTRICALCHARACTERISTICS FOR L7906C (refer to the test circuits,Tj= 0 to150oC,
OutputNoise VoltageB = 10Hz to 100KHz Tj=25oC175µ V
e
N
SVRSupply Voltage Rejection∆V
V
Dropout VoltageIo=1ATj=25oC
d
ShortCircuit Current1.5A
I
sc
I
ShortCircuit Peak CurrentTj=25oC2.5A
scp
* Load and line regulation are specified at constant junction temperature. Changes in Vodue to heating effects must be taken into account
separately. Pulce testing with low duty cycle is used.
=-11.5to -23 V
V
i
=-11 to -17V Tj=25oC
V
i
= 250 to 750mATj=25oC
I
o
=10Vf=120Hz5460dB
i
=100mV
∆V
O
-7.6-8-8.4V
160
80
160
80
mV
mV
mV
mV
1.1V
4/13
Page 5
L7900
ELECTRICALCHARACTERISTICS FOR L7912C (refer to the test circuits,Tj= 0 to150oC,
OutputNoise VoltageB = 10Hz to 100KHz Tj=25oC250µ V
e
N
SVRSupply Voltage Rejection∆V
V
Dropout VoltageIo=1ATj=25oC
d
ShortCircuit Current1.3A
I
sc
I
ShortCircuit Peak CurrentTj=25oC2.2A
scp
* Load and line regulation are specified at constant junction temperature. Changes in Vodue to heating effects must be taken into account
separately. Pulce testing with low duty cycle is used.
=-18.5to -30 V
V
i
=-20 to -26V Tj=25oC
V
i
= 250 to 750mATj=25oC
I
o
=10Vf=120Hz5460dB
i
=100mV
∆V
O
-14. 3-15-15. 7V
300
150
300
150
mV
mV
mV
mV
1.1V
5/13
Page 6
L7900
ELECTRICALCHARACTERISTICS FOR L7918C (refer to the test circuits,Tj= 0 to150oC,
OutputNoise VoltageB = 10Hz to 100KHz Tj=25oC350µ V
e
N
SVRSupply Voltage Rejection∆V
V
Dropout VoltageIo=1ATj=25oC
d
ShortCircuit Current0.9A
I
sc
I
ShortCircuit Peak CurrentTj=25oC2.5A
scp
* Load and line regulation are specified at constant junction temperature. Changes in Vodue to heating effects must be taken into account
separately. Pulce testing with low duty cycle is used.
=-24 to -35V
V
i
=-26 to -32V Tj=25oC
V
i
= 250 to 750mATj=25oC
I
o
=10Vf=120Hz5460dB
i
=100mV
∆V
O
-19-20-21V
400
200
400
200
mV
mV
mV
mV
1.1V
6/13
Page 7
L7900
ELECTRICALCHARACTERISTICS FOR L7922C (refer to the test circuits,Tj= 0 to150oC,
OutputNoise VoltageB = 10Hz to 100KHz Tj=25oC400µ V
e
N
SVRSupply Voltage Rejection∆V
V
Dropout VoltageIo=1ATj=25oC
d
ShortCircuit Current1.1A
I
sc
I
ShortCircuit Peak CurrentTj=25oC2.2A
scp
* Load and line regulation are specified at constant junction temperature. Changes in Vodue to heating effects must be taken into account
separately. Pulce testing with low duty cycle is used.
1. To specify an output voltage, substitute voltage value for ”XX”.
2. Required for stability. For value given, capacitor must be solid
tantalum. If aluminium electrolitics are used, at least ten times
value should be selected. C
appreciable distance from power supply filter.
3. To improve transient response. If large capacitors are used, a
high current diode from input to output (1N4001 or similar) should
be introduced to protect the device from momentary input short
circuit.
is required if regulator is located an
1
Against potential latch-up problems.
Figure3 : Circuit for IncreasingOutput Voltage.Figure 4 : High CurrentNegative Regulator
(– 5V/4Awith 5A currentlimiting).
R
+
R
1
=
V
V
O
XX
2
R
2
V
XX
> 3
I
d
R
2
C3 Optional for improved transient response and ripple rejection.
Figure5 : TypicalECL System Power Supply
(– 5.2V/4A).
Optional dropping resistor to reduce the power dissipated in the
boost transistor.
Information furnished is believed to be accurateand reliable.However, SGS-THOMSONMicroelectronics assumes no responsabilityfor the
consequences of use of such informationnor for any infringement of patents or other rights of third parties whichmay resultsfrom its use. No
licenseis granted by implication or otherwise underanypatent orpatent rights ofSGS-THOMSON Microelectronics. Specifications mentioned
in this publicationare subject to change without notice.This publicationsupersedesand replaces all informationpreviously supplied.
SGS-THOMSONMicroelectronicsproducts are notauthorizedfor useas critical components in lifesupport devicesor systems withoutexpress
writtenapproval of SGS-THOMSONMicroelectonics.
1997 SGS-THOMSONMicroelectronics- Printedin Italy - All Rights Reserved
Australia- Brazil- Canada- China - France - Germany - Hong Kong- Italy- Japan - Korea - Malaysia - Malta - Morocco- TheNetherlands -
Singapore- Spain- Sweden - Switzerland- Taiwan - Thailand - United Kingdom- U.S.A
SGS-THOMSONMicroelectronics GROUPOF COMPANIES
.
13/13
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