SG29125/125A

12/90 Rev 1.1 2/94

Copyright

© 1994

11861 Western Avenue

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∞

∞

∞

∞ Garden Grove, CA 92841

1

(714) 898-8121

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∞ FAX: (714) 893-2570

FEATURES

••••• 2% Internally Trimmed Output

••••• Two regulated outputs

••••• Output current in excess of

1000mA

••••• Low quiescent current standby

regulator

••••• Input-output differential less than

0.6V at 0.5A

••••• Reverse battery protection

••••• 60V load dump protection

••••• -50V reverse transient protection

••••• Short circuit protection

••••• Internal thermal overload protec-

tion

••••• Available in plastic TO-220

••••• ON/OFF switch for high current

output

DESCRIPTION

The SG29125/125A is a dual 12V/5V positive voltage regulator. One output is a high

current (up to 1000 mA) regulator that can be turned on or off by a high impedance low

current TTL compatible switch. The second or standby output remains on regardless.

The on/off switch not only shuts off the high current output but actually puts the IC in

a micropower mode making possible a low quiescent current. This unique character-

istic coupled with an extremely low dropout, (.55V for output current of 10mA) makes

the SG29125/125A well suited for power systems that require standby memory. The

SG29125/125A includes other features which were originally designed for automotive

applications. These include protection from reverse battery installations and double

battery jumps. The high current regulator has overvoltage shutdown to protect both

the internal circuitry and the load during line transients, such as load dump (60V). In

addition, the high current regulator design also has built-in protection for short circuit

and thermal overload. During these fault conditions of the primary regulator the

standby regulator will continue to power its load.

The SG29125 is the 12 volt, ±5% version of a family of dual regulators with a standby

output voltage of 5V. Other high current outputs of 5 and 8.2 volts are available. Also

available is the SG29125A which offers an improved output voltage tolerance of ±2%.

They are available in the plastic TO-220 power package and are designed to function

over the automotive ambient temperature range of -40

°C to 85°C.

LOW DROPOUT DUAL REGULATOR

TYPICAL APPLICATION CIRCUIT

* Required if regulator is located far from power

supply filter.

** Required for stability. May be increased without

bound. Capacitor must be rated to operate at the

minimum temperature expected for the regulator

system.

OVERVOLTAGE

THERMAL

SHUTDOWN

REGULATOR

BIAS

1.23V

REFERENCE

5V STANDBY

REGULATOR

5.6V

OUTPUT VOLTAGE

(12V, 1000mA)

STANDBY OUTPUT

(5V, 50mA)

INPUT VOLTAGE

ON/OFF SWITCH

(for output voltage only)

GROUND

C1

*

0.1

µF

C3

**

10

µF

C2

**

10

µF

2

5

3

1

4

SG29125/125A