SG137A/SG137 SERIES

2/92 Rev 1.1 2/94

Copyright

© 1994

11861 Western Avenue

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the SG137A flows from input to output. If this current is not

absorbed by the load, the output of the regulator will rise above

the regulated value. The current drawn by R

high enough to absorb the current, but care must be taken in no–

load situations where R

value for the operating current, which must be absorbed, is 5mA

for the SG137A, If input-output voltage differential is less than

10V, the operating current that must be absorbed drops to 3mA.

The output stability, load regulation, line regulation, thermal

EXAMPLES:

1. A precision 10V regulator to supply up to 1Amp load current.

a. Select R

b. Calculate R

2

=

=

= 704W

2. A 15V regulator to run off batteries and supply 50mA.

V

a. To minimize battery drain, select R

1

as high as possible

R

= 417

Ω, use 404Ω, 1%

V

(V

10V - 1.25V

(1.25V/100W) + 65mA

1.25V

3mA

TYPICAL APPLICATIONS

regulation, temperature drift, long term drift, and noise, can be

improved by a factor of 6.6 over the standard regulator configu-

ration. This assumes a zener whose drift and noise is considera-

bly better than the regulator itself. The LM329B has 20PPM/°C

maximum drift and about 10 times lower noise than the regulator.

In the application shown Figure 8, regulators #2 to #N will track

regulator #1 to within ±24mV initially, and to ±60mV over all load,

line, and temperature conditions.

If any regulator output is

shorted to ground, all other outputs will drop to

-2V.

Load

regulation of regulators #2 to #N will be improved by V

compared to a standard regulator, so regulator #1 should be the

one which has the lowest load current.

FIGURE 11 - DUAL TRACKING SUPPLY ±1.25V to ±20V

FIGURE 10 - CURRENT REGULATOR

FIGURE 9 - HIGH STABILITY REGULATOR

FIGURE 8 - MULTIPLE TRACKING REGULATORS