Circuit Description—PS 503A
25
Fig.
5-1.
Simplified
block diagram
of PS 503A.
Load Regulation
With
no load connected to the output terminals, all of
the
output current flows through feedback divider R50A-
R50B-R42 (approximately
2
mA/V) and back to the minus
side of
C10. When a load is connected
to the output
terminals,
output
current must increase to maintain the
output
voltage.
An increase
in
output current
cannot occur unless the
drive
to
the base of Q85 and the series-pass transistor
(located in
power
module) is also increased. The increase
in
the voltage differential between pin 2 and 3
of U45
necessary
to
drive Q85
and the series-pass transistor
(refer to
the discussion of constant voltage/current limited
operation) is obtained by applying the lower
voltage at the
+
output
terminal
to the inverting input (pin 2) of U45
causes
a more positive output
at pin 6 of U45, reducing the
conduction of CR45.
The current no longer going through
CR45
now goes to the base of Q85.
Fig. 5-2. Operating
charactertistics with various voltages,
current,
and loads.
Power
Line Regulation
Q1
5 and
associated components make-up a
shut-down
equalizer
circuit. When the TM 500 Series Power Module
5-2
Summary of Contents for PS 503A
Page 1: ...Tektronix COMMITTED TO EXCELLENCE PS 503A DUAL POWER SUPPLY INSTRUCTION MANUAL...
Page 4: ...Fig 1 1 PS 503A Dual Power Supply plug in module PS 503A...
Page 36: ...Options PS 503A OPTIONS No options are available at this time...
Page 41: ...I8S4 OX R V P FEB IR77 PS 5O3A...
Page 42: ...is 4 qx FL V P FEB IR77 Poweb Supply J bm bowo t above...
Page 45: ...TO...
Page 46: ...1834 04...
Page 47: ...PARTIAL POWER SUPPLY...
Page 52: ...REV A DEC 1975 21...
Page 53: ......
