HP 13255 Technical Information page 12

13255
Power Supply Module
13255-91142/10
Rev SEP-06-77
3.2.4
3.2.5
3.2.6
3.2.7
3.2.8
guarantee that both the chopper transistors can never be turned on at
the same time, and in fact, guarantees a delay of 2 microseconds be-
tween one turning off and the next one turning on.
Voltage Variable One-Shot.
This block accepts the error correction
~oltage
from the regulator
block and outputs a pulse which varies from about 5 microseconds to 18
microseconds depending on the value of the correction voltage. The re-
petition rate ot the pulse is 50 kHZ and is triggered by the output of
the divide-by-l00 block.
Fegulator.
This blOCK senses the +5 volt supply on the power Supply peA and gen-
erates a correction voltaqe which is applied to the voltage variable
one-shot block. The control which adjusts the output voltage of the
supply is located in this block.
Power On Reset.
The Power On (PWR ON) siqnal is a logic line that is held low until
about 100 milliseconds after the +5 volt supply comes UP. Power on
reset will occur whenever the +5 volt supply goes low and then recovers
(e.g., after a current limit condition).
4.915 MHz Oscillator.
The 4.915 ~Hz oscillator is a crystal oscillator Which generates the
Syste~
CLOCK (SYS eLK) signal that is buffered by a driver gate and
applied to tne loqic bus.
Divide-By-100 Counter.
This block divides the System Clock signal by 100 In order to make a
usable clock rate for the power supply.