Theory Of Operation; Power Supply; Integrated Circuit U1 - HP LOGIC PULSER 546A Operating And Service Manual

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Modei546A
THEORY OF OPERATION
The major circuits of the Pulser are contained in integrated circuit U1 as shown in Figure 9. Operating
voltage is supplied by a power supply and outputs are sent to the output drive circuits and to the dis-
play LED's.
Power
Supply
The power supply converts the de input voltage to a regulated voltage for low power logic. The circuit
provides reverse voltage and overvoltage protection.
Integrated Circuit U1
Several functions are provided by U1 as described in the following paragraphs.
VOLTAGE REGULATOR.
Provides voltage and temperature compensated reference and control cir-
cuitry for the low voltage logic on the IC.
MODE SELECT CONTROL. Determines whether the instrument is programming a mode or execut-
ing a mode and when to reset.
SWITCH INPUT CONTROL.
Presets the time base/counter and burst control circuit; generates a
single-shot pulse to the output and debounces the switch.