Outputs; Error Output; Period, Delay And Width Generation - HP 8112A Operating, Programming And Servicing Manual

Period, Delay and Width
Generation
Because CUR REF, FRQ IN and TIME IN are virtual earth inputs,
the external input currents can be produced by a voltage source and
series resistance. The control mode functions (PERC, DELC, WIDC)
are produced by feeding the conditioned control input voltage to the
TIME IN input of the relevant timing IC. The approximate value of
current drawn by the input current pins is shown below.
Table 10.3-5. Reference current input levels
Reference Current
mode approx 80 PA 2 mA - 0.2 mA 0.2 mA const
RATE
mode approx 80 PA
TIME
mode approx 80 PA
C T R L

outputs

The three outputs of the Timing ICs (OUT, OUT, ERROR OUT)
are all open-collector with a fixed current (HI = 0 mA, LO = 12 mA)
and a fixed transition time of 2.5 ns.
Error Output. The error output from the timing IC indicates that
a trigger signal has been received before the completion of the
previously triggered event.
Period, Delay and Width signals are generated by Timing ICs U200,
I
(LEE 8 TRE MUST BE LESS THAN WIDTH)
Figure 10.3-2. Example of signal generation
Period Generator
The period generator operating in the RATE mode produces 50%
duty cycle square wave output pulses at a repetition rate governed
by the analog current input (from the Period DAC or Control Input)
and the internal range data.
FRQ IN
2
2
L I
WIDTH (WIDTH MUST BE LESS
THAN PERIOD)
Servicing the Timing and 10.3-5
TIME IN
0.2
2
(DEL MODE)
OUTPUT (DEL MODE)
Slope Generators