976 Quad 250-MHz Counter/Timer

clock

provide1 MHzCrystal controlled internal clock±50 ppm. The clock period is1μsWhen, the temperature coefficient
<2 ppm/°C, jitter<3 ppm, the clock period is1 mstime<5 ppm。

time delay
uncertainty

equal to one clock cycle.

CH 1、2、
3 & 4 IN

Accept the positiveTTLor fast negativeNIMsignal. The minimum pulse width is2 ns. The pulse pair resolution is4 ns. Accept Gundam250 MHz。Z_in= 50 Ω。LEMO 00connector.

No.5
partIN

Accept Gundam80 MHzof righteousnessTTLor fast negativeNIMsignal.Z_in= 50 Ω。LEMO 00connector.

CH 1and3door

Accept the positiveTTLor fast negativeNIMlevel.Z_in= 50 Ω。LEMO 00connector.

CH 2and4door

Accept the positiveTTLor fast negativeNIMsignal. The bridge input allows a variety of connections.Z_in= 1kΩ。LEMO 00connector.

CH 2 & 4carry

Provides fastNIMoutput, allowing cascading operations.LEMO 00connector.

reset

input clears all four counter inputs and accepts positiveTTLor fast negativeNIMlevel.Z_in= 50 Ω。LEMO 00connector.

Load

The input terminal accepts positiveTTLor fast negativeNIMsignal.Z_in= 50 Ω。Lemo 00connector. Load the thumbwheel switch preset5Part counter. inREPmode will disable the loading input, while inSGLThe counter starts counting in mode.

Please note that if the5Some counters have errors due to the following reasons:
• Use greater than80 MHzexternal clock.
• Use pulse width<3 nsexternal clock.
• Change the external clock frequency.
• Switch from internal clock to external clock.

LOAD(Load) input signal (orLOADbutton) will reset the5part.

OUT

As long as the counter content is not zero, two independent outputs provide negativeNIMLevel output (-800 mV). The trailing edge of an input pulse will initiateNIMlevel output, and the trailing edge of an input pulse switches the output to zero.

end tag

NegativeNIMLevel output (-800 mV). The pulse width can be50 nsto1 μsadjust between.

CH 1、2、3
& 4 standard,
door,GT &
CLRswitch

Switch counter mode:
• Standard – The counter free runs and increments based on the input.
• door – The counter only runs in the presence of the door.
• GT& clear - The counter operates in the presence of the gate, and the leading edge of the gate clears the contents of the counter.

A logic signal at the reset input resets all four counters to zero, and individual channels can also be manually reset by pressing the corresponding channel's reset button.

RST CH1、CH2、
CH3 & CH4
switch

The corresponding channel can be manually reset to zero by pressing a button.

end tag
(trimming potentiometer)

Screwdriver adjustment controls are available at50 nsand1 μsAdjust the pulse width of the end mark.

SGL/REPswitch

Used to switch the5part of the operating mode.SGLor single mode is disabled during countingLOADinput terminal.LOADThe input can start a new count after the count is complete. After starting, the counter will count to zero and then stop.LOADThe button can start a new count at any time, even during a count. Note that the counter will delay accepting manualLOADPulse (use button)80 ns。REPOr the repeating pattern will end at the end of the cycle2Generate an automaticLOADpulse. Connect the closing tag output toLOADThe input terminal can eliminate the2seconds delay. inREPmode,LOADThe input is disabled. Note thatLOADThe button can still be used to restart the count at any time.

counter/timer switch

Used to switch the function of the fifth channel, used as a counter or timer.

1 µs/1 ms
switch

Used to switch the clock frequency in "Timer" mode to1 μslocational1 MHzand1 mslocational1 kHz。

LOAD(Load) switch

The push button switch can be5Part of the counter or timer mode loads the thumbwheel settings.

Please note that if the5Some counters have errors due to the following reasons:
• Use greater than80 MHzexternal clock.
• Use pulse width<3 nsexternal clock.
• Change the external clock frequency.
• Switch from internal clock to external clock.

LOADbutton (orLOADinput signal) will reset the5part.

Thumbwheel switch

Seven-section switch, can be the5Part of the counter or timer settings preset value.

Required power supply

+6 V, 0.7 A; –6V, 0.9 A

weight

Net weight:1.02Kilogram (2.3pounds). Shipping weight:3.7Kilogram (8.2pounds).

Size

NIMStandard double wide module,6.90 x 22.13cm (2.70 x 8.714inches) front panel, conforming toDOE/ER-0457Trequirements.

Model

Description

976

four way250-MHzcounter/timer