Datasheet
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34980A system control modules
34950A 64-bit digital I/O with memory and counter
This module can be used to simulate or detect digital patterns. It has eight 8-bit digital I/O channels with
handshaking, pattern memory, two 10 MHz counters with gate functions, and a programmable clock
output.
Digital input/output
The digital I/O bits are organized into two banks of 32-bits. The I/O bits can be configured and
programmed as inputs or outputs in 8-bit channels. The digital outputs can be configured as active drive
or open drain outputs with a 10 kΩ pull up. User supplied pull up resistors for up to 5 V outputs are also
acceptable. The digital inputs have programmable thresholds up to 5 V for compatibility with most digital
logic standards.
The onboard pattern memory can be used to select and output digital stimulus or bit- stream patterns, or
to capture external digital data. Each bank has independent memory and directional control so that one
bank can output data while the other captures data. The memory can be divided up to 64 Kbytes per 8-bit
channel.
Specifically, the digital I/O channels also have:
• Variable active high drive output from 1.65 V to 5 V or open drain
• Variable input thresholds from 0 V to 5 V
• Configurable handshaking protocols including synchronous, and strobe
• Programmable polarity
• Source or sink up to 24 mA with a Imax of 400 mA per module.
• Internal alarming for maskable pattern match
• 1 hardware pattern interrupt per bank
• Connections via standard 78-pin Dsub cables or detachable terminal block
Frequency counter/totalizer
The two channels can be used to count digital events, frequency, period, duty cycle, totalize, and pulse
width. The counter/ totalizer also includes:
• Programmable gate functionality
• Programmable input thresholds levels 0 V to 3 V
34950A 64 bit I/O
Digital input/output characteristics
Number of channels
Eight 8 bit. Input or output, non-isolated
Vin
0 V – 5V
1
Vout
1.65 V – 5 V
1,2
Iout
(max) 24 mA
2
Frequency (max)
10 MHz
3
I
load
(max)
400 mA
t
rise
+ t
fall
(typ)
6 ns
5
Handshake lines
Vin
0 V – 5V
Vout
1.65 V – 5 V
2,4
Iout (max)
24 mA
2
Frequency (max)
10 MHz