Datasheet

www.keithley.com
1.888.KEITHLEY
(U.S. only)
26
SWITCHING AND CONTROL
A GREATER MEASURE OF CONFIDENCE
3750
Multifunction Control Card
40 digital I/O bits, 2 analog output channels, and 4 counters
Channels 1–5: Bidirectional, high current digital I/O (40 bits)
Channels 6–9: 32-bit counters (4 counters)
Channels 10–11: Isolated voltage or current analog outputs (2 each)
Digital
Inputs
or
Digital
Outputs
Total of 5 banks
8 bits per bank
Channels
1–5
1
2
3
4
8 Bits
5
6
7
8
Bank 1
Counter
Total of 4 counters
Gate +
Gate –
32 Bit
Count
Input +
Input –
Counter 1
TTL
or
AC
Channels
6–9
Total of 2 analog outputs
(isolated from earth)
Channels
10–11
VOUT
±12V
(0–20mA)
(4–20mA)
VCOM
IOUT
ICOM
Analog Output 1
16 Bits
DAC
VOUT
IOUT
10mA max.
Sourcing Only
300mA max.
Sinking Only
Optional Jumper
Self
Resetting
Input
Simplified Digital I/O Schematic
System 5V
Output
Pull-up
Resistor
~68kΩ
Pull-up Voltage
(8 DIO)
+
–
DIO n
Logic Supply
(50mA max.)
V EXTERNAL
(VEXT1, VEXT2)
(30V max.)
Specifications
DIGITAL I/O
1
CONFIGURATION: 40 bidirectional digital I/O bits arranged in 5 banks of 8 bits each.
Each bank can be configured for either input or output capability. 1 bank of I/O is equivalent
to 1 system channel.
DIGITAL INPUT SPECIFICATIONS
An internal weak pull-up resistor of approximately 68kW is provided on the card for each I/O.
This pull-up resistor can be removed via onboard jumper on a channel (8 bit) basis. The pull-up
voltage can either connect to the internally supplied 5V or an externally supplied voltage of up
to 30V via onboard jumper. An internal 5V supply connection is separately available to run
external logic circuits.
DIGITAL INPUT LOGIC LOW VOLTAGE: 0.8V max.
DIGITAL INPUT LOGIC HIGH VOLTAGE: 2V min.
DIGITAL INPUT LOGIC LOW CURRENT: –600μA max @ 0V.
DIGITAL INPUT LOGIC HIGH CURRENT: 50μA max @ 5V.
LOGIC: Positive true.
SYSTEM INPUT MINIMUM READ SPEED
2
: 1000 readings/second.
MAXIMUM EXTERNALLY SUPPLIED PULL-UP VOLTAGE: 30V.
MAXIMUM EXTERNALLY SUPPLIED VOLTAGE TO ANY DIGITAL I/O LINE: Pull-up voltage
(5V internal or up to 30V external).
DIGITAL OUTPUT SPECIFICATIONS
Each output has an internal fly-back diode for driving inductive loads. Each output is protected
against continuous short circuits and over temperature. An internal 5V supply connection is
separately available to run external logic circuits.
DIGITAL OUTPUT LOGIC HIGH VOLTAGE: 2.4V minimum @ Iout = 10mA, sourcing only.
DIGITAL OUTPUT LOGIC LOW VOLTAGE: 0.5V maximum @ Iout = -300mA, sinking only.
MAXIMUM OUTPUT SINK CURRENT: 300mA per output, 3.0A total per card.
LOGIC: Positive true.
SYSTEM OUTPUT MINIMUM WRITE SPEED
3
: 1000 readings/second.
MAXIMUM EXTERNALLY SUPPLIED VOLTAGE TO ANY DIGITAL I/O LINE: Pull-up voltage
(5V internal or up to 30V external).
ALARM: Trigger generation is supported for a maskable pattern match or state change on any of
channels 1 through 5.
PROTECTION: Optional disconnect (set to inputs) during output fault conditions.
INTERNAL 5V LOGIC SUPPLY: The internal logic supply is designed for powering external logic
circuits of up to 50mA maximum. The logic supply is internally protected with a self-resetting
fuse. Fuse reset time < 1 hour.
NOTES
1. All channels power up configured as inputs.
2. All channels configured as inputs.
3. All channels configured as outputs.
Figure 2. Simplified I/O schematic
Figure 1. Block diagram
Model 3750 specifications Model 3750 specifications