DBK54-Channel Current-Output CardFeatures• Provides four isolated 4 to 20 mA current outputs• Complies with current loop resistancesof up to 1950 Ohms
• Compatible with 12V to 45V current
loop supplies• Features predictable power-on andfault states• Provides 12-bit resolution
The DBK5 current-output card provides
IOtech’s data acquisition systems with theability to control four isolated 4 to 20 mA
current loops*. The DBK5 acts as a current
loop transmitter by modulating current froman external loop power source. The DBK5 canbe programmed with a static value whenever
the data acquisition system is not transferring
A/D data. As many as 64 DBK5s can be usedin one system to ­obtain up to 256 outputs.
Architecture. Each of the DBK5’s channels
contains a 12-bit D/A converter to set theloop current. All channels are opticallyisolated from the data acquisition systemand from one another by 500V. A regulator
allows the isolated circuitry to draw powerfrom the external loop power supply. The
card’s current buffers provide per-channel
trim adjustments via potentiometers. (Seediagram at right for DBK5 architecture.)

The DBK5 current-output card controls four isolated 4 to 20 mA current loops

DBK5 Current-Output Card Block Diagram
Regulator
Optocouplers

DAC

Current
bufferZero
adjustCardaddress
dipswitch

P1Applications. The DBK5 is ideal for applications that require test and calibration ofcurrent loop receivers, including actuators
or final-control elements such as pneumatic valves and hydraulic cylinders. It isalso useful for research applications that
require control of such actuators.

Sub-channel
address
dipswitch

Spanadjust

Regulator
OptocouplersDAC

Current
bufferSS&H
4A 3- A 02

G 1- G 0

ZeroadjustµP

SpanadjustRegulator
Optocouplers

DAC

Current Loop. The DBK5 is compatible withregulated or unregulated loop supplies of
12 to 45 VDC. It also provides compliancewith loop resistances of up to 1950 Ohms,depending on the source magnitude.

Current
bufferZeroadjustSpanadjustRegulator
Optocouplers

DAC

Current
bufferZeroadjustSpanadjust* Not recommended for closed-loop control greaterthan 1 Hz

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DBK5Specifications & Ordering Information
Ordering Information

A Typical DBK5 Application

Description
4-channel current-output card

CablesLoop Power Supply *Vloop+ –Daq
Data Acquisition System
P1

Current Loop Transmitter
DBK5+(1-channel)–

Part No.
DBK5

Current Loop Transmitter
Receiver*Rloop* User-supplied

For use with DBK10, use CA-37-x ribbon cable, orcontact factory of additional cabling options
For use with DBK60 or LogBook/360, no cable isrequired (except from DBK60 or LogBook/360 tothe A/D mainframe)
For use with no enclosure, use CA-37-x where x is thenumber of DBK devices attached
For use with DaqLab Series (internal slots), use
CA-255-2T with one board, or CA-37-2 for use with
two DBK cards (or contact factory for additionalcabling options)

Product Compatibility
Isolation. The DBK5 provides 500V
­channel-to-channel and 500V channelto-­system optical isolation for system
protection.
Current Loop-Powered Outputs. Since
the isolated outputs of the DBK5 are loop
powered, the card maintains control of theloop current even when the data acquisition system is powered down. When loop
power is first applied, the DBK5’s outputs
assume their 4 mA default state. If at any
time the data acquisition system’s poweris lost or communication with the dataacquisition system fails, the DBK5’s outputs
retain their last set values.

Specifications

Connectors: DB37 male, mates with P1**; screw ­terminals
for signal outputs
Accuracy/Linearity: 0.1% full scale
Resolution: 4 µA/LSB, monotonic
Hysteresis: 0.02% full scale
Regulation: 0.05% full scale
Isolation Voltage
Channel-to-Channel: 500V
Channel-to-System: 500V
Voltage Range:  Vloop = 12 to 45VCompliance: Rloop = (Vloop - 6) / 0.020✔ DaqBook✔ DaqLab✔ DaqScan✔ DaqBoard/2000 Series

Example Voltage
MDR†@ Vexc = 35V
1450 Ohms@ Vexc = 25V
950 Ohms@ Vexc = 15V
450 Ohms
Power Consumption:  135 mW** Attachment to the DaqBoard/2000 Series requires a DBK200, DBK202, DBK203A, DBK209, DBK213, orDBK214† MDR (maximum drive resistance)

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