DBK18

4-Channel Low-Pass Filter & Amplifier CardFeatures• Provides four independent 3-pole lowpass filter channels• Provides a separate ­instrumentation
amplifier input stage for each ­channel• User-configurable from DC to 50 kHz
cut-off• One system can accept up to 64 DBK18
cards for a total of 256 ­inputs
The DBK18 low-pass filter card provides
IOtech’s data acquisition systems with four
low-pass filters that can be individuallyconfigured for a cut-off frequency fromDC to 50 kHz Butterworth. Each DBK18
provides four channels of differential voltage input. The systems’ 16 analog input
channels can each accept four DBK18 cards,
for a total of 256 analog input ­channels
with low-pass filtering.

See DBK45 for SSH plus low-pass filter

The DBK18 provides four individually configured low-pass filters

Each of the DBK18’s four channels ­features
an instrumentation amplifier with switch-­selectable gains of x1, 10, 100, 200, and500. Each channel is also equipped witha location for a user-selected gain resistor,
allowing you to select a custom gain rangeof up to x500. Each of the instrumentation amplifier input stages are followed
by separate active low-pass filter stages
whose outputs are connected to an ­output
multiplexer stage.

DBK18 Low-Pass Filter Card Block Diagram
Gain set switch

Filterenable/bypass
headerBypass

10K

Ch 1

200pF

Low-pass Enablefilter

IA200pF

The DBK18’s frequency-determined ­resistor
and capacitor locations are on machinedpin IC sockets for maximum flexibility.
The card is provided with blank plug-in
headers for each channel, to which passive
components for particular frequencies canbe added. Pre-configured plug-in headers
for several preselected cutoff frequencies
are optionally available.

Cardaddressrecognition
circuitENB

Ch 2

Low-pass filter
per channel

IACh 4IA

Low-pass filter
per channelIA

Low-pass filter
per channel

P1

Channel address lines

RCmD+V2

Outputchannel
selection
HDR

Mux
Ch 3

The DBK18 is equipped with BNC input connectors. Its differential inputs are equippedwith switchable 100k bias ­resistors that arereferenced to analog common.

RCmE

RCmF

2

RCmH–V

10VOUT

91213

87

14

150K
1000pF

20K

Note: The DBK18 is also recommended for highgain DC applications.

Signalout

10K

VIN

RCmA

45–+

–50K

A46RCmB

1000pF

UAF42+–A150K+

A2

32RCmC–+A3

11
RCm components are containedin plug-in frequency modules

Note: Ch 1 is typical of Ch 2, Ch 3, and Ch 4

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DBK18Specifications & Ordering Information
Specifications

Connector: DB37 male, mates with P1*; signal inputs
accepted via BNC connectors
Number of Channels: 4
Number of Cards Addressable: 64Input Type: Differential
Voltage Input Ranges:
0 to ±5 VDC
0 to ±500 mVDC
0 to ±50 mVDC
0 to ±25 mVDC
0 to ±10 mVDC
For Custom Gains:

R user =40,000- 80
Gain-1(Ohms)

Input Amplifier Slew Rate: 12 V/µs min
Input Gains: x1, 10, 100, 200, 500, and user determined up to 500
Input Offset Voltage: [500 + 5000/G] µV max (nullable)
Input Offset Drift: [±5 + 100/G] µV/˚C max
Input Bias Current: 100 pA max
Input Offset Current: 50 pA max
Input Impedance: 5 x 1012 Ohms parallel with 6 pF
Switchable Bias Resistors: 100 kOhms each to analog
commonGain Errors:x1		
±0.04% max
x10±0.1% max
x100±0.2% maxx200
±0.4% maxx500
±1.0% max
Gain vs. Temperature:x1		
±20 ppm/˚C max
x10±20 ppm/˚C max
x100±40 ppm/˚C max
x200±60 ppm/˚C max
x500±100 ppm/˚C max
Non-Linearity:x1		
±0.015% FS max
x10±0.015% FS max
x100±0.025% FS max
x200±0.025% FS max
x500±0.045% FS max
Common-Mode Rejection:
x1		70 dB min
x1087 dB minx100100 dB min
x200
100 dB min
x500
100 dB min
Active Filter Device: UAF42 (Burr-Brown)
Number of Poles/Filter: 3
Types of Filters: Bessel, Butterworth, and Chebyshev
Bandwidth: 72.4 kHz (filter bypass)Frequency Range: 0.1 Hz to 50 kHz; the frequency is
set by installation of 4 to 6 resistors and/or capacitors in the provided socket locations
Frequency Modules: Optional frequency module
kits are available that consist of 4 plug-in resistor/
capacitor (RC) headers preconfigured for any of thefollowing frequencies—5 Hz, 10 Hz, 100 Hz, 500 Hz,or 1 kHz; all are Butterworth type filters

Ordering Information
Description
4-channel low-pass filter card withfour blank headers for user-configured
cutoff frequencies

Part No.
DBK18Accessories
Additional set of four blank headers

FM/USER

Pre-Configured Frequency Modules (Butterworth)(set of four)
100 HzFM100
500 Hz
FM500
1 kHz
FM1000

CablesFor use with DBK10, use CA-37-x ribbon cable, or
contact 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 withtwo DBK cards (or contact factory for additional
cabling options)

Product Compatibility✔ LogBook✔ DaqBook✔ DaqLab✔ DaqScan✔ DaqBoard/2000 Series

Note: For simultaneous sample and hold with antialias filter, see DBK45.
Power Consumption:  1085 mW* Attachment to the DaqBoard/2000 Series requires a DBK200, DBK202, DBK203A, DBK209, DBK213, orDBK214

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