DBK18

4-Channel Low-Pass Filter CardOverview ...... 1
Hardware Setup ...... 1
Card Connection ...... 1
Card Configuration ...... 2
CE Compliance ...... 3
DaqBook/100 Series & /200 Series and DaqBoard [ISA type] Configuration ...... 3
DaqBook/2000 Series and DaqBoard/2000 Series Configuration ...... 3
Configuring DBK18 Filter Sections ...... 3

Software Setup ...... 5
DBK18 – Specifications ...... 6

Reference Notes:
o Chapter 2 includes pinouts for P1, P2, P3, and P4. Refer to pinouts applicableto your system, as needed.
o In regard to calculating system power requirements, refer to DBK Basics locatednear the front of this manual.

Overview
Each DBK18 low-pass filter (LPF) card provides 4 input channels to a LogBook or a Daq device system.
Each of sixteen channels can accept four DBK18 cards for a maximum of 256 analog inputs. The input
connectors are BNC type connectors. The differential inputs are provided with switchable 100 KΩ bias
resistors to analog common.
The DBK18 features an instrumentation amplifier for each channel, with switch-selected gains of×1, ×10, ×100, ×200 and ×500. A socket is provided for a gain resistor for custom gain selection insteadof unity gain (×1). Gain for any channel can be set to any value between unity and ×500 by installing anappropriate resistor. Four separate filter stages follow the 4 input stages. The outputs are connected to a
4-channel multiplexer stage. The enabled output MUX allows up to four DBK18s to share a common
analog base channel.

BNC

Terminal
Block+ _Gain-Select Switches
SW1-SW4

aAmplifier

Switchable
bias resistors(per channel)
SW5Filter-Bypass/
Enable Jumpers
J3-J6
BYLPFENf

Low-Pass
FilterCH 0 (1 of 4 identical channels)
CH 1
CH 2
CH 3

P1
J1 Output channel 16
selection header
MUX

Board-SelectSwitch
SW6

Card Address
recognition stage

2Channel address lines

2

DBK18 Block Diagram

Hardware Setup
Card Connection
The DBK18 is equipped with BNC connectors for easy access to all of the analog inputs. Connections areprovided for 4 differential inputs. The card also includes a terminal block as a connection-option to theBNC connectors.
Note: New versions of the DBK18 have been enhanced by the addition of a terminal block. The BNC
connectors are still usable, and board functions have not been changed.

DBK Option Cards and Modules

918894

DBK18, pg. 1

Card Configuration
Factory Defaults•

100K bias resistors – Enabled•

Low-Pass Filter – Bypassed (Disabled)•Gain – x1

Input Termination

OPEN

1 2 3 4 5 6 7 8Terminal
Block+ _SW5

DBK18 provides two 100 KΩ bias resistors foreach analog input. For balanced 200 KΩ input
impedance, both resistors should be switched in.
An 8-position DIP switch (SW5) can selectivelyengage the bias resistors. The input circuit andswitch positions are shown in the figure. Theswitches must be in the closed position to engage
the termination resistors. For unbalanced highinput, only the (-) resistor should be used. Ifneither resistor is used, some external bias current
path is required.

44+
33+
22+
11+

N+-100 kΩAA

Input Impedance/Termination

Examples of Bias Resistor Selection Options

Gain Settings
On the card, each channel has a gain-set switch labeled GAIN 1 (SW1) to GAIN
4 (SW4) and holes for gain resistors labeled RG1 to RG4. The table in the figureshows gain values for switch settings 0 to 4. If a custom gain is desired, theswitch is set to position 0; and a gain resistor must be mounted and soldered ontothe card. The value of the gain resistor is determined by the formula:
RGAIN = [40,000 / (Gain -1)] - 50 ΩAddress Configuration
Up to 4 DBK18s can be connected to each analog channel. Since this is adaisy-chain interface, each card must have a unique address (channel number
and card number). Note that the default setting of SW6 is Card 1.
To configure the card, locate the 16 × 2-pin header labeled JP1 near the front ofthe board. The 16 jumper locations on this header are labeled CH0 throughCH15. Place the jumper on the channel you wish to use. Only one jumper isused on a single card. Four cards in the daisy-chain can have the same channel
number as long as each card number is unique.
Set switch SW6 for each of the 4 DBK18s on a single channel. Verify that only
one card in a system is set to a particular channel and card number.

DBK18, pg. 2918894

DBK Option Cards and Modules

CE Compliance
Reference Notes:
Should your data acquisition system need to comply with CE standards, refer tothe CE Compliance section of the Signal Management chapter.

DaqBook/100 Series & /200 Series and DaqBoard [ISA type] Configuration
Use of the DBK18 requires setting jumpers in DaqBooks/100 Series & /200 Series devices andDaqBoards [ISA type].
1.

If not using auxiliary power, place the JP1 jumper in the Analog Option Card mode.

Configuration Jumpers
Note: The default position is necessary to power the interface circuitry of the DBK18 via theinternal ±15 VDC power supply. If using auxiliary power (e.g., DBK32A, DBK33), youmust remove both JP1 jumpers. Refer to Power Requirements in the DBK Basics section andto the DBK32A and DBK33 sections, as applicable.
2.

For DaqBook/100, /112, and /120 only, place the JP4 jumper in single-ended mode.
Note: Analog expansion cards convert all input signals to single-ended voltages referenced
to analog common.

DaqBook/2000 Series and DaqBoard/2000 Series Configuration
No jumper configurations are required for these /2000 series devices.

Configuring DBK18 Filter Sections
There are 4 low-pass, 3-pole active filters on the DBK18. Each filter can be enabled (EN), or bypassed(BY) by placement of the jumper on J3 for channel 0, J4 for channel 1, J5 for channel 2, or J6 forchannel 3. The factory-default setting is bypassed (BY) for each channel.
Each filter can be configured as a Butterworth, Bessel, or Chebyshev filter with corner frequencies up to50 kHz. Filter properties depend on the values of resistors and capacitors installed in several circuit
locations. Above 10 Hz, installing capacitors is unnecessary because capacitors in the ICs are sufficient.
In all cases, three resistors are required to complete the active filter circuits contained mostly within theUAF42 ICs.
The following circuit diagram shows the active filter IC in a typical section of the DBK18. The resistors
and capacitors outside the IC have a physical location in a DIP-16 socket (dual in-line, 16 pins) with anRCnn designator. The RC indicates the needed part is a resistor or capacitor; the 3rd character is thechannel number; and the 4th character corresponds to the socket position (A-H).

DBK Option Cards and Modules

918894

DBK18, pg. 3

Filter Circuit Diagram
A machined-pin IC socket in each filter RC location can accept resistors and capacitors that plug directly
into the socket; however, this is not recommended. Two much better approaches exist. The first is to use
pre-configured plug-in filter modules; the second is to configure your own plug-in module using a blank
CN-115. Both of these options are depicted in the following illustration.
The use of plug-in modules provides excellent “gold-to-gold” contact between the components of theplug-in module and the on-board header.

The following figure shows the DIP-16 component pattern typical of the 4 filter sections.

DIP-16 Component Pattern

Note: In the DIP-16 figure, “n” corresponds to “channel number.”Note: In the DIP-16 figure, pin 7 of the DIP-16 socket:• connects to pin 8 for low-pass filtering• connects to pin 6 for band-pass filtering
DBK18, pg. 4918894

DBK Option Cards and Modules

The following table lists values of components for common corner frequencies in Butterworth filters. If designing
your own filter, software from Burr-Brown provides the component values to create the desired filter. Note thatthe design math is beyond the scope of this manual.
3-Pole Butterworth Filter Components
3dB (Hz)
RCnA
RCnB
RCnC
RCnD
RCnE
RCnF
0.05
1 µF
none
1 µF
3.16 MΩ
3.16 MΩ
3.16 MΩ
0.10
1 µF
none
1 µF
1.58 MΩ
1.58 MΩ
1.58 MΩ
0.20
1 µF
none
1 µF
787 kΩ
787 kΩ
787 kΩ
0.50
0.1 µFnone
0.1 µF3.16 MΩ
3.16 MΩ
3.16 MΩ
10.1 µF
none
0.1 µF1.58 MΩ
1.58 MΩ
1.58 MΩ
20.1 µF
none
0.1 µF787 kΩ
787 kΩ
787 kΩ
5*0.01 µF
none
0.01 µF
3.16 MΩ
3.16 MΩ
3.16 MΩ
10*0.01 µF
none
0.01 µF1.58 MΩ
1.58 MΩ
1.58 MΩ
200.01 µF
none
0.01 µF
787 kΩ
787 kΩ
787 kΩ
500.001µF
none
none
3.16 MΩ
3.16 MΩ
3.16 MΩ
100*0.001µF
none
none
1.58 MΩ
1.58 MΩ
1.58 MΩ
2000.001µF
none
none
787 kΩ
787 kΩ
787 kΩ
500*0.001µF
none
none
316 kΩ
316 kΩ
316 kΩ
1000*0.001µF
none
none158 kΩ
158 kΩ
158 kΩ
20000.001µF
none
none
78.7 kΩ78.7 kΩ78.7 kΩ
50000.001µF
none
none
31.6 kΩ31.6 kΩ31.6 kΩ100000.001µF
none
none
15.8 kΩ15.8 kΩ15.8 kΩ*These pre-configured Butterworth frequency modules are available from the manufacturer.

RCnG
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none

RCnH
1 µF
1 µF
1 µF
0.1 µF0.1 µF0.1 µF0.01 µF
0.01 µF
0.01 µF
none
none
none
none
none
none
none
none

You have the option to configure the filter sections as band-pass filters rather than low-pass filters. The
component selection program provides band-pass component values. The program also computes anddisplays phase and gain characteristics of the filter sections as a function of frequency.

Software Setup
Reference Notes:
o DaqView users - Refer to chapter 3, DBK Setup in DaqView.
o LogView users - Refer to chapter 4, DBK Setup in LogView.

DBK Option Cards and Modules

918894

DBK18, pg. 5

DBK18 – Specifications
Name/Function: Low-Pass Filter Card
Number of Channels: 4Input Connections: 4 BNC connectors
Output Connector: DB37 male, connects to P1 with a CA-37-x cable
Number of Cards Addressable: 64
Input Type: Differential
Voltage Input Ranges:
0 to ±5000 mVDC
0 to ±500 mVDC
0 to ±50 mVDC
0 to ±25 mVDC
0 to ±10 mVDC
Input Amplifier Slew Rate: 12 V/µs minimum
Input Gains: ×1, ×10, ×100, ×200, x500 and user-set
Input Offset Voltage: 500 µV + 5000/G maximum (nullable)
Input Offset Drift: ±5 + 100/G µV/°C maximum
Input Bias Current: 100 pA maximum
Input Offset Currents: 50 pA maximum
12Input Impedance: 5 × 10 parallel with 6 pF
Switchable Bias Resistors: 100 KΩ each to analog common
Gain Errors:
0.04% @ ×1
0.1% @ ×100.2% @ ×100
0.4% @ ×200
1.0% @ ×500
Gain vs Temperature:
×1 @ ±20 ppm/°C
×10 @ ±20 ppm/°C
×100 @ ±40 ppm/°C
×200 @ ±60 ppm/°C
×500 @ ±100 ppm/°C
Non-Linearity:
×1 to ±0.015 % full-scale
×10 to ±0.015 % full-scale
×100 to ±0.025 % full-scale
×200 to ±0.025 % full-scale
×500 to ±0.045 % full-scale
Common-Mode Rejection:
70 dB minimum @ ×1
87 dB minimum @ ×10
100 dB minimum @ ×100
100 dB minimum @ ×200
100 dB minimum @ ×500
Active Filter Device: UAF42 (Burr-Brown)
Number of Poles/Filter: 3
Types of Filters: Bessel, Butterworth, Chebyshev
Frequency Range:
0.1 Hz to 20 kHz
The frequency is set by the installation of4-6 resistors, and/or capacitors, in sockets.
Default Frequency:
1 Hz
Other frequencies may be implemented bysoldering resistors, and/or capacitors, tolocations on the 4 blank plug-in headers.
Values for common frequencies and theircomponent values are provided with theblank headers.

DBK18, pg. 6918894

DBK Option Cards and Modules