Owner's manual

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Bridge Supply
The bridge excitation supply is a very well regulated low noise
output designed to drive either full or half bridge transducers
from 0 to 120mA output current. The output can be set to a
fixed +10V by setting DIP switch SW1 ON. By setting SW1
OFF the output can be adjusted from +4 to +10Volts by
adjusting the bridge supply adjust trimpot.
The bridge supply uses + and - sense connections to
compensate for any line drops that might be present when
using remote transducers. See the applications examples for
more information on properly using the + and - sense pins. If
remote sensing is not required connect +Sense (Pin D) to
Bridge Supply (Pin 4) and -Sense (Pin 9) to Common (Pin B)
directly at the mounting kit socket. The maximum voltage
difference between the Bridge Supply, Pin 4 and the +Sense,
Pin D, is 0.4V.
Half Bridge Completion/Bridge Balance
Two 10K ohm thin film resistors are connected to the excitation
supply sense lines and their center connection is brought out
to pin R. These resistors have a low temperature coefficient
and track to 5 PPM/°C. This circuit can be used as the other
half of a Half Bridge transducer to provide a common mode
voltage to the instrumentation amplifier. Pin R can be connected
to either the + or - input pin, depending on the polarity of the
transducer output signal.
A Bridge Balance circuit is also provided. RP6, BAL ADJ, is
also connected across the excitation sense leads and it's
swinger is brought out to Pin 14 through R18. With pin 14
connected to the same amplifier input as a 350 ohm Half
Bridge transducer, a bridge balance range of ±50% is available.
Alternately, pin 14 can be connected to the Bridge Completion
resistors. However, in this case R18 should be increased to 1
megohm to reduce the sensitivity of the adjustment. The
Bridge Balance pin can be connected to either input when a
Full Bridge transducer is used.
General Calibration Procedures
The OM2-163 comes from the factory adjusted to the following
specifications:
GAIN .................................... 333 V/V
INPUT OFFSET ................... Adjusted to 0, ±2mV
OUTPUT OFFSET ............... J1 Installed
BRIDGE SUPPLY ................ SW1 CLOSED, Bridge Output
at +10 Volts
FILTER ................................. SW2 - SW5 OFF, Filter at 1 kHz
BRIDGE BALANCE ............. Pin 14 at 0 Volts
When adjusting the OM2-163 to other values the following
methodology should be used,
1) Ground the inputs, set the input offset trimpot to get 0
Volts on the output you will be using (Pins N or P). Input
offset is for amplifier nulling only. Do not use the input
offset for zeroing systems offsets, use the bridge balance
or the output offset adjustments for system offset
correction.
FIGURE 2. Dip switch settings and equations required to set the
filter cutoff frequency.
Fc
1000
Fc
1000
1000
Fc
ycneuqerFffotuC2WS3WS4WS5WS
zH01NONO
zH001NONO
zH0001
tceleSresUro
FFOLLA
FIGURE 3.
163MK INPUT AMP RESPONSE
3 db FREQUENCY, HERTZ
GAIN
10
0
10
1
10
2
10
3
10
4
10
6
10
5
10
4
10
3
If pin K is used as the Output Offset control, than J1 should be
installed to prevent interaction of RP1.
Filter Cutoff Frequency Adjustment
CX1 = CX2 = 0.0024 µF -1
CUTOFF FREQUENCY > 1000 Hz
RX1 = 35,000/ -1
RX2 = 105,000/ -1
BUILT IN LOW PASS FILTER FREQUENCY RESPONSE
FREQUENCY (Hz)
GAIN (db) PIN P - PIN N
10
0
-10
-20
-30
-40
-50
1 10 100 1000 10000 1000000
10Hz
100Hz 1000Hz