Datasheet

LOAD
V
SUPPLY
1
C
FILT
V+
R
1
R
L
R
1
5 kW
R R
SHUNT FILTER
<<
R 100
FILT
< W R 100
FILT
< W
V
IN+
f
-3dB
2 (2 R ) Cp
FILT FILT
f =
-3dB
V
IN-
+5 V
5 kW
OUT
INA193A
INA193A-EP
www.ti.com SBOS400A –MAY 2007–REVISED SEPTEMBER 2013
Figure 5. Input Filter (Gain Error – 15% to –2.2%)
Inside the INA193A
The INA193A uses a new, unique internal circuit topology that provides common-mode range extending from –16
V to 80 V while operating from a single power supply. The common-mode rejection in a classic instrumentation
amp approach is limited by the requirement for accurate resistor matching. By converting the induced input
voltage to a current, the INA193A provides common-mode rejection that is no longer a function of closely
matched resistor values, providing the enhanced performance necessary for such a wide common-mode range.
A simplified diagram (shown in Figure 6) shows the basic circuit function. When the common-mode voltage is
positive, amplifier A2 is active.
The differential input voltage, (V
IN+
) – (V
IN–
) applied across R
S
, is converted to a current through a resistor. This
current is converted back to a voltage through R
L
, and then amplified by the output buffer amplifier. When the
common-mode voltage is negative, amplifier A1 is active. The differential input voltage, (V
IN+
) – (V
IN–
) applied
across R
S
, is converted to a current through a resistor. This current is sourced from a precision current mirror
whose output is directed into R
L
converting the signal back into a voltage and amplified by the output buffer
amplifier. Patent-pending circuit architecture ensures smooth device operation, even during the transition period
where both amplifiers A1 and A2 are active.
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