Datasheet

R
S
A1
A2
R
(1)
L
Load
V
IN+
Negative
and
Positive
Common-Mode
Voltage
V
IN+
V
IN-
V+
I
S
OUT
INA193-INA198
R
1
(1)
5kW
G=20,R =100kW
L
G=50,R =250kW
L
G=100,R =500kW
L
R
1
(1)
5kW
INA193, INA194
INA195, INA196
INA197, INA198
SBOS307F –MAY 2004–REVISED FEBRUARY 2010 www.ti.com
INSIDE THE INA193-INA198 The differential input voltage, (V
IN+
) − (V
IN−
) applied
across R
S
, is converted to a current through a
The INA193-INA198 uses a new, unique internal
resistor. This current is converted back to a voltage
circuit topology that provides common-mode range
through R
L
, and then amplified by the output buffer
extending from −16V to +80V while operating from a
amplifier. When the common-mode voltage is
single power supply. The common-mode rejection in
negative, amplifier A1 is active. The differential input
a classic instrumentation amplifier approach is limited
voltage, (V
IN+
) − (V
IN−
) applied across R
S
, is
by the requirement for accurate resistor matching. By
converted to a current through a resistor. This current
converting the induced input voltage to a current, the
is sourced from a precision current mirror whose
INA193-INA198 provides common-mode rejection
output is directed into R
L
converting the signal back
that is no longer a function of closely matched
into a voltage and amplified by the output buffer
resistor values, providing the enhanced performance
amplifier. Patent-pending circuit architecture ensures
necessary for such a wide common-mode range. A
smooth device operation, even during the transition
simplified diagram (shown in Figure 23) shows the
period where both amplifiers A1 and A2 are active.
basic circuit function. When the common-mode
voltage is positive, amplifier A2 is active.
(1) Nominal resistor values are shown. ±15% variation is possible. Resistor ratios are matched to ±1%.
Figure 23. INA193-INA198 Simplified Circuit Diagram
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