LTC2053 Linear Technology, LTC2053 Datasheet - Page 9

• Manufacturer Part Number: LTC2053
• Description: Precision/ Rail-to-Rail Input and Output/ Zero-Drift Instrumentation Amplifier with Resistor-Programmable Gain
• Manufacturer: Linear Technology

PI FU CTIO S
BLOCK DIAGRA
EN (Pin 1): Active Low Enable Pin.
–IN (Pin 2): Inverting Input.
+IN (Pin 3): Noninverting Input.
V
REF (Pin 5): Voltage Reference (V
Theory of Operation
The LTC2053 uses an internal capacitor (C
differential input signal riding on a DC common mode
voltage (see Block Diagram). This capacitor’s charge is
transferred to a second internal hold capacitor (C
lating the common mode of the input differential signal to
that of the REF pin. The resulting signal is amplified by a
zero-drift op amp in the noninverting configuration. The
RG pin is the negative input of this op amp and allows
external programmability of the DC gain. Simple filtering
can be realized by using an external capacitor across the
feedback resistor.
Input Voltage Range
The input common mode voltage range of the LTC2053 is
rail-to-rail. However, the following equation limits the size
of the differential input voltage:
APPLICATIO S I FOR ATIO
–
V
U
(Pin 4): Negative Supply.
–
(V
+IN
U
– V
–IN
U
) + V
U
REF
W
U
V
+
REF
– 1.3
) for Amplifier Output.
W
3
2
+IN
–IN
S
) to sample a
U
H
) trans-
C
S
5
REF
C
H
6
Where V
pins respectively, V
is the positive supply voltage.
For example, with a 3V single supply and a 0V to 100mV
differential input voltage, V
1.6V.
When using the LTC2053 with supplies over 5.5V, care
must be taken to limit the maximum difference between
any of the input pins (+IN or –IN) and the REF pin to 5.5V;
if not, the device will be damaged. For example, if rail-to-
rail input operation is desired when the supplies are at
example, if V
should not exceed 5.5V.
RG (Pin 6): Inverting Input of Internal Op Amp. With a
resistor, R2, connected between the OUT pin and the RG
pin and a resistor, R1, between the RG pin and the REF pin,
the DC gain is given by 1 + R2 / R1.
OUT (Pin 7): Amplifier Output.
V
RG
+
5 Volt Operation
5V, the REF pin should be 0V, 0.5V. As a second
V
–
+
(Pin 8): Positive Supply.
OUT
8
4
V
V
ZERO-DRIFT
+
–
OP AMP
= GAIN (V
+IN
1
EN
and V
+
OUT
is 10V and V
2053 BD
7
–IN
+IN
REF
are the voltages of the +IN and –IN
– V
is the voltage at the REF pin and V
–IN
–
REF
and REF are at 0V, the inputs
) + V
must be between 0V and
REF
LTC2053
2053fa
9
+