OPA2835 Datasheet, PDF (23/53 Pages) National Semiconductor (TI) – Ultra Low-Power, Rail-to-Rail Out, Negative Rail In, VFB Op Amp

www.ti.com
OPA835
OPA2835
SLOS713E – JANUARY 2011 – REVISED JULY 2013
APPLICATION INFORMATION
The following circuits show application information for the OPA835 and OPA2835. For simplicity, power supply
decoupling capacitors are not shown in these diagrams.
Non-Inverting Amplifier
The OPA835 and OPA2835 can be used as non-inverting amplifiers with signal input to the non-inverting input,
V_IN+. A basic block diagram of the circuit is shown in Figure 53.
If we set V_IN = V_REF + V_SIG, then
æ
VOUT
=
V_SIG
ç¹
è
+
R_F
R_G
ö
÷
ø
+ V_REF
(1)
G = 1 + ^RF
The signal gain of the circuit is set by:
R_{G , and VREF provides a reference around which the input and}
output signals swing. Output signals are in-phase with the input signals.
The OPA835 and OPA2835 are designed for the nominal value of R_F to be 2kΩ in gains other than +1. This
gives excellent distortion performance, maximum bandwidth, best flatness, and best pulse response. R_F = 2kΩ
should be used as a default unless other design goals require changing to other values All test circuits used to
collect data for this data sheet had R_F = 2kΩ for all gains other than +1. Gain of +1 is a special case where R_F is
shorted and R_G is left open.
V_SIG
V_REF
V_S+
V_IN
R_G
V_REF
OPA 835
V_S-
V_OUT
V_REF
GV_SIG
R_F
Figure 53. Non-Inverting Amplifier
Inverting Amplifier
The OPA835 and OPA2835 can be used as inverting amplifiers with signal input to the inverting input, V_IN-,
through the gain setting resistor R_G. A basic block diagram of the circuit is shown in Figure 54.
If we set V_IN = V_REF + V_SIG, then
VOUT
=
V_SIG
æ
ç
è
-R_F
R_G
ö
÷ ^{+ V}REF
ø
(2)
G = ^-RF
The signal gain of the circuit is set by:
R_{G and VREF provides a reference point around which the input}
and output signals swing. Output signals are 180˚ out-of-phase with the input signals. The nominal value of R_F
should be 2kΩ for inverting gains.
Copyright © 2011–2013, Texas Instruments Incorporated
Product Folder Links: OPA835 OPA2835
Submit Documentation Feedback
23