Datasheet

OPA 835
Load
V
SIG
2.5 V
R
G
5 V
R
F
V
OUT
OPA 835
Load
V
SIG
R
G
R
F
V
OUT
+2.5 V
-2.5 V
OPA835
OPA2835
www.ti.com SLOS713E –JANUARY 2011–REVISED JULY 2013
Figure 61. Split Supply Operation
Single-Supply Operation (2.5V to 5.5V)
Many newer systems use single power supply to improve efficiency and reduce the cost of the power supply.
OPA835 and OPA2835 are designed for use with single-supply power operation and can be used with single-
supply power with no change in performance from split supply as long as the input and output are biased within
the linear operation of the device.
To change the circuit from split supply to single supply, level shift of all voltages by ½ the difference between the
power supply rails. For example, changing from ±2.5 V split supply to 5 V single supply is shown conceptually in
Figure 62.
Figure 62. Single Supply Concept
A more practical circuit will have an amplifier or other circuit before to provide the bias voltage for the input and
the output provides the bias for the next stage.
Figure 63 shows a typical non-inverting amplifier situation. With 5V single supply, a mid supply reference
generator is needed to bias the negative side via R
G
. To cancel the voltage offset that would otherwise be
caused by the input bias currents, R
1
is chosen to be equal to R
F
in parallel with R
G
. For example if gain of 2 is
required and R
F
= 2 kΩ, select R
G
= 2 kΩ to set the gain and R
1
= 1 kΩ for bias current cancellation. The value
for C is dependent on the reference, but at least 0.1µF is recommended to limit noise.
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