OPA2835 Datasheet, PDF (32/53 Pages) National Semiconductor (TI) – Ultra Low-Power, Rail-to-Rail Out, Negative Rail In, VFB Op Amp

OPA835
OPA2835
SLOS713E – JANUARY 2011 – REVISED JULY 2013
www.ti.com
Signal and bias
from previous stage
V_SIG
0V
5V
R₁
OPA 835
R_G
RF
R_O
V_OUT
GV_SIG
0V
Signal and bias to
next stage
Figure 67. Non-Inverting Single Supply with Pulse
If the input signal pulses negative from ground, an inverting amplifier is more appropriate as shown in Figure 68.
A key consideration in both non-inverting and inverting cases is that the input and output voltages are kept within
the limits of the amplifier, and since the V_ICR of the OPA835 includes the negative supply rail, the op amp lends
itself to this application.
R₁
R_G
Signal and bias
from previous stage
0V
V_SIG
5V
OPA 835
R_F
R_O
V_OUT
GV_SIG
0V
Signal and bias to
next stage
Figure 68. Inverting Single Supply with Pulse
Power-Down Operation
The OPA835 and OPA2835 include a power-down mode. Under logic control, the amplifiers can be switched
from normal operation to a standby current of <1.5 µA. When the PD pin is connected high, the amplifier is
active. Connecting PD pin low disables the amplifier, and places the output in a high impedance state. Note: the
op amp’s output in gain of +1 is high impedance similar to a 3-state high impedance gate, but in other gains the
feedback network is a parallel load.
The PD pin must be actively driven high or low and should not be left floating. If the power-down mode is not
used, PD should be tied to the positive supply rail.
PD logic states are TTL with reference to the negative supply rail, V_S-. When the op amp is powered from single
supply and ground, driving from logic devices with similar V_DD voltages to the op amp should not require any
special consideration. When the op amp is powered from split supply, V_S- is below ground and an open collector
type of interface with pull-up resistor is more appropriate. Pull-up resistor values should be lower than 100k and
the drive logic should be negated due to the inverting action of an open collector gate.
32
Submit Documentation Feedback
Copyright © 2011–2013, Texas Instruments Incorporated
Product Folder Links: OPA835 OPA2835