OPA835IDBVT datasheet(32/53 Pages) NSC

32 / 53 page

OPA 835

Signal and bias

from previous stage

Signal and bias to

next stage

5 V

GVSIG

0 V

VSIG

VOUT

OPA 835

Signal and bias

from previous stage

Signal and bias to

next stage

5 V

0 V

VSIG

VOUT

GVSIG

0 V

OPA835

OPA2835

SLOS713E – JANUARY 2011 – REVISED JULY 2013

www.ti.com

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 VICR of the OPA835 includes the negative supply rail, the op amp lends

itself to this application.

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, VS-. When the op amp is powered from single

supply and ground, driving from logic devices with similar VDD voltages to the op amp should not require any

special consideration. When the op amp is powered from split supply, VS- 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.

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OPA835IDBVT Datasheet(PDF) 32 Page - National Semiconductor (TI)

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