9.4 Device Functional Modes

9.4.1 EN Pin

When the EN pin of the REF34xx is pulled high, the device is in active mode. The device must be in active mode

for normal operation. The REF34xx can be placed in a low-power mode by pulling the ENABLE pin low. When in

shutdown mode, the output of the device becomes high impedance and the quiescent current of the device

reduces to 2 µA in shutdown mode. The EN pin must not be pulled higher than VIN supply voltage. See the

Section 7.5 for logic high and logic low voltage levels.

9.4.2 Negative Reference Voltage

For applications requiring a negative and positive reference voltage, the REF34xx and OPA735 can be used to

provide a dual-supply reference from a 5-V supply. Figure 9-1 shows the REF34xx used to provide a 2.5-V

supply reference voltage. The low drift performance of the REF34xx complements the low offset voltage and

zero drift of the OPA735 to provide an accurate solution for split-supply applications. Take care to match the

temperature coefficients of R1 and R2.

-2.5 V

+2.5 V

+5 V

1

2

5

6

3

4

R

1

10 kΩ R

2

10 kΩ

-5 V

+5 V

OPA735

REF3425

Copyright © 2017, Texas Instruments Incorporated

Figure 9-1. REF34xx and OPA735 Create Positive and Negative Reference Voltages

REF3425, REF3430, REF3433, REF3440, REF3450

SBAS804C – SEPTEMBER 2017 – REVISED FEBRUARY 2021

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