9 Detailed Description

9.1 Overview

The REF70 is family of ultra low-noise, precision bandgap voltage references that are specifically designed for

excellent initial voltage accuracy and drift. The Section 9.2 is a simplified block diagram of the REF70 showing

basic band-gap topology.

9.2 Functional Block Diagram

EN

Enable

Controller

Digital

Core

Bandgap

Core

Reference

Buffer

OUTF

+

Å

OUTS

VIN

GND

VIN

9.3 Feature Description

9.3.1 Low Temperature Drift

The REF70 is designed for minimal drift error, which is defined as the change in output voltage over

temperature. The drift is calculated using the box method, as described by Equation 3:

REF(MAX)

REF(MIN)

6

REF

V

V

Drift =

10

V

Temperature Range

·

§

u

¸

¨

u

©

¹

(3)

9.4 Device Functional Modes

9.4.1 EN Pin

REF70 to be left floating. When the EN pin of the REF70 is pulled high, the device is in active mode. The device

must be in active mode for normal operation. The REF70 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 10 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.

REF70

SNAS781 – OCTOBER 2020

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