10.2.1.1 Design Requirements

The design requirements are as follows:

1. Supply voltage: 5.0 V

2. Load current: ±2.5 A

3. Output: 250 mV to 2.75 V

4. Maximum shunt voltage: ±25 mV

10.2.1.2 Detailed Design Procedure

Low-side current sensing is desirable because the common-mode voltage is near ground. Therefore, the current-

sensing solution is independent of the bus voltage, VBUS. When sensing bidirectional currents, use a differential

amplifier with a reference pin. This procedure allows for the differentiation between positive and negative

currents by biasing the output stage such that it can respond to negative input voltages. There are a variety of

methods for supplying power (V+) and the reference voltage (VREF, or VBIAS) to the differential amplifier. For a

low-drift solution, use a monolithic reference that supplies both power and the reference voltage. Figure 10-2

shows the general circuit topology for a low-drift, low-side, bidirectional, current-sensing solution. This topology

is particularly useful when interfacing with an ADC; see Figure 10-1. Not only do VREF and VBIAS track over

temperature, but their matching is much better than alternate topologies. For a more detailed version of the

design procedure, refer to TIDU357.

RSHUNT

±I

LOAD

V

BUS

+

IN+

IN-

REF

OUT

+

Bandgap

V+

V

CC

V

REF

V

BIAS

V

IN

EN

GND

GND

V

OUT

REF20xx

INA213B

+

±

+

±

± V

SHUNT

Figure 10-2. Low-Drift, Low-side, Bidirectional, Current-Sensing Circuit Topology

The transfer function for the circuit given in Figure 10-2 is as shown in Equation 5:

‡

‡

‡

OUT

SHUNT

BIAS

LOAD

SHUNT

BIAS

V

G

V

V

G

I

R

V

r

r

(5)

www.ti.com

REF2025, REF2030, REF2033, REF2041

SBOS600E – JULY 2018 – REVISED FEBRUARY 2022

Copyright © 2022 Texas Instruments Incorporated

Submit Document Feedback

21

Product Folder Links: REF2025 REF2030 REF2033 REF2041