Table 9-1. Design Parameters (continued)

PARAMETER

EXAMPLE VALUE

RSense

15mΩ

R1

5.1Ω

R2

510Ω

9.2.1.2 Detailed Design Procedure

RSense is chosen in the range of milli ohms for lower power dissipation and high gain due to precision

characteristic of OPAx620. The op-amp's low offset voltage and rail to rail output are able to significantly impact

measurement accuracy, especially when the shunt voltage is small or the sensed current is low. A larger output

voltage swing post calibration allows a larger gain and smaller RSense for improved accuracy and lower power

dissipation.

The output voltage is given by,

VOUT = G × ISense × RSense,   where G = R2R1 = 100V/V

(1)

Output offset, VOSOUT = VOSIN× G = ±1mV × 100 = ±0.1mV

(2)

Max Output Swing, VOPP = VMAXOUT− 2 ×VOSOUT ,where VMAXOUT is maximum voltage swing at the output (3)

VOPP = 3.3− 0.2 − 2 ×0.1mV =2.9V 

(4)

Hence, having precision amplifier gives a larger usable output swing. This setup is a great choice for electric

vehicle systems like traction inverters, onboard chargers, and DC/DC converters, where minor current changes

and responding to current faults in < 1μs is essential for protecting SiC/GaN-based power stages.

9.2.1.3 Application Curve

Max VOS (mV)

0

2

4

6

8

10

12

14

0.5

1

1.5

2

2.5

3

3.5

OPA620

Next Best

VS = 3.3V

Figure 9-2. Max VOS vs Max Output Swing

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OPA620, OPA2620

SLOSEG2A – APRIL 2026 – REVISED JUNE 2026

Copyright © 2026 Texas Instruments Incorporated

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