OPAX607 datasheet(24/52 Pages) TI

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9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

9.1 Application Information

The OPAx863 are classic voltage-feedback amplifiers with two high-impedance inputs and a low-impedance

output. These devices have a GBW of 50 MHz, 5.9 nV/√Hz of noise, RRIO capability, and precision performance

consuming only 700 µA quiescent current per channel These features make the OPAx863 an excellent choice

for use in low-side current sensing, ADC input driver, and reference buffering with fast settling, buffers, high

gain and filter circuits. The overload power limit makes the OPAx863 truly low-power in high-gain, multichannel

systems limiting any increase in quiescent current during output overload conditions.

9.2 Typical Applications

9.2.1 Low-Side Current Sensing

Power converters use current-mode feedback control for excellent transient response and multiphase load

sharing. Inverter stages control the phase currents for torque control in motor drives. As a result of the simplicity

and low-cost, many of these topologies use difference-amplifier-based, low-side current sensing. Figure 9-1

shows the use of the OPAx863 in a difference amplifier circuit for low-side current sensing.

600Ÿ

12kŸ

RSH

1.65V

GND

Switchi ng

Circuit

ISH

VOUT

3.3V

OPA x863

250Ÿ

ADS705 6

3.3V

TLV320 1

VTH

MCU

Interrupt

Digital I/O

300V

3.3V

220pF

Figure 9-1. Low-Side Current Sensing in Power Converters

9.2.1.1 Design Requirements

Table 9-1. Design Requirements

PARAMETER

DESIGN REQUIREMENT

Shunt resistor

10 mΩ

Input current

15 APP

Output voltage

3 VPP

Switching frequency

50 kHz

Data acquisition

1 MSPS with 0.1% accuracy

Input voltage due to ground bounce

10 Vpk

OPA863, OPA2863, OPA4863

SBOS982J – JUNE 2020 – REVISED JUNE 2023

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