7.3 Feature Description

7.3.1 Current Limit

The OPA593 has a high-accuracy, externally programmable current limit that has a ±5% tolerance for output

currents ≥ 50 mA. The current limit is set through the ILIMIT pin and is programmable from 10 mA to 250 mA

(typical). A resistor can be used to limit the current to a fixed value or a digital-to-analog converter (DAC) can be

used to vary the current limit during operation. Figure 7-1 shows a simplified diagram of the current-limit mirror

configurations, as well as common resistor or DAC settings and the respective output current limit.

56.7 k

DAC

V– Supply

3.687 V

V–

ILIMIT

56.7 k

V– Supply

3.687 V

V–

ILIMIT

Figure 7-1. OPA593 Internal Current Limit Configurations

pin and the negative supply (V–). With this configuration, Equation 1 and Equation 2 are used to calculate the

current limit based on the external resistor value or the resistor needed given the desired current limit value:

56.7 kΩ+RCL

(1)

ILIMIT –56.7 kΩ

(2)

An alternative to fixing the current limit to a single value using an external resistor is to use a DAC, which

enables a variable current limit.

CAUTION

With this configuration, the output of the DAC must not exceed the ILIMIT specification in Section 6.1

to avoid reverse biasing the internal current limit circuitry and potentially damaging the device.

4000

(3)

Several nominal current limit values along with their respective external resistor values and DAC output voltages

are listed in Table 7-1.

Table 7-1. Nominal Current-Limit Values

OUTPUT CURRENT LIMIT (mA)

RESISTOR (kΩ)

DAC VOLTAGE (V)

50

237

2.98

100

90.9

2.27

200

16.9

0.85

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OPA593

SBOS659A – JANUARY 2022 – REVISED MARCH 2022

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