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ZHCSMD4C January 2022 – December 2022 OPA593

PRODUCTION DATA

封装选项

机械数据 (封装 | 引脚)

DNT|12
- MPDS488B

散热焊盘机械数据 (封装 | 引脚)

订购信息

7.3.1 Current Limit

The OPA593 current limit is set through the ILIMIT pin and is programmable from ±25 mA to ±250 mA, typical. The device is specified and tested for current limits of ±25 mA, ±50 mA, ±100 mA, ±250 mA. 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.

Figure 7-1 OPA593 Internal Current Limit Configurations

The most common configuration is to set the current limit using a resistor (R_CL) connected between the ILIMIT 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:

Equation 1.

I_{L I M I T} = \frac{3.687 V \times 4000}{56.7 k Ω + R_{C L}}

Equation 2.

R_{C L} = \frac{3.687 V \times 4000}{I_{L I M I T}} –56.7 k Ω

An alternative to fixing the current limit to a single value using an external resistor is to use a source measure unit (SMU) or digital-to-analog converter (DAC), which enables a variable current limit.

CAUTION: With this configuration, the output of the SMU or DAC must not exceed the I_LIMIT specification in Section 6.1 to avoid reverse biasing the internal current limit circuitry and potentially damaging the device.

Use Equation 3 to set the current limit when a DAC is used (V_LIMIT = DAC output voltage):

Equation 3.

V_{L I M I T} = 3.687 V - \frac{I_{L I M I T} \times 56.7 k Ω}{4000}

Be aware that the SMU or DAC output voltage must be referenced to the negative supply of the OPA593. Several nominal current-limit values along with the respective external resistor values and DAC output voltages are listed in Table 7-1.

Table 7-1 Nominal Current-Limit Values

CURRENT LIMIT, I_LIMIT(mA)	RESISTOR, R_CL (kΩ)	DAC VOLTAGE, V_LIMIT (V)⁽¹⁾
25	536	3.33
50	237	2.98
100	90.9	2.27
200	16.9	0.85
250	2.29	0.14

(1) Voltages are referenced to the negative supply, V−

While the current limit tolerance of the OPA593 is specified for specific current limit levels, any resistor, SMU, or DAC inaccuracies add to the listed tolerance. To achieve the desired system level accuracy, take care when selecting these external components. Figure 7-2 shows a correlation between the ideal or calculated output current limit and the actual current limit as measured on the OPA593.

Figure 7-2 Typical Output Current vs Current-Limit Resistor Value