ZHCSKM1D October 1997 – December 2019 OPA548
PRODUCTION DATA.
The OPA548 features an accurate, user-selected current limit. The current limit is set from 0 A to 5 A by controlling the input to the ILIM pin. Unlike other designs, which use a power resistor in series with the output current path, the OPA548 senses the load indirectly. This allows the current limit to be set with a 0-μA to 330-μA control signal. In contrast, other designs require a limiting resistor to handle the full output current (5 A in this case).
With the OPA548, the simplest method for adjusting the current limit uses a resistor or potentiometer connected between the ILIM pin and V– according to the Equation 1:
The low-level control signal (0 μA to 330 μA) also allows the current limit to be digitally controlled.
See Figure 41 for a simplified schematic of the internal circuitry used to set the current limit. Leaving the ILIM pin open programs the output current to zero, while connecting ILIM directly to V– programs the maximum output current limit, typically 5 A.