ZHCSRG7 January 2023 DRV2901
PRODUCTION DATA
The device has independent, fast-reacting current detectors with programmable trip threshold (OC threshold) on all high-side and low-side power-stage FETs. See the following table for OC-adjust resistor values. The detector outputs are closely monitored by two protection systems. The first protection system controls the power stage in order to prevent the output current from further increasing, i.e., it performs a current-limiting function rather than prematurely shutting down during combinations of high-level transients and extreme load impedance drops. If the high-current situation persists, i.e., the power stage is being overloaded, a second protection system triggers a latching shutdown, resulting in the power stage being set in the high-impedance (Hi-Z) state. Current limiting and overload protection are independent for half-bridges A and B
Unfortunately, most inductors have decreasing inductance with increasing temperature and increasing current (saturation). To some degree, an increase in temperature naturally occurs when operating at high output currents, due to core losses and the dc resistance of the inductor's copper winding. A thorough analysis of inductor saturation and thermal properties is strongly recommended.
Setting the OC threshold too low might cause issues such as lack of enough output power and/or unexpected shutdowns due to too-sensitive overload detection.
For added flexibility, the OC threshold is programmable within a limited range using a single external resistor connected between the OC_ADJ pin and AGND. (See the Electrical Characteristics section of this data sheet for information on the correlation between programming-resistor value and the OC threshold.) It should be noted that a properly functioning overcurrent detector assumes the presence of a properly designed demodulation filter at the power-stage output. Short-circuit protection is not provided directly at the output pins of the power stage but only on the transducer terminals (after the demodulation filter). It is required to follow certain guidelines when selecting the OC threshold and an appropriate demodulation inductor:
OC-Adjust Resistor Values (kΩ) | Max. Current Before OC Occurs (A) |
---|---|
22 | 12.2 |
27 | 10.5 |
47 | 6.4 |
68 | 4.0 |
100 | 3.0 |