Hello, on DRV84x2 there is OC_ADJ pin to set current limit by resistor to AGND. Is it possible to use it as a variable current limit by appling external voltage or current by DAC?
I am thinking of the simplest option: to use MCU voltage DAC connected to OC_ADJ thru resistor. Is this possible?
Thank you, Jan
Hi Jan,
Is it possible to use it as a variable current limit by appling external voltage or current by DAC?
Technically it may work but it is not recommended. A voltage is generated at the OC_ADJ pin by the driver sourcing a fix current to the external resistor. The voltage is then compared internally to set the appropriate OC limit. For this to work, the OC_ADJ voltage for each OC level needs to be know (shown below). If the sourcing current at the OC_ADJ pin is known, the voltage for each level can be easily calculated by multiplying the current with the resistance. However, in order for the device to remain operational during OC limiting, the OC protection type should be set to CBC (cycle-by-cycle) which does not support 100% duty cycle driving. OC latching (other protection type) will latched the outputs during OC protection.
Are you open to using another driver? We have the DRV8462/DRV8962 which is similar in spec to the DRV8412. The main exception being the lower operation PWM frequency of the DRV8462/8962. These two devices have built in current regulation that can be adjusted with a reference voltage pin.
Regards,
Pablo Armet
