Part Number:DRV8809
Hi,
I’m having an intermittent problem with the DRV8809 doing a thermal shutdown (TSD). I noticed it tends to happen when the motors (2 steppers) are moving, but I don’t think the chip is actually reaching the shutdown temperature.
I’ve confirmed a TSD is happening by looking at the LOG_OUT pin and playing with the TSD operation (bits 13-15 of the extended setup register).
I tried to monitor the temperature by configuring TH_OUT as an analog output (setting bit 12 on the extended setup register) and connecting an external pull up resistor to 3.3V. The voltage is always close to 3.3V, even when the motors are running, which I assume means that it is not heating up too much.
I then configured TH_OUT as a digital output (Pre-TSD) to see if I could at least see a warning before the chip actually shut off, but the Pre-TSD signal does not assert before the TSD signal, even though it should be coming 20° before the TSD.
The only way I’ve been able to “fix” the issue is by disabling the TSD (bit 7 of extended setup register), but I’m not sure if that’s dangerous.
Any ideas why it would randomly issue a TSD? And why the Pre-TSD does not trigger before the TSD??
Thank you!
PS: My problem sounds very similar to the one described in the following link but I could not see a solution. (http://e2e.ti.com/support/applications/motor_drivers/f/38/t/343406?DRV8809-shutting-down).