Other Parts Discussed in Thread: DRV8873
Hi all,
sorry for my poor english...
I've made a board based on drv8873H. My problem is that the IC burn very frequently on a minimal overload.
VM is 24V, the load is a linear actuator (dc motor brushed) . Without load the motor use less than 300 mA, with load about 2-2,5 A max
I use full bridge operation because the actuator is bidirectional.
The frequency of PWM is about 16 Khz
There is a very large copper surface in both side of the printed circuit board
I have noticed some strange things:
1- the voltage across the low-side mosfet during ON period is about 1 Volt even with low current
2- if the load on actuator increase rapidly, the driver burn immediatly
3-during tests I have a bulb lamp in parallel with the motor for a visual feedback . With lamp present the driver is more robust, without lamp the driver burn istelf more frequently.
4- When it burns, the load become disconnected but the IC sink some current (about 150mA) . When I switch off and on again the power suppy, the driver is in full short circuit (0V with 3 Amps) and must be replaced.
I have already used many PWM driver (different chips) in various project without problems, so I'm very surprised of what happens.
I have made many trials, burned about 15 IC's, I have read the datasheet many and many times and I do not have found any reason for such problems.
I have make a firmware functions for current control but sofware is non so fast as the IC ad it burns again.
Why the current and temperature internal protection does not works properly?
Thanks in advance for any help
Franco
