Hi all,
I have designed motor drive using DRV8873H-Q1 (HARDWARE VERSION)
1) selected mode=H for PWM
2) pl let me know what is the max PWM frequency ?
3) Can some one share out1 & out2 wave forms w.r.t. IN1 & IN2 in PWM mode.
4) Normal current of the motor is 4A to 5 A, If motor current Exceeds ( in Rotor Lock ) 6.5A will nFAULT pin goes LOW
with iTRIP enabled.
regards
M.Sreenivasan
msvasan@iepl.in
Hi Sreenivasan,
1. This is correct setting for PWM bridge control mode.
2. It can accept up to 100 kHz.
3. For PWM bridge control follow the PWM mode truth table in the datasheet. When the motor is off both IN1 = IN2 = 1. This also keeps the bridge in high-side recirculation during PWM on/off. The bridge will be active during PWM LOW and in recirculation while PWM is HIGH. One of the inputs must be 1, while other input is driven with a PWM input for proper recirculation during PWM off time.
Do not use: If you set IN1 = IN2 = 0 and keep one of the inputs 0 while driving the other with a PWM the bridge will enter Hi-Z every time during PWM off. There won't be proper recirculation happening resulting with improper drive waveform at the output due to back EMF from the motor during Hi-Z. It looks like you were facing this issue and you were requesting for OUT1 and 2 waveforms with INx PWM.
See below OUT1 & 2 and IN1 & 2 captures. Yellow trace is IN1, pink is IN2, green OUT1 and blue OUT2. PWM mode control as described in bullet #3.
25% duty cycle at the output, 20 kHz PWM in one direction of bridge operation:
75% duty cycle at the output, 20 kHz PWM in one direction of bridge operation:
25% duty cycle at the output, 20 kHz PWM in opposite direction of bridge operation:
75% duty cycle at the output, 20 kHz PWM in opposite direction of bridge operation:
4. No nFAULT reporting for Itrip in the DRV8873H-Q1. It is a programmable option in the DRV8873S-Q1.
Regards, Murugavel
