Other Parts Discussed in Thread: DRV8412, TAS5624A, TAS5634, TAS5624,
Hi,
we are designing a voice coil driver using DRV8432 and suddenly we found that there are literally no datasheets on DRV8432 right now and we cannot order it on the retailers!! We search an alternate upgrade DRVs and find that TI is recommend DRV8962DDV over DRV8432.
The application at hand requires direct PWM control of each Half bridge with a DSP (TMS320C2000) in the loop for a voice coil position control. We would like to achieve prompt and precise control, so the following specifications are considered.
1. The current sensing accuracy and update time. We need to control PWM cycle by cycle using current feed back to the DSP, we found that TI says the IPROP accuracy is 4% and the delay might be 2us or 3.5us the worst case. So, is this specification mars with DRV8432? 3.5 us means that the on time of the PWM may not be adjusted during this time interval in a closed loop control. Do we need an external shunt resistor for timely closed loop current control?
2. The PWM frequency of DRV8432 is 500 KHz, in a prototype we designed we used an external shunt resistor together with a closed loop control update interval of 2 us in DSP. For DRV8962, the maximum PWM is reduced to 200KHz which is a minimum 5 us. Moreover, the dead time, propagation time of DRV8432 is 5.5 ns and 38 ns respectively, compared to DRV8962 300 ns and 600 ns respectively, I do not think DRV8962 might be well replace DRV8432. (And yes, our engineering team do love DRV8432!!!!! why remove it ...). These parameters, PWM frequency, IPROP delay, DEAD time, PROPAGATION time matters for voice coil applications, is it right? Is DRV8962 capable doing these like DRV8432, so we can confidently remove existing drv8432 designs with drv8962?
3. Is there any integrated FET high frequency DRV chips (or planning)? We expect a PWM in the range of 500KHz or more, 1 MHz.
Best regards. Benyuan
