Tool/software:
Hi team，
1. For DRV8705-Q1, can we provide the following external gates recommended content similar to those described in the DRV8703-Q1 datasheet? For example, the recommended maximum PWM frequency and the maximum Q value.
2. May I know if there are recommended Qg and Qgd values for External MOSFETs at 16Khz frequency and IDRIVE set to Level 4?
Thanks.
Regards,
Ivy
Hi Ivy,
DRV8705-Q1 is new generation could be replaced by DRV8703-Q1. DRV8705-Q1 released almost 5 years ago. Customer is better to consider DRV8705-Q1 for new design.
1) Old datasheet of DRV8703-Q1 does not have it.
2) 16KHz is pretty normal use case. Normally automotive motor driver case, external FET Qg is ~100nC range. Customer should check on the bench to set final IDRIVE, but normally ~8-16mA setting is good enough, although DRV9705-Q1 can support up to 62mA.
regards
Shinya
Hi Shinya,
Thanks for your suggestions.
Based on your recommendation, the customer has selected 16 Khz, 70% duty cycle PWM to control the external MOSFET, the MOSFET is BUK7Y2R0-40H, the Qg parameters are shown in the following figure. The maximum value is 90.5nC, which is less than 100nC.
The IDRIVE for the DRV8705H is set to Level 4 (12-20mA; typ16mA). In practical testing, customer has found that switching loss account for 50% of the total loss, resulting in a high MOSFET temperature rise.
Based on this test result, could you help recommend the more appropriate Qg and Qgd value for External MOSFETs or a suitable driver circuit for external MOSFETs?
Many thanks!
Regards,
Ivy
