Part Number: DRV3946-Q1
Tool/software:
Hi experts
We use DRV3946 to drive relays with frequency of 20KHz, slew rate of 0x40, CE3 exceeded at 8M with P5 wire of relay control(HV+,HV-,DC+,DC- closed). The block as below. Detailed schematic attached too.
Do you have some suggestions to promote the CE3 performance? 
CE3 result:
Detailed schematic:
CE3 setup(P5 is the green one, the relays are installed in the load box):
Load box:
Hi Ibinu
The config B3 bit 14 is 0X0 and the bit 15 is 0X1, is that the preferred configuration for the EMC performance?
Additional, 1. What the SSC stand for? 2. What's the charge pump's description?
Another side is about the HW circuit, Do you have any suggestion for the schematic optimization?
For example, the common mode choke? will it be better to change it to a differential mode inductor like below or replace it with a different type of common mode choke?
BR
Lin Song
Hi Song,
Please refer to this slide on SSC (EMI Reduction Technique, Dual Random Spread Spectrum (Rev. A)):
In this case SSC for the digital oscillator is disabled by default: BIT 15 - 0x1. Please set to 0x0 to enable SSC on digital oscillator.
There is already spread spectrum on the CP oscillator, to further increase, you can set to BIT 14 - 0x1.
Can you try each of them individually to assess the impact?
In terms of hardware, I will take a look and get back to you.
Best,
Keerthi
Hi Song,
Is there some sort of filter on the supply to the DRV3946-Q1. I see that you already have capacitor on the outputs. Here is what we recommend:
Let me check internally if there is anything else that can be done.
Best,
Keerthi
