Original question:
Hi TI
I use DRV8714 in my design， when open load, I put sleep high, then set registers.
I test SO1 & SO2's voltage, Vso1=3.4V，Vso2=2.2V, it make me confused.
My question is
1. why Vso1 and Vso2 has too much diff?
2. when open load, I think Vso1 and Vso2 should be 2.5V, It doesn't meet my test result.
register setting:
0x07set: 0xe6
0x08set: 0x42
0x28set: 0x07
0x27set: 0x07
other register is default setting.
Hi,
Thank you for your questions.
VSO1 and VSO2 are output of amp. Therefore some factor impact to output voltage level.
1) SPx/SNx voltage difference will impact directly to SO. I recommend to connect SPx and SNx then short to AGND. I guess SOx output will be same after this change.
2) If GAIN and DIV are set differently, SO will be different. Please review CSA_CTRL1 addr=0x26h
regards
Shinya Morita
Hi
Thanks for your reply, but you didn't resolve my problem.
addr=0x26h, I use defualt setting. So I think it doesn't my setting cause this.
My design is similar as below design block：
Hi,
Thank you for your update.
Based on given feedback, if you try following setting, then I think SO1 and SO2 will be same as expected. I suggest to start with this trial first to narrow down root cause.
1) SPx/SNx voltage difference will impact directly to SO. I recommend to connect SPx and SNx then short to AGND. I guess SOx output will be same after this change.
regards
Shinya Morita
Hi,
Thank you for your update. Your VSO is very strange if SPx/SPNx pins are shorted together and 0V.
1) How many units did you test? If only 1pcs, one possibility is device was damaged or somehow failure units. Can you test second one?
2) If 1) is not root cause, could you share the schematic?
3) Which DRV8714-Q1 are you testing?
4) What is AREF voltage input?
If 5V, AREF/2 as default then VSO should be ~ 2.5V while SPx=SNx=0V.
If 3.3V, AREF/2 as default then VSO should be ~ 1.65V while SPx=SNx=0V.
Do you see VSO change if you change CSA_DIV_1 and CSA_DIV_2 to AREF/8 ?
regards
Shinya Morita
