BQ32000: Calibration Mechanism

Part Number: BQ32000

Tool/software:

Hi Team,

My customer reported that the crystal frequency isn't accuracy, they are going to use BQ32000 calibration function to adjust the crystal frequency.

I followed the E2E post instructions, and I can observe that the IRQ has output the 1Hz clock.

However, the crystal frequency seems not change after adjusting 0x07 register. May I know is there any command wrong? 

1. Unclock 0x22 register：
   1. i2cset -f -y 7 0x68 0x20 0x5E
   2. i2cset -f -y 7 0x68 0x21 0xC7
2. Enable IRQ 1Hz：
   1. i2cset -f -y 7 0x68 0x22 0x01
3. Set PPM value to +8：
   1. Calculated as 0x48 → 01001000（OUT=0, FT=1, S=0, CAL=8）
   2. i2cset -f -y 7 0x68 0x07 0x48

(+) BQ32002: BQ32002 improper time - Clock & timing forum - Clock & timing - TI E2E support forums

Or maybe our mechanism is different from another P2P competitor ISL1208 which use the internal capacitor to adjust the frequency.

My hypothesis is that BQ32000 adjust its 1Hz frequency instead of adjusting the crystal frequency. Please kindly let me know your idea. Thank you.

ISL1208 Datasheet

Best regards,

Mike