LMX2595: Read back register in full assist mode

Taketo Sato

Part Number: LMX2595

Hello team,

I have a question about read back function when full assist mode.

In full assist mode, can the device read back properly from R110, R111 and R112 the values of VCO_DACISET, VCO_CAPCTRL, VCO_SEL which are set in R16, R19 and R20?

According to customer's experiment, VCO_SEL is correctly read, however others are not.

Changing clock speed for the read back gives some improvement but not 100%.

So I would like to know if the device supports the read back in full assist mode.

Best regards,

over 5 years ago

0 Noel Fung over 5 years ago

TI__Guru** 108270 points

Hi Sato-san,

In full-assist mode, we manually set the values for VCO_DACISET, VCO_CAPCTRL, VCO_SEL. Don't forget to set VCO_DACISET_FORCE, VCO_CAPCTRL_FORCE, VCO_SEL_FORCE to 1. Otherwise, you may get a different value from readback because calibration will over write their values.

0 Taketo Sato over 5 years ago in reply to Noel Fung

TI__Genius 10325 points

Hello Noel-san,

Customer properly set VCO_DACISET_FORCE, VCO_CAPCTRL_FORCE, VCO_SEL_FORCE to 1.

However they cannot readback the resister value.

Does the device support read back function in full assist mode?

Best regards,

0 Noel Fung over 5 years ago in reply to Taketo Sato

TI__Guru** 108270 points

Hi Sato-san,

I think so, I will check this out, stay tuned.

0 Noel Fung over 5 years ago in reply to Noel Fung

TI__Guru** 108270 points

Hi Sato-san,

I checked this out, I could readback VCO_SEL and VCO_DACISET values correctly. However, the read back value of VCO_CAPCTRL is not the force value, it is the last value obtained from calibration.

0 Taketo Sato over 5 years ago in reply to Noel Fung

TI__Genius 10325 points

Hello Noel-san,

Do you mean the readback function especially for VCO_CAPCTRL may not work in full assist mode as device specification?

Best regards,

0 Noel Fung over 5 years ago in reply to Taketo Sato

TI__Guru** 108270 points

Hi Sato-san,

I tested one chip, I can read back VCO_SEL and VCO_DACISET correctly but the readback value of VCO_CAPCTRL is not correct.

Clock & timing

Clock & timing forum

LMX2595: Read back register in full assist mode