LMX2594: 10ms wait in Sync and PFD mode

Taketo Sato

Genius 9855 points

Part Number: LMX2594
Other Parts Discussed in Thread: LMX2592

Hello team,

I have questions about LMX2594 as below. Could you please answer below?

1) 10ms wait time in initial power up sequence programming

Where should we add 10ms wait when Sync mode operation, for example category 2 sync?

Is below sequence correct?

Device power up
Program RESET = 1
Program RESET = 0
Program Reg109
Program Reg108
.....
Program Reg1
Program Reg0 for Sync mode enable
Wait 10ms
Program Reg0 for FCAL_EN

2) PFD control

We can change PFD mode with LMX2592. However in LMX2594, there seems no register for the setting.

In LMX2594 default setting, which PFD mode, Dual or Single is used?

Best regards,

over 5 years ago

0 Noel Fung over 5 years ago

TI__Guru* 88310 points

Hi Sato-san,

I suggest do the initial power up without SYNC first.
Enable SYNC or other functions after Vcc power up is done.

LMX2594 uses dual PFD. Although single PFD mode is possible (configurable), but we think there is no need to use single PFD mode and we therefore hide the register.

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

TI__Genius 9855 points

Hello Noel-san,

Thanks for the answers.
Which below a) or b) correct for sync mode power up?

a)
Program RESET=1
Program RESET=0
Program registers in reverse order(Reg109 - Reg0)
Wait 10ms
Program Reg0 for Sync mode enable
Program Reg0 for FCAL_EN

or

b)
Program RESET=1
Program RESET=0
Program registers in reverse order(Reg109 - Reg0)
Wait 10ms
Program Reg0 for FCAL_EN
Program Reg0 for Sync mode enable
Program Reg0 for FCAL_EN

Best regards,

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

TI__Genius 9855 points

Hello Noel-san,

Which is correct timing for 10ms a) or b)?

Best regards,

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

TI__Guru* 88310 points

Hi Sato-san,

(b) is better but I don't think the last R0 programming step is necessary because SYNC and FCAL_EN are all sitting in R0.

Clock & timing

Clock & timing forum

LMX2594: 10ms wait in Sync and PFD mode