SN65DSI85: PLL can't be locked

Antony Lin

Part Number: SN65DSI85

Hi,

Customer can lock PLL (PLL_EN_STAT read as '1') under REFCLK mode (0x0A set as 0x04 & 0x0B set as 0x00) but they can’t lock PLL (PLL_EN_STAT read as '0') under MIPI CLK mode (0x0A set as 0x05 & 0x0B set as 0x10). Please advise what should be checked as the next step to debug on this.

THanks!

Antony

over 6 years ago

0 Yaser Ibrahim over 6 years ago

TI__Genius 10250 points

Hello,

Please check and make sure that the initialization sequence (Table 5 in datasheet) is followed. If that is the case, then another thing to check is the signal integrity on the MIPI side (examine the eye diagram of the DSI clock and data and make sure the eye is open). What is the operating mode (see Table 4 in the datasheet)? What is the DSI clock frequency? How long is the connection between MIPI source and DSI85?

Regards,

Yaser

0 Ikechukwu Anyiam over 6 years ago

TI__Mastermind 35130 points

Is this issue still open?

0 Antony Lin over 6 years ago in reply to Ikechukwu Anyiam

TI__Genius 13480 points

It looks like PLL can’t lock because of the initial sequence. Customer will fix the initial sequence later, and use REFCLK as short-term solution. The display has been brought up successfully now.

Issue can be closed for the moment.

THanks!

Antony

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SN65DSI85: PLL can't be locked