DS250DF230: 2.4756Gbps CDR Bypass Mode

Yuta Nishie

Genius 3655 points

Part Number: DS250DF230

Hi,

Our customer operates under the following conditions.

1. Is there any guarantee that it will work under these conditions?

・Data Rate Range = 2.4756Gbps

・Frequency = 25MHz

・Register Address = Setting

　0x09 = 0x04,

　0x18 = 0x10,

　0x60, 0x61 = 0x26,

　0x62, 0x63 = 0xB1,

　0x64 = 0xFF

Also, the thread below says "By setting it to CDR Bypass Mode, 2.4756 Gbps may be operated."

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/866016/ds250df230-calibration-clock/3227145?tisearch=e2e-sitesearch&keymatch=DS250DF230#3227145

2. Please tell me the register to check CDR Bypass Mode setting.

3. Please tell me the register to set CDR Bypass Mode.

Best Regards,

Nishie

over 1 year ago

+1 Rodrigo Natal over 1 year ago

TI__Mastermind 19235 points

Hi,

The configuration for CDR bypass mode is a bit different for DS250DF230 versus previous generation TI 10G retimers. See excerpts below from the 25G retimer programming guide

6.34 Select Output Mode when CDR is Not Locked

By default, the DS2x0DFx10 output is muted when the CDR is not locked. The DS2x0DFx10 can optionally be configured to output raw, un-retimed data when the CDR is not in lock.

Table 61. Select output mode when CDR is not locked

STEP

SHARED/ CHANNEL REGISTER SET

OPERATION

REGISTER ADDRESS [HEX]

REGISTER VALUE [HEX]

WRITE MASK [HEX]

COMMENT

Channel

Write

PFD_SEL_DATA_PRELCK=3'

b111: Mute (default)

Note: Reg_0x09[5] must be 0, which is the default.

PFD_SEL_DATA_PRELCK=3'

b000: Raw, un-retimed data Note: Reg_0x09[5] must be 0, which is the default.

6.35 Select Output Mode when CDR is Locked

By default, the DS2x0DFx10 outputs retimed data when the CDR is locked. The DS2x0DFx10 can optionally be configured to output raw, un-retimed data or mute when the CDR is in lock.

Table 62. Select output mode when CDR is locked

STEP	SHARED/ CHANNEL REGISTER SET	OPERATION	REGISTER ADDRESS [HEX]	REGISTER VALUE [HEX]	WRITE MASK [HEX]	COMMENT
1	Channel	Write	A5	20	E0	PFD_SEL_DATA_PSTLCK=3' b001: Retimed (default) Note: Reg_0x09[5] must be 0, which is the default.
				00	E0	PFD_SEL_DATA_PSTLCK=3' b000: Raw, un-retimed data Note: Reg_0x09[5] must be 0, which is the default.
				E0	E0	PFD_SEL_DATA_PSTLCK=3' b111: Mute Note: Reg_0x09[5] must be 0, which is the default.

Thanks,

Rodrigo Natal

Interface

Interface forum

DS250DF230: 2.4756Gbps CDR Bypass Mode