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[FAQ] DS250DF230: CTLE Boost Table

Part Number: DS250DF230
Other Parts Discussed in Thread: DS250DF210, DS250DF410, DS250DF810, , DS280DF810

Tool/software:

Across all 25-28G retimers (DS250DF210, DS250DF230, DS250DF410, DS250DF810, DS280DF810) there are 255 total CTLE boost settings. A subset of these settings, spanning the full range of the CTLE, makes up the CTLE boost table. Most 25-28G retimers use the same CTLE boost table, which includes 16 indexes spanning from 9.2 dB @ 13 GHz to 26.4 dB @ 13 GHz. DS250DF230 uses a unique CTLE boost table, which includes 20 indexes spanning from 0.6 dB @ 13 GHz to 26.4 dB @ 13 GHz.

CTLE Boost Table (DS250DF210, DS250DF410, DS250DF810, DS280DF810)

EQ Table Index

CTLE Boost Settings

Reg_0x03[7:0] [Hex]

High-Frequency Boost

(10 MHz vs. 13 GHz) [dB]

0 00 9.2
1 40 13.0
2 50 15.0
3 80 14.6
4 90 16.6
5 C0 16.0
6 D0 17.9
7 D1 18.9
8 D5 20.3
9 D8 20.9
10 EA 23.5
11 F7 23.8
12 FD 24.3
13 EE 24.5
14 EF 25.3
15 FF 26.4

CTLE Boost Table (DS250DF230 only)

EQ Table Index

CTLE Boost Settings

Reg_0x03[7:0] [Hex]

High-Frequency Boost

(10 MHz vs. 13 GHz) [dB]

0 00 0.6
1 01 2.0
2 02 3.2
3 03 5.4
4 00 9.2
5 40 13.0
6 50 15.0
7 80 14.6
8 90 16.6
9 C0 16.0
10 D0 17.9
11 D1 18.9
12 D5 20.3
13 D8 20.9
14 EA 23.5
15 F7 23.8
16 FD 24.3
17 EE 24.5
18 EF 25.3
19 FF 26.4

On the DS250DF230, the first three stages of the CTLE can be bypassed so that a very small amount of gain can be applied in the fourth stage only. This is why the DS250DF230 CTLE boost table includes 4 additional indexes and the minimum boost is much lower than other retimers. For short channel/low insertion loss use cases, DS250DF230 may be a better choice than other 25-28G retimers because of its minimum CTLE boost.

For all 25-28G retimers, the boost values for CTLE indexes 0-15 are programmed in channel registers 0x40 -- 0x4F, respectively. For DS250DF230, the boost values for CTLE indexes 16-19 are programmed in channel registers 0x50 -- 0x53, respectively. These registers are reserved for all other 25-28G retimers. TI strongly does not recommend making any changes to the boost values for each CTLE index.

If DS250DF230 is being configured through an external EEPROM, 4 bytes need to be included in the EEPROM hex file for registers 0x50 -- 0x53. These should be inserted between bytes which program channel registers 0x4F and 0x60. These 4 bytes are not included in the EEPROM hex file for all other 25-28G retimers.

EEPROM Register Map Excerpt (DS250DF210, DS250DF410, DS250DF810, DS280DF810)

EEPROM Address Byte Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
46 (0x2E) 0x4E[7] 0x4E[6] 0x4E[5] 0x4E[4] 0x4E[3] 0x4E[2] 0x4E[1] 0x4E[0]
1 1 1 0 1 1 1 1
47 (0x2F) 0x4F[7] 0x4F[6] 0x4F[5] 0x4F[4] 0x4F[3] 0x4F[2] 0x4F[1] 0x4F[0]
1 1 1 1 1 1 1 1
48 (0x30) 0x60[7] 0x60[6] 0x60[5] 0x60[4] 0x60[3] 0x60[2] 0x60[1] 0x60[0]
0 0 0 0 0 0 0 0
49 (0x31) 0x61[7] 0x61[6 0x61[5] 0x61[4] 0x61[3] 0x61[2] 0x61[1] 0x61[0]
0 0 0 0 0 0 0 0

EEPROM Register Map Excerpt (DS250DF230 only)

EEPROM Address Byte Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
46 (0x2E) 0x4E[7] 0x4E[6] 0x4E[5] 0x4E[4] 0x4E[3] 0x4E[2] 0x4E[1] 0x4E[0]
1 1 1 0 1 0 1 0
47 (0x2F) 0x4F[7] 0x4F[6] 0x4F[5] 0x4F[4] 0x4F[3] 0x4F[2] 0x4F[1] 0x4F[0]
1 1 1 1 0 1 1 1
48 (0x30) 0x50[7] 0x50[6] 0x50[5] 0x50[4] 0x50[3] 0x50[2] 0x50[1] 0x50[0]
1 1 1 1 1 1 0 1
49 (0x31) 0x51[7] 0x51[6] 0x51[5] 0x51[4] 0x51[3] 0x51[2] 0x51[1] 0x51[0]
1 1 1 0 1 1 1 0
50 (0x32) 0x52[7] 0x52[6] 0x52[5] 0x52[4] 0x52[3] 0x52[2] 0x52[1] 0x52[0]
1 1 1 0 1 1 1 1
51 (0x33) 0x53[7] 0x53[6] 0x53[5] 0x53[4] 0x53[3] 0x53[2] 0x53[1] 0x53[0]
1 1 1 1 1 1 1 1
52 (0x34) 0x60[7] 0x60[6] 0x60[5] 0x60[4] 0x60[3] 0x60[2] 0x60[1] 0x60[0]
0 0 0 0 0 0 0 0
53 (0x35) 0x61[7] 0x61[6 0x61[5] 0x61[4] 0x61[3] 0x61[2] 0x61[1] 0x61[0]
0 0 0 0 0 0 0 0