DS125BR820 Datasheet, PDF (38/62 Pages) Texas Instruments – Low-Power 12.5 Gbps 8-Channel Linear Repeater

DS125BR820
SNLS491B – JULY 2014 – REVISED FEBRUARY 2015
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Address
Register
Name
0x40
CH7 - CHA_3
RXDET
0x41
CH7 - CHA_3
EQ
0x42
CH7 - CHA_3
VOD
0x43
CH7 - CHA_3
VOD_DB
Table 9. SMBus Slave Mode Register Map (continued)
Bit
Field
Type Default
EEPROM
Reg Bit
Description
7:6 Reserved
Set bits to 0
5:4 Reserved
Yes Set bits to 0
00'b = Input is Hi-Z impedance
01'b = Auto Rx-Detect,
outputs test every 12 ms for 600 ms (50 times) then
stops; termination is Hi-Z until detection; once detected
input termination is 50 Ω
3:2
RXDET
R/W 0x00
Yes
10'b = Auto Rx-Detect,
outputs test every 12 ms until detection occurs;
termination is Hi-Z until detection; once detected input
termination is 50 Ω
11'b = Input is 50 Ω
Note: Override RXDET pin and enable register control
via Reg 0x08[3]
1:0 Reserved
Set bits to 0
7:0 EQ Control R/W 0x2F
Yes
INA_3 EQ Control - total of four levels.
See Table 4.
7
Short Circuit
Protection
Yes
1 = Enable the short circuit protection
0 = Disable the short circuit protection
6:3 Reserved
Yes Set bits to 0101'b
R/W 0xAD
2:0 VOD Control
OUTA_3 VOD Control: VOD / VID Ratio
000'b = 0.57
001'b = 0.65
010'b = 0.71
Yes 011'b = 0.77
100'b = 0.83
101'b = 0.90 (default)
110'b = 1.00 (recommended)
111'b = 1.04
7 RXDET Status
R
Observation bit for RXDET CH7 - CHA_3
1 = Input 50 Ω terminated to VDD
0 = Input is Hi-Z
6:5 Reserved
Set bits to 0
4:3 Reserved
Set bits to 0
0x02
2:0
VOD_DB ^R/W
Control
OUTA_3 VOD_DB Control
000'b = 0 dB (recommended)
001'b = –1.5 dB
010'b = –3.5 dB (default)
011'b = –5 dB
Yes
100'b = –6 dB
101'b = –8 dB
110'b = –9 dB
111'b = –12 dB
Note: Changing VOD_DB bits effectively lowers the
output VOD dynamic range by a factor of the
corresponding amount of dB reduction.
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