LMH0384 Datasheet, PDF (15/29 Pages) National Semiconductor (TI) – 3 Gbps HD/SD SDI Extended Reach and Configurable Adaptive Cable Equalizer

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Programming (continued)
LMH0384
SNLS308G – APRIL 2009 – REVISED JUNE 2015
(CD = 0) || (CLI > 180m)
(Reg 00h, bit 7 = 0) || (Reg 03h, bits [7:3] > 10010)
Normal Mode
(CD = 1) && (CLI < 180m)
(Reg 00h, bit 7 = 1) && (Reg 03h, bits [7:3] < 10010)
Extended 3G Reach Æ Normal
Register Processing:
1. Force EQ to Sleep: Reg 00h, bits [4:3] = 10
2. Force Extended 3G Reach Mode OFF: Reg 00h, bit 2 = 0
3. Wait > 1 ms
4. Set Sleep Mode to Auto: Reg 00h, bits [4:3] = 01
Normal Æ Extended 3G Reach
Register Processing:
1. Force EQ to Sleep: Reg 00h, bits [4:3] = 10
2. Force Extended 3G Reach Mode ON: Reg 00h, bit 2 = 1
3. Wait > 1 ms
4. Set Sleep Mode to Auto: Reg 00h, bits [4:3] = 01
CD = 0
(Reg 00h, bit 7 = 0)
Extended 3G
Reach Mode
Figure 10. Extended 3G Reach Mode State Machine Example
7.5.7 Explanation of Extended 3G Reach Mode State Machine (Figure 10)
When the LMH0384 is powered on, it will be in normal mode. If there is no input signal (register 00h, bit 7 = 0) or
if the input cable is longer than a user programmable cable length (that is 180m, which means register 03h, bits
[7:3] > 10010), then the device should remain in normal mode.
Once an input signal is detected (register 00h, bit 7 = 1) AND the detected cable length is shorter than the user
programmed cable length of 180m (register 03h, bits [7:3] < 10010), then the equalizer can enter the extended
3G reach mode to allow for longer cable lengths at 2.97 Gbps. This requires the following procedure:
1. Force the equalizer to sleep by writing “10” to bits [4:3] of register 00h.
2. Turn on the extended 3G reach mode by writing “1” to bit 2 of register 00h.
3. Wait at least 1ms.
4. Set the sleep mode to auto by writing “01” to bits [4:3] of register 00h. Alternately, sleep mode may be set to
off by writing “00” to bits [4:3] of register 00h.
The equalizer remains in extended 3G reach mode until the cable length is changed. If the cable length is
changed, the input signal drops out momentarily. Once this happens (register 00h, bit 7 = 0), then the following
procedure must be used to set the device back to normal mode:
1. Force the equalizer to sleep by writing “10” to bits [4:3] of register 00h.
2. Turn off the extended 3G reach mode by writing “0” to bit 2 of register 00h.
3. Wait at least 1ms.
4. Set the sleep mode to auto by writing “01” to bits [4:3] of register 00h. Alternately, sleep mode may be set to
off by writing “00” to bits [4:3] of register 00h.
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