Datasheet

Normal Mode

Normal Æ Extended 3G Reach

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) || (CLI > 180m)

(CD = 1) && (CLI < 180m)

Extended 3G

Reach Mode

Extended 3G Reach Æ Normal

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

(Reg 00h, bit 7 = 0) || (Reg 03h, bits [7:3] > 10010)

(Reg 00h, bit 7 = 1) && (Reg 03h, bits [7:3] < 10010)

(Reg 00h, bit 7 = 0)

CD = 0

LMH0384

SNLS308F –APRIL 2009–REVISED APRIL 2013

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The extended 3G reach mode is accessible via bit 2 of SPI register 00h. In order to achieve longer 3G cable

reach while still maintaining the performance at HD and SD data rates, a state machine can be implemented as

shown in Figure 8. (Note: If this procedure is not followed, the maximum equalizable cable lengths for HD and

SD data rates will be limited to less than what can be achieved in normal mode).

Figure 8. Extended 3G Reach Mode State Machine Example

EXPLANATION OF EXTENDED 3G REACH MODE STATE MACHINE (Figure 8)

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 (i.e.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.

Product Folder Links: LMH0384