LMH0366

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SNAS585D – APRIL 2012 – REVISED APRIL 2013

Parameters for a suitable crystal are given in Table 6. A single crystal can be used as the 27 MHz reference for

multiple reclockers by connecting the XTAL_OUT output of one reclocker to the XTAL_IN input of the next ,

propagating the 27 MHz reference signal through a cascade of reclockers.

Table 6. Recommended Crystal Parameters

Parameter

Value

Frequency

27 MHz

Frequency Stability

±50 ppm @ Recommended Drive Level

Operating Mode

Fundamental Mode, Parallel Resonant

Load Capacitance

20 pF

Shunt Capacitance

7 pF

Series Resistance

40

Ω max

Recommended Drive Level

100 µW

Maximum Drive Level

250 µW

Operating Temperature Range

−10°C to +60°C

SD/HD Indication

The SD/HD output indicates whether the LMH0366 is processing SD or HD/3G data rates. It may be used to

control the slew rate of another device such as the LMH0303 cable driver. This output is high when the data rate

is 270 Mbps, and this output is low for all other data rates. When the PLL is not locked (the LOCK_DETECT

output is low), the SD/HD output is low.

Data Rate Indication

Details about the currently locked data rate can be obtained via the SPI. Register 0x03 bits 7:5 (RATE_STATUS)

indicate the locked data rate according to Table 7.

The LMH0366 will detect the presence of a 27 MHz reference clock on the XTAL_IN pin (register 0x41 bit 3,

REF_CLK_DET, indicates the presence of the reference clock). When using an external reference, the LMH0366

can distinguish between 1.4835 and 1.485 Gbps, and between 2.967 and 2.97 Gbps. This is indicated in the

RATE_STATUS register bits. Also, when the reference clock is present, register 0x41 bit 2 (RATE_1_OV_M)

indicates if the detected data rate is a 1 over M rate (1.485/1.001 or 2.97/1.001 Gbps).

Table 7. Data Rate Indication (via Register 0x03 bits 7:5)

RATE_STATUS[2:0]

Data Rate Indication

External Reference Mode

Referenceless Mode

000

125 Mbps

125 Mbps

001

270 Mbps

270 Mpbs

010

1.4835 Gbps

N/A

011

1.485 Gbps

1.485 or 1.4835 Gbps

100

2.967 Gbps

N/A

101

2.97 Gbps

2.97 or 2.967 Gbps

111

Unlocked

Unlocked

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