14

LMH0356

SNLS270L – AUGUST 2007 – REVISED JANUARY 2016

www.ti.com

Product Folder Links: LMH0356

Submit Documentation Feedback

Copyright © 2007–2016, Texas Instruments Incorporated

8.3.2.8 ENABLE

The ENABLE pin is used to enable or disable the LMH0356. When the device is disabled, the output drivers and

most of the internal circuitry are powered down. The crystal oscillator and external clock reference circuitry

(XTAL IN and XTAL OUT) remain active regardless of the state of ENABLE, allowing the 27-MHz reference clock

signal to be generated and passed on to additional reclockers. The ENABLE pin is active high and has an

internal pullup device to enable the LMH0356 by default.

8.3.2.9 Crystal or External Clock Reference

The LMH0356 uses a 27-MHz crystal or external clock signal as a timing reference input. A 27-MHz parallel

resonant crystal and load network may be connected to the XTAL IN/EXT CLK and XTAL OUT pins.

Alternatively, a 27-MHz LVCMOS compatible clock signal may be input to XTAL IN/EXT CLK. Parameters for a

suitable crystal are given in Table 4.

Table 4. Crystal Parameters

PARAMETER

VALUE

Frequency

27 MHz

Frequency stability

±50 ppm at recommended drive level

Operating mode

Fundamental mode, parallel resonant

Load capacitance

20 pF

Shunt capacitance

7 pF

Series resistance

40

Ω (maximum)

Recommended drive level

100 µW

Maximum drive level

500 µW

Operating temperature

−10°C to 60°C

8.4 Device Functional Modes

The LMH0356 features are programmed using pin control. Refer to Control Inputs and Indicator Outputs for

details.