Specifications

AMBE-3000™ Vocoder Chip Users Manual
Version 2.8, August, 2011
H
ardware Information
2.7 Crystal / Oscillator Usage
The AMBE-3000™ Vocoder Chip has an on-chip, PLL-based clock module and requires an input clock frequency of 29.4912
MHz. The PLL-based clock module provides all the necessary clocking signals for the device, as well as control for low-
power mode entry. The AMBE-3000™ Vocoder Chip two modes of operation:
External clock source operation (See Figure 7 X1/XCLKIN and X2 with TTL/CMOS Clock Source)
 Th
is mode allows the internal oscillator to be bypassed. The device clocks are generated from an external clock
source input on the X1/XCLKIN pin.
Crystal-operation (See Figure 8 X1/XCLKIN and X2 with Crystal Oscillator)
 Th
is mode allows the use of an external crystal/resonator to provide the time base to the device.
The following points should be noted when designing any printed circuit board layout:
 Keep X1/XCLKIN and X2 away from high frequency digital traces to avoid coupling.
 Keep the crystal and external capacitors as close to the X1/XCLKIN and X2 pins as possible to minimize board stray
capacitance.
2.7.1 External Clock Source
When an external source is used as the clock input. Connect X1/XCLKIN and X2 as follows:
Figure 7 X1/XCLKIN and X2 with TTL/CMOS Clock Source
(Subject to Change) Page 18
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