CDC3RL02YFPR Datasheet, PDF (9/15 Pages) Texas Instruments – LOW PHASE-NOISE TWO-CHANNEL CLOCK FAN-OUT BUFFER

CDC3RL02
www.ti.com
SCHS371 – NOVEMBER 2009
APPLICATION INFORMATION
Typical Application
The CDC3RL02 is ideal for use in mobile applications as shown in Figure 1. In this example, a single low noise
TCXO system clock source is buffered to drive a mobile GPS receiver and WLAN transceiver. Each peripheral
independently requests an active clock by asserting a single clock request line (CLK_REQ_1 or CLK_REQ_2).
When both clock request lines are inactive, the CDC3RL02 enters a low current shutdown mode. In this mode,
the LDO output, CLK_OUT_1, and CLK_OUT_2 are pulled to GND and the TCXO will be unpowered.
2.2 µF
TCXO
V_LDO
LDO
V_BATT
MCLK_IN
CLK_REQ_1
CLK_OUT_1
CLK_REQ_2
CLK_OUT_2
CDC3RL02 _GND
1 µF
Li
GPS
TCXO REQ
TCXO CLK
TCXO REQ
TCXO CLK
WLAN
Figure 1. Mobile Application
When either peripheral requests the clock, the CDC3RL02 will enable the LDO and power the TCXO. The TCXO
output (square wave, sine wave, or clipped sine wave) is converted to a square wave and buffered to the
requested output.
Input Clock Squarer
Figure 2 shows the input stage of the CDC3RL02. The input signal at MCLK_IN can be a square wave or sine
wave. CMCLK is an internal AC coupling capacitor that allows a direct connection from the TCXO to the
CDC3RL02 without an external capacitor.
MCLK _IN
C_MCLK
Figure 2. Input Stage
Any external component added in the series path of the clock signal will potentially add phase noise and jitter.
The error source associated with the internal decoupling capacitor is included in the specification of the
CDC3RL02. The recommended clock frequency band of the CDC3RL02 is 10 MHz to 52 MHz for specified
functionality. All performance metrics are specified at 26 MHz. The lowest acceptable sinusoidal signal amplitude
is 0.8 V_PP for specified performance. Amplitudes as low as 0.3 V_PP are acceptable but with reduced phase noise
and jitter performance.
Copyright © 2009, Texas Instruments Incorporated
Product Folder Link(s): CDC3RL02
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