CDB5378 datasheet(23/72 Pages) CIRRUS

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CDB5378

DS639DB3

If no system clock is supplied to CDB5378, the DIGITAL FILTER CLOCK jumper (J16) can select a PLL

input clock from a local oscillator. Using a clock divider, the on-board oscillator produces 1.024 MHz,

2.048 MHz, 4.096 MHz and 32.768 MHz clock outputs that can be applied to the CS5378 CLK input.

2.3.2

Interface CPLD

A Xilinx CPLD is included on CDB5378 (XCR3128XL-10VQ100I) as an interface between the CS5378

digital filter and the microcontroller. By default the CPLD only passes through the interface signals, but

can be reprogrammed to disconnect the on-board 8051 microcontroller and connect to another external

microcontroller through the spare dual-row headers. Control signals taken off the CDB5378 board to an

external microcontroller should pair with a ground return wire to maintain signal integrity.

Free software tools and an inexpensive hardware programmer for the Xilinx CPLD are available from the

internet (http://www.xilinx.com). The hardware programmer interfaces with the Xilinx JTAG programming

port (J39) on CDB5378. Note that early versions of the Xilinx WebPack tools (7.1i SP1 and earlier) have

a bug in the JEDEC programming file for the CPLD included on CDB5378, and WebPack version 7.1i SP2

or later is required.

Included below is the default Verilog HDL file used by CDB5378 inside the interface CPLD. Comparing

the input and output definitions of this file with the CPLD schematic pinout should demonstrate how sig-

nals are selected and passed through from the microcontroller to the CS5378 digital filter. Several signal

connections to the CPLD are not defined in the default HDL file, but are routed to the CPLD on CDB5378

for convenience during custom reprogramming.

Specification

Value

Oscillator - Citizen 32.768 MHz VCXO

CSX750VBEL32.768MTR

Surface Mount Package Type

Leadless 6-Pin, 5x7 mm

Supply Voltage, Current

3.3 V, 11 mA

Frequency Stability, Pullability

± 50 ppm, ± 90 ppm

Startup Time

4 ms

Specification

Value

Clock Divider - TI LittleLogic D-Flop

SN74LVC2G74DCTR

Surface Mount Package Type

SSOP8-199

Supply Voltage, Current

3.3 V, 10

µA

CDB5378 Datasheet(PDF) 23 Page - Cirrus Logic

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