CDCM7005_13 datasheet(17/45 Pages) TI

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T0061-01

CTRL_DATA

CTRL_LE

CTRL_CLK

su5

su6

Bit31(MSB)

Bit2

Bit1

Bit0

Bit30

su1

CDCM7005

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SCAS793E – JUNE 2005 – REVISED FEBRUARY 2013

PARAMETER MEASUREMENT INFORMATION (continued)

SPI CONTROL INTERFACE

The serial interface of the CDCM7005 is a simple SPI-compatible interface for writing to the registers of the

device and consists of three control lines: CTRL_CLK, CTRL_DATA, and CTRL_LE. There are four 32-bit wide

registers, which can be addressed by the two LSBs of a transferred word (bit 0 and bit 1). Every transmitted word

must have 32 bits, starting with MSB first. Each word can be written separately. Bit 7, 8, 10, and Bit 12 to 31 of

Word 3 are reserved for factory test purposes and must be filled with zeros. The transfer is initiated with the

falling edge of CTRL_LE; as long as CTRL_LE is high, no data can be transferred. During CTRL_LE, low data

can be written. The data has to be applied at CTRL_DATA and has to be stable before the rising edge of

CTRL_CLK. The transmission is finished by a rising edge of CTRL_LE. With the rising edge of CTRL_LE, the

new word is asynchronously transferred to the internal register (e.g., N, M, P, ...). Each word has to be

separately transmitted by this procedure. Unused or floating inputs must be tied to proper logic level. A 20k

Ω or

larger pull

−up resistor to VCC is recommended.

Figure 14. Timing Diagram SPI Control Interface

The SPI serial protocol accepts word Write operation only. There is neither a read, acknowledge, nor a

handshake operation.

The following four words include the register settings of the programmable functions of the CDCM7005. It can be

modified to the customer application by changing one or more bits. It comes up with a default register setting

after power up or if the power down (PD) control signal is applied. The default setting is shown in column five of

the following words.

It is recommended to program Word 0, Word 1, Word 2 and Word 3 right after power up and PD becomes HIGH.

A low active function is shown as [0] and a high active function is shown as [1].

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