CS5460A datasheet(43/54 Pages) CIRRUS

43 / 54 page

CS5460A

DS487F4

slow rise times and/or noisy control signals. (It is

not uncommon to experience temporary periods of

abnormally high noise and/or slow, gradual resto-

ration of power, during/after a power “black-out” or

power “brown-out” event.) Once the RESET pin is

de-asserted, the internal reset circuitry remains ac-

tive for 5 MCLK cycles to insure resetting the syn-

chronous circuitry in the device. The modulators

are held in reset for 12 MCLK cycles after RESET

is de-asserted. After a hardware or software reset,

the internal registers (some of which may drive out-

put pins) will be reset to their default values on the

first MCLK received after detecting a reset event

(see Table 3). The CS5460A will then assume its

active state. (The term active state, as well as the

other possible power states of the CS5460A, are

described in Section 4.6).

The reader should refer to Section 5 for a complete

description of the registers listed in Table 3.

4.5 Serial Port Initialization

It is possible for the serial interface to become un-

synchronized with respect to the SCLK input. If

this occurs, any attempt to clock valid CS5460A

commands into the serial interface will result in ei-

ther no operation or unexpected operation be-

cause the CS5460A will not interpret the input

command bits correctly. The CS5460A’s serial port

must then be re-initialized. To initialize the serial

port, any of the following actions can be performed:

1) Power on the CS5460A. (Or if the device is al-

ready powered on, recycle the power.)

2) Hardware Reset.

3) Issue the Serial Port Initialization Sequence,

which is performed by clocking 3 (or more)

SYNC1 command bytes (0xFF) followed by

one SYNC0 command byte (0xFE) to the serial

interface.

4.6 CS5460A Power States

Active state denotes the operation of CS5460A

when the device is fully powered on (i.e., not in

sleep state or stand-by state). Performing any of

the following actions will insure that the CS5460A

is operating in the active state:

1) Power on the CS5460A. (Or if the device is al-

ready powered on, recycle the power.)

2) Hardware Reset

3) Software Reset

In addition to the three actions listed above, if the

device is operating in sleep state or stand-by state,

waking up the device out of sleep state or stand-by

state (by issuing the Power-Up/Halt command) will

also insure that the device is set into active state.

But in order to send the Power-Up/Halt command

to the device, the serial port has to be initialized.

Therefore, successful wake-up of the device can

be insured by writing the serial port initialization se-

quence to the serial interface, prior to writing the

Power-Up/Halt command.

For a description of the sleep power state and the

stand-by power state, see the Power Down Com-

mand, located in Section 4.1.

Configuration Register:

0x000001

DC offset registers:

0x000000

Gain registers

0x400000

Pulse-Rate Register:

0x0FA000

Cycle-Counter Register:

0x000FA0

Timebase Register:

0x800000

Status Register:

(see Section 5)

Mask Register:

0x000000

Control Register:

0x000000

AC offset registers:

0x000000

Power Offset Register:

0x000000

All data registers:

0x000000

All unsigned data registers

0x000000

Table 3. Default Register Values upon Reset Event

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