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AS3977

Data Sheet - A p p l i c a t i o n I n f o r m a t i o n

9.4 ENABLE Signal Functionality

Figure 21 summarizes the function of ENABLE in combination with the SDI state and the logical level of CLK and DATAIO.

Table 21. ENABLE Signal Functionality

State

ENABLE

CLK

DATAIO

Description

Power Down Mode

↑

XX

resets the SDI and state machine

activates the crystal oscillator (PD is set to low)

sets the lock transmit bit

0

X

indicates data are sampled at the falling edge of CLK

1

X

indicates data are sampled at the rising edge of CLK

X0

X

1

MCCLK configuration is unchanged

All

↑

XX

resets the Power Down Timer

resets the SDI Interface

(re-)enters the Active state

Active, Transmit

↓

XX

activates the Power Down Timer; after 2

cycles the IC reaches the Power Down Mode

Active, Transmit

X

X

indicates the end of Read/Write

All

0

X

X

disables CLK and DATAIO

sets DATAIO to high impedance

Transmit

↓

XX

switches off the PA (if enabled)

latches DATAIO (if enabled)