Preliminary W91030B

Publication Release Date: March 2000

- 11 -

Revision A1

Demodulated

internal

bit stream

start

0

b0

b1

b2

b3

b4

b5

b6

b7

1

0

stop

stop

start

DATA

b0 b1 b2 b3 b4 b5 b6 b7

DCLK

FDRN

b7

b6

b5

1

b0

b0

b7

b6

Nth byte data

(N + 1)th byte data

(N - 1)th byte data

Nth byte data

Note 2

Note 1

1. FDRN cleared to high by DCLK.

2. FDRN not cleared, low for maximum time (1/2 bit width).

Notes:

Figure 7-8. Serial Data Interface Timing of FSK Demodulation in Mode 1

Other Functions

Interrupt

The interrupt INTN is an open drain output and is used to interrupt the microcontroller. Either RNGON

low, FDRN low or ALGO high will set INTN low and will remain low until all of these three pins return

to an inactive state. The microcontroller must read these pins to know what kind of interrupt occurred

and to make the correct interrupt response.

When the system is powered on, there is no charge on the capacitors. The voltage on the RNGRC pin

is low and RNGON will be low. Also the voltage on the ALGRC pin is high and ALGO will be high if

the SLEEP pin is low. This will cause an interrupt upon power up which will not be cleared until both

capacitors are charged. The microcontroller should therefore ignore the interrupt from these source

until the capacitors are charged up. The microcontroller can examine the RNGON and ALGO pins

and wait until these signals are inactive during a power on interrupt.

It is possible to clear the ALGO pin and its interrupt quickly by setting the SLEEP pin high. In the

sleep mode, the ALGO pin is forced low and the charge switch in Figure 7-4 will turn on, forcing the

capacitor to charge up rapidly.

Sleep Mode

The W91030B can go into a sleep mode by setting SLEEP high, resulting in reduced power

consumption. In this mode, the gain control op-amp, oscillator and all internal circuits, except the ring

detector are disabled. The RNGDI, RNGRC and RNGON pins are not affected, so the device can still

react to call arrival indicators and activate an interrupt to wake up the microcontroller. The sleep

mode can be disabled by the microcontroller.