14

ATR2406 [Preliminary]

4779F–ISM–09/04

Received Signal Strength

Indication RSSI

The RSSI is given as an analog voltage at the RSSI pin. A typical plot of the RSSI value

is shown in Figure 6.

Figure 6. Typical RSSI Value versus Input Power

Table 9. Description of the Conditions/States

Conditiion

Description

C1

Power-down

ATR2406 is switched off and the supply current is lower than 1 µA.

C2

Power-up

ATR2406 is powered up by toggling PU_REG and PU_RTX to high.

PU_REG enables the external AUX-Regulator transistor and PU_TRX

enables the internal regulator like VCO_REG (VCO supply voltage

regulator) as well as wakes up the PLL, the VCO, the demodulator,

mixer, etc.

It is necessary to wait at least 40 µs until the different supply voltage

regulators have settled.

C3

Programming

Via the tree-wire-interface the internal register of ATR2406 is programmed.

At TX, this is just the PLL (transmit channel) and the deviation (gaussian

filter).

At RX, this is just the PLL (receive channel) and if the clock recovery is

used also the bits to enable this option. At start of the

three-wire-programming, the enable signal is toggled from high to low to

enable clocking the data into the internal register. When the enable signals

rises again to high, the programmed data is latched. This is the time point

at which the settling of the PLL is starting. It is necessary to wait the

settling time of 350 µs so that the VCO-Frequency is stable.

The reference clock needs to be applied to ATR2406 at minimum the time

when the PLL is in operation - which is the programming state (C3) and the

active slot (C4, C5). Out of the reference clock, several internal signals are

also derived, i.e., the gaussian filter circuitry and TX_DATA sampling.

C4

This is the receive slot where the transmit burst is received and data as

well as recovered clock are available.

C5

This is the active transmit slot. As soon as TX_DATA is applied to

ATR2406, the signal nOLE toggles to low which enables modulation in

open-loop-mode.

0.0

0.5

1.0

1.5

2.0

2.5

-130

-110

-90

-70

-50

-30

-10

10

RF Level (dBm)