T5744 Ver la hoja de datos (PDF) - Atmel Corporation

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Fabricante

T5744

UHF ASK/FSK Receiver

Atmel Corporation 

Pin ENABLE

T5744

Pin MODE can now be set in accordance with the desired clock cycle TClk. TClk controls

the following application-relevant parameters:

Timing of the analog and digital signal processing

IF filter center frequency (fIF0)

Most applications are dominated by two transmission frequencies: fSend = 315 MHz is

mainly used in USA, fSend = 433.92 MHz in Europe. In order to ease the usage of all TClk-

dependent parameters, the electrical characteristics display three conditions for each

parameter.

• Application USA

(fXTO = 4.90625 MHz, MODE = L, TClk = 2.0383 µs)

• Application Europe

(fXTO = 6.76438 MHz, MODE = H, TClk = 2.0697 µs)

• Other applications

(TClk is dependent on fXTO and on the logical state of Pin MODE. The electrical

characteristic is given as a function of TClk).

The clock cycle of some function blocks depends on the selected baud rate range

(BR_Range) which is defined by the Pins BR_0 and BR_1. This clock cycle TXClk is

defined by the following formulas for further reference:

BR_Range = BR_Range0:

BR_Range1:

BR_Range2:

BR_Range3:

TXClk = 8 ´ TClk

TXClk = 4 ´ TClk

TXClk = 2 ´ TClk

TXClk = 1 ´ TClk

Via the Pin ENABLE the operating mode of the receiver can be selected (see Figure 10

and Figure 11).

If the Pin ENABLE is held to Low, the receiver remains in sleep mode. All circuits for sig-

nal processing are disabled and only the XTO is running in that case. The current

consumption is IS = ISoff in that case. During the sleep mode the receiver is not sensitive

to a transmitter signal.

To activate the receiver, the Pin ENABLE must be held to High. During the start-up

period, TStartup, all signal processing circuits are enabled and settled. The duration of the

start-up period depends on the selected baud-rate range (BR_Range).

After the start-up period, all circuits are in a stable condition and the receiver is in the

receiving mode.

In receiving mode, the internal data signal (Dem_out) is switched to Pin DATA. To avoid

incorrect timing at the begin of the data stream, the begin is synchronized to a falling

edge of the incoming data signal. The receiver stays in the receiving mode until it is

switched back to sleep mode via Pin ENABLE.

During start-up and receiving mode, the current consumption is IS = ISon.

9

4521B–RKE–01/03

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