T5760 データシートの表示（PDF） - Atmel Corporation

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T5760

UHF ASK/FSK Receiver

Atmel Corporation 

T5760 / T5761

ing bit-check mode, the incoming data stream is analyzed

bit by bit contra a valid transmitter signal. If no valid

signal is present, the receiver is set back to sleep mode af-

ter the period TBit-check. This period varies check by

check as it is a statistical process. An average value for

TBit-check is given in the electrical characteristics. During

TStartup and TBit-check the current consumption is IS = ISon.

The condition of the receiver is indicated on Pin IC_AC-

TIVE. The average current consumption in polling mode

is dependent on the duty cycle of the active mode and can

be calculated as:

ISpoll + ISoff

TSleep ) ISon (TStartup ) T ) Bitcheck

TSleep ) TStartup ) TBitcheck

During TSleep and TStartup the receiver is not sensitive to

a transmitter signal. To guarantee the reception of a trans-

mitted command the transmitter must start the telegram

with an adequate preburst. The required length of the

preburst depends on the polling parameters TSleep,

TStartup, TBit-check and the start-up time of a connected µC

(TStart,µC). Thus, TBit-check depends on the actual bit rate

and the number of bits (NBit-check) to be tested.

The following formula indicates how to calculate the

preburst length.

TPreburst w TSleep + TStartup + TBit-check + TStart_mC

Sleep Mode

The length of period TSleep is defined by the 5-bit word

Sleep of the OPMODE register, the extension factor

XSleep (according to table 9), and the basic clock cycle

TClk. It is calculated to be:

TSleep = Sleep XSleep 1024 TClk

In US- and European applications, the maximum value of

TSleep is about 60 ms if XSleep is set to 1. The time reso-

lution is about 2 ms in that case. The sleep time can be

extended to almost half a second by setting XSleep to 8.

XSleep can be set to 8 by bit XSleepStd to’1’.

According to table 8, the highest register value of sleep

sets the receiver into a permanent sleep condition. The re-

ceiver remains in that condition until another value for

Sleep is programmed into the OPMODE register. This

function is desirable where several devices share a single

data line and may also be used for µC polling – via Pin

POLLING/_ON, the receiver can be switched on and off.

Rev. A2, 19-Oct-00

7 (32)

Preliminary Information

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