XE1209 データシートの表示（PDF） - Semtech Corporation

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XE1209

30 – 70 kH Ultra Low Power CMOS Transceiver

Semtech Corporation 

XE1209

Ultra Low Power CMOS Transceiver

Symb

Parameters

Conditions

Min

Typ

Max

Unit

RAC Receiver Activation time from

carrier-detector

-

1.6

2.5

ms

mode and with oscillator

running

XOAC Xtal oscillator activation

time

at temp =-10 to +60°C

0.2

2

s

LL

Logical low level

VSS

-

0.2*VDD

V

HL

Logical high level

0.8*VDD

-

VDD

V

6 INPUT/OUTPUT RF SIGNALS

6.1 TRANSMIT MODE

The transmitter is composed of a DDS and a power amplifier. The DDS is a 12-bits counter, which is incremented by

256+13 when the input data is 1 and by 256-13 when the input data is 0. This way, the frequency deviation is equal

to:

∆f

= 13 ⋅ N ⋅ FREF

212

,

Where N is the multiplying factor of the PLL, and FREF the frequency of the reference clock. With N=18 and

FREF=32.768 kHz, the expression gives ∆f=1872 Hz.

The power amplifier delivers a square wave current whose amplitude is programmable (see the configuration register

section below). The figure below shows the shapes of the signals when, as an example, ISINK=110 mA. The

transmitter processes the input data in real time without any additional sampling or filtering, which means that the

data rate does not depend on the XE1209.

DDS output

PA sink current

IS IN K

110 mA

0 mA

© Semtech 2005

www.semtech.com

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