MICRF219 datasheet(8/24 Pages) MICREL

8 / 24 page

Micrel

MICRF219

January 2009

M9999-011509

(408) 944-0800

ceiver not to learn the

eceiver gain, so the receiver only r

the transmitter at close range.

de-s

hro

ramm g.

E: Desens

Desense

Desense is a function designed to reduce th

of the MICRF219 receiver to a maximum

training the MICRF219 receiver. This is done

recognize an intended transmitter. Very often

needs to learn how to recognize a particular

It is important for the re

sensitivity

45dB for

in order to

ansmitter.

signal of a

is to turn

ecognizes

ugh seria

a receiver

stray transmitter near by. The simplest solutio

down the r

The

ense functio is accessible only t

prog

MOD

No Desense - default

6dB Desense

16dB Desense

30dB Desense

42dB Desense

ts in Reference and Control sub-

: 1) Reference Oscillator and 2) Control Logic

1, SHDN

MICRF219 (Figure 2.

a basic Pierce crystal

S transconductor to

gh the MICRF219 has

build-in load capacitors for the crystal oscillator, the

required for tuning it to

frequency. R01 and R02 are external pins of

ect the crystal to the reference

ncy can be calculated:

FREF OSC = FRF/(32 + 1.1/12)

For 433.92 MHz, FREF OSC = 13.52127 MHz.

To operate the MICRF219 with minimum offset, crystal

frequencies should be specified with 10pF loading

capacitance.

V BIAS

Reference Control

There are 2 componen

block

through parallel Inputs: S

Reference Oscillator

The reference oscillator in the

Reference Oscillator Circuit

EL0, SEL

) uses

oscillator configuration with MO

provide negative resistance. Thou

external load capacitors are still

the right

the MICRF219 to conn

oscillator.

Reference oscillator crystal freque

RO2

RO1

Figure 2. Reference Oscillator Circuit

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