MICRF219 datasheet(16/24 Pages) MICREL

16 / 24 page

Micrel

MICRF219

January 2009

M9999-011509

(408) 944-0800

the o

a d

ean

e de

and

See

d Figure 10 below. Please note that Sq

action is based on the Bitcheck operation and m

optimized using the Bitcheck Window serial re

shown in the figure below depending upon

band noise. The penalty for using squelch is

getting a good signal in the DO pin. This m

takes longer for the data to show up. Th

dep

upon many factors such as

intensity, data profile, data rate, CTH

capacitor values, and outside band noise.

utside

elay in

that it

lay is

signal

CAGC

Figure

uelch

ay be

gister

endent

setting.

Figure 9. Data Out Pin with No Squelch (SQ = 1).

Figure 10. Data Out Pin with Squelch (SQ = 0).

Other components used are C5, which is a decoupling

capacitor for the Vdd line; R3 for the shutdown pin

(SHDN = 0, device is operation), which can be

removed if that pin is connected to a microcontroller or

an external switch; and R1 and R2 which form a

voltage divider for the AGC pin. One can force a

rposely decrease the

is needed when doing

eration, as an external control of the AGC

and may not work the

omment. They are the

s. The DO pin has a

is is good enough for

he market today. The

n of the RF signal

intensity versus voltage. It is very useful to determine

RF link, crude range

ter source and AM

a low CAGC capacitor

useful to save energy.

DN = 1), the device is

t consumption is less

ve R3). When toggling

a time required for the

device to come to steady-state mode, and a time for

data to show up in the DO pin. This time will be

dependent upon many things such as temperature,

the crystal used, and if there is an external oscillator

with faster startup time. See Figure 11 and 12 for

time-to-good-data on both 433.92MHz and 315MHz

versions.

voltage in this AGC pin to pu

device sensitivity. Special care

this op

voltage may vary from lot to lot

same in several devices.

Three other pins are worthy of c

DO, RSSI, and shutdown pin

driving capability of 0.4mA. Th

most of the logic family ICs on t

RSSI pin provides a transfer functio

the signal-to-noise ratio of the

estimate from the transmit

demodulation, which requires

value.

The shutdown pin (SHDN) is

Making its level close to VDD (SH

not in operation. Its DC curren

than 1µA (do not forget to remo

from high to low, there will be

Figure 11. Time-to-Good-Data After Shut Down Cycle,

433.92MHz, Room Temperature.

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