Micrel

MICRF218

November 2011

2

M9999-111111

(408) 944-0800

315MHz/315.802, 900Hz Baud Rate Example

Pin Configuration

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

RO1

GNDRF

ANT

GNDRF

Vdd

IF_BW

SEL0

SHDN

GND

DO

SEL1

CTH

CAGC

RSSI

NC

RO2

MICRF218AYQS

Pin Description

16-Pin

QSOP

Pin

Name

Pin Function

1

RO1

Reference resonator input connection to Colpitts oscillator stage. May also be driven by external

reference signal of 1.5V p-p amplitude maximum.

2

GNDRF

Negative supply connection associated with ANT RF input.

3

ANT

RF signal input from antenna. Internally AC-Coupled. It is recommended that a matching network

with an inductor to RF ground is used to improve ESD protection.

4

GNDRF

Negative supply connection associated with ANT RF input.

5

VDD

Positive supply connection for all chip functions.

6

IF_BW

IF bandwidth control logic input. Use VDD for Wide IF Bandwidth or VSS for Narrow IF Bandwidth.

This pin must not be left floating, must be tied to VDD or VSS.

7

SEL0

Logic control input with active internal pull-up. Used in conjunction with SEL1 to control the

demodulator low pass filter bandwidth. (See filter table for SEL0 and SEL1 in application

subsection)

8

SHDN

Shutdown logic control input. Active internal pull-up and must be pulled low for Normal Operation.

9

GND

Negative supply connection for all chip functions except RF input.

16-Pin

QSOP

Pin

Name

Pin Function

10

DO

Demodulated data output.

11

SEL1

Logic control input with active internal pull-up. Used in conjunction with SEL0 to control the

demodulator low pass filter bandwidth. (See filter table for SEL0 and SEL1 in application

subsection)

12

CTH

Demodulation threshold voltage integration capacitor. Capacitor to GND sets the settling time for

the demodulation data slicing level. Values above 1nF are recommended and should be optimized

for data rate and data profile.

13

CAGC

AGC filter capacitor. A capacitor, normally greater than 0.47uF, is connected from this pin to GND

14

RSSI

Received signal strength indication output. Output is from a buffer with 200 ohms typical output

impedance.

15

NC

Not Connected

16

RO2

Reference resonator connection. 7pF in parallel with low resistance MOS switch to GND during

normal operation. Driven by startup excitation circuit during the internal startup control sequence.