Micrel

MICRF218

September 2007

2

M9999-090607

(408) 944-0800

Application Example

+3V

C4

0.1µF

16V

C2

1.5pF 50V

ANT

PCB Pattern

C5

4.7µF

6.3V

Y1

9.8131MHz

C1

6.8pF

U1 MICRF218AYQS

1

2

3

4

5

6

7

89

10

11

12

13

14

15

16

RO1

GNDRF

ANT

GNDRF

VDD

IF_BW

SEL0

SHDN

GND

DO

SEL1

CTH

CAGC

RSSI

NC

RO2

C3

0.1µF 16V

L1

39nH

L2

68nH

DO

RSSI

IF_BW CONTROL

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.