Micrel, Inc.

MICRF219A

July 2011

2

M9999-071811-A

RadioTech@micrel.com

Pin Configuration

MICRF219AAYQS

Pin Description

Pin

Number

Pin

Name

Pin Function

1

RO1

Reference resonator connection to the Pierce oscillator. May also be driven by external reference signal of

200mVp-p to 1.5V p-p amplitude maximum. Internal capacitance of 7pF to GND during normal operation.

2

GNDRF

Ground connection for ANT RF input. Connect to PCB ground plane.

3

ANT

Antenna Input: RF Signal Input from Antenna. Internally AC coupled. It is recommended to use a matching

network with an inductor to RF ground to improve ESD protection.

4

GNDRF

Ground connection for ANT RF input. Connect to PCB ground plane.

5

VDD

Positive supply connection for all chip functions. Bypass with 0.1μF capacitor located as close to the VDD

pin as possible.

6

SQ

Squelch Control Logic-Level Input. An internal pull-up (5μA typical) pulls the logic-input HIGH when the

device is enabled. A logic LOW on SQ squelches, or reduces, the random activity on DO pin when there is

no RF input signal.

7

SEL0

Tie this pin to VDD to ensure robust register programming. Use register bits D[4:3] to set demodulation

bandwidth.

8

SHDN

Shutdown Control Logic-Level Input. A logic-level LOW enables the device. A logic-level HIGH places the

device in low-power shutdown mode. An internal pull-up (5μA typical) pulls the logic input HIGH. To ensure

that the part starts up correctly, connect a 1μF capacitor from VDD to SHDN, and a 50kΩ resistor from

SHDN pin to GND. After the supply voltage settles, apply a HIGH logic level voltage to SHDN to turn the

part off, then a LOW logic level voltage to turn the part on before programming or operating the device.

9

GND

Ground connection for all chip functions except for RF input. Connect to PCB ground plane.

10

DO

Data Output. Demodulated data output. A current limited CMOS output during normal operation, 25kΩ pull-

down is present when device is in shutdown.

11

SEL1

Tie this pin to VDD to ensure robust register programming. Use register bits D[4:3] to set demodulation

bandwidth.

or (408) 944-0800