Micrel, Inc.

MICRF230

Pin Description (Continued)

Pin

Number

Pin

Name

Type

Pin Function

10

DO

Output

Demodulation data output. A current limited CMOS output in normal operation. An internal

pull-

down of 25kΩ is present when device is in shutdown.

11

SEL1

Input

Logic control input with active internal pull-up (3µA typical). It can be used to select the low-

pass filter bandwidth in the absence register control (Table 1).

12

SEL0

Input

Logic control input with active internal pull-up (3µA typical). It can be used to select the low-

pass filter bandwidth in the absence register control (Table 1).

13

CTH

Input/Output

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

for the demodulation data slice level. Values above 1nF are recommended and should be

optimized for data rate and data profile. Connect a 0.1µF capacitor from CTH pin to GND to

provide a stable slicing threshold.

14

AGC

Input/Output

AGC filter capacitor connection. Connect a capacitor from this pin to GND. Refer to the “AGC

Loop” in the Receiver Operation section for information on the capacitor value.

15

RSSI

Output

Received Signal Strength Indicator output. The voltage on this pin is an inversed amplified

version of the voltage on AGC. Output is from a buffer with typically 200

Ω output impedance.

16

RO2

Output

Pierce Oscillator Output for Crystal Output: Internal capacitance of 7pF to GND during

normal operation.

April 15, 2015

3

Revision 2.0