Micrel, Inc.

MICRF112

February 2013

19

M9999-020713

FSK Operation

The Bill of Materials tables describe the components needed for ASK operation for 433.92MHz and 315MHz.

Table 5 lists the component values that change between ASK and FSK operation. Note that use of a high FSK data rate

may excite parasitic resonant modes with some crystal types. Recommended crystals from the Bill of Materials tables are

good for both ASK and FSK.

Mode

R1

R2

R5

R6

JPR1

JPR2

C8

ASK

NP

100kΩ

0Ω

NP

0Ω

NP

NP

FSK

0Ω

NP

NP

100kΩ

NP

0Ω

3.3pF

(1)

10pF

(2)

Notes:

1.

C8 = 3.3pF for 1kHz using HC49/U or HC49US type crystals.

2.

C8= 10pF for 10kHz using HC49/U, (high profile) only.

Table 5. ASK and FSK Settings

R3

R4

Constant ON

0Ω

NP

External Standby Control

NP

100kΩ

Table 6. Enable Control (Shutdown)