MICRF112 datasheet(14/20 Pages) MICREL

14 / 20 page

Micrel, Inc.

MICRF112

December 2011

M9999-120911

(408) 944-0800

Application Information

Figure 6. ASK 433.92MHz and 315MHz

Note: Values in parenthesis are for 315MHz

The MICRF112 is well suited to drive a 50 ohms source,

monopole or a loop antenna. Figure 6 is an example of a

loop antenna configuration. Figure 6 also shows both

315MHz and 433.92MHz ASK configurations for a loop

antenna. Besides using a different crystal, Table 1 lists

modified values needed for the listed frequencies.

Frequency

(MHz)

(nH)

(pF)

(nH)

Y1 (MHz)

315.0

470

150

6.8

9.84375

433.92

680

4.7

13.5600

Table 1

The reference design shown in Figure 6 has an antenna

optimized for using the matching network as described in

Table 1.

Power Control Using External Resistor

R7 is used to adjust the RF output levels which may be

needed to meet compliance. As an example, the

following tables list typical values of conducted RF

output levels and corresponding R7 resistor values for

the 50Ω test board shown in Figure 2. R7 of the TX112

Demo board using the loop antenna can be adjusted for

the appropriate radiated field allowed by FCC or ETSI

compliance. Contact Micrel for suggested values to meet

FCC and ETSI compliances.

R7, Ω

Output Power, dBm

IDD, mA

6.7

8.5

6.3

100

8.0

6.2

500

1.6

4.13

1000

-3.8

4.87

Output Power Versus External Resistor at 315MHz

R7, Ω

Output Power, dBm

IDD, mA

8.68

7.5

8.34

7.33

100

8.02

7.3

500

4.34

6.3

1000

0.42

5.5

Output Power Versus External Resistor at 433.92 MHz

MICRF112 Datasheet(PDF) 14 Page - Micrel Semiconductor

MICRF112 Datasheet(HTML) 14 Page - Micrel Semiconductor

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Datasheet Download

Link URL