MC33493DTB Datasheet MC33493DTB, MC33493DTBER2, MC33493MOD315 | P13-P15

Output Power Measurement

PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 1.7

Freescale Semiconductor 13

11 Output Power Measurement

The RF output levels given in Section 9, “Electrical Characteristics,” are measured with a 50 Ω load directly connected to the

RFOUT pin, as shown below in Figure 9. This wideband coupling method gives results independent of the application.

Figure 9. Output Power Measurement Configurations

The configuration shown in Figure 10(a) provides better efficiency in terms of output power and harmonics rejection. The

schematic on Figure 10(b) gives the equivalent circuit of the RFOUT pin and the DC bias impeder as well as matching network

components for 434 MHz frequency band.

Figure 10. Output Model and Matching Network for 434 MHz Band

RFOUT

RF output

=50W

100 pF

Impeder: TDK MMZ1608Y102CTA00

VCC

RFOUT

RF output

=50

Impeder: TDK MMZ1608Y102CTA00

VCC

Matching

Network

1.5 pF 250

Matching

330pF

39 nH

RFOUT pin

Load

Impeder

(a)

(b)

Network

PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 1.7

Complete Application Schematic and PCB for OOK Modulation

Freescale Semiconductor14

Figure 11 shows the output power versus the R

ext

resistor value with 50

load and with matching network.

Figure 11. Output Power at 434 MHz Band vs R

ext

Value

The 50 Ω matching network used for the 868 MHz band is similar to the 434 MHz, excepting components values: L1 is changed

to 8.2 nH and C3 to 470 pF in Figure 11. The typical gain of this 868 MHz matching network is 4 dB compared to unmatched

configuration.

12 Complete Application Schematic and PCB for OOK

Modulation

Figure 12 shows a complete application schematic using a MC68HC908RK2 microcontroller. OOK modulation is selected,

carrier

= 433.92 MHz. The C

to C

capacitors can be removed if switch debounce is done by software.

Output power measurement in typical conditions (434MHz - Vcc=3V - 25°C)

Output power when matched (dBm)

-0.35dB/kΩ

ΩΩ

Ω # -0.35mA/kΩ

ΩΩ

Output power on 50Ω

ΩΩ

Ω load (dBm)

-6

-4

-2

6 9 12 15 18 21 24

Rext (kΩ

ΩΩ

Ω)

RFOUT

Level (dBm)

REXT SPECIFIED RANGE

Complete Application Schematic and PCB for OOK Modulation

PLL Tuned UHF Transmitter for Data Transfer Applications, Rev. 1.7

Freescale Semiconductor 15

Figure 12. Application Schematic for OOK Modulation, 434 MHz Frequency Band

For 868 MHz band application, the input pin BAND must be wired to ground. See component description on Table 6 and

Table 7.

Table 6. External Components Description for OOK

Examples of crystal reference are given below (see characteristics in Table 7) for different application bands:

• at 315 MHz band (f

reference

= 9.84375 MHz, –40 °C < T

85 °C): NDK LN-G102-950,

• at 434/868 MHz bands (f

reference

= 13.56 MHz, –40 °C < T

< 125 °C): NDK NX8045GB/CSJ S1-40125-8050-12

and NDK NX1255GA.

Component Function Value Unit

Y1 Crystal,

see Tabl e 7

315 MHz band: 9.84 MHz

434 MHz band: 13.56 MHz

868 MHz band: 13.56 MHz

R2 RF output level setting

resistor (R

ext

)

12 kΩ

C6 Crystal load capacitor 8.2

C6 value equals recommended crystal load capacitance reduced by the PCB stray capacitances.

C7 Power supply decoupling

capacitors

22 nF

C8 100 pF

Vbat

SW1

SW2

SW2a

SW1a

8.2pF

2.2nF

22nF

750

13.56MHz

LED1

2.2pF

100pF

12K

1 2

MC68HC908RK2

PTA0

PTB0/MCLK

PTB1

PTB2/TCH0

PTB4/TCH1

PTB5

PTB3/TCLK

OSC1

OSC2

VSS

VDD

IRQ1

RST

PTA7

PTA6/KBD6

PTA5/KBD5

PTA4/KBD4

PTA3/KBD3

PTA2/KBD2

PTA1/KBD1

C10

100nF

MC33493

DATACLK

DATA

BAND

GND

XTAL1

XTAL0

REXT

CFSK

VCC

RFOUT

GNDRF

VCC

ENABLE

MODE

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P22

MC33493DTB

Mfr. #:

Buy MC33493DTB

Manufacturer:

NXP / Freescale

Description:

RF Transmitter 315 434 868 MHz

Lifecycle:

New from this manufacturer.

Delivery:

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MC33493DTB

MC33493DTB

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