LANSDALE Semiconductor, Inc.

ML13175/ML13176

RFOut

SM

A

8

7

6

5

4

3

2

1

Osc

Tank

Coilcraft

150–05J08

0.165

µ

(2)

VEE

0.1

µ

1.0k

150p

f/N

ML13175

Crystal

3rd Overtone

40.0000 MHz

27k

(5)

VCC

RFC1

150p

Z = 50

(1)

9

10

11

12

13

14

15

16

3.3k

Rmod

Figure 21. ASK 320 MHz Application Circuit

NOTES: 1. 50

Ω coaxial balun, 1/10 wavelength line (1.5") provides the best

match to a 50

Ω load.

2. Pins 5, 10 and 15 are ground and connnected to VEE which is

the component/DC ground plane side of PCB. These pins must

be decoupled to VCC; decoupling capacitors should be placed

as close as possible to the pins.

3. The crystal oscillator circuit may be adjusted for frequency with

the variable inductor (MC13175); 1.0 k resistor shunting the

crystal prevents it from oscillating in the fundamental mode.

Recommended source is Coilcraft “slot seven” 7.0 mm tuneable

inductor, part #7M3–821.

100p

(ML13176)

VCC

30p

(ML13175)

ML13175–30p

ML13176–180p

0.82

µ

1.0k

0.01

µ

ML13176

Crystal

Fundamental

10 MHz

(3)

VCC

(4)

On–Off Keyed Input

TTL Level 10 kHz

0.01

µ

VEE

S1

VEE

0.1

µ

4. The On–Off keyed signal turns the output of the transmitter off and on with

TTL level pulses through Rmod at Pin 16. The "On" power and ICC is set

by the resistor which sets Imod = VTTL – 0.8 / Rmod. (see Figure 23).

5. S1 simulates an enable gate pulse from a microprocessor which will

enable the transmitter. (see Figure 4 to determine precise value of the

enabling resistor based on the potential of the gate pulse and the

desired enable.)

Legacy Applications Information

Figure 21 shows a typical application in which the output

power has been reduced for linearity and current drain. The

current draw on the device is 16 mA ICC (average) and –22.5

dBm (average power output) using a 10 kHz modulating rate

for the on–off keying. This equates to 20 mA and –2.3 dBm

“on”, 13 mA and –41 dBm “Off ”. The crystal oscillator

enable time is needed to set the acquisition timing. It takes

typically 4.0 msec to reach full magnitude of the oscillator

waveform. A square waveform of 3.0 V peak with a period

that is greater than the oscillator enable time is applied to the

Enable (Pin 11)

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