TX4915 Ver la hoja de datos (PDF) - Princeton Technology

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Fabricante

TX4915

Low Power ASK Transmitter IC

Princeton Technology 

TX4915

Pin Descriptions

Number Name

Description

1

OSCIN

This pin is connected directly to the base of the reference oscillator transistor. The

reference oscillator uses a modified Colpitts configuration.

2

OSCOUT This pin is connected directly to the emitter of the reference oscillator transistor.

3

TXEN

Transmitter enable control (TXEN = low = power down mode; TXEN = high = nor-

mal operation mode).

4

VSS

Ground connection for the transmit output amplifier.

5

TXOUT

Transmitter output. This pin is an open collector output and requires a pull-up

inductor for bias/matching and a tapped capacitor network for matching.

6

VSS1

Ground connection for the transmit driver amplifier.

7

VCC1

Nominal supply voltage for the transmit driver amplifier.

8

MODIN ASK modulation input. An external resistor, RMODIN, connected from the MODIN

pin to supply voltage is used to bias the transmit amplifier chain.

9

VCC2

Nominal supply voltage for the VCO and PLL circuitry.

10 VSS2

Ground connection for the PLL circuitry.

11 NC

No connection.

12 RES

13 RES

Differential open collector VCO outputs.

14 DO

Output of the charge pump. An R-C network from this pin to ground is used to

establish the PLL bandwidth. The DO pin is internally connected to the tuning volt-

age input of the VCO thru a 4 KΩ series resistor.

15 LD

Lock detector output. This pin is used to set the threshold of the lock detect circuitry

which enables or disables the transmit amplifier. A shunt capacitor should be used to

set an R-C time constant with the on-chip series 1 KΩ resistor. The time constant

should be set to approximately 15 times the reference period.

16 SW

Prescaler modulus control input (SW = high = ÷ 64; SW = low = ÷ 128).

Page 3

March 2005

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