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SSTX4915

Pin Descriptions

Rev.2.02 8/06/2003

Number

Name

Description

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 = normal operation mode).

4

VSS

Ground connection for the transmit output amplifier.

5

TXOUT

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

bias/matching and a tapped capacitor for matching.

6

VSS1

Ground connection for the transmit driver amplifier.

7VCC1

Nominal supply voltage for the transmit driver amplifier.

8

MODIN

ASK modulation input. An external resistor R

the entire transmit amplifier chain through this pin.

9VCC2

Nominal supply voltage for the VCO and PLL circuitry.

10

VSS2

Ground connection for the PLL circuitry.

11

NC

No connection.

12

RES

Differential open collector VCO outputs.

13

RES

14

DO

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

establish the PLL bandwidth.

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 1k

Ω 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).

OSCIN

OSCOUT

TXEN

VSS

TXOUT

VSS1

VCC1

MODIN

SW

LD

DO

RES

RESB

VREFP

VSS2

VCC2

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9