ADF7020 datasheet(10/40 Pages) AD

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ADF7020

Preliminary Technical Data

Rev. PrH | Page 10 of 40

Pin No.

Mnemonic

Function

GND2

Ground for Digital Section.

ADCIN

Analog-to-Digital Converter Input. The internal 7-bit ADC can be accessed through this pin. Full scale is 0 to

1.9 V. Readback is made using the SREAD pin.

VREG2

Regulator Voltage for Digital Block. A 100 nF capacitor should be placed between this pin and ground for

regulator stability and noise rejection.

VDD2

Voltage Supply for Digital Block. A decoupling capacitor (X7R or Tantalum) of 0.01 µF should be placed as

close as possible to this pin.

INT/LOCK

Bidirectional Pin. In output mode (INTerrupt mode), the ADF7020 asserts the INT/ LOCK pin when it has found

a match for the preamble sequence.

In input mode (lock mode), the microcontroller can be used to lock the demodulator threshold when a valid

preamble has been detected. Once the threshold is locked, NRZ data can be reliably received. In this mode, a

demod lock can be asserted with minimum delay.

DATA I/O

Transmit Data Input/Received Data Output. This is a digital pin and normal CMOS levels apply.

DATA CLK

In receive mode, the pin outputs the synchronized data clock. The positive clock edge is matched to the

center of the received data.

In GFSK transmit mode, the pin outputs an accurate clock to latch the data from the microcontroller into the

transmit section at the exact required data rate. See the Gaussian Frequency Shift Keying (GFSK) section.

CLKOUT

A Divided-Down Version of the Crystal Reference with Output Driver. The digital clock output can be used to

drive several other CMOS inputs such as a microcontroller clock. The output has a 50:50 mark-space ratio.

MUXOUT

This pin provides the Lock_Detect signal, which is used to determine if the PLL is locked to the correct

frequency. Other signals include Regulator_Ready, which is an indicator of the status of the serial interface

regulator.

OSC2

The reference crystal should be connected between this pin and OSC1. A TCXO reference can be used by

driving this pin with CMOS levels and disabling the crystal oscillator.

OSC1

The reference crystal should be connected between this pin and OSC2.

VDD3

Voltage Supply for the Charge Pump and PLL Dividers. This pin should be decoupled to ground with a

0.01 µF capacitor.

VREG3

Regulator Voltage for Charge Pump and PLL Dividers. A 100 nF capacitor should be placed between this pin

and ground for regulator stability and noise rejection.

CPOUT

Charge Pump Output. This output generates current pulses that are integrated in the loop filter. The

integrated current changes the control voltage on the input to the VCO.

VDD

Voltage Supply for VCO Tank Circuit. This pin should be decoupled to ground with a 0.01 µF capacitor.

44–47

GND

Grounds for VCO Block.

CVCO

A 22 nF capacitor should be placed between this pin and VREG1 to reduce VCO noise.

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