RF2968 Просмотр технического описания (PDF) - RF Micro Devices

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RF2968

BLUETOOTH™ TRANSCEIVER

RF Micro Devices 

RF2968

Preliminary

Pin Function Description

Interface Schematic

17

BRCLK Reference clock output. This is a crystal controlled reference clock in

the 10-40MHz range, typically 13MHz.

VCC

BRCLK

18

OSC O Same as pin 19.

See pin 19.

19

OSC I

The OSC pins are used to produce the reference frequency by means

of negative feedback. A crystal and resistor are placed in parallel from

OSC I to OSC O to provide the feedback path and establish the reso-

nant frequency. A shunt capacitor is placed on each OSC pin to provide

OSC I

the proper loading of the crystal. If an external reference is used, it is

connected to OSC I through a DC-blocking capacitor, and OSC O is

connected to OSC I through a 470kΩ resistor.

20

BnDEN Latches data entered into the serial port. Data is clocked into the latch See pin 23.

on the rising edge of BnDEN.

21

BDDATA Serial data port. Read/write data is sent through this pin into / out of the READ DATA

on chip shift register. Read data is transferred on the rising edge of

BDCLK. Write data is transferred on the falling edge of BDCLK.

WRITE DATA

22

BDCLK Serial port input clock.This pin is used to clock data into the serial port. See pin 23.

To minimize the hop frequency programming time, a BDCLK frequency

of 10-20MHz is recommended.

23

BnPWR This pin is part of the chip power control circuit. It is used to power up

the chip from the “off” state.

OSC O

Pin 21

VCC

BnPWR

11

24

PLL GND Ground connection for the RF synthesizer, crystal oscillator, and serial

port.

25

VCC6

Supply voltage for the RF synthesizer, crystal oscillator, and serial port.

26

D0

This is the output of the charge pump for the RF PLL. An RC network

from this pin to ground is used to establish the PLL bandwidth. To mini-

mize synthesizer settling time and phase noise, a dual loop bandwidth

scheme is implemented. During the initial period of frequency acquisi-

tion, a wide loop bandwidth is used. RSHUNT is used to switch to a

narrow loop bandwidth near the end of the frequency acquisition, pro-

viding improved VCO phase noise. The time at which the bandwidth

switches is set by the PLLDel bits.

VCC

D0

27

RSHUNT Switches the loop filter from wide to narrow bandwidth by shunting the

midpoint of two external series resistors to ground.

28

RESNTR- The RESNTR pins are used to supply DC voltage to the VCO as well

as to tune the center frequency of the VCO. Two inductors are required

RESNTR+ RESNTR-

between RESNTR- and RESNTR+ to resonate with the internal capac- D0

itance. Inductance of traces from the RESNTR pins to the inductor

4 kΩ

should be taken into account in the board layout.

11-122

Rev A13 010912

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