TSA5059TS datasheet(10/24 Pages) PHILIPS

10 / 24 page

1999 Oct 05

Philips Semiconductors

Preliminary speciﬁcation

2.7 GHz I2C-bus controlled low phase

noise frequency synthesizer

TSA5059

XT/COMP frequency output

It is possible to output either the crystal or the comparison

frequency at this pin to be used in the application, for

example to drive a second PLL synthesizer, saving a

quartz crystal in the bill of material. To output fxtal, it is

necessary to set bit XCE to logic 1 and bit XCS to logic 0,

or bit XCE to logic 0 and bit XCS to logic 1 during a test

mode, while to output fcomp, it is necessary to set both

bits XCE and XCS to logic 1.

If the output signal at this pin is not used, it is

recommended to disable it, setting both bits XCE and XCS

to logic 0. Table 10 shows how this pin is programmed.

At power-on, the XT/COMP output is set, with the fxtal

signal selected.

Prescaler enable

Even if the TSA5059 is able to work with the relation

fcomp = step size for an input frequency up to 2.7 GHz, this

IC is designed to be backward compatible with existing ICs

for which this relation is only valid for an RF frequency up

to 2.0 GHz and in which it is necessary to select a fixed

divide-by-two prescaler for frequencies between 2.0 and

2.7 GHz.

The prescaler is selected by setting bit PE to logic 1 and

it is not in use if bit PE is set to logic 0.

For new designs, and especially if it is important to reach

a low phase noise on the controlled VCO, it is

recommended to set bit PE to logic 0, and not to use the

prescaler, allowing the comparison frequency to be equal

to the step size, whatever the RF frequency is between

64 and 2700 MHz.

Test modes

It is possible to access the test modes setting bit XCE to

logic 0 and bit XCS to logic 1. One specific test mode is

then selected using bits T2, T1 and T0, as described in

Table 10.

Table 10 XT/COMP and test mode selection; note 1

Notes

1. X = don’t care.

2. Status at Power-on reset.

XCE

XCS

XT/COMP OUTPUT

TEST MODE

disabled

normal operation

XXX

fxtal

normal operation

XXX

fcomp

normal operation

01000

fxtal

test operation: charge pump sink;

status byte: bit FL = 1

01001

fxtal

test operation: charge pump source;

status byte: bit FL = 0

01010

fxtal

test operation: charge pump disabled;

status byte: bit FL = 0

01011

fxtal

test operation: 1

⁄2fDIV switched to Port P0

011

fxtal

test operation: tuning voltage (pin VT) is

off (high-impedance); note 2

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