XE1203F Ver la hoja de datos (PDF) - Semtech Corporation

Número de pieza

componentes Descripción

Fabricante

XE1203F

433 MHz / 868 MHz / 915 MHz Low-Power, Integrated UHF Transceiver

Semtech Corporation 

XE1203F

The values recommended for applications using bit rates up to 38.4kbit/s are given in Table 25 below:

Name

CL1

CL2

RL1

Typical Value

for 434 MHz

22 nF

1.2 nF

560Ω

Typical Value

for 868 MHz

22 nF

1.2 nF

470Ω

Typical Value

for 915 MHz

22 nF

1.2 nF

470Ω

Tolerance

± 5%

± 5%

± 5%

Table 25: Typical loop filter values for bit rates up to 38.4 kbit/s

The values recommended for applications using bit rates higher than 38.4 kbit/s are given in Table 26 below:

Name

CL1

CL2

RL1

Typical Value

for 434 MHz

3.3 nF

220 pF

1.2 kΩ

Typical Value

for 868 MHz

4.7nF

330 pF

1 kΩ

Typical Value

for 915 MHz

4.7 nF

330 pF

1 kΩ

Tolerance

± 5%

± 5%

± 5%

Table 26: Typical loop filter values for bit rates higher than 38.4 kbit/s

6.5 FREQUENCY SYNTHESIZER REFERENCE CRYSTAL

For narrow band applications, where the lowest frequency deviation and the narrowest baseband filter are selected,

the crystal for reference oscillator of the frequency synthesizer should have the following typical characteristics:

Name

Fs

Description

Nominal frequency

CL

Rm

Cm

C0

∆fs(0)

∆fs(∆T)

∆fs(∆t)

Load capacitance for fs (on-chip)

Motional resistance

Motional capacitance

Shunt capacitance

Calibration tolerance at 25 °C

Stability over temperature range

(-40 °C to 85 °C)

Aging tolerance in first 5 years

Min. value

-

-

-

-

-

-

-

Typ. value

39.0 MHz

(fundamental)

8 pF (*)

-

-

-

-

-

Max. value

-

-

40Ω

30 fF

7 pF (*)

10 ppm

10 ppm

-

-

5 ppm

Table 27: Crystal characteristics

(*) The on-chip oscillator mode is user-defined by programming ADParam_Xsel parameter: the first for CL = 8 pF

and C0 = 7pF, and the second for CL = 8 pF and C0 = 3 pF; the latter will allow higher amplitude for the internal

signal with a slightly lower consumption.

The electrical specifications given in section 3.2.2 are valid for a crystal having the specifications given in Table 27.

For wide band applications requiring less frequency stability, the values for ∆fs(0), ∆fs(∆T), and/or ∆fs(∆t) can be

relaxed. In this case foffset + BWssb should be lower than BWfilter, where foffset is the offset (error) on the carrier

frequency (the sum of ∆fs(0), ∆fs(∆T), and/or ∆fs(∆t)), BWssb is the single side-band bandwidth of the signal, and

BWfilter is the single side-band bandwidth of the base-band filter.

The overtone crystal usage may result in higher oscillator start-up time than fundamental mode. The overtone

crystal should be designed for Cload = 8 to 10 pF and has parameters of Rm < 60Ω, C0 < 7 pF.

© Semtech 2007

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