PRODUCT SPECIFICATION
nRF2402 Single Chip 2.4 GHz Radio Transmitter
Nordic Semiconductor ASA - Vestre Rosten 81, N-7075 Tiller, Norway - Phone +4772898900 - Fax +4772898989
Revision: 2.2 Page 27 of 33 May 2006
Frequency Reference MCU
In direct mode there is a requirement on the accuracy of the data rate. For the receiver to
detect the incoming data and recover the clock, the data rate must be within ±200ppm, given
that the data is "random", i.e. there is a statistical calculation on how often a preamble like
sequence is present in the data. The clock is synchronized for any preamble detection, be it a
dedicated preamble or part of the data stream.
PCB layout and de-coupling guidelines
A well-designed PCB is necessary to achieve good RF performance. Keep in mind that a poor
layout may lead to loss of performance, or even functionality, if due care is not taken. A fully
qualified RF-layout for the nRF2402 and its surrounding components, including matching
networks, can be downloaded from
www.nordicsemi.no.
A PCB with a minimum of two layers including a ground plane is recommended for optimum
performance. The nRF2402 DC supply voltage should be de-coupled as close as possible to
the VDD pins with high performance RF capacitors, see Table
17. It is preferable to mount a
large surface mount capacitor (e.g. 4.7µF tantalum) in parallel with the smaller value
capacitors. The nRF2402 supply voltage should be filtered and routed separately from the
supply voltages of any digital circuitry.
Long power supply lines on the PCB should be avoided. All device grounds, VDD
connections and VDD bypass capacitors must be connected as close as possible to the
nRF2402 IC. The VSS pins should be connected directly to the ground plane. One via hole
should be used for each VSS pin.
Full swing digital data or control signals should not be routed close to the crystal or the
power supply lines.
