NRF2401G IC Nordic VLSI, NRF2401G IC Datasheet - Page 33

• Manufacturer Part Number: NRF2401G IC
• Description: RF Transceiver, Single chip 2.4GHz Transceiver, 24-QFN
• Manufacturer: Nordic VLSI

PRODUCT SPECIFICATION
nRF2401 Single Chip 2.4 GHz Radio Transceiver
Sharing crystal with micro controller.
When using a micro controller to drive the crystal reference input XC1 of the
nRF2401 transceiver some rules must be followed.
Crystal parameters:
When the micro controller drives the nRF2401 clock input, the requirement of load
capacitance C
is still required to get a functional radio link. The nRF2401 will load the crystal by
0.5pF at XC1 in addition to the PBC routing.
Input crystal amplitude & Current consumption
The input signal should not have amplitudes exceeding any rail voltage, but any DC-
voltage within this is OK. Exceeding rail voltage will excite the ESD structure and the
radio performance is degraded below specification. If testing the nRF2401 with a RF
source with no DC offset as the reference source, the input signal will go below the
ground level, which is not acceptable.
It is recommended to use a DC-block before the XC1 pin so that the internal ESD
structures will self bias the XC1 voltage .
The nRF2401 crystal oscillator is amplitude regulated. To achieve low current
consumption and also good signal- to-noise ratio, it is recommended to use an input
signal larger than 0.4 V-peak. The needed input swing is independent of the crystal
Nordic Semiconductor ASA - Vestre Rosten 81, N-7075 Tiller, Norway -
Revision: 1.1
L
is set by the micro controller only. The frequency accuracy of 30 ppm
Figure 20
Vss
ESD
Vdd
XC1
Principle of crystal oscillator
Page 33 of 39
current source
Current starved
XO_OUT
full swing
Amplitude
XC2
controlled
Sine to
Buffer:
XOSC core
inverter:
ESD
Vdd
Phone [phone]
Vss
-
Fax [phone]
June 2004