nRF904 Nordic VLSI, nRF904 Datasheet - Page 7

• Manufacturer Part Number: nRF904
• Description: RF Transmitter 902-928MHz
• Manufacturer: Nordic VLSI

PRODUCT SPECIFICATION
The suggested value of R3 is 15 k . Using the above equation this should provide a
typical output voltage of 1.0Vpp. Note that if a significant capacitive load (more than
a few picofarads) is present at the XO8 pin this will lead to a voltage loss due to
lowpass filtering. Using a capacitive load of 10 pF the typical output voltage swing
will drop from 1.0Vpp to 0.8Vpp.
The XO8 signal will be present in Transmit mode and Clock mode if R3 is connected
to VDD. If the XO8 pin is not used, it should be connected directly to ground on the
circuit board.
If a micro-controller is being used any internal pull up resistor within the micro-
controller should also be factored into the above equation.
Power Down mode is used to achieve very low current consumption. Effectively the
chip is disabled with minimal leakage current consumption, typically less than 10nA.
Operating in this mode when not transmitting data significantly increases battery
lifetime.
The resistor R1 connected from the crystal pin towards VDD supplies the crystal
oscillator with bias current (see Figure 4). When R1 is connected to ground, the chip
enters Power Down mode. A typical value for R1 is 150 k .
Nordic VLSI ASA
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Vestre Rosten 81, N-7075 Tiller, Norway
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Phone [phone]
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Fax [phone]
Revision: 2.1
October 2001
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