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nRF24AP2-USB Product Specification

6

On-chip oscillator

In order to provide the necessary clocks for the ANT protocol stack, nRF24AP2 contains one high

frequency oscillator used by the RF transceiver. The high frequency clock source must be a 16 MHz crystal

oscillator.

6.1

Features

•

Low-power, amplitude regulated 16 MHz crystal oscillator

6.2

Block diagram

Figure 23. Block diagram of 16 MHz crystal oscillator

6.3

Functional description

6.3.1

16 MHz crystal oscillator

The 16 MHz crystal oscillator is designed to be used with an AT-cut quartz crystal in parallel resonant

mode. To achieve correct oscillation frequency it is very important that the load capacitance matches the

specification in the crystal datasheet. The load capacitance is the total capacitance from the perspective of

the crystal across its terminals:

Amplitude

regulator

XC1

XC2

Crystal

PIN

PCB

PIN

PCB

LOAD

C

C

C

C

C

C

C

C

C

C

C

C

C

+

+

=

+

+

=

+

⋅

=

2

2

'

2

1

1

'

1

'

2

'

1

'

2

'

1