Data Sheet

NAU7802 24-bit ADC
Nuvoton Confidential - 24 - Revision 1.7
8.10 Oscillator Features
This device may either accept an external clock, use an internal RC oscillator, or use a built-in crystal
oscillator for its time base. An accurate clock is important for the digital filtering of 50Hz or 60Hz
components to work optimally. The internal oscillator is trimmed at the factory for good accuracy.
The internal RC or crystal oscillator frequency may be output on the DRDY pin. This is done by
programming R0x06 as follows:
 Write REG00[6] = 0: Use oscillator as system clock
 Write REG01[6] = 1: Output system clock on DRDY pin
8.10.1 External Crystal Oscillator
When an external 4.9152MHz crystal oscillator is used, the preferred application circuit on the
XIN & XOUT pins is as shown below. The crystal oscillator could operate without the 270
Ohm resistor and without the 18pF capacitor on XIN at a reduced performance.
8.10.2 External Clock Source
When the clock for the NAU7802 may also be provided from an external source. To use this
feature, the device is configured in the same way as for using a crystal and the external clock
signal is applied to the XIN pin.
XOUT
XIN
18pF
cap
18pF
cap
270ohm
resistor
on
off
chip
XOUT
XIN
18pF
cap
18pF
cap
270ohm
resistor
on
off
chip