Datasheet

C515C
Data Sheet 45 2003-02
10-Bit A/D Converter
The C515C includes a high performance / high speed 10-bit A/D-Converter (ADC) with
8 analog input channels. It operates with a successive approximation technique and
uses self calibration mechanisms for reduction and compensation of offset and linearity
errors. The A/D converter provides the following features:
• 8 multiplexed input channels (port 6), which can also be used as digital inputs
• 10-bit resolution
• Single or continuous conversion mode
• Internal or external start-of-conversion trigger capability
• Interrupt request generation after each conversion
• Using successive approximation conversion technique via a capacitor array
• Built-in hidden calibration of offset and linearity errors
The main functional blocks of the A/D converter are shown in Figure 19.
The A/D converter uses basically two clock signals for operation: the input clock
f
IN
(= 1/t
IN
) and the conversion clock f
ADC
(= 1/t
ADC
). These clock signals are derived from
the C515C system clock
f
OSC
which is applied at the XTAL pins. The input clock f
IN
is
equal to
f
OSC
. The conversion clock is limited to a maximum frequency of 2 MHz and
therefore must be adapted to
f
OSC
by programming the conversion clock prescaler. The
table in Figure 18 shows the prescaler ratios and the resulting A/D conversion times
which must be selected for typical system clock rates.