Z8F1680SH020SG Datasheet, PDF (211/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
186
Chapter 14. Analog-to-Digital Converter
The Z8 Encore! includes an eight-channel Successive Approximation Register Analog-to-
Digital converter (SAR ADC). The ADC converts an analog input signal to a 10-bit binary
number. The features of the ADC include:
• Eight analog input sources multiplexed with general-purpose I/O ports
• Fast conversion time, less than 4.9 µs
• Programmable timing controls
• Interrupt on conversion complete
• Internal 1.6 V voltage reference generator
• Internal reference voltage available externally
• Ability to supply external reference voltage
14.1. Architecture
The ADC architecture, shown in Figure 30, consists of an 8-input multiplexer, sample-
and-hold amplifier and 10-bit SAR ADC. The ADC digitizes the signal on a selected
channel and stores the digitized data in the ADC data registers. In environments with high
electrical noise, an external RC filter must be added at the input pins to reduce high-
frequency noise.
14.2. Operation
The ADC converts the analog input, ANA_X, to a 10-bit digital representation. The
equation for calculating the digital value is calculated by:
ADC Output = 1024  ANA_x  V_REF
Assuming zero gain and offset errors, any voltage outside the ADC input limits of AV_SS
and V_REF returns all 0s or 1s, respectively.
A new conversion can be initiated by software write to the ADC Control Register’s start
bit. Initiating a new conversion stops any conversion currently in progress and begins a
new conversion. To avoid disrupting a conversion already in progress, this start bit can be
read to indicate ADC operation status (busy or available).
PS025015-1212
PRELIMINARY
Analog-to-Digital Converter