HT66F302 Datasheet, PDF (92/129 Pages) Holtek Semiconductor Inc – Cost-Effective Flash MCU with EEPROM

HT66F302/HT66F303
Cost-Effective Flash MCU with EEPROM
Analog to Digital Converter – ADC
The need to interface to real world analog signals is a common requirement for many electronic
systems. However, to properly process these signals by a microcontroller, they must first be
converted into digital signals by A/D converters. By integrating the A/D conversion electronic
circuitry into the microcontroller, the need for external components is reduced significantly with the
corresponding follow-on benefits of lower costs and reduced component space requirements.
A/D Overview
The devices contain a multi-channel analog to digital converter which can directly interface
to external analog signals, such as that from sensors or other control signals and convert these
signals directly into a 12-bit digital value. The external or internal analog signal to be converted
is determined by the SAINS and SACS bit fields. Note that when the internal analog signal is
to be converted, the selected external input channel will automatically be disconnected to avoid
malfunction. More detailed information about the A/D input signal is described in the “A/D
Converter Control Registers” and “A/D Converter Input Signal” sections respectively.
Device
HT66F302/HT66F303
Input Channels
4
A/D Channel Select Bits
SAINS2~SAINS0,
SACS1~SACS0
Input Pins
AN0~AN3
The accompanying block diagram shows the overall internal structure of the A/D converter, together
with its associated registers.
fSYS
AVDD
Psine-leschtaiorend
AN0
AN1
SACS1~SACS0
AN3
SAINS2~SAINS0
SSAACCKKSS20~
(N÷=02~^N7)
A/D Clock
ENADC
AVSS
ADRFS
A/D Converter
SADOL
SADOH
RAe/DgiDstaetras
START ADBZ ENADC
A/D Reference Voltage
VREFO
AVDD
AVDD/2
AVDD/4
VBG (1.0V)
VREFI
SAVRS3~SAVRS0
VRI OPA
(Gain=1~4)
AVDD
VR
VREFO
VREFI
ENOPA
A/D Converter Structure
Rev. 1.11
92
April 11, 2017