Analog To Digital Converter; A/D Overview - Holtek HT45F23A Manual

Analog to Digital Converter

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 an 8/10-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 either a 12-bit digital value.
Part No.
HT45F23A
HT45F24A
The accompanying block diagram shows the overall internal structure of the A/D converter, together
with its associated registers.
P C R 5 ~ P C R 0
A N 0 o r I / O
~
A N 5 o r I / O
O P A 1 o u t p u t ( A N 6 )
O P A 2 o u t p u t ( A N 7 )
P C R 7 ~ P C R 0
A N 0 o r I / O
~
A N 7 o r I / O
O P A 1 o u t p u t ( A N 8 )
O P A 2 o u t p u t ( A N 9 )
Rev. 1.40
TinyPower Flash MCU with OPA & Comparators
TM
Input Channels
6+2 (from OPA1 and OPA2 output pins)
8+2 (from OPA1 and OPA2 output pins)
A D C S 2 ~ A D C S 0
A / D C l o c k
A C S 2 ~ A C S 0 S T A R T
HT45F23A A/D Converter Structure
A D C S 2 ~ A D C S 0
A / D C l o c k
A C S 3 ~ A C S 0
S T A R T
HT45F24A A/D Converter Structure
78
HT45F23A/HT45F24A
A/D Channel Select Bits
ACS2~ACS0
ACS3~ACS0
f
S Y S
V
D D
C l o c k
D i v i d e r
P C 4 / V R E F
A D O N B
B i t V R S E L
B i t
A / D R e f e r e n c e V o l t a g e
A / D C o n v e r t e r
V
S S
E O C B A D O N B
f
S Y S
V
D D
C l o c k
D i v i d e r
P C 4 / V R E F
A D O N B
B i t
V R S E L
B i t
A / D R e f e r e n c e V o l t a g e
A / D C o n v e r t e r
V
S S
E O C B A D O N B
Input Pins
AN0~AN7
AN0~AN9
A D R L
A / D D a t a
R e g i s t e r s
A D R H
A D R L
A / D D a t a
R e g i s t e r s
A D R H
March 29, 2019