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Rev. 1.50
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HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
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
These 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. It also can convert the internal signals, such as the Bandgap
reference voltage, into a 12-bit digital value. The external or internal analog signal to be converted is
determined by the SAINS2~SAINS0 bits together with the SACS2~SACS0 bits. Note that when the
external and internal analog signals are simultaneously selected to be converted, the internal analog
signal will have the priority. In the meantime the external analog signal will temporarily be switched
off until the internal analog signal is deselected. 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.
The accompanying block diagram shows the internal structure of the A/D converter together with its
associated registers.
Device
External Input Channel
Internal Analog Signals
A/D Signal Select Bits
HT66F01�5
�N0~�N�
V
DD
� V
DD
/�� V
DD
/4� V
R
� V
R
/�� V
R
/4
S�INS�~S�INS0;
S�CS�~S�CS0
HT66F01�5
�N0~�N�
V
DD
� V
DD
/�� V
DD
/4� V
R
� V
R
/�� V
R
/4
S�INS�~S�INS0;
S�CS�~S�CS0
�CE�~�CE0
S�CS�~S�CS0
S�INS�~S�INS0
�/D Converter
ST�RT
�DBZ
�DCEN
V
SS
�/D Clock
÷ �
N
(N=0~�)
f
SYS
S�CKS�~
S�CKS0
V
DD
�DCEN
S�DOL
S�DOH
�N0
�N1
�N�
�/D Reference Volta�e
�/D Data
Re�isters
V
DD
V
DD
/�
V
DD
/4
V
R
V
R
/�
V
R
/4
�DRFS
PG�
V
RI
V
REFI
V
BG
(Gain=1~4)
S�VRS3~S�VRS0
�DPG�EN
V
REF
V
R
V
DD
VREFPS
VREFIPS
A/D Converter Structure