
Rev. 2.50
�68
��ne 22� 20��
Rev. 2.50
�69
��ne 22� 20��
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
Aanlog 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 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 either a 12-bit digital value.
Part No.
Input Channels
A/D Channel Select Bits
Input Pins
HT66F20
HT66F30
HT66F40
HT66F50
8
ACS4� ACS2~ACS0
AN0~AN�
HT66F60
�2
ACS4� ACS3~ACS0
AN0~AN��
The accompanying block diagram shows the overall internal structure of the A/D converter, together
with its associated registers.
A/D Converter Structure
A/D Converter Register Description
Overall operation of the A/D converter is controlled using six registers. A read only register pair
exists to store the ADC data 12-bit value. The remaining three or four registers are control registers
which setup the operating and control function of the A/D converter.
Register Name
Bit
7
6
5
4
3
2
1
0
ADRL(ADRFS=0)
D3
D2
D�
D0
—
—
—
—
ADRL(ADRFS=�)
D�
D6
D5
D4
D3
D2
D�
D0
ADRH(ADRFS=0)
D��
D�0
D9
D8
D�
D6
D5
D4
ADRH(ADRFS=�)
—
—
—
—
D��
D�0
D9
D8
ADCR0
START
EOCB
ADOFF ADRFS
—
ACS2
ACS�
ACS0
ADCR�
ACS4
V�25EN
—
VREFS
—
ADCK2 ADCK� ADCK0
ACERL
ACE�
ACE6
ACE5
ACE4
ACE3
ACE2
ACE�
ACE0
HT66F20/HT66F30/HT66F40/HT66F50 A/D Converter Register List