HT45F3420 Datasheet, PDF (89/141 Pages) Holtek Semiconductor Inc – Personal Care Flash MCU

HT45F3420/HT45F3430
Personal Care Flash MCU
SAINS[3:0]
0000, 0100,
1100~1111
0001
0010
0011
0101
0110
0111
1000
1001
1010
1011
SACS[3:0]
0000~0011
0000~0111
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
xxxx
Input Signals
AN0~AN3
AN0~AN7
VDD
VDD/2
VDD/4
VR
VR/2
VR/4
OCPAO
OVP_ADIN
VBAT_ADIN
Ground
Description
External channel analog input
A/D converter power supply voltage
A/D converter power supply voltage/2
A/D converter power supply voltage/4
Internal reference voltage
Internal reference voltage/2
Internal reference voltage/4
OCP circuit OPA output
From the integrated voltage diving circuit
From the integrated voltage diving circuit
Unused
A/D Converter Input Signals Selection
Conversion Rate and Timing Diagram
A complete A/D conversion contains two parts, data sampling and data conversion. The data
sampling which is defined as tADS takes 4 A/D clock cycles and the data conversion takes 12 A/D
clock cycles. Therefore a total of 16 A/D clock cycles for an A/D conversion which is defined as tADC
are necessary.
Maximum single A/D conversion rate=A/D clock period / 16
However, there is a usage limitation on the next A/D conversion after the current conversion is
complete. When the current A/D conversion is complete, the converted digital data will be stored
in the A/D data register pair and then latched after half an A/D clock cycle. If the START bit is set
to 1 in half an A/D clock cycle after the end of A/D conversion, the converted digital data stored
in the A/D data register pair will be changed. Therefore, it is recommended to initiate the next A/
D conversion after a certain period greater than half an A/D clock cycle at the end of current A/D
conversion.
ENADC
off
START
tON2ST
on
A/D sampling time
tADS
Start of A/D conversion
A/D sampling time
tADS
Start of A/D conversion
off
on
Start of A/D conversion
ADBZ
End of A/D
conversion
End of A/D
conversion
SACS[3:0] 0011B
A/D channel
switch
0010B
0000B
tADC
A/D conversion time
tADC
A/D conversion time
A/D Conversion Timing
0001B
tADC
A/D conversion time
Rev. 1.31
89
April 11, 2017