FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-13105-3E
Linear IC Converter
CMOS
A/D Converter
(With 4-channel Input at 12-bit Resolution)
MB88101A
s
DESCRIPTION
The MB88101A is an analog-to-digital converter that converts its analog input to a 12-bit digital value and outputs it
as serial data.
The MB88101A employs a successive approximation method for A/D conversion.
The MB88101A has four input channels selectable for analog input under control of the dedicated external pins.
The MB88101A can be switched to a mode for continuous A/D conversion, in which it outputs serial data from the
MSB or LSB selectable depending on the mode setting.
s
FEATURES
•
•
•
•
•
•
•
•
•
4-channel analog input
One analog input channel selectable for conversion by external control
CR-type successive approximation system with a sample-and-hole circuit
12-bit resolution
Serial output of 12-bit digital data
Capable of continuous conversion (continuous conversion mode)
MSB or LSB selectable for serial output
CMOS process
Package options of 16-pin DIP 16-pin SSOP and 16-pin SOP available
,
,
s
PACKAGES
16-pin Plastic DIP
16-pin Plastic SSOP
16-pin Plastic SOP
(DIP-16P-M04)
(FPT-16P-M05)
(FPT-16P-M06)
MB88101A
s
PIN DESCRIPTION
Pin no.
1
2
5
6
14
13
12
Symbol
AN
0
AN
1
AN
2
AN
3
DO
CLK
CS
I/O
I
Descriptions
Analog input pins. One of these channels can be selected depending on
the C
0
and C
1
settings.
O
I
I
This pin outputs the result of A/D conversion. The result is 12-bit serial
data output in synchronization with the rise of CLK.
Clock input pin for A/D conversion
Chip select signal input pin. Setting the signal level to “L” after turning
the power on starts A/D conversion; setting it to “H” stops A/D
conversion. When this pin is “H”, the DO and SAMP pins are “Hi-Z”.
Input pins for selecting the analog input channels from among pins AN
0
to AN
3
. See Table 1 for the correspondence between the pin settings
and the channels selected. To switch the channel in mode 2 or 3, set
these pins before the SAMP pin goes “H”.
Conversion mode setting pins. For the correspondence between the pin
settings and the modes selected, see Table 2 and “s FUNCTIONAL
DESCRIPTION.”
This pin becomes active in prior to data output. Serial data is output from
the DO pin five clock cycles after the signal level at this pin goes “L” after
“H” for one clock cycle.
Reference voltage input pin
Analog circuit ground pin
Digital circuit ground pin
Power supply pin
11
10
C
0
C
1
I
7
8
15
MOD0
MOD1
SAMP
I
O
3
4
9
16
Hi-Z : High-Z
• Channel selection
Table 1
C
1
L
L
H
H
V
REF
A
GND
D
GND
V
CC
—
—
—
—
• Mode selection
Table 2
MOD 0
L
L
H
H
Pin Settings and Mode Selection
MOD1
L
H
L
H
Mode
Mode 1
Mode 2
(Disabled)
Mode 3
Pin Settings and Channel Selection
C
0
L
H
L
H
Channel
AN
0
AN
1
AN
2
AN
3
3
MB88101A
s
FUNCTIONAL DESCRIPTION
1. Mode 1
This mode sets the DO pin to “L” and stops conversion upon completion of conversion of 12 bits. To restart
conversion, set CS to “H” once then to “L”. In this mode, converted data is output from the MSB.
• Timing diagram
CS
MOD0, MOD1
C
0
, C
1
CLK
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
1
2
Sampling
Bit
Trial
DO
SAMP
Hi-Z
B11 B10 B9 B8 B7
B6 B5 B4 B3 B2
B1 B0
Sampling
B11
B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
Hi-Z
Hi-Z
Hi-Z
2. Mode 2
This mode continues conversion until CS becomes “H” after it becomes “L”. Converted data is output from the
LSB, with the first piece of converted data output 20 clock cycles after CS becomes “L”. Changing the channel
select pin settings before starting sampling of one analog input allows another to be converted.
• Timing diagram
CS
MOD0, MOD1
C
0
, C
1
CLK
Mode 2
AN
0
AN
2
AN
1
16CLK
Bit
Trial
DO
Hi-Z
SAMP
MSB (AN
0
)
⇒
LSB
Hi-Z
MSB (AN
2
)
⇒
LSB
LSB (AN
0
)
⇒
MSB
MSB (AN
1
)
⇒
LSB
LSB (AN
2
)
⇒
MSB
Hi-Z
Hi-Z
5
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