BLOCK DIAGRAM
1
May 1997
ML2281, ML2282
*
,
ML2284
#
, ML2288
#
Serial I/O 8-Bit A/D Converters with
Multiplexer Options
GENERAL DESCRIPTION
The ML2281 family are 8-bit successive approximation
A/D converters with serial I/O and configurable input
multiplexers with up to 8 input channels.
All errors of the sample-and-hold, incorporated on the
ML2281 family are accounted for in the analog-to-digital
converters accuracy specification.
The voltage reference can be externally set to any value
between GND and V
CC
, thus allowing a full conversion
over a relatively small voltage span if desired.
The ML2281 family is an enhanced double polysilicon
CMOS pin compatible second source for the ADC0831,
ADC0832, ADC0834, and ADC0838 A/D converters. The
ML2281 series enhancements are faster conversion time,
true sample-and-hold function, superior power supply
rejection, improved AC common mode rejection, faster
digital timing, and lower power dissipation. All parameters
are guaranteed over temperature with a power supply
voltage of 5V 10%.
FEATURES
s Conversion time: 6s
s Total unadjusted error: 1/2LSB or 1LSB
s Sample-and-hold: 375ns acquisition
s 2, 4 or 8-input multiplexer options
s 0 to 5V analog input range with single 5V
power supply
s Operates ratiometrically or with up to 5V
voltage reference
s No zero or full-scale adjust required
s ML2281 capable of digitizing a 5V, 40kHz sine wave
s Low power: 12.5mW MAX
s Superior pin compatible replacement for ADC0831,
ADC0832, ADC0834, and ADC0838
s Analog input protection: 25mA (min) per input
s Now in 8-Pin SOIC Package (ML2281, ML2282)
INPUT
SHIFT-REGISTER
OUTPUT
SHIFT-REGISTER
SHUNT
REGULATOR
CONTROL
AND
TIMING
DI
SARS
CLK
CS
DO
4-BIT
SE
DGND
V+
V
CC
V
REF
AGND
COMMON
CH7
CH6
CH5
CH4
CH3
CH2
CH1
CH0
A/D
CONVERTER
WITH
SAMPLE & HOLD
FUNCTION
MULTIPLEXER
(ML2288 SHOWN)
V
REF
CLK
CS
V
IN
SUCCESSIVE
APPROXIMATION
REGISTER
D/A
CONVERTER
+
OUTPUT
SHIFT-REGISTER
CONTROL
AND
TIMING
COMP
A/D WITH SAMPLE & HOLD FUNCTION
8pF
8pF
+
V
IN+
V
CC
GND
DO
ML2281
ML2288
(8-Channel SE or 4-Channel Diff Multiplexer)
ML2284
(4-Channel SE or 2-Channel Diff Multiplexer)
ML2284
(2-Channel SE or 1-Channel Diff Multiplexer)
(* Indicates Part is Obsolete)
(# Indicates Part is End Of Life as Of July 1, 2000)
ML2281, ML2282, ML2284, ML2288
2
PIN CONFIGURATION
CS
V
IN+
V
IN
GND
V
CC
CLK
DO
V
REF
1
2
3
4
8
7
6
5
TOP VIEW
TOP VIEW
CS
V
IN+
V
IN
GND
V
CC
CLK
DO
V
REF
1
2
3
4
8
7
6
5
TOP VIEW
CS
CH0
CH1
GND
V
CC
(V
REF
)
CLK
DO
DI
1
2
3
4
8
7
6
5
TOP VIEW
V+
CS
CH0
CH1
CH2
CH3
DGND
V
CC
DI
CLK
SARS
DO
V
REF
AGND
1
2
3
4
5
6
7
14
13
12
11
10
9
8
ML2281
Single Differential Input
8-Pin DIP
ML2282
2-Channel MUX
8-Pin DIP
ML2281
8-Pin SOIC
ML2282
8-Pin SOIC
ML2284
14-Pin SOIC
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
DGND
V
CC
V+
CS
DI
CLK
SARS
DO
SE
V
REF
AGND
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
TOP VIEW
ML2288
8-Channel MUX
20-Pin DIP
CS
DI
CLK
SARS
DO
CH3
CH4
CH5
CH6
CH7
9
10
11
12
13
CH2
CH1
CH0
V
CC
V+
COM
DGND
AGND
V
REF
SE
4
5
6
7
8
3
2
1
20
19
18
17
16
15
14
TOP VIEW
TOP VIEW
V+
CS
CH0
CH1
CH2
CH3
DGND
V
CC
DI
CLK
SARS
DO
V
REF
AGND
1
2
3
4
5
6
7
14
13
12
11
10
9
8
ML2284
4-Channel MUX
14-Pin DIP
ML2288
8-Channel MUX
20-Pin PCC
CS
CH0
CH1
GND
V
CC
(V
REF
)
CLK
DO
DI
1
2
3
4
8
7
6
5
TOP VIEW
ML2281, ML2282, ML2284, ML2288
3
NAME
FUNCTION
V
CC
Positive supply. 5V 10%
DGND
Digital ground. 0 volts. All digital inputs and
outputs are referenced to this point.
AGND
Analog ground. The negative reference voltage
for A/D converter.
CH0-7,
Analog inputs. Digitally selected to be single
V
IN
+, V
IN
ended (V
IN
) or; V
IN
+ or V
IN
of a differential
input. Analog range = GND - V
IN
- V
CC
.
COM
Common reference point for analog inputs.
A/D conversion is performed on voltage
difference between analog input and this
common reference point if single-end
conversion is specified.
V
REF
Reference. The positive reference voltage for
A/D converter.
SE
Shift enable. Input controls whether LSB first
bit stream is shifted out on serial output DO.
If SE = 1, MSB first is shifted out only. If SE = 0,
an MSB first bit stream is shifted out, then a
second bit stream with LSB first is shifted out
after end of conversion.
V+
Input to the Shunt Regulator.
PIN DESCRIPTION
NAME
FUNCTION
DO
Data out. Digital output which contains result
of A/D conversion. The serial data is clocked
out on falling edges of CLK.
SARS
Successive approximation register status.
Digital output which indicates that a
conversion is in progress. When SARS goes
to 1, the sampling window is closed and
conversion begins. When SARS goes to 0,
conversion is completed. When CS = 1, SARS
is in high impedance state.
CLK
Clock. Digital input which clocks data in on
DI on rising edges and out on DO on falling
edges. Also used to generate clocks for A/D
conversion.
DI
Data input. Digital input which contains serial
data to program the MUX and channel
assignments.
CS
Chip select. Selects the chip for multiplexer
and channel assignment and A/D conversion.
When CS = 1, all digital outputs are in high
impedance state. When CS = 0, normal A./D
conversion takes place.
ML2281, ML2282, ML2284, ML2288
4
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, T
A
= T
MIN
to T
MAX
, V
CC
= V
REF
= 5V 10%, and f
CLK
= 1.333MHz.
ML228XB
ML228XC
TYP
TYP
SYMBOL
PARAMETER
CONDITIONS
MIN
NOTE 3
MAX
MIN
NOTE 3
MAX
UNITS
CONVERTER AND MULTIPLEXER CHARACTERISTICS
Total Unadjusted
V
REF
= V
CC
(Notes 4, 6)
1/2
1
LSB
Error
Reference Input
(Notes 4, 7)
10
15
20
10
15
20
k
W
Resistance
Common-Mode
(Notes 4, 8)
GND
V
CC
GND
V
CC
V
Input Range
0.05
+0.05
0.05
+0.05
DC Common-Mode Common mode voltage
1/16
1/4
1/16
1/4
LSB
Error
voltage GND to V
CC/2
(Note 5)
AC Common-Mode Common mode voltage
1/4
1/4
LSB
Error
GND to V
CC/2
,
0 to 50kHz (Note 5)
DC Power Supply
V
CC
= 5V 10%
1/32
1/4
1/32
1/4
LSB
Sensitivity
V
REF
- V
CC
+0.1V
(Note 5)
AC Power Supply
100mV
P-P
, 25kHz sine
1/4
1/4
LSB
Sensitivity
on V
CC
(Note 5)
Change in Zero
15mA into V+
1/2
1/2
LSB
Error from V
CC
=5V
V
CC
= N.C. V
REF
= 5V
to Internal Zener
(Note 5)
Operation
V
Z
Internal Diode
15mA into V+
6.9
6.9
V
Regulated Break-
down (at V+)
V+
Input Resistance
(Note 4)
20
35
20
35
k
W
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings are those values beyond which
the device could be permanently damaged. Absolute
maximum ratings are stress ratings only and functional
device operation is not implied.
Current into V+ ...................................................... 15mA
Supply Voltage, V
CC
................................................. 6.5V
Voltage
Logic Inputs ........................................... 7 to V
CC
+7V
Analog Inputs ................................ 0.3V to V
CC
+0.3V
Input Current per Pin (Note 1) .............................. 25mA
Storage Temperature ................................ 65C to 150C
Package Dissipation
at T
A
= 25C (Board Mount) ............................. 800mW
Lead Temperature (Soldering 10 sec.)
Dual-In-Line Package (Molded) .......................... 260C
Dual-In-Line Package (Ceramic) ......................... 300C
Molded Chip Carrier Package
Vapor Phase (60 sec.) ..................................... 215C
Infrared (15 sec.) ............................................. 220C
OPERATING CONDITIONS
Supply Voltage, V
CC
............................ 4.5V
DC
to 6.3V
DC
Temperature Range (Note 2) ................. T
MIN
- T
A
- T
MAX
ML2281/2/4/8 BIX .................................. 40C to 85C
ML2281/2/4/8 CIX
ML2281/2/4/8 BCX .................................... 0C to 70C
ML2281/2/4/8 CCX
ML2281, ML2282, ML2284, ML2288
5
ELECTRICAL CHARACTERISTICS
(Continued)
ML228XB
ML228XC
TYP
TYP
SYMBOL
PARAMETER
CONDITIONS
MIN
NOTE 3
MAX
MIN
NOTE 3
MAX
UNITS
CONVERTER AND MULTIPLEXER CHARACTERISTICS (CONTINUED)
I
OFF
Off Channel
On channel = V
CC
1
1
A
Leakage Current
Off channel = 0V
(Notes 4, 9)
On channel = 0V
+1
+1
A
Off channel = V
CC
(Notes 4, 9)
I
ON
On Channel
On channel = 0V
1
1
A
Leakage Current
Off channel = V
CC
(Notes 4, 9)
On channel = V
CC
+1
+1
A
Off channel = 0V
(Notes 4, 9)
DIGITAL AND DC CHARACTERISTICS
V
IN(1)
Logical "1"
(Note 4)
2.0
2.0
V
Input Voltage
V
IN(0)
Logical "0"
(Note 4)
0.8
0.8
V
Input Voltage
I
IN(1)
Logical "1" Input
V
IN
= V
CC
(Note 4)
1
1
A
Current
I
IN(0)
Logical "0" Input
V
IN
= 0V (Note 4)
1
1
A
Current
V
OUT(1)
Logical "1"
I
OUT
= 2mA (Note 4)
4.0
4.0
V
Output Voltage
V
OUT(0)
Logical "0"
I
OUT
= 2mA (Note 4)
0.4
0.4
V
Output Voltage
I
OUT
HI-Z Output
V
OUT
= 0V (Note 4)
1
1
A
Current
V
OUT
= V
CC
1
1
A
I
SOURCE
Output Source
V
OUT
= 0V (Note 4)
6.5
6.5
mA
Current
I
SINK
Output Sink Current V
OUT
= V
CC
(Note 4)
8.0
8.0
mA
I
CC
Supply Current
ML2281, ML2284
1.3
2.5
1.3
2.5
mA
ML2288 (Note 4)
ML2282 Includes ladder
1.8
3.5
1.8
3.5
mA
Current (Note 4)
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