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: 6µs
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)
(* Indicates Part is Obsolete)
(# Indicates Part is End Of Life as Of July 1, 2000)
BLOCK DIAGRAM
ML2281
CONTROL
AND
TIMING
CS
CLK
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)
DI
INPUT
SHIFT-REGISTER
SARS
OUTPUT
SHIFT-REGISTER
DO
4-BIT
CONTROL
AND
TIMING
CLK
CS
V
IN+
A/D WITH SAMPLE & HOLD FUNCTION
+
SUCCESSIVE
+
APPROXIMATION
COMP
–
–
REGISTER
8pF
Σ
OUTPUT
SHIFT-REGISTER
CH0
CH2
CH3
CH4
CH5
CH6
CH7
MULTIPLEXER
(ML2288 SHOWN)
DO
CH1
V
REF
SE
V
IN–
D/A
CONVERTER
8pF
A/D
CONVERTER
WITH
SAMPLE & HOLD
FUNCTION
DGND
SHUNT
REGULATOR
AGND
V
REF
V
CC
V+
V
CC
GND
COMMON
1
ML2281, ML2282, ML2284, ML2288
PIN CONFIGURATION
ML2281
Single Differential Input
8-Pin DIP
CS
V
IN+
V
IN–
GND
1
2
3
4
8
7
6
5
ML2282
2-Channel MUX
8-Pin DIP
CS
CH0
CH1
GND
1
2
3
4
8
7
6
5
V
CC
CLK
DO
V
REF
V
CC
(V
REF
)
CLK
DO
DI
TOP VIEW
TOP VIEW
ML2281
8-Pin SOIC
CS
V
IN+
V
IN–
GND
1
2
3
4
8
7
6
5
ML2282
8-Pin SOIC
V
CC
CLK
DO
V
REF
CS
CH0
CH1
GND
1
2
3
4
8
7
6
5
V
CC
(V
REF
)
CLK
DO
DI
TOP VIEW
TOP VIEW
ML2284
14-Pin SOIC
ML2284
4-Channel MUX
14-Pin DIP
V
CC
DI
CLK
SARS
DO
V
REF
AGND
V+
CS
CH0
CH1
CH2
CH3
DGND
1
2
3
4
5
6
7
14
13
12
11
10
9
8
V+
CS
CH0
CH1
CH2
CH3
DGND
1
2
3
4
5
6
7
14
13
12
11
10
9
8
V
CC
DI
CLK
SARS
DO
V
REF
AGND
TOP VIEW
TOP VIEW
ML2288
8-Channel MUX
20-Pin PCC
CH2
CH1
CH0
V
CC
V+
ML2288
8-Channel MUX
20-Pin DIP
CH0
CH1
CS
DI
CLK
SARS
DO
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
V
CC
V+
CS
DI
CLK
SARS
DO
SE
V
REF
AGND
3
2
1
20
19
18
17
16
15
14
CH3
CH4
CH5
CH6
CH7
4
5
6
7
8
9
10
11
12
13
CH2
CH3
CH4
CH5
CH6
CH7
COM
DGND
DGND
AGND
COM
V
REF
SE
TOP VIEW
TOP VIEW
2
ML2281, ML2282, ML2284, ML2288
PIN DESCRIPTION
NAME
FUNCTION
NAME
FUNCTION
V
CC
DGND
AGND
Positive supply. 5V ± 10%
Digital ground. 0 volts. All digital inputs and
outputs are referenced to this point.
Analog ground. The negative reference voltage
for A/D converter.
DO
Data out. Digital output which contains result
of A/D conversion. The serial data is clocked
out on falling edges of CLK.
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.
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.
Data input. Digital input which contains serial
data to program the MUX and channel
assignments.
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.
SARS
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.
Reference. The positive reference voltage for
A/D converter.
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.
Input to the Shunt Regulator.
CLK
V
REF
SE
DI
CS
V+
3
ML2281, ML2282, ML2284, ML2288
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 ................................ –65°C to 150°C
Package Dissipation
at T
A
= 25°C (Board Mount) ............................. 800mW
Lead Temperature (Soldering 10 sec.)
Dual-In-Line Package (Molded) .......................... 260°C
Dual-In-Line Package (Ceramic) ......................... 300°C
Molded Chip Carrier Package
Vapor Phase (60 sec.) ..................................... 215°C
Infrared (15 sec.) ............................................. 220°C
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 .................................. –40°C to 85°C
ML2281/2/4/8 CIX
ML2281/2/4/8 BCX .................................... 0°C to 70°C
ML2281/2/4/8 CCX
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, T
A
= T
MIN
to T
MAX
, V
CC
= V
REF
= 5V ±10%, and f
CLK
= 1.333MHz.
ML228XB
TYP
MIN
NOTE 3
ML228XC
TYP
NOTE 3
SYMBOL
PARAMETER
CONDITIONS
MAX
MIN
MAX
UNITS
CONVERTER AND MULTIPLEXER CHARACTERISTICS
Total Unadjusted
Error
Reference Input
Resistance
Common-Mode
Input Range
V
REF
= V
CC
(Notes 4, 6)
(Notes 4, 7)
(Notes 4, 8)
10
GND
–0.05
±1/16
15
±1/2
20
V
CC
+0.05
±1/4
10
GND
–0.05
±1/16
15
±1
20
V
CC
+0.05
±1/4
LSB
kW
V
LSB
DC Common-Mode Common mode voltage
Error
voltage GND to V
CC/2
(Note 5)
AC Common-Mode Common mode voltage
Error
GND to V
CC/2
,
0 to 50kHz (Note 5)
DC Power Supply
Sensitivity
AC Power Supply
Sensitivity
Change in Zero
Error from V
CC
=5V
to Internal Zener
Operation
V
Z
Internal Diode
Regulated Break-
down (at V+)
Input Resistance
V
CC
= 5V ±10%
V
REF
- V
CC
+0.1V
(Note 5)
100mV
P-P
, 25kHz sine
on V
CC
(Note 5)
15mA into V+
V
CC
= N.C. V
REF
= 5V
(Note 5)
15mA into V+
±1/4
±1/4
LSB
±1/32
±1/4
±1/32
±1/4
LSB
±1/4
±1/2
±1/2
±1/4
LSB
LSB
6.9
6.9
V
V+
(Note 4)
20
35
20
35
kW
4
ML2281, ML2282, ML2284, ML2288
ELECTRICAL CHARACTERISTICS
(Continued)
SYMBOL
PARAMETER
CONDITIONS
ML228XB
TYP
MIN
NOTE 3
MAX
MIN
ML228XC
TYP
NOTE 3
MAX
UNITS
CONVERTER AND MULTIPLEXER CHARACTERISTICS (CONTINUED)
I
OFF
Off Channel
Leakage Current
On channel = V
CC
Off channel = 0V
(Notes 4, 9)
On channel = 0V
Off channel = V
CC
(Notes 4, 9)
I
ON
On Channel
Leakage Current
On channel = 0V
Off channel = V
CC
(Notes 4, 9)
On channel = V
CC
Off channel = 0V
(Notes 4, 9)
–1
–1
–1
µA
+1
+1
µA
–1
µA
+1
+1
µA
DIGITAL AND DC CHARACTERISTICS
V
IN(1)
V
IN(0)
I
IN(1)
I
IN(0)
V
OUT(1)
V
OUT(0)
I
OUT
I
SOURCE
I
SINK
I
CC
Logical “1”
Input Voltage
Logical “0”
Input Voltage
Logical “1” Input
Current
Logical “0” Input
Current
Logical “1”
Output Voltage
Logical “0”
Output Voltage
HI-Z Output
Current
Output Source
Current
(Note 4)
(Note 4)
V
IN
= V
CC
(Note 4)
V
IN
= 0V (Note 4)
I
OUT
= –2mA (Note 4)
I
OUT
= 2mA (Note 4)
V
OUT
= 0V (Note 4)
V
OUT
= V
CC
V
OUT
= 0V (Note 4)
–1
1
–6.5
8.0
1.3
1.8
2.5
3.5
1.3
1.8
–6.5
8.0
2.5
3.5
–1
4.0
0.4
–1
1
2.0
0.8
1
–1
4.0
0.4
2.0
0.8
1
V
V
µA
µA
V
V
µA
µA
mA
mA
mA
mA
Output Sink Current V
OUT
= V
CC
(Note 4)
Supply Current
ML2281, ML2284
ML2288 (Note 4)
ML2282 Includes ladder
Current (Note 4)
5
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