ML2281.pdf
(
369 KB
)
Pobierz
May 1997
ML2281, ML2282
*
,
ML2284
#
, ML2288
#
Serial I/O 8-Bit A/D Converters with
Multiplexer Options
GENERAL DESCRIPTION
FEATURES
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.
Conversion time: 6
µ
s
Total unadjusted error:
±
1/2LSB or
±
1LSB
Sample-and-hold: 375ns acquisition
All errors of the sample-and-hold, incorporated on the
ML2281 family are accounted for in the analog-to-digital
converters accuracy specification.
2, 4 or 8-input multiplexer options
0 to 5V analog input range with single 5V
power supply
Operates ratiometrically or with up to 5V
voltage reference
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.
No zero or full-scale adjust required
ML2281 capable of digitizing a 5V, 40kHz sine wave
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
Low power: 12.5mW MAX
Superior pin compatible replacement for ADC0831,
ADC0832, ADC0834, and ADC0838
Analog input protection: 25mA (min) per input
Now in 8-Pin SOIC Package (ML2281, ML2282)
(* Indicates Part is Obsolete)
(# Indicates Part is End Of Life as Of July 1, 2000)
±
10%.
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)
BLOCK DIAGRAM
ML2281
CS
CONTROL
AND
TIMING
DI
INPUT
SHIFT-REGISTER
CLK
SARS
CONTROL
AND
TIMING
4-BIT
CLK
CS
DO
OUTPUT
SHIFT-REGISTER
A/D WITH SAMPLE & HOLD FUNCTION
DO
V
IN+
OUTPUT
SHIFT-REGISTER
+
Σ
SUCCESSIVE
APPROXIMATION
REGISTER
+
–
COMP
–
CH0
SE
8
pF
CH1
CH2
V
REF
DGND
CH3
A/D
CONVERTER
WITH
SAMPLE & HOLD
FUNCTION
V
IN–
CH4
CH5
D/A
CONVERTER
8
pF
CH6
SHUNT
REGULATOR
CH7
V
CC
V
REF
V
CC
GND
COMMON
V+
AGND
REV. 1.0 10/10/2000
ML2281, ML2282, ML2284, ML2288
PIN CONFIGURATION
ML2281
Single Differential Input
8-Pin DIP
ML2282
2-Channel MUX
8-Pin DIP
CS
V
IN+
V
IN–
GND
V
CC
CLK
DO
V
REF
1
2
3
4
8
7
6
5
CS
CH0
CH1
GND
V
CC
(V
REF
)
CLK
DO
DI
1
2
3
4
8
7
6
5
T
O
P VIEW
T
OP VIEW
ML2282
8-Pin SOIC
ML2281
8-Pin SOIC
CS
V
IN+
V
IN–
GND
V
CC
CLK
DO
V
REF
CS
CH0
CH1
GND
V
CC
(V
REF
)
CLK
DO
DI
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
TOP VIEW
TOP VIEW
ML2284
14-Pin SOIC
ML2284
4-Channel MUX
14-Pin DIP
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
V+
CS
CH0
CH1
CH2
CH3
DGND
V
CC
DI
CLK
SARS
DO
V
REF
AGND
1
2
14
13
3
4
12
11
5
6
7
10
9
8
TOP VIEW
TOP VIEW
ML2288
8-Channel MUX
20-Pin PCC
ML2288
8-Channel MUX
20-Pin DIP
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
DGND
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
321 0 9
18
CH3
4
CS
CH4
5
17
DI
CLK
CH5
6
16
CH6
CH7
7
15
SARS
8
14
DO
9 0 1 2 3
TOP VIEW
TOP VIEW
2
REV. 1.0 10/10/2000
ML2281, ML2282, ML2284, ML2288
PIN DESCRIPTION
NAME
FUNCTION
NAME
FUNCTION
V
CC
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
Positive supply. 5V
±
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.
≤
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.
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.
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.
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.
V+
Input to the Shunt Regulator.
3
REV. 1.0 10/10/2000
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.
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
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) ..............................
Infrared (15 sec.) ............................................. 220
°
C
OPERATING CONDITIONS
Supply Voltage, V
CC
............................. 4.5V
DC
to 6.3V
DC
Temperature Range (Note 2) ................. T
MIN
±
25mA
≤
T
A
≤
T
MAX
Storage Temperature ................................ –65
C to 150
C
°
°
ML2281/2/4/8 BIX.................................. –40
°
C to 85
°
C
Package Dissipation
at T
A
= 25
ML2281/2/4/8 CIX
ML2281/2/4/8 BCX .................................... 0
°
C (Board Mount) ............................. 800mW
°
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
±
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
Ω
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
Ω
4
REV. 1.0 10/10/2000
ML2281, ML2282, ML2284, ML2288
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
µ
A
Leakage Current
Off channel = 0V
(Notes 4, 9)
On channel = 0V
+1
+1
µ
A
Off channel = V
CC
(Notes 4, 9)
I
ON
On Channel
On channel = 0V
–1
–1
µ
A
Leakage Current
Off channel = V
CC
(Notes 4, 9)
On channel = V
CC
+1
+1
µ
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
µ
A
Current
I
IN(0)
Logical “0” Input
V
IN
= 0V (Note 4)
–1
–1
µ
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
µ
A
Current
V
OUT
= V
CC
1
1
µ
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)
5
REV. 1.0 10/10/2000
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