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
a73 Conversion time: 6µs
a73 Total unadjusted error: ±1/2LSB or ±1LSB
a73 Sample-and-hold: 375ns acquisition
a73 2, 4 or 8-input multiplexer options
a73 0 to 5V analog input range with single 5V
power supply
a73 Operates ratiometrically or with up to 5V
voltage reference
a73 No zero or full-scale adjust required
a73 ML2281 capable of digitizing a 5V, 40kHz sine wave
a73 Low power: 12.5mW MAX
a73 Superior pin compatible replacement for ADC0831,
ADC0832, ADC0834, and ADC0838
a73 Analog input protection: 25mA (min) per input
a73 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
REFAGND
COMMON
CH7
CH6
CH5
CH4
CH3
CH2
CH1
CH0
A/D
CONVERTER
WITH
SAMPLE & HOLD
FUNCTION
MULTIPLEXER
(ML2288 SHOWN)
Σ
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(* Indicates Part is Obsolete)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)