General Description
The MAX127/MAX128 are multirange, 12-bit data
acquisition systems (DAS) that require only a single
+5V supply for operation, yet accept signals at their
analog inputs that may span above the power-supply
rail and below ground. These systems provide eight
analog input channels that are independently software
programmable for a variety of ranges: 10V, 5V, 0 to
+10V, 0 to +5V for the MAX127; and V
REF
, V
REF
/2, 0
to +V
REF
, 0 to +V
REF
/2 for the MAX128. This range
switching increases the effective dynamic range to 14
bits and provides the flexibility to interface 420mA,
12V, and 15V-powered sensors directly to a single
+5V system. In addition, these converters are fault pro-
tected to 16.5V; a fault condition on any channel will
not
affect the conversion result of the selected channel.
Other features include a 5MHz bandwidth track/hold,
an 8ksps throughput rate, and the option of an internal
4.096V or external reference.
The MAX127/MAX128 feature a 2-wire, I
2
C-compatible
serial interface that allows communication among multi-
ple devices using SDA and SCL lines.
A hardware shutdown input (SHDN) and two software-
programmable power-down modes (standby and full
power-down) are provided for low-current shutdown
between conversions. In standby mode, the reference-
buffer remains active, eliminating start-up delays.
The MAX127/MAX128 are available in 24-pin DIP or
space-saving 28-pin SSOP packages.
Applications
Industrial Control Systems
Data-Acquisition Systems
Robotics
Automatic Testing
Battery-Powered Instruments
Medical Instruments
Features
o
12-Bit Resolution, 1/2 LSB Linearity
o
+5V Single-Supply Operation
o
I
2
C-Compatible, 2-Wire Serial Interface
o
Four Software-Selectable Input Ranges
MAX127: 0 to +10V, 0 to +5V, 10V, 5V
MAX128: 0 to +V
REF
, 0 to +V
REF
/2, V
REF
,
V
REF
/2
o
8 Analog Input Channels
o
8ksps Sampling Rate
o
16.5V Overvoltage-Tolerant Input Multiplexer
o
Internal 4.096V or External Reference
o
Two Power-Down Modes
o
24-Pin Narrow DIP or 28-Pin SSOP Packages
EVALUATION KIT
AVAILABLE
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
MAX127/MAX128
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
________________________________________________________________
Maxim Integrated Products
1
V
DD
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
DGND
0.01
F
C
4.7
F
0.1
F
1k
SHDN
MAX127
MAX128
+5V
ANALOG
INPUTS
SCL
SDA
A0
A1
A2
REF
REFADJ
AGND
SCL
SDA
Typical Operating Circuit
19-4773; Rev 0; 7/98
Ordering Information continued at end of data sheet.
PART
MAX127
ACNG
MAX127ACNG
0C to +70C
0C to +70C
TEMP. RANGE
PIN-PACKAGE
24 Narrow Plastic DIP
24 Narrow Plastic DIP
1
1/2
INL
(LSB)
Pin Configurations appear at end of data sheet.
Ordering Information
MAX127/MAX128
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
V
DD
to AGND............................................................-0.3V to +6V
AGND to DGND.....................................................-0.3V to +0.3V
CH0CH7 to AGND ......................................................... 16.5V
REF to AGND..............................................-0.3V to (V
DD
+ 0.3V)
REFADJ to AGND.......................................-0.3V to (V
DD
+ 0.3V)
A0, A1, A2 to DGND...................................-0.3V to (V
DD
+ 0.3V)
SHDN, SCL, SDA to DGND ......................................-0.3V to +6V
Max Current into Any Pin ....................................................50mA
Continuous Power Dissipation (T
A
= +70C)
24-Pin Narrow DIP (derate 13.33mW/C above +70C)..1067mW
28-Pin SSOP (derate 9.52mW/C above +70C) ...............762mW
Operating Temperature Ranges
MAX127_ C_ _/MAX128_ C_ _ .............................0C to +70C
MAX127_ E_ _/MAX128_ E_ _ ..........................-40C to +85C
Storage Temperature Range ............................-65C to +150C
Lead Temperature (soldering, 10sec) ............................+300C
MAX127A/MAX128A
4kHz, V
IN
= 5V (Note 3)
Up to the 5th harmonic
Bipolar
MAX127B/MAX128B
Unipolar
CONDITIONS
10
Aperture Jitter
ns
200
Aperture Delay
dB
-86
Channel-to-Channel Crosstalk
dB
81
SFDR
Spurious-Free Dynamic Range
dB
-87
-80
THD
Total Harmonic Distortion
dB
70
LSB
1/2
INL
Integral Nonlinearity
Bits
12
Resolution
0.3
LSB
0.1
Channel-to-Channel Offset
Error Matching
10
5
1
LSB
1
DNL
Differential Nonlinearity
LSB
3
Offset Error
5
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
Bipolar
Unipolar
5
ppm/C
3
Gain Tempco (Note 2)
10
7
LSB
7
Gain Error (Note 2)
10
SINAD
Signal-to-Noise plus Distortion
Ratio
ns
Bipolar
Unipolar
Bipolar
MAX127B/MAX128B
MAX127B/MAX128B
Unipolar
MAX127B/MAX128B
MAX127B/MAX128B
MAX127A/MAX128A
MAX127A/MAX128A
MAX127A/MAX128A
MAX127A/MAX128A
ELECTRICAL CHARACTERISTICS
(V
DD
= +5V 5%; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7F at REF; external clock, f
CLK
= 400kHz;
T
A
= T
MIN
to T
MAX
; unless otherwise noted. Typical values are at T
A
= +25C.)
DYNAMIC SPECIFICATIONS
(800Hz sine-wave input, 10Vp-p (MAX127) or 4.096Vp-p (MAX128), f
SAMPLE
= 8ksps)
DC, V
IN
= 16.5V
-96
ACCURACY
(Note 1)
MAX127/MAX128
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V 5%; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7F at REF pin; external clock, f
CLK
= 400kHz;
T
A
= T
MIN
to T
MAX
; unless otherwise noted. Typical values are at T
A
= +25C.)
MAX128
MAX127
MAX127
-600
360
I
IN
-1200
720
A
V
REF
/2 range
V
REF
range
5V range
-1200
10
10V range
-600
10
Bipolar
Input Voltage Range
V
IN
-10
10
TC V
REF
-5
5
MAX127
-V
REF
V
REF
-V
REF
/2
V
REF
/2
MAX128
Bipolar,
Table 3
MAX127
MAX128
0 to 5V or 0 to V
REF
/2 range
0 to 10V or 0 to V
REF
range
5V or V
REF
/2 range
10V or V
REF
range
Buffer Voltage Gain
1.638
V/V
REFADJ Adjustment Range
1.5
%
Figure 12
Capacitive Bypass at REF
4.7
F
REFADJ Output Voltage
2.465
2.500
2.535
V
Load Regulation (Note 5)
10
mV
0 to 0.5mA output current
0
V
REF
0
V
REF
/2
Unipolar,
Table 3
Input Resistance
V
IN
I
IN
21
k
16
-10
360
Unipolar
Input Current
-10
720
Bipolar
MAX128
0 to 5V range
-10
0.1
10
0 to 10V range
Unipolar
2.5
Small-Signal Bandwidth
5
MHz
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
2.5
-3dB
rolloff
1.25
0
10
V
0
5
Track/Hold Acquisition Time
3
s
Input Capacitance
40
pF
REFOUT Voltage
V
REF
4.076
4.096
4.116
V
REFOUT Tempco
15
ppm/C
Output Short-Circuit Current
30
mA
CONDITIONS
(Note 4)
T
A
= +25C
MAX127_C/MAX128_C
30
MAX127_E/MAX128_E
ANALOG INPUT
INTERNAL REFERENCE
MAX127/MAX128
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
4
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V 5%; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7F at REF pin; external clock, f
CLK
= 400kHz;
T
A
= T
MIN
to T
MAX
; unless otherwise noted. Typical values are at T
A
= +25C.)
V
2.4
4.18
Input Voltage Range
V
V
DD
- 0.5
REFADJ Threshold for
Buffer Disable
Normal or STANDBY power-down mode
k
10
Input Resistance
FULL power-down mode
5
M
External reference = 4.096V
CONDITIONS
FULL power-down mode
LSB
0.1
0.5
PSRR
Power-Supply Rejection Ratio
(Note 7)
s
V
4.75
5.25
V
DD
Supply Voltage
6.0
7.7
10.0
t
CONV
Conversion Time
120
220
Normal mode, bipolar ranges
700
850
Normal mode, unipolar ranges
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
STANDBY power-down mode (Note 6)
mA
18
I
DD
Supply Current
6
10
A
Internal reference
0.5
0.4
f
CLK
External Clock Frequency Range
MHz
Power-up (Note 8)
s
200
Bandgap Reference
Start-Up Time
ksps
8
Throughput Rate
C
IN
15
pF
(Note 4)
Input Leakage Current
I
IN
0.1
10
A
V
IN
= 0 or V
DD
Input Low Threshold Voltage
V
IL
0.8
V
Input High Threshold Voltage
V
IH
2.4
V
Input Capacitance
V
HYS
0.2
V
Input Hysteresis
400
V
REF
=
4.18V
A
1
Input Current
FULL power-down mode
Normal, or STANDBY
power-down mode
To 0.1mV, REF bypass
capacitor fully discharged
ms
8
Reference Buffer Settling Time
POWER REQUIREMENTS
TIMING
REFERENCE INPUT
(buffer disabled, reference input applied to REF)
DIGITAL INPUTS
(SHDN, A2, A1, A0)
C
REF
= 4.7F
C
REF
= 33F
60
MAX127/MAX128
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
_______________________________________________________________________________________
5
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V 5%; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7F at REF pin; external clock, f
CLK
= 400kHz;
T
A
= T
MIN
to T
MAX
; unless otherwise noted. Typical values are at T
A
= +25C.)
Input Hysteresis
V
HYS
0.05 x V
DD
V
Input Low Threshold Voltage
V
IL
0.3 x V
DD
V
Input High Threshold Voltage
V
IH
0.7 x V
DD
V
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
TIMING CHARACTERISTICS
(V
DD
= +4.75V to +5.25V; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7F at REF pin; T
A
= T
MIN
to T
MAX
;
unless otherwise noted. Typical values are at T
A
= +25C.)
Input Capacitance
C
IN
15
pF
(Note 4)
Input Leakage Current
I
IN
0.1
10
A
V
IN
= 0 or V
DD
Three-State Output Capacitance
C
OUT
15
pF
(Note 4)
Output Low Voltage
V
OL
0.4
V
I
SINK
= 3mA
2-WIRE FAST MODE
Hold Time (Repeated)
START Condition
t
HD,STA
0.6
s
Bus Free Time Between a
STOP and START Condition
t
BUF
1.3
s
SCL Clock Frequency
f
SCL
400
kHz
PARAMETERS
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
Set-Up Time for a Repeated
START Condition
t
SU,STA
0.6
s
High Period of the SCL Clock
t
HIGH
0.6
s
Low Period of the SCL Clock
t
LOW
1.3
s
Rise Time for Both SDA and SCL
Signals (Receiving)
t
R
20 +
300
0.1 x C
b
ns
C
b
= Total capacitance of one bus line in pF
Data Setup Time
t
SU,DAT
100
ns
Data Hold Time
t
HD,DAT
0
0.9
s
DIGITAL INPUTS
(SDA, SCL)
DIGITAL OUTPUTS
(SDA)
I
SINK
= 6mA
0.6
Fall Time for Both SDA and SCL
Signals (Receiving)
t
F
C
b
= Total capacitance of one bus line in pF
20 +
300
0.1 x C
b
ns
Fall Time for Both SDA and SCL
Signals (Transmitting)
t
F
C
b
= Total capacitance of one bus line in pF
20 +
250
0.1 x C
b
ns
Set-Up Time for STOP Condition
t
SU,STO
0.6
s
Capacitive Load for Each
Bus Line
C
b
400
pF
Pulse Width of Spike Suppressed
t
SP
0
50
ns
2-WIRE FAST MODE
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