19-4773; Rev 0; 7/98
KIT
ATION
EVALU
BLE
AVAILA
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
General Description
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
MAX127/MAX128
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 4–20mA,
±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,
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.
I
2
C-compatible
Typical Operating Circuit
+5V
0.1µF
µC
V
DD
SCL
SDA
Applications
Industrial Control Systems
Data-Acquisition Systems
Robotics
Automatic Testing
Battery-Powered Instruments
Medical Instruments
ANALOG
INPUTS
SHDN
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
1k
MAX127
MAX128
REF
REFADJ
SCL
SDA
A0
A1
A2
AGND
Ordering Information
PART
MAX127ACNG
MAX127ACNG
TEMP. RANGE
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
24 Narrow Plastic DIP
24 Narrow Plastic DIP
INL
(LSB)
±1/2
±1
4.7µF
0.01µF
DGND
Ordering Information continued at end of data sheet.
Pin Configurations appear at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
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.
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
MAX127/MAX128
ABSOLUTE MAXIMUM RATINGS
V
DD
to AGND............................................................-0.3V to +6V
AGND to DGND.....................................................-0.3V to +0.3V
CH0–CH7 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
= +70°C)
24-Pin Narrow DIP (derate 13.33mW/°C above +70°C)..1067mW
28-Pin SSOP (derate 9.52mW/°C above +70°C) ...............762mW
Operating Temperature Ranges
MAX127_ C_ _/MAX128_ C_ _.............................0°C to +70°C
MAX127_ E_ _/MAX128_ E_ _ ..........................-40°C to +85°C
Storage Temperature Range ............................-65°C to +150°C
Lead Temperature (soldering, 10sec) ............................+300°C
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.
ELECTRICAL CHARACTERISTICS
(V
DD
= +5V ±5%; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7µF at REF; external clock, f
CLK
= 400kHz;
T
A
= T
MIN
to T
MAX
; unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
ACCURACY
(Note 1)
Resolution
Integral Nonlinearity
Differential Nonlinearity
INL
DNL
Unipolar
Offset Error
Bipolar
Channel-to-Channel Offset
Error Matching
Unipolar
Bipolar
Unipolar
Gain Error (Note 2)
Bipolar
Gain Tempco (Note 2)
Unipolar
Bipolar
MAX127A/MAX128A
MAX127B/MAX128B
MAX127A/MAX128A
MAX127B/MAX128B
3
5
MAX127A/MAX128A
MAX127B/MAX128B
MAX127A/MAX128A
MAX127B/MAX128B
±0.1
±0.3
±7
±10
±7
±10
ppm/°C
LSB
MAX127A/MAX128A
MAX127B/MAX128B
12
±1/2
±1
±1
±3
±5
±5
±10
LSB
LSB
Bits
LSB
LSB
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DYNAMIC SPECIFICATIONS
(800Hz sine-wave input, ±10Vp-p (MAX127) or ±4.096Vp-p (MAX128), f
SAMPLE
= 8ksps)
Signal-to-Noise plus Distortion
Ratio
Total Harmonic Distortion
Spurious-Free Dynamic Range
Channel-to-Channel Crosstalk
Aperture Delay
Aperture Jitter
SINAD
THD
SFDR
4kHz, V
IN
= ±5V (Note 3)
DC, V
IN
= ±16.5V
Up to the 5th harmonic
81
-86
-96
200
10
70
-87
-80
dB
dB
dB
dB
ns
ns
2
_______________________________________________________________________________________
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V ±5%; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7µF at REF pin; external clock, f
CLK
= 400kHz;
T
A
= T
MIN
to T
MAX
; unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
ANALOG INPUT
Track/Hold Acquisition Time
±10V or ±V
REF
range
Small-Signal Bandwidth
-3dB
rolloff
±5V or ±V
REF
/2 range
0 to 10V or 0 to V
REF
range
0 to 5V or 0 to V
REF
/2 range
MAX127
Unipolar,
Table 3
MAX128
Input Voltage Range
V
IN
MAX127
Bipolar,
Table 3
MAX128
MAX127
MAX128
Input Current
I
IN
Bipolar
MAX128
Input Resistance
Input Capacitance
INTERNAL REFERENCE
REFOUT Voltage
REFOUT Tempco
Output Short-Circuit Current
Load Regulation (Note 5)
Capacitive Bypass at REF
REFADJ Output Voltage
REFADJ Adjustment Range
Buffer Voltage Gain
Figure 12
0 to 0.5mA output current
4.7
2.465
2.500
±1.5
1.638
2.535
V
REF
TC V
REF
T
A
= +25°C
MAX127_C/MAX128_C
MAX127_E/MAX128_E
4.076
4.096
±15
±30
30
10
4.116
V
ppm/°C
mA
mV
µF
V
%
V/V
∆V
IN
∆I
IN
Unipolar
Bipolar
(Note 4)
MAX127
±10V range
±5V range
±V
REF
range
±V
REF
/2 range
0 to 10V range
0 to 5V range
0
0
0
0
-10
-5
-V
REF
-V
REF
/2
-10
-10
-10
-1200
-600
-1200
-600
21
16
40
0.1
5
2.5
2.5
1.25
10
5
V
REF
V
REF
/2
10
5
V
REF
V
REF
/2
720
360
10
720
360
10
10
kΩ
pF
µA
V
MHz
3
µs
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX127/MAX128
Unipolar
_______________________________________________________________________________________
3
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
MAX127/MAX128
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V ±5%; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7µF at REF pin; external clock, f
CLK
= 400kHz;
T
A
= T
MIN
to T
MAX
; unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Input Voltage Range
Input Current
V
REF
=
4.18V
Normal, or STANDBY
power-down mode
FULL power-down mode
10
5
V
DD
- 0.5
SYMBOL
CONDITIONS
MIN
2.4
TYP
MAX
4.18
400
1
kΩ
MΩ
V
UNITS
V
µA
REFERENCE INPUT
(buffer disabled, reference input applied to REF)
Input Resistance
REFADJ Threshold for
Buffer Disable
POWER REQUIREMENTS
Supply Voltage
V
DD
Normal or STANDBY power-down mode
FULL power-down mode
4.75
Normal mode, bipolar ranges
Normal mode, unipolar ranges
STANDBY power-down mode (Note 6)
FULL power-down mode
External reference = 4.096V
Internal reference
6
700
120
±0.1
±0.5
5.25
18
10
850
220
±0.5
V
mA
µA
LSB
Supply Current
I
DD
Power-Supply Rejection Ratio
(Note 7)
TIMING
External Clock Frequency Range
Conversion Time
Throughput Rate
Bandgap Reference
Start-Up Time
Reference Buffer Settling Time
PSRR
f
CLK
t
CONV
6.0
7.7
0.4
10.0
8
Power-up (Note 8)
To 0.1mV, REF bypass
capacitor fully discharged
C
REF
= 4.7µF
C
REF
= 33µF
200
8
60
2.4
0.8
V
IN
= 0 or V
DD
(Note 4)
0.2
±0.1
±10
15
MHz
µs
ksps
µs
ms
DIGITAL INPUTS
(SHDN, A2, A1, A0)
Input High Threshold Voltage
Input Low Threshold Voltage
Input Leakage Current
Input Capacitance
Input Hysteresis
V
IH
V
IL
I
IN
C
IN
V
HYS
V
V
µA
pF
V
4
_______________________________________________________________________________________
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V ±5%; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7µF at REF pin; external clock, f
CLK
= 400kHz;
T
A
= T
MIN
to T
MAX
; unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
DIGITAL INPUTS
(SDA, SCL)
Input High Threshold Voltage
Input Low Threshold Voltage
Input Hysteresis
Input Leakage Current
Input Capacitance
DIGITAL OUTPUTS
(SDA)
Output Low Voltage
Three-State Output Capacitance
V
OL
C
OUT
I
SINK
= 3mA
I
SINK
= 6mA
(Note 4)
0.4
0.6
15
V
pF
V
IH
V
IL
V
HYS
I
IN
C
IN
V
IN
= 0 or V
DD
(Note 4)
0.3 x V
DD
0.05 x V
DD
±0.1
±10
15
0.7 x V
DD
V
V
V
µA
pF
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX127/MAX128
TIMING CHARACTERISTICS
(V
DD
= +4.75V to +5.25V; unipolar/bipolar range; external reference mode, V
REF
= 4.096V; 4.7µF at REF pin; T
A
= T
MIN
to T
MAX
;
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETERS
2-WIRE FAST MODE
2-WIRE FAST MODE
SCL Clock Frequency
Bus Free Time Between a
STOP and START Condition
Hold Time (Repeated)
START Condition
Low Period of the SCL Clock
High Period of the SCL Clock
Set-Up Time for a Repeated
START Condition
Data Hold Time
Data Setup Time
Rise Time for Both SDA and SCL
Signals (Receiving)
Fall Time for Both SDA and SCL
Signals (Receiving)
Fall Time for Both SDA and SCL
Signals (Transmitting)
Set-Up Time for STOP Condition
Capacitive Load for Each
Bus Line
Pulse Width of Spike Suppressed
f
SCL
t
BUF
t
HD,STA
t
LOW
t
HIGH
t
SU,STA
t
HD,DAT
t
SU,DAT
t
R
t
F
t
F
t
SU,STO
C
b
t
SP
0
C
b
= Total capacitance of one bus line in pF
C
b
= Total capacitance of one bus line in pF
C
b
= Total capacitance of one bus line in pF
1.3
0.6
1.3
0.6
0.6
0
100
20 +
0.1 x C
b
20 +
0.1 x C
b
20 +
0.1 x C
b
0.6
400
50
300
300
250
0.9
400
kHz
µs
µs
µs
µs
µs
µs
ns
ns
ns
ns
µs
pF
ns
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
_______________________________________________________________________________________
5
测试/测量
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