General Description
The MAX1270/MAX1271 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 can 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 MAX1270; ±V
REF
, ±V
REF
/2, 0 to
V
REF
, 0 to V
REF
/2 for the MAX1271. This range switch-
ing 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 protected to
±16.5V; a fault condition on any channel will not affect
the conversion result of the selected channel. Other fea-
tures include a 5MHz bandwidth track/hold, software-
selectable internal/external clock, 110ksps throughput
rate, and internal 4.096V or external reference operation.
The MAX1270/MAX1271 serial interface directly
connects to SPITM/QSPITM and MICROWIRETM devices
without external logic.
A hardware shutdown input (SHDN) and two software-
programmable power-down modes, standby (STBYPD)
or full power-down (FULLPD), are provided for low-cur-
rent shutdown between conversions. In standby mode,
the reference buffer remains active, eliminating startup
delays.
The MAX1270/MAX1271 are available in 24-pin narrow
PDIP or space-saving 28-pin SSOP packages.
Applications
Features
12-Bit Resolution, 0.5 LSB Linearity
+5V Single-Supply Operation
SPI/QSPI and MICROWIRE-Compatible
3-Wire Interface
Four Software-Selectable Input Ranges
MAX1270: 0 to +10V, 0 to +5V, ±10V, ±5V
MAX1271: 0 to V
REF
, 0 to V
REF
/2, ±V
REF
,
±V
REF
/2
Eight Analog Input Channels
110ksps Sampling Rate
±16.5V Overvoltage-Tolerant Input Multiplexer
Internal 4.096V or External Reference
Two Power-Down Modes
Internal or External Clock
24-Pin Narrow PDIP or 28-Pin SSOP Packages
MAX1270/MAX1271
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
________________________________________________________________ Maxim Integrated Products
1
V
DD
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
DGND
4.7µF
0.1µF
0.01µF
SHDN
MAX1270
MAX1271
+5V
ANALOG
INPUTS
CS
SCLK
DIN
DOUT
SSTRB
I/O
SCK
MOSI
MISO
REF
REFADJ
AGND
MC68HCXX
Typical Operating Circuit
PART
TEMP RANGE
PIN-PACKAGE
INL
(LSB)
MAX1270ACNG
0°C to +70°C
24 Narrow PDIP
±0.5
MAX1270BCNG
0°C to +70°C
24 Narrow PDIP
±1
MAX1270ACAI
0°C to +70°C
28 SSOP
±0.5
MAX1270BCAI
0°C to +70°C
28 SSOP
±1
Ordering Information
19-4782; Rev 2; 9/04
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Pin Configurations appear at end of data sheet.
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
Ordering Information continued at end of data sheet.
EVALUATION KIT
AVAILABLE
Industrial Control Systems
Data-Acquisition Systems
Battery-Powered
Instruments
Automatic Testing
Robotics
Medical Instruments
MAX1270/MAX1271
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
DD
= +5.0V ±5%; unipolar/bipolar range; external reference mode, V
REF
= +4.096V; 4.7µF at REF; external clock; f
CLK
= 2.0MHz,
50% duty cycle (MAX127_B); f
CLK
= 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, T
A
= T
MIN
to T
MAX
, unless
otherwise noted. Typical values are T
A
= +25°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.
V
DD
to AGND............................................................-0.3V to +6V
AGND to DGND.....................................................-0.3V to +0.3V
CH0CH7 to AGND ......................................................... ±16.5V
REF, REFADJ to AGND ..............................-0.3V to (V
DD
+ 0.3V)
SSTRB, DOUT to DGND.............................-0.3V to (V
DD
+ 0.3V)
SHDN, CS, DIN, SCLK 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_ _......................................................0°C to +70°C
MAX127_E_ _......................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL CONDITIONS MIN TYP MAX UNITS
ACCURACY (Note 1)
Resolution
12
Bits
MAX127_A
±0.5
Integral Nonlinearity
INL
MAX127_B
±1.0
LSB
Differential Nonlinearity
DNL
No missing codes over temperature
±1
LSB
MAX127_A
±3
Unipolar
MAX127_B
±5
MAX127_A
±5
Offset Error
Bipolar
MAX127_B
±10
LSB
Unipolar
±0.1
Channel-to-Channel Offset Error
Matching
Bipolar
±0.3
LSB
MAX127_A
±7
Unipolar
MAX127_B
±10
MAX127_A
±7
Gain Error (Note 2)
Bipolar
MAX127_B
±10
LSB
Unipolar, external reference
±3
Gain Error Temperature
Coefficient (Note 2)
Bipolar, external reference
±5
ppm/°C
DYNAMIC SPECIFICATIONS (10kHz sine-wave input, ±10V
P-P
(MAX1270), or ±4.096V
P-P
(MAX1271), f
SAMPLE
= 110ksps
(MAX127_B), f
SAMPLE
= 100ksps (MAX127_A))
Signal-to-Noise + Distortion Ratio
SINAD
70
dB
Total Harmonic Distortion
THD
Up to the 5th harmonic
-87
-78
dB
Spurious-Free Dynamic Range
SFDR
80
dB
50kHz (Note 3)
-86
Channel-to-Channel Crosstalk
DC, V
IN
=
±16.5V
-96
dB
Aperture Delay
External clock mode
15
ns
External clock mode
<50
ps
Aperture Jitter
Internal clock mode
10
ns
MAX1270/MAX1271
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5.0V ±5%; unipolar/bipolar range; external reference mode, V
REF
= +4.096V; 4.7µF at REF; external clock; f
CLK
= 2.0MHz,
50% duty cycle (MAX127_B); f
CLK
= 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, T
A
= T
MIN
to T
MAX
, unless
otherwise noted. Typical values are T
A
= +25°C.)
PARAMETER
SYMBOL CONDITIONS MIN TYP MAX UNITS
ANALOG INPUT
MAX127_A, f
CLK
= 1.8MHz
3.3
Track/Hold Acquisition Time
t
ACQ
MAX127_B, f
CLK
= 2.0MHz
3.0
µs
±10V or ±V
REF
range
5
±5V or ±V
REF
/2
range
2.5
0 to 10V or 0 to
V
REF
range
2.5
Small-Signal Bandwidth
-3dB rolloff
0 to 5V or 0 to
V
REF
/2 range
1.25
MHz
RNG = 1
0
10
MAX1270
RNG = 0
0
5
RNG = 1
0
V
REF
Unipolar (BIP =
0), Table 3
MAX1271
RNG = 0
0
V
REF
/2
RNG = 1
-10
+10
MAX1270
RNG = 0
-5
+5
RNG = 1
-V
REF
+V
REF
Input Voltage Range
(Table 3)
V
IN
Bipolar (BIP =
1), Table 3
MAX1271
RNG = 0
-V
REF
/2
+V
REF
/
2
V
0 to 10V
range
-10
+720
MAX1270
0 to 5V
range
-10
+360
Unipolar
MAX1271
-10
0.1
+10
±10V
range
-1200
+720
MAX1270
±5V range
-600
+360
±V
REF
range
-1200
+10
Input Current
I
IN
Bipolar
MAX1271
±V
REF
/2
range
-600
+10
µA
Unipolar
21
Dynamic Resistance
V
IN
/
I
IN
Bipolar
16
k
Input Capacitance
(Note 4)
40
pF
MAX1270/MAX1271
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
4
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5.0V ±5%; unipolar/bipolar range; external reference mode, V
REF
= +4.096V; 4.7µF at REF; external clock; f
CLK
= 2.0MHz,
50% duty cycle (MAX127_B); f
CLK
= 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, T
A
= T
MIN
to T
MAX
, unless
otherwise noted. Typical values are T
A
= +25°C.)
PARAMETER
SYMBOL CONDITIONS MIN TYP MAX UNITS
INTERNAL REFERENCE
REF Output Voltage
V
REF
T
A
= +25°C
4.076
4.096
4.116
V
MAX1270_C/MAX1271_C
±15
REF Output Tempco
TC V
REF
MAX1270_E/MAX1271_E
±30
ppm/
°C
Output Short-Circuit Current
30
mA
Load Regulation
0 to 0.5mA output current (Note 5)
10
mV
Capacitive Bypass at REF
4.7
µF
Capacitive Bypass at REFADJ
0.01
µF
REFADJ Output Voltage
2.465
2.500
2.535
V
REFADJ Adjustment Range
Figure 1
±1.5
%
Buffer Voltage Gain
1.638
V/V
REFERENCE INPUT (Reference buffer disabled, reference input applied to REF)
Input Voltage Range
2.40
4.18
V
Normal or STBYPD
400
Input Current
V
REF
= 4.18V
FULLPD
1
µA
Normal or STBYPD
10
k
Input Resistance
V
REF
= 4.18V
FULLPD
4.18
M
REFADJ Threshold for Buffer
Disable
V
DD
-
0.5
V
POWER REQUIREMENT
Supply Voltage
V
DD
4.75
5.25
V
Bipolar range
18
Normal
Unipolar range
6
10
mA
STBYPD power-down mode (Note 6)
700
850
Supply Current
I
DD
FULLPD power-down mode
120
220
µA
External reference = 4.096V
±0.1
±0.5
Power-Supply Rejection
Ratio (Note 7)
PSRR
Internal reference
±0.5
LSB
TIMING
MAX127_A
0.1
1.8
External Clock Frequency Range
f
SCLK
MAX127_B
0.1
2.0
MHz
MAX127_A
3.3
External clock mode
(Note 8)
MAX127_B
3.0
Acquisition Phase
Internal clock mode, Figure 9
3
5
µs
MAX1270/MAX1271
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
_______________________________________________________________________________________
5
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5.0V ±5%; unipolar/bipolar range; external reference mode, V
REF
= +4.096V; 4.7µF at REF; external clock; f
CLK
= 2.0MHz,
50% duty cycle (MAX127_B); f
CLK
= 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, T
A
= T
MIN
to T
MAX
, unless
otherwise noted. Typical values are T
A
= +25°C.)
PARAMETER
SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX127_A
6.6
External clock mode
(Note 8)
MAX127_B
6.0
Conversion Time
t
CONV
Internal clock mode, Figure 9
6
7.7
11
µs
MAX127_A
100
External clock mode
MAX127_B
110
Throughput Rate
Internal clock mode
43
ksps
Bandgap Reference Startup Time
Power-up (Note 9)
200
µs
C
REF
= 4.7µF
8
Reference Buffer Settling Time
To 0.1mV, REF bypass
capacitor fully
discharged
C
REF
= 33µF
60
ms
DIGITAL INPUTS (DIN, SCLK, CS, and SHDN)
Input High Threshold Voltage
V
IH
2.4
V
Input Low Threshold Voltage
V
IL
0.8
V
Input Hysteresis
V
HYS
0.2
V
Input Leakage Current
I
IN
V
IN
= 0 to V
DD
-10
+10
µA
Input Capacitance
C
IN
(Note 4)
15
pF
DIGITAL OUTPUTS (DOUT, SSTRB)
I
SINK
= 5mA
0.4
Output Voltage Low
V
OL
I
SINK
= 16mA
0.4
V
Output Voltage High
V
OH
I
SOURCE
= 0.5mA
V
DD
-
0.5
V
Tri-State Leakage Current
I
L
CS = V
DD
-10
+10
µA
Tri-State Output Capacitance
C
OUT
CS = V
DD
(Note 4)
15
pF
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