19-4782; Rev 2; 9/04
IT
TION K
VALUA
E
BLE
AVAILA
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
General Description
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
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 4–20mA, ±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 SPI™/QSPI™ and MICROWIRE™ 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.
Typical Operating Circuit
+5V
0.1µF
V
DD
Applications
Industrial Control Systems Automatic Testing
Data-Acquisition Systems Robotics
Battery-Powered
Medical Instruments
Instruments
ANALOG
INPUTS
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
SHDN
MAX1270
MAX1271
MC68HCXX
CS
SCLK
DIN
DOUT
SSTRB
AGND
I/O
SCK
MOSI
MISO
Ordering Information
PART
MAX1270ACNG
MAX1270BCNG
MAX1270ACAI
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
24 Narrow PDIP
24 Narrow PDIP
28 SSOP
INL
(LSB)
±0.5
±1
±0.5
±1
4.7µF
0.01µF
REF
REFADJ
DGND
MAX1270BCAI
0°C to +70°C 28 SSOP
Ordering Information continued at end of data sheet.
Pin Configurations appear at end of data sheet.
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
________________________________________________________________
Maxim Integrated Products
1
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.
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
MAX1270/MAX1271
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, 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
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
= +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
ACCURACY (Note 1)
Resolution
Integral Nonlinearity
Differential Nonlinearity
INL
DNL
MAX127_A
MAX127_B
No missing codes over temperature
Unipolar
Offset Error
Bipolar
Channel-to-Channel Offset Error
Matching
Unipolar
Bipolar
Unipolar
Gain Error (Note 2)
Bipolar
Gain Error Temperature
Coefficient (Note 2)
MAX127_A
MAX127_B
MAX127_A
MAX127_B
±3
±5
MAX127_A
MAX127_B
MAX127_A
MAX127_B
±0.1
±0.3
±7
±10
±7
±10
ppm/°C
LSB
12
±0.5
±1.0
±1
±3
±5
±5
±10
LSB
LSB
Bits
LSB
LSB
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Unipolar, external reference
Bipolar, external reference
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
Total Harmonic Distortion
Spurious-Free Dynamic Range
Channel-to-Channel Crosstalk
Aperture Delay
Aperture Jitter
SINAD
THD
SFDR
50kHz (Note 3)
DC, V
IN
=
±16.5V
External clock mode
External clock mode
Internal clock mode
Up to the 5th harmonic
80
-86
-96
15
<50
10
70
-87
-78
dB
dB
dB
dB
ns
ps
ns
2
_______________________________________________________________________________________
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
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
ANALOG INPUT
Track/Hold Acquisition Time
t
ACQ
MAX127_A, f
CLK
= 1.8MHz
MAX127_B, f
CLK
= 2.0MHz
±10V
or
±V
REF
range
±5V
or
±V
REF
/2
range
Small-Signal Bandwidth
-3dB rolloff
0 to 10V or 0 to
V
REF
range
0 to 5V or 0 to
V
REF
/2 range
MAX1270
Unipolar (BIP =
0), Table 3
MAX1271
Input Voltage Range
(Table 3)
V
IN
Bipolar (BIP =
1), Table 3
MAX1271
MAX1270
RNG = 1
RNG = 0
RNG = 1
RNG = 0
RNG = 1
RNG = 0
RNG = 1
RNG = 0
0 to 10V
range
Unipolar
MAX1270
0 to 5V
range
MAX1271
Input Current
I
IN
MAX1270
Bipolar
MAX1271
±V
REF
/2
range
Dynamic Resistance
Input Capacitance
∆V
IN
/∆I
IN
Unipolar
Bipolar
(Note 4)
-600
21
16
40
+10
kΩ
pF
±10V
range
±5V
range
±V
REF
range
-10
-10
-1200
-600
-1200
0.1
+360
+10
+720
+360
+10
µA
0
0
0
0
-10
-5
-V
REF
-V
REF
/2
-10
2.5
1.25
10
5
V
REF
V
REF
/2
+10
+5
+V
REF
+V
REF
/
2
+720
V
5
2.5
MHz
3.3
3.0
µs
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1270/MAX1271
_______________________________________________________________________________________
3
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
MAX1270/MAX1271
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
INTERNAL REFERENCE
REF Output Voltage
REF Output Tempco
Output Short-Circuit Current
Load Regulation
Capacitive Bypass at REF
Capacitive Bypass at REFADJ
REFADJ Output Voltage
REFADJ Adjustment Range
Buffer Voltage Gain
REFERENCE INPUT (Reference buffer disabled, reference input applied to REF)
Input Voltage Range
Input Current
Input Resistance
REFADJ Threshold for Buffer
Disable
POWER REQUIREMENT
Supply Voltage
V
DD
Normal
Supply Current
I
DD
Bipolar range
Unipolar range
6
700
120
±0.1
±0.5
0.1
0.1
MAX127_A
MAX127_B
3.3
3.0
3
5
µs
1.8
2.0
4.75
5.25
18
10
850
220
±0.5
V
mA
µA
LSB
V
REF
= 4.18V
V
REF
= 4.18V
Normal or STBYPD
FULLPD
Normal or STBYPD
FULLPD
10
4.18
V
DD
-
0.5
2.40
4.18
400
1
V
µA
kΩ
MΩ
V
Figure 1
0 to 0.5mA output current (Note 5)
4.7
0.01
2.465
2.500
±1.5
1.638
2.535
V
REF
TC V
REF
T
A
= +25°C
MAX1270_C/MAX1271_C
MAX1270_E/MAX1271_E
4.076
4.096
±15
±30
30
10
4.116
V
ppm/°C
mA
mV
µF
µF
V
%
V/V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
STBYPD power-down mode (Note 6)
FULLPD power-down mode
External reference = 4.096V
Internal reference
MAX127_A
MAX127_B
External clock mode
(Note 8)
Power-Supply Rejection
Ratio (Note 7)
TIMING
External Clock Frequency Range
PSRR
f
SCLK
MHz
Acquisition Phase
Internal clock mode, Figure 9
4
_______________________________________________________________________________________
Multirange, +5V, 8-Channel,
Serial 12-Bit ADCs
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
Conversion Time
SYMBOL
t
CONV
CONDITIONS
External clock mode
(Note 8)
MAX127_A
MAX127_B
MAX127_A
MAX127_B
200
C
REF
= 4.7µF
C
REF
= 33µF
8
ms
60
MIN
6.6
6.0
6
7.7
11
100
110
43
µs
ksps
µs
TYP
MAX
UNITS
MAX1270/MAX1271
Internal clock mode, Figure 9
Throughput Rate
Bandgap Reference Startup Time
Reference Buffer Settling Time
DIGITAL INPUTS (DIN, SCLK,
CS,
and
SHDN)
Input High Threshold Voltage
Input Low Threshold Voltage
Input Hysteresis
Input Leakage Current
Input Capacitance
DIGITAL OUTPUTS (DOUT, SSTRB)
Output Voltage Low
Output Voltage High
Tri-State Leakage Current
Tri-State Output Capacitance
V
OL
V
OH
I
L
C
OUT
I
SINK
= 5mA
I
SINK
= 16mA
I
SOURCE
= 0.5mA
CS
= V
DD
CS
= V
DD
(Note 4)
V
IH
V
IL
V
HYS
I
IN
C
IN
V
IN
= 0 to V
DD
(Note 4)
External clock mode
Internal clock mode
Power-up (Note 9)
To 0.1mV, REF bypass
capacitor fully
discharged
2.4
0.8
0.2
-10
+10
15
0.4
0.4
V
DD -
0.5
-10
+10
15
V
V
V
µA
pF
V
V
µA
pF
_______________________________________________________________________________________
5
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