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General Description
The MAX1274/MAX1275 low-power, high-speed, serial-
output, 12-bit, analog-to-digital converters (ADCs) oper-
ate at up to 1.8Msps. These devices feature true-differen-
tial inputs, offering better noise immunity, distortion
improvements, and a wider dynamic range over single-
ended inputs. A standard SPITM/QSPITM/MICROWIRETM
interface provides the clock necessary for conversion.
These devices easily interface with standard digital signal
processor (DSP) synchronous serial interfaces.
The MAX1274/MAX1275 operate from a single +4.75V to
+5.25V supply voltage and require an external reference.
The MAX1274 has a unipolar analog input, while the
MAX1275 has a bipolar analog input. These devices fea-
ture a partial power-down mode and a full power-down
mode for use between conversions, which lower the sup-
ply current to 1mA (typ) and 1A (max), respectively. Also
featured is a separate power-supply input (V
L
), which
allows direct interfacing to +1.8V to V
DD
digital logic. The
fast conversion speed, low-power dissipation, excellent
AC performance, and DC accuracy (1 LSB INL) make
the MAX1274/MAX1275 ideal for industrial process con-
trol, motor control, and base-station applications.
The MAX1274/MAX1275 come in a 12-pin TQFN pack-
age, and are available in the commercial (0C to +70C)
and extended (-40C to +85C) temperature ranges.
Applications
Data Acquisition
Communications
Bill Validation
Portable Instruments
Motor Control
Features
1.8Msps Sampling Rate
Only 45mW (typ) Power Dissipation
Only 1A (max) Shutdown Current
High-Speed, SPI-Compatible, 3-Wire Serial Interface
70dB S/(N + D) at 525kHz Input Frequency
Internal True-Differential Track/Hold (T/H)
External Reference
No Pipeline Delays
Small 12-Pin TQFN Package
MAX1274/MAX1275
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
________________________________________________________________
Maxim Integrated Products
1
12
AIN+
11
N.C.
10
SCLK
4
5
N.C.
6
GND
1
2
REF
3
9
8
7
RGND
CNVST
DOUT
V
L
MAX1274
MAX1275
AIN-
V
DD
TQFN
TOP VIEW
PART
TEMP RANGE
PIN-
PACKAGE
INPUT
MAX1274
ACTC-T
0C to +70C
12 TQFN-12
Unipolar
MAX1274BCTC-T
0C to +70C
12 TQFN-12
Unipolar
MAX1274AETC-T
-40C to +85C 12 TQFN-12
Unipolar
MAX1274BETC-T
-40C to +85C 12 TQFN-12
Unipolar
MAX1275
ACTC-T
0C to +70C
12 TQFN-12
Bipolar
MAX1275BCTC-T
0C to +70C
12 TQFN-12
Bipolar
MAX1275AETC-T
-40C to +85C 12 TQFN-12
Bipolar
MAX1275BETC-T
-40C to +85C 12 TQFN-12
Bipolar
Pin Configuration
Ordering Information
MAX1274
MAX1275
DOUT
AIN+
REF
4.7F
10F
10F
4.75V TO +5.25V
0.01F
0.01F
0.01F
+1.8V TO V
DD
AIN-
REF
V
DD
DIFFERENTIAL
INPUT
VOLTAGE
RGND
V
L
GND
CNVST
SCLK
C/DSP
+
-
Typical Operating Circuit
19-3158; Rev 0; 1/04
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.
SPI/QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
MAX1274/MAX1275
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
DD
= +5V 5%, V
L
= V
DD
, V
REF
= 4.096V, f
SCLK
= 28.8MHz, 50% duty cycle, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical
values are at T
A
= +25C.)
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 GND ..............................................................-0.3V to +6V
V
L
to GND ...................-0.3V to the lower of (V
DD
+ 0.3V) or +6V
Digital Inputs
to GND ....................-0.3V to the lower of (V
DD
+ 0.3V) or +6V
Digital Output
to GND .......................-0.3V to the lower of (V
L
+ 0.3V) or +6V
Analog Inputs and
REF to GND.............-0.3V to the lower of (V
DD
+ 0.3V) or +6V
RGND to GND .......................................................-0.3V to +0.3V
Maximum Current into Any Pin............................................50mA
Continuous Power Dissipation (T
A
= +70C)
12-Pin TQFN (derate 16.9mW/C above +70C) ......1349mW
Operating Temperature Ranges
MAX127_ CTC ...................................................0C to +70C
MAX127_ ETC.................................................-40C to +85C
Junction Temperature ......................................................+150C
Storage Temperature Range .............................-60C to +150C
Lead Temperature (soldering, 10s) .................................+300C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC ACCURACY
Resolution
12
Bits
MAX127_A
-1.0
+1.0
Relative Accuracy
INL
(Note 1)
MAX127_B
-1.75
+1.75
LSB
MAX127_A
-1.0
+1.0
Differential Nonlinearity
DNL
(Note 2)
MAX127_B
-1.0
+1.75
LSB
Offset Error
6.0
LSB
Offset-Error Temperature
Coefficient
1
ppm/C
Gain Error
Offset nulled
6.0
LSB
Gain Temperature Coefficient
2
ppm/C
DYNAMIC SPECIFICATIONS
(f
IN
= 525kHz sine wave, V
IN
= V
REF
, unless otherwise noted.)
MAX127_A
69
70
Signal-to-Noise Plus Distortion
SINAD
MAX127_B
67
70
dB
Total Harmonic Distortion
(Up to the 5th Harmonic)
THD
-80
-76
dB
Spurious-Free Dynamic Range
SFDR
-83
-76
dB
Intermodulation Distortion
IMD
f
IN1
= 250kHz, f
IN2
= 300kHz
-78
dB
Full-Power Bandwidth
-3dB point, small-signal method
20
MHz
Full-Linear Bandwidth
S/(N + D)
68dB, single ended
1.2
MHz
CONVERSION RATE
Minimum Conversion Time
t
CONV
(Note 3)
0.556
s
Maximum Throughput Rate
1.8
Msps
M i ni m um Thr oug hp ut Rate
( N ote 4) 10
ksps
Track-and-Hold Acquisition Time
t
ACQ
(Note 5)
104
ns
Aperture Delay
5
ns
Aperture Jitter
(Note 6)
30
ps
External Clock Frequency
f
SCLK
28.8
MHz
MAX1274/MAX1275
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V 5%, V
L
= V
DD
, V
REF
= 4.096V, f
SCLK
= 28.8MHz, 50% duty cycle, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical
values are at T
A
= +25C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
ANALOG INPUTS (AIN+, AIN-)
AIN+ - AIN-, MAX1274
0
V
REF
Differential Input Voltage Range
V
IN
AIN+ - AIN-, MAX1275
-V
REF
/ 2
+V
REF
/ 2
V
Absolute Input Voltage Range
0
V
DD
V
DC Leakage Current
1
A
Input Capacitance
Per input pin
16
pF
Input Current (Average)
Time averaged at maximum throughput rate
75
A
REFERENCE INPUT (REF)
REF Input Voltage Range
V
REF
1.0
V
DD
+
50mV
V
Input Capacitance
20
pF
DC Leakage Current
1
A
Input Current (Average)
Time averaged at maximum throughput rate
400
A
DIGITAL INPUTS (SCLK, CNVST)
Input Voltage Low
VIL
0.3 x V
L
V
Input Voltage High
VIH
0.7 x V
L
V
Input Leakage Current
I
IL
0.05
10
A
DIGITAL OUTPUT (DOUT)
Output Load Capacitance
C
OUT
For stated timing performance
30
pF
Output Voltage Low
V
OL
I
SINK
= 5mA, V
L
1.8V
0.4
V
Output Voltage High
V
OH
I
SOURCE
= 1mA, V
L
1.8V
V
L
- 0.5V
V
Output Leakage Current
I
OL
Output high impedance
0.2
10
A
POWER REQUIREMENTS
Analog Supply Voltage
V
DD
4.75
5.25
V
Digital Supply Voltage
V
L
1.8
V
DD
V
Static, f
SCLK
= 28.8MHz
7
9
Static, no SCLK
4
5
Analog Supply Current,
Normal Mode
I
DD
Operational, 1.8Msps
9
11
mA
fSCLK = 28.8MHz
1
Analog Supply Current,
Partial Power-Down Mode
I
DD
No SCLK
1
mA
fSCLK = 28.8MHz
1
Analog Supply Current,
Full Power-Down Mode
I
DD
No SCLK
1
A
Operational, full-scale input at 1.8Msps
1
2.5
Static, f
SCLK
= 28.8MHz
0.4
1
Partial/full power-down mode,
f
SCLK
= 28.8MHz
0.2
0.5
mA
Digital Supply Current (Note 7)
Static, no SCLK, all modes
0.1
1
A
Positive-Supply Rejection
PSR
V
DD
= 5V 5%, full-scale input
0.2
3.0
mV
MAX1274/MAX1275
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
4
_______________________________________________________________________________________
Note 1: Relative accuracy is the deviation of the analog value at any code from its theoretical value after the gain error and the offset
error have been nulled.
Note 2: No missing codes over temperature.
Note 3: Conversion time is defined as the number of clock cycles (16) multiplied by the clock period.
Note 4: At sample rates below 10ksps, the input full-linear bandwidth is reduced to 5kHz.
Note 5: The listed value of three SCLK cycles is given for full-speed continuous conversions. Acquisition time begins on the 14th ris-
ing edge of SCLK and terminates on the next falling edge of CNST. The IC idles in acquisition mode between conversions.
Note 6: Undersampling at the maximum signal bandwidth requires the minimum jitter spec for SINAD performance.
Note 7: Digital supply current is measured with the V
IH
level equal to V
L
, and the V
IL
level equal to GND.
TIMING CHARACTERISTICS
(V
DD
= +5V 5%, V
L
= V
DD
, V
REF
= 4.096V, f
SCLK
= 28.8MHz, 50% duty cycle, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical
values are at T
A
= +25C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SCLK Pulse-Width High
t
CH
V
L
= 1.8V to V
DD
15.6
ns
SCLK Pulse-Width Low
t
CL
V
L
= 1.8V to V
DD
15.6
ns
C
L
= 30pF, V
L
= 4.75V to V
DD
14
C
L
= 30pF, V
L
= 2.7V to V
DD
17
SCLK Rise to DOUT Transition
t
DOUT
C
L
= 30pF, V
L
= 1.8V to V
DD
24
ns
DOUT Remains Valid After SCLK
t
DHOLD
V
L
= 1.8V to V
DD
4
ns
CNVST Fall to SCLK Fall
t
SETUP
V
L
= 1.8V to V
DD
10
ns
CNVST Pulse Width
t
CSW
V
L
= 1.8V to V
DD
20
ns
Power-Up Time; Full Power-Down
T
PWR-UP
2
ms
Restart Time; Partial Power-Down
t
RCV
16
Cycles
CNVST
SCLK
DOUT
t
DHOLD
t
DOUT
t
SETUP
t
CSW
t
CL
t
CH
Figure 1. Detailed Serial-Interface Timing
GND
6k
C
L
DOUT
DOUT
C
L
GND
V
L
a) HIGH-Z TO V
OH
, V
OL
TO V
OH
,
AND V
OH
TO HIGH-Z
b) HIGH-Z TO V
OL
, V
OH
TO V
OL
,
AND V
OL
TO HIGH-Z
6k
Figure 2. Load Circuits for Enable/Disable Times
MAX1274/MAX1275
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
_______________________________________________________________________________________
5
Typical Operating Characteristics
(V
DD
= +5V, V
L
= V
DD
, V
REF
= 4.096V, f
SCLK
= 28.8MHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are measured
at T
A
= +25C)
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1274)
MAX1274 toc01
DIGITAL OUTPUT CODE
INL (LSB)
4000
3000
1000
2000
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-0.8
0
5000
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1275)
MAX1274 toc02
DIGITAL OUTPUT CODE
INL (LSB)
4000
3000
1000
2000
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-0.8
0
5000
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1274)
MAX1274 toc03
DIGITAL OUTPUT CODE
DNL (LSB)
4000
3000
1000
2000
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-0.8
0
5000
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1275)
MAX1274 toc04
DIGITAL OUTPUT CODE
DNL (LSB)
4000
3000
1000
2000
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-0.8
0
5000
OFFSET ERROR
vs. TEMPERATURE (MAX1274)
MAX1274 toc05
TEMPERATURE (C)
OFFSET ERROR (LSB)
60
35
-15
10
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
-0.4
-40
85
OFFSET ERROR
vs. TEMPERATURE (MAX1275)
MAX1274 toc06
TEMPERATURE (C)
OFFSET ERROR (LSB)
60
35
-15
10
-0.75
-0.50
-0.25
0
0.25
0.50
0.75
1.00
-1.00
-40
85
GAIN ERROR
vs. TEMPERATURE (MAX1274)
MAX1274 toc07
TEMPERATURE (C)
GAIN ERROR (LSB)
60
35
10
-15
-2.5
-2.0
-1.5
-1.0
-0.5
-3.0
-40
85
GAIN ERROR
vs. TEMPERATURE (MAX1275)
MAX1274 toc08
TEMPERATURE (C)
GAIN ERROR (LSB)
60
35
10
-15
-2.5
-3.0
-2.0
-1.5
-1.0
-0.5
-40
85
FFT PLOT (MAX1274)
MAX1274 toc09
ANALOG INPUT FREQUENCY (kHz)
AMPLITUDE (dB)
800
600
400
200
-120
-100
-80
-60
-40
-20
0
-140
0
1000
f
SAMPLE
= 2Msps
f
SCLK
= 32MHz
f
IN
= 100kHz
SINAD = 70.74dB
SNR = 70.82dB
THD = -88.63dB
SFDR = 87.07dB
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