19-3158; Rev 1; 4/09
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
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 SPI™/QSPI™/MICROWIRE™
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 1µA (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 extended (-40°C to +85°C)
temperature range.
♦
1.8Msps Sampling Rate
♦
Only 45mW (typ) Power Dissipation
♦
Only 1µA (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
Features
MAX1274/MAX1275
Ordering Information
PART
MAX1274AETC+T
MAX1274BETC+T
MAX1275AETC+T
MAX1275BETC+T
TEMP RANGE
PIN-
PACKAGE
INPUT
Unipolar
Unipolar
Bipolar
Bipolar
-40°C to +85°C 12 TQFN
-40°C to +85°C 12 TQFN
-40°C to +85°C 12 TQFN
-40°C to +85°C 12 TQFN
Applications
Data Acquisition
Bill Validation
Motor Control
Communications
Portable Instruments
+Denotes
a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
Pin Configuration
TOP VIEW
AIN+
12
N.C.
11
SCLK
10
10μF
AIN-
REF
RGND
1
2
3
9
8
7
CNVST
DOUT
V
L
DIFFERENTIAL +
INPUT
VOLTAGE -
+4.75V TO +5.25V
Typical Operating Circuit
+1.8V TO V
DD
0.01μF
V
DD
AIN+
AIN-
0.01μF
V
L
DOUT
10μF
MAX1274
MAX1275
MAX1274
MAX1275
REF
4.7μF
0.01μF
REF
RGND
μC/DSP
CNVST
SCLK
4
V
DD
5
N.C.
6
GND
GND
TQFN
SPI/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 Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
MAX1274/MAX1275
ABSOLUTE MAXIMUM RATINGS
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
= +70°C)
12-Pin TQFN (derate 16.9mW/°C above +70°C) ......1349mW
Operating Temperature Range
MAX127_ ETC.................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°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
= +5V ±5%, V
L
= V
DD
, V
REF
= 4.096V, f
SCLK
= 28.8MHz, 50% duty cycle, T
A
= -40°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
DC ACCURACY
Resolution
Relative Accuracy
Differential Nonlinearity
Offset Error
Offset-Error Temperature
Coefficient
Gain Error
Gain Temperature Coefficient
DYNAMIC SPECIFICATIONS (f
IN
= 525kHz sine wave, V
IN
= V
REF
, unless otherwise noted.)
Signal-to-Noise Plus Distortion
Total Harmonic Distortion
(Up to the 5th Harmonic)
Spurious-Free Dynamic Range
Intermodulation Distortion
Full-Power Bandwidth
Full-Linear Bandwidth
CONVERSION RATE
Minimum Conversion Time
Maximum Throughput Rate
Minimum Throughput Rate
Track-and-Hold Acquisition Time
Aperture Delay
Aperture Jitter
External Clock Frequency
f
SCLK
(Note 6)
t
ACQ
(Note 4)
(Note 5)
t
CONV
(Note 3)
1.8
10
104
5
30
28.8
0.556
µs
Msps
ksps
ns
ns
ps
MHz
SINAD
THD
SFDR
IMD
f
IN1
= 250kHz, f
IN2
= 300kHz
-3dB point, small-signal method
S/(N + D) > 68dB, single ended
MAX127_A
MAX127_B
69
67
70
70
-80
-83
-78
20
1.2
-76
-76
dB
dB
dB
dB
MHz
MHz
Offset nulled
±2
±1
±6.0
INL
DNL
(Note 1)
(Note 2)
MAX127_A
MAX127_B
MAX127_A
MAX127_B
12
-1.0
-1.75
-1.0
-1.0
+1.0
+1.75
+1.0
+1.75
±6.0
Bits
LSB
LSB
LSB
ppm/°C
LSB
ppm/°C
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V ±5%, V
L
= V
DD
, V
REF
= 4.096V, f
SCLK
= 28.8MHz, 50% duty cycle, T
A
= -40°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
ANALOG INPUTS (AIN+, AIN-)
Differential Input Voltage Range
Absolute Input Voltage Range
DC Leakage Current
Input Capacitance
Input Current (Average)
REFERENCE INPUT (REF)
REF Input Voltage Range
Input Capacitance
DC Leakage Current
Input Current (Average)
DIGITAL INPUTS (SCLK, CNVST)
Input Voltage Low
Input Voltage High
Input Leakage Current
DIGITAL OUTPUT (DOUT)
Output Load Capacitance
Output Voltage Low
Output Voltage High
Output Leakage Current
POWER REQUIREMENTS
Analog Supply Voltage
Digital Supply Voltage
Analog Supply Current,
Normal Mode
Analog Supply Current,
Partial Power-Down Mode
Analog Supply Current,
Full Power-Down Mode
V
DD
V
L
Static, f
SCLK
= 28.8MHz
I
DD
Static, no SCLK
Operational, 1.8Msps
I
DD
I
DD
f
SCLK
= 28.8MHz
No SCLK
f
SCLK
= 28.8MHz
No SCLK
Operational, full-scale input at 1.8Msps
Static, f
SCLK
= 28.8MHz
Digital Supply Current (Note 7)
Partial/full power-down mode,
f
SCLK
= 28.8MHz
Static, no SCLK, all modes
Positive-Supply Rejection
PSR
V
DD
= 5V ±5%, full-scale input
1
0.4
0.2
0.1
±0.2
4.75
1.8
7
4
9
1
1
1
1
2.5
1
0.5
1
±3.0
µA
mV
mA
5.25
V
DD
9
5
11
mA
µA
mA
V
V
C
OUT
V
OL
V
OH
I
OL
For stated timing performance
I
SINK
= 5mA, V
L
≥
1.8V
I
SOURCE
= 1mA, V
L
≥
1.8V
Output high impedance
V
L
- 0.5V
±0.2
±10
30
0.4
pF
V
V
µA
V
IL
V
IH
I
IL
0.7 x V
L
0.05
±10
0.3 x V
L
V
V
µA
Time averaged at maximum throughput rate
400
V
REF
1.0
20
±1
V
DD
+
50mV
V
pF
µA
µA
Per input pin
Time averaged at maximum throughput rate
16
75
V
IN
AIN+ - AIN-, MAX1274
AIN+ - AIN-, MAX1275
0
-V
REF
/2
0
V
REF
+V
REF
/2
V
DD
±1
V
V
µA
pF
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1274/MAX1275
_______________________________________________________________________________________
3
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
MAX1274/MAX1275
TIMING CHARACTERISTICS
(V
DD
= +5V ±5%, V
L
= V
DD
, V
REF
= 4.096V, f
SCLK
= 28.8MHz, 50% duty cycle, T
A
= -40°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
PARAMETER
SCLK Pulse-Width High
SCLK Pulse-Width Low
SCLK Rise to DOUT Transition
DOUT Remains Valid After SCLK
Rise
CNVST Fall to SCLK Fall
CNVST Pulse Width
Power-Up Time; Full Power-Down
Restart Time; Partial Power-Down
SYMBOL
t
CH
t
CL
t
DOUT
CONDITIONS
V
L
= 1.8V to V
DD
V
L
= 1.8V to V
DD
C
L
= 30pF, V
L
= 4.75V to V
DD
C
L
= 30pF, V
L
= 2.7V to V
DD
C
L
= 30pF, V
L
= 1.8V to V
DD
t
DHOLD
t
SETUP
t
CSW
t
PWR-UP
t
RCV
V
L
= 1.8V to V
DD
V
L
= 1.8V to V
DD
V
L
= 1.8V to V
DD
4
10
20
2
16
MIN
15.6
15.6
14
17
24
ns
ns
ns
ms
Cycles
ns
TYP
MAX
UNITS
ns
ns
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 CNVST. 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.
V
L
CNVST
t
CSW
t
SETUP
SCLK
t
CL
t
CH
DOUT
DOUT
6kΩ
DOUT
t
DHOLD
t
DOUT
6kΩ
GND
a) HIGH-Z TO V
OH
, V
OL
TO V
OH
,
AND V
OH
TO HIGH-Z
C
L
C
L
GND
b) HIGH-Z TO V
OL
, V
OH
TO V
OL
,
AND V
OL
TO HIGH-Z
Figure 1. Detailed Serial-Interface Timing
Figure 2. Load Circuits for Enable/Disable Times
4
_______________________________________________________________________________________
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
Typical Operating Characteristics
(V
DD
= +5V, V
L
= V
DD
, V
REF
= 4.096V, f
SCLK
= 28.8MHz, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are measured
at T
A
= +25°C)
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1274)
MAX1274 toc01
MAX1274/MAX1275
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1275)
MAX1274 toc02
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1274)
0.6
0.4
DNL (LSB)
0.2
0
-0.2
-0.4
-0.6
-0.8
MAX1274 toc03
0.8
0.6
0.4
INL (LSB)
0.8
0.6
0.4
INL (LSB)
0.2
0
-0.2
-0.4
-0.6
-0.8
0.8
0.2
0
-0.2
-0.4
-0.6
-0.8
0
1000
2000
3000
4000
5000
DIGITAL OUTPUT CODE
0
1000
2000
3000
4000
5000
0
1000
2000
3000
4000
5000
DIGITAL OUTPUT CODE
DIGITAL OUTPUT CODE
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1275)
MAX1274 toc04
OFFSET ERROR
vs. TEMPERATURE (MAX1274)
MAX1274 toc05
OFFSET ERROR
vs. TEMPERATURE (MAX1275)
0.75
OFFSET ERROR (LSB)
0.50
0.25
0
-0.25
-0.50
-0.75
-1.00
MAX1274 toc06
0.8
0.6
0.4
DNL (LSB)
0.2
0
-0.2
-0.4
-0.6
-0.8
0
1000
2000
3000
4000
0.4
0.3
OFFSET ERROR (LSB)
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
1.00
5000
-40
-15
10
35
60
85
-40
-15
10
35
60
85
DIGITAL OUTPUT CODE
TEMPERATURE (°C)
TEMPERATURE (°C)
GAIN ERROR
vs. TEMPERATURE (MAX1274)
MAX1274 toc07
GAIN ERROR
vs. TEMPERATURE (MAX1275)
MAX1274 toc08
FFT PLOT (MAX1274)
f
SAMPLE
= 2Msps
f
SCLK
= 32MHz
f
IN
= 100kHz
SINAD = 70.74dB
SNR = 70.82dB
THD = -88.63dB
SFDR = 87.07dB
MAX1274 toc09
-0.5
-0.5
0
-20
-40
-60
-80
-100
-1.0
GAIN ERROR (LSB)
-1.0
GAIN ERROR (LSB)
-1.5
-1.5
-2.0
-2.0
-2.5
-2.5
AMPLITUDE (dB)
-15
10
35
60
85
-120
-140
0
200
400
600
800
1000
TEMPERATURE (°C)
ANALOG INPUT FREQUENCY (kHz)
-3.0
-40
-15
10
35
60
85
-3.0
-40
TEMPERATURE (°C)
_______________________________________________________________________________________
5
京公网安备 11010802033920号
EEWORLD
