19-3364; Rev 1; 4/09
KIT
ATION
EVALU
BLE
AVAILA
1.8Msps, Single-Supply, Low-Power, True-
Differential, 12-Bit ADCs with Internal Reference
General Description
The MAX1276/MAX1278 are low-power, high-speed, seri-
al-output, 12-bit, analog-to-digital converters (ADCs) that
operate at up to 1.8Msps and have an internal reference.
These devices feature true-differential inputs, offering bet-
ter 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 MAX1276/MAX1278 operate from a single +4.75V to
+5.25V supply voltage. The MAX1276/MAX1278 include
a 4.096V internal reference. The MAX1276 has a unipolar
analog input, while the MAX1278 has a bipolar analog
input. These devices feature a partial power-down mode
and a full power-down mode for use between conver-
sions, which lower the supply current to 2mA (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 (±1.25 LSB INL) make the MAX1276/MAX1278
ideal for industrial process control, motor control, and
base-station applications.
The MAX1276/MAX1278 come in a 12-pin TQFN pack-
age, and are available in the extended (-40°C to +85°C)
temperature range.
o
1.8Msps Sampling Rate
o
Only 55mW (typ) Power Dissipation
o
Only 1µA (max) Shutdown Current
o
High-Speed, SPI-Compatible, 3-Wire Serial Interface
o
70dB S/(N + D) at 525kHz Input Frequency
o
Internal True-Differential Track/Hold (T/H)
o
Internal 4.096V Reference
o
No Pipeline Delays
o
Small 12-Pin TQFN Package
Features
MAX1276/MAX1278
Ordering Information
PART
MAX1276ETC+T
MAX1278ETC+T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
12 TQFN
12 TQFN
INPUT
Unipolar
Bipolar
+Denotes
a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
Applications
Data Acquisition
Bill Validation
Motor Control
Communications
Portable Instruments
Typical Operating Circuit
4.75V TO +5.25V
10μF
0.01μF
V
DD
DIFFERENTIAL +
INPUT
VOLTAGE -
AIN+
AIN-
+1.8V TO V
DD
Pin Configuration
TOP VIEW
AIN+
12
N.C.
11
SCLK
10
0.01μF
V
L
DOUT
10μF
AIN-
REF
RGND
1
2
3
9
8
7
CNVST
DOUT
V
L
MAX1276
MAX1278
MAX1276
MAX1278
REF
4.7μF
0.01μF
RGND
μC/DSP
CNVST
SCLK
GND
4
V
DD
5
N.C.
6
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 with Internal Reference
MAX1276/MAX1278
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) and +6V
Digital Inputs
to GND .................-0.3V to the lower of (V
DD
+ 0.3V) and +6V
Digital Output
to GND ....................-0.3V to the lower of (V
L
+ 0.3V) and +6V
Analog Inputs and
REF to GND..........-0.3V to the lower of (V
DD
+ 0.3V) and +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
, 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
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
ANALOG INPUTS (AIN+, AIN-)
Differential Input Voltage Range
Absolute Input Voltage Range
V
IN
AIN+ - AIN-, MAX1276
AIN+ - AIN-, MAX1278
0
-V
REF
/ 2
0
V
REF
+V
REF
/ 2
V
DD
V
V
f
SCLK
(Note 7)
t
ACQ
(Note 5)
(Note 6)
t
CONV
(Note 4)
1.8
10
104
5
30
28.8
0.556
µs
Msps
ksps
ns
ns
ps
MHz
SINAD
THD
SFDR
IMD
(Note 1)
Up to the 5th harmonic (Note 1)
(Note 1)
f
IN1
= 250kHz, f
IN2
= 300kHz
-3dB point, small-signal method
S/(N + D) > 68dB, single ended
69
70
-80
-83
-78
20
2.0
-76
-76
dB
dB
dB
dB
MHz
MHz
Offset nulled
±2
±1
±6.0
INL
DNL
(Notes 1, 2)
(Notes 1, 3)
12
-1.25
-1.0
+1.25
+1.0
±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 with Internal Reference
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V ±5%, V
L
= V
DD
, 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 Leakage Current
Input Capacitance
Input Current (Average)
REFERENCE OUTPUT (REF)
REF Output Voltage Range
Voltage Temperature Coefficient
Load Regulation
Line Regulation
DIGITAL INPUTS (SCLK, CNVST)
Input Voltage Low
Input Voltage High
Input 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 8)
Partial/full power-down mode,
f
SCLK
= 28.8MHz
Static, no SCLK, all modes
Positive-Supply Rejection
DIGITAL OUTPUT (DOUT)
Output Load Capacitance
Output Voltage Low
Output Voltage High
Output Leakage Current
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
PSR
V
DD
= 5V ±5%, full-scale input
4.75
1.8
8
5
10
2
2
1
0.3
1
0.4
0.2
0.1
±0.2
1
2.5
1
0.5
1
±3.0
µA
mV
mA
5.25
V
DD
11
7
13
mA
µA
mA
V
V
VIL
VIH
I
IL
0.7 x V
L
Output high impedance
±0.2
±10
0.3 x V
L
V
V
µA
I
SOURCE
= 0 to 2mA
I
SINK
= 0 to 200µA
V
DD
= 4.75V to 5.25V, static
Static, T
A
= +25°C
4.086
4.096
±50
0.3
0.5
0.5
4.106
V
ppm/°C
mV/mA
mV/V
Per input pin
Time averaged at maximum throughput rate
16
75
SYMBOL
CONDITIONS
MIN
TYP
MAX
±1
UNITS
µA
pF
µA
MAX1276/MAX1278
_______________________________________________________________________________________
3
1.8Msps, Single-Supply, Low-Power, True-
Differential, 12-Bit ADCs with Internal Reference
MAX1276/MAX1278
TIMING CHARACTERISTICS
(V
DD
= +5V ±5%, V
L
= V
DD
, 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
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
t
DHOLD
t
SETUP
t
CSW
t
PWR-UP
t
RCV
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
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:
-40°C performance is guaranteed by design.
Note 2:
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 3:
No missing codes over temperature.
Note 4:
Conversion time is defined as the number of clock cycles (16) multiplied by the clock period.
Note 5:
At sample rates below 10ksps, the input full-linear bandwidth is reduced to 5kHz.
Note 6:
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 7:
Undersampling at the maximum signal bandwidth requires the minimum jitter spec for SINAD performance.
Note 8:
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 with Internal Reference
Typical Operating Characteristics
(V
DD
= +5V, V
L
= V
DD
, f
SCLK
= 28.8MHz, f
SAMPLE
= 1.8Msps, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are
meas- ured at T
A
= +25°C.)
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1276)
MAX1276/78 toc01
MAX1276/MAX1278
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1278)
MAX1276/78 toc02
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1276)
0.75
0.50
DNL (LSB)
0.25
0
-0.25
-0.50
-0.75
-1.00
MAX1276/78 toc03
1.00
0.75
0.50
INL (LSB)
0.25
0
-0.25
-0.50
-0.75
-1.00
0
1024
2048
3072
1.0
0.8
0.6
0.4
INL (LSB)
0.2
0
-0.2
-0.4
-0.6
-0.8
1.00
4096
-1.0
-2048
-1024
0
1024
2048
0
1024
2048
3072
4096
DIGITAL OUTPUT CODE
DIGITAL OUTPUT CODE
DIGITAL OUTPUT CODE
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE (MAX1278)
MAX1276/78 toc04
OFFSET ERROR
vs. TEMPERATURE (MAX1276)
MAX1276/78 toc05
OFFSET ERROR
vs. TEMPERATURE (MAX1278)
0.75
OFFSET ERROR (LSB)
0.50
0.25
0
-0.25
-0.50
-0.75
-1.00
MAX1276/78 toc06
1.0
0.8
0.6
0.4
DNL (LSB)
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
-2048
-1024
0
1024
0.4
0.3
OFFSET ERROR (LSB)
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-40
-15
10
35
60
1.00
2048
85
-40
-15
10
35
60
85
DIGITAL OUTPUT CODE
TEMPERATURE (°C)
TEMPERATURE (°C)
GAIN ERROR
vs. TEMPERATURE (MAX1276)
MAX1276/78 toc07
GAIN ERROR
vs. TEMPERATURE (MAX1278)
MAX1276/78 toc08
DYNAMIC PERFORMANCE
vs. INPUT FREQUENCY (MAX1276)
MAX1276/78 toc09
-0.5
-0.5
72.0
SNR
71.5
-1.0
GAIN ERROR (LSB)
-1.0
GAIN ERROR (LSB)
-1.5
-1.5
DYNAMIC PERFORMANCE (dB)
71.0
SINAD
70.5
-2.0
-2.0
-2.5
-2.5
-3.0
-40
-15
10
35
60
85
-3.0
-40
70.0
-15
10
35
60
85
100
200
300
400
500
TEMPERATURE (°C)
ANALOG INPUT FREQUENCY (kHz)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
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