19-1387; Rev 2; 10/05
+2.7V, Low-Power, 2-Channel, 108ksps,
Serial 12-Bit ADCs in 8-Pin µMAX
General Description
The MAX144/MAX145 low-power, 12-bit analog-to-
digital converters (ADCs) are available in 8-pin µMAX
®
and DIP packages. Both devices operate with a single
+2.7V to +5.25V supply and feature a 7.4µs succes-
sive-approximation ADC, automatic power-down, fast
wake-up (2.5µs), an on-chip clock, and a high-speed,
3-wire serial interface.
Power consumption is only 3.2mW (V
DD
= +3.6V) at the
maximum sampling rate of 108ksps. At slower through-
put rates, the automatic shutdown (0.2µA) further
reduces power consumption.
The MAX144 provides 2-channel, single-ended opera-
tion and accepts input signals from 0 to V
REF
. The
MAX145 accepts pseudo-differential inputs ranging
from 0 to V
REF
. An external clock accesses data-
through the 3-wire serial interface, which is SPI™,
QSPI™, and MICROWIRE™-compatible.
Excellent dynamic performance and low power, com-
bined with ease of use and small package size, make
these converters ideal for battery-powered and data-
acquisition applications, or for other circuits with
demanding power-consumption and space require-
ments. For pin-compatible 10-bit ADCs, see the
MAX157 and MAX159 data sheets.
Features
♦
Single-Supply Operation (+2.7V to +5.25V)
♦
Two Single-Ended Channels (MAX144) One
Pseudo-Differential Channel (MAX145)
♦
Low Power
0.9mA (108ksps, +3V Supply)
100µA (10ksps, +3V Supply)
10µA (1ksps, +3V Supply)
0.2µA (Power-Down Mode)
♦
Internal Track/Hold
♦
108ksps Sampling Rate
♦
SPI/QSPI/MICROWIRE-Compatible 3-Wire Serial
Interface
♦
Space-Saving 8-Pin µMAX Package
♦
Pin-Compatible 10-Bit Versions Available
MAX144/MAX145
Ordering Information
PART
MAX144ACUA
MAX144BCUA
MAX144ACPA
MAX144BCPA
MAX144BC/D
TEMP
RANGE
0°C to
+70°C
0°C to
+70°C
0°C to
+70°C
0°C to
+70°C
0°C to
+70°C
-40°C to
+85°C
-40°C to
+85°C
-40°C to
+85°C
-40°C to
+85°C
-55°C to
+125°C
-55°C to
+125°C
PIN-
PACKAGE
8 µMAX
8 µMAX
8 Plastic DIP
8 Plastic DIP
Dice*
8 µMAX
8 µMAX
8 Plastic DIP
8 Plastic DIP
8 CERDIP**
8 CERDIP**
INL
(LSB)
±0.5
±1
±0.5
±1
±1
±0.5
±1
±0.5
±1
±0.5
±1
PKG
CODE
U8-1
U8-1
P8-1
P8-1
—
U8-1
U8-1
P8-1
P8-1
J8-2
J8-2
Applications
Battery-Powered Systems
Portable Data Logging
Isolated Data Acquisition
Instrumentation
Test Equipment
Medical Instruments
Process-Control Monitoring System Supervision
Pin Configuration
TOP VIEW
V
DD
1
CH0 (CH+)
2
CH1 (CH-)
3
8
7
SCLK
DOUT
CS/SHDN
REF
MAX144AEUA
MAX144BEUA
MAX144AEPA
MAX144BEPA
MAX144AMJA
MAX144BMJA
MAX144
MAX145
6
5
GND
4
( ) ARE FOR MAX145 ONLY
µMAX/DIP
*Dice
are specified at T
A
= +25°C, DC parameters only.
**Contact
factory for availability.
Ordering Information continued at end of data sheet.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
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.
+2.7V, Low-Power, 2-Channel, 108ksps,
Serial 12-Bit ADCs in 8-Pin µMAX
MAX144/MAX145
ABSOLUTE MAXIMUM RATINGS
V
DD
to GND ..............................................................-0.3V to +6V
CH0, CH1 (CH+, CH-) to GND ................. -0.3V to (V
DD
+ 0.3V)
REF to GND .............................................. -0.3V to (V
DD
+ 0.3V)
Digital Inputs to GND. ............................................. -0.3V to +6V
DOUT to GND............................................ -0.3V to (V
DD
+ 0.3V)
DOUT Sink Current ........................................................... 25mA
Continuous Power Dissipation (T
A
= +70°C)
µMAX (derate 4.1mW/°C above +70°C) .................... 330mW
Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW
CERDIP (derate 8.00mW/°C above +70°C) . .............. 640mW
Operating Temperature Ranges (T
A
)
MAX144/MAX145_C_A .......................................0°C to +70°C
MAX144/MAX145_E_A. ...................................-40°C to +85°C
MAX144/MAX145_M_A ................................ -55°C to +125°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
= +2.7V to +5.25V, V
REF
= 2.5V, 0.1µF capacitor at REF, f
SCLK
= 2.17MHz, 16 clocks/conversion cycle (108ksps),
CH- = GND for MAX145, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
DC ACCURACY
(Note 1)
Resolution
Relative Accuracy (Note 2)
Differential Nonlinearity
Offset Error
Gain Error
Gain Temperature Coefficient
Channel-to-Channel Offset
Matching
Channel-to-Channel Gain
Matching
(Note 3)
±0.8
±0.05
±0.05
RES
INL
DNL
MAX14_A
MAX14_B
No missing codes over temperature
12
±0.5
±1
±0.75
±3
±3
Bits
LSB
LSB
LSB
LSB
ppm/°C
LSB
LSB
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DYNAMIC SPECIFICATIONS
(f
IN(sine-wave)
= 10kHz, V
IN
= 2.5Vp-p, 108ksps, f
SCLK
= 2.17MHz, CH- = GND for MAX145)
Signal-to-Noise Plus
Distortion Ratio
Total Harmonic Distortion
(including 5th-order harmonic)
Spurious-Free Dynamic Range
Channel-to-Channel Crosstalk
Small-Signal Bandwidth
Full-Power Bandwidth
CONVERSION RATE
Conversion Time (Note 5)
T/H Acquisition Time
Aperture Delay
Aperture Jitter
Serial Clock Frequency
2
f
SCLK
External clock mode
Internal clock mode, for data transfer only
0.1
0
t
CONV
t
ACQ
25
<50
2.17
5
External clock, f
SCLK
= 2.17MHz,
16 clocks/conversion cycle
Internal clock
7.4
5
7
2.5
µs
ns
ps
MHz
µs
SINAD
THD
SFDR
f
IN
= 65kHz, V
IN
= 2.5Vp-p (Note 4)
-3dB rolloff
80
-85
2.25
1.0
70
-80
dB
dB
dB
dB
MHz
MHz
_______________________________________________________________________________________
+2.7V, Low-Power, 2-Channel, 108ksps,
Serial 12-Bit ADCs in 8-Pin µMAX
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +5.25V, V
REF
= 2.5V, 0.1µF capacitor at REF, f
SCLK
= 2.17MHz, 16 clocks/conversion cycle (108ksps),
CH- = GND for MAX145, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
ANALOG INPUTS
Analog Input Voltage Range
Multiplexer Leakage Current
Input Capacitance
EXTERNAL REFERENCE
Input Voltage Range
Input Current
Input Resistance
Shutdown REF Input Current
DIGITAL INPUTS (CS/SHDN) AND OUTPUT (DOUT)
V
DD
≤
3.6V
Input High Voltage
V
IH
V
DD
> 3.6V
Input Low Voltage
Input Hysteresis
Input Leakage Current
Input Capacitance
Output Low Voltage
Output High Voltage
Three-State Output Leakage
Current
Three-State Output Capacitance
POWER REQUIREMENTS
Positive Supply Voltage
Positive Supply Current
Power-Supply Rejection
V
DD
I
DD
PSR
Operating mode
Shutdown,
CS/SHDN
= GND
V
DD
= 2.7V to 5.25V,
V
REF
= 2.5V, full-scale input (Note 9)
2.7
0.9
0.2
±0.15
5.25
2.0
5
V
mA
µA
mV
C
OUT
V
IL
V
HYS
I
IN
C
IN
V
OL
V
OH
V
IN
= 0 or V
DD
(Note 8)
I
SINK
= 5mA
I
SINK
= 16mA
I
SOURCE
= 0.5mA
CS/SHDN
= V
DD
CS/SHDN
= V
DD
(Note 8)
V
DD
- 0.5
±10
15
0.5
0.2
±1
15
0.4
2.0
3.0
0.8
V
REF
(Note 7)
V
REF
= 2.5V
18
0
100
25
0.01
10
V
DD
+ 50mV
140
V
µA
kΩ
µA
C
IN
V
IN
(Note 6)
On/off leakage current, V
IN
= 0 to V
DD
0
±0.01
16
V
REF
±1
V
µA
pF
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX144/MAX145
V
V
V
µA
pF
V
V
µA
pF
_______________________________________________________________________________________
3
+2.7V, Low-Power, 2-Channel, 108ksps,
Serial 12-Bit ADCs in 8-Pin µMAX
MAX144/MAX145
TIMING CHARACTERISTICS (Figure 7)
(V
DD
= +2.7V to +5.25V, V
REF
= 2.5V, 0.1µF capacitor at REF, fSCLK = 2.17MHz, 16 clocks/conversion cycle (108ksps), CH-= GND
for MAX145, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Wake-Up Time
CS/SHDN
Fall to Output Enable
CS
/SHDN Rise to Output Disable
SCLK Fall to Output Data Valid
SCLK Clock Frequency
tDV
tTR
tDO
fSCLK
CL = 100pF
CL = 100pF, Figure 1
CL = 100pF, Figure 1
External clock
Internal clock, SCLK for data transfer only
External clock
SCLK Pulse Width High
tCH
Internal clock, SCLK for data transfer only
(Note 8)
External clock
SCLK Pulse Width Low
SCLK to
CS
/SHDN Setup
CS
/SHDN Pulse Width
tCL
tSCLKS
tCS
Internal clock, SCLK for data transfer only
(Note 8)
20
0.1
0
215
50
215
50
60
60
ns
ns
ns
ns
SYMBOL
CONDITIONS
MIN
2.5
120
120
120
2.17
5
TYP
MAX
UNITS
µs
ns
ns
ns
MHz
Note 1:
Tested at V
DD
= +2.7V.
Note 2:
Relative accuracy is the deviation of the analog value at any code from its theoretical value after full-scale range has been
calibrated.
Note 3:
Offset nulled.
Note 4:
"On" channel is grounded; sine wave applied to "off" channel (MAX144 only).
Note 5:
Conversion time is defined as the number of clock cycles times the clock period; clock has 50% duty cycle.
Note 6:
The common-mode range for the analog inputs is from GND to V
DD
(MAX145 only).
Note 7:
ADC performance is limited by the converter’s noise floor, typically 300µVp-p.
Note 8:
Guaranteed by design. Not subject to production testing.
Note 9:
Measured as V
FS
(2.7V) -V
FS
(5.25V).
4
_______________________________________________________________________________________
+2.7V, Low-Power, 2-Channel, 108ksps,
Serial 12-Bit ADCs in 8-Pin µMAX
Typical Operating Characteristics
(V
DD
= +3.0V, V
REF
= 2.5V, 0.1µF at REF, f
SCLK
= 2.17MHz, 16 clocks/conversion cycle (108ksps), CH- = GND for MAX145, T
A
= +25°C,
unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX144/5-01
MAX144/MAX145
SUPPLY CURRENT
vs. TEMPERATURE
MAX144/5-02
SUPPLY CURRENT
vs. SAMPLING RATE
V
DD
= V
REF
C
L
= 20pF
CODE = 101010100000
MAX144/5-03
1500
1300
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
V
REF
= V
DD
R
L
=
∞
C
L
= 50pF
CODE = 101010100000
1500
V
REF
= V
DD
R
L
=
∞
C
L
= 50pF
CODE = 101010100000
10,000
1000
1250
1100
100
1000
900
10
700
750
1
500
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
500
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
0.1
0.1
1
10
100
1k
10k
100k
SAMPLING RATE (sps)
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
MAX144/5-04
SHUTDOWN CURRENT
vs. TEMPERATURE
MAX144/5-05
OFFSET ERROR
vs. SUPPLY VOLTAGE
MAX144/5-06
1000
V
REF
= V
DD
SHUTDOWN CURRENT (nA)
800
1000
V
REF
= V
DD
1.0
SHUTDOWN CURRENT (nA)
800
0.8
OFFSET ERROR (LSB)
-60 -40 -20 0
20 40 60 80 100 120 140
600
600
0.6
400
400
0.4
200
200
0.2
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
0
TEMPERATURE (°C)
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
OFFSET ERROR
vs. TEMPERATURE
MAX144/5-07
GAIN ERROR
vs. SUPPLY VOLTAGE
MAX144/5-08
GAIN ERROR
vs. TEMPERATURE
0.4
0.3
GAIN ERROR (LSB)
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
MAX144/5-09
1.0
0.9
0.8
OFFSET ERROR (LSB)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-60
-35
-10
15 40 65 90
TEMPERATURE (°C)
0.5
0.4
0.3
GAIN ERROR (LSB)
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
0.5
115 140
-0.5
2.5
3.0
3.5
4.0
V
DD
(V)
4.5
5.0
5.5
-0.5
-60
-35
-10
15
40
65
90
115 140
TEMPERATURE (°C)
_______________________________________________________________________________________
5
Embedded System
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