__________________General Description
The MAX1240/MAX1241 are low-power, 12-bit analog-
to-digital converters (ADCs) available in 8-pin pack-
ages. The MAX1240 operates with a single +2.7V to
+3.6V supply, and the MAX1241 operates with a single
+2.7V to +5.25V supply. Both devices feature a 7.5s
successive-approximation ADC, a fast track/hold
(1.5s), an on-chip clock, and a high-speed, 3-wire ser-
ial interface.
Power consumption is only 37mW (V
DD
= 3V) at the
73ksps maximum sampling speed. A 2A shutdown
mode reduces power at slower throughput rates.
The MAX1240 has an internal 2.5V reference, while the
MAX1241 requires an external reference. The MAX1241
accepts signals from 0V to V
REF
, and the reference
input range includes the positive supply rail. An exter-
nal clock accesses data from the 3-wire interface,
which connects directly to standard microcontroller I/O
ports. The interface is compatible with SPITM, QSPITM,
and MICROWIRETM.
Excellent AC characteristics and very low power com-
bined with ease of use and small package size make
these converters ideal for remote-sensor and data-
acquisition applications, or for other circuits with
demanding power consumption and space require-
ments. The MAX1240/MAX1241 are available in 8-pin
DIP and SO packages.
Applications
Battery-Powered Systems
Portable Data Logging
Isolated Data Acquisition
Process Control
Instrumentation
________________________________Features
o
Single-Supply Operation:
+2.7V to +3.6V (MAX1240)
+2.7V to +5.25V (MAX1241)
o
12-Bit Resolution
o
Internal 2.5V Reference (MAX1240)
o
Small Footprint: 8-Pin DIP/SO Packages
o
Low Power: 3.7W (73ksps, MAX1240)
3mW (73ksps, MAX1241)
66W (1ksps, MAX1241)
5W (power-down mode)
o
Internal Track/Hold
o
SPI/QSPI/MICROWIRE 3-Wire Serial Interface
o
Internal Clock
MAX1240/MAX1241
+2.7V, Low-Power,
12-Bit Serial ADCs in 8-Pin SO
________________________________________________________________
Maxim Integrated Products
1
19-1155; Rev 2; 11/98
SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp.
Ordering Information continued at end of data sheet.
*
Dice are specified at T
A
= +25C, DC parameters only.
TOP VIEW
1
2
3
4
8
7
6
5
SCLK
CS
DOUT
GND
REF
SHDN
AIN
V
DD
DIP/SO
MAX1240
MAX1241
Pin Configuration
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
PART
MAX1240
ACPA
MAX1240BCPA
0C to +70C
0C to +70C
TEMP. RANGE
PIN-
PACKAGE
8 Plastic DIP
8 Plastic DIP
INL
(LSB)
1
/
2
1
MAX1240ACSA
0C to +70C
8 SO
1
/
2
MAX1240BC/D
0C to +70C
Dice*
1
Ordering Information
EVALUATION KIT
AVAILABLE
MAX1240BCSA
0C to +70C
8 SO
1
Functional Diagram
7
AIN
T/H
DOUT
6
1
OUTPUT
SHIFT
REGISTER
CONTROL
LOGIC
INT
CLOCK
12-BIT
SAR
8
2
3
5
REF
4
SHDN
2.5V REFERENCE
(MAX1240 ONLY)
GND
SCLK
CS
MAX1240
MAX1241
V
DD
MAX1240CCPA
0C to +70C
8 Plastic DIP
1
MAX1240CCSA
0C to +70C
8 SO
1
MAX1240/MAX1241
+2.7V, Low-Power,
12-Bit Serial ADCs in 8-Pin SO
2
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS
(V
DD
= +2.7V to +3.6V (MAX1240); V
DD
= +2.7V to +5.25V (MAX1241); 73ksps, f
SCLK
= 2.1MHz (50% duty cycle); MAX1240--4.7F
capacitor at REF pin, MAX1241--external reference; V
REF
= 2.500V applied to REF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
V
DD
to GND .............................................................-0.3V to +6V
AIN 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 Current ..................................................................25mA
Continuous Power Dissipation (T
A
= +70C)
Plastic DIP (derate 9.09mW/C above +70C) ...........727mW
SO (derate 5.88mW/C above +70C)........................471mW
CERDIP (derate 8.00mW/C above +70C)................640mW
Operating Temperature Ranges
MAX1240_C_A/MAX1241_C_A .........................0C to +70C
MAX1240_E_ A/MAX1241_E_ A .....................-40C to +85C
MAX1240_MJA/MAX1241_MJA ...................-55C to +125C
Storage Temperature Range............................-60C to +150C
Lead Temperature (soldering, 10sec) ............................+300C
ABSOLUTE MAXIMUM RATINGS
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.
71.5
MAX124_C
Input Voltage Range
0
V
REF
V
Input Capacitance
Aperture Jitter
<50
ps
16
pF
MAX124_A
MAX124_B/C
Aperture Delay
t
APR
30
ns
Figure 8
Track/Hold Acquisition Time
t
ACQ
1.5
s
Throughput Rate
73
ksps
f
SCLK
= 2.1MHz
Conversion Time
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
0.5
3.0
Offset Error
LSB
Differential Nonlinearity
DNL
1
LSB
1.0
Gain Temperature Coefficient
0.5
4.0
Gain Error (Note 3)
LSB
0.5
4.0
Resolution
12
Bits
Relative Accuracy (Note 2)
INL
0.5
LSB
t
CONV
5.5
7.5
s
Small-Signal Bandwidth
Signal-to-Noise Plus
Distortion Ratio
SINAD
70
dB
2.25
MHz
Full-Power Bandwidth
Total Harmonic Distortion
THD
-80
dB
1.0
-3dB rolloff
MHz
CONDITIONS
Spurious-Free Dynamic Range
ppm/C
No missing codes over temperature
MAX124_B/C
0.25
SFDR
MAX124_A/B
80
Up to the 5th harmonic
dB
MAX124_A/B
MAX124_A
MAX124_A/B
MAX124_C
-88
MAX124_C
88
ANALOG INPUT
CONVERSION RATE
DYNAMIC SPECIFICATIONS
(10kHz sine-wave input, 0V to 2.500Vp-p, 73ksps, f
SCLK
= 2.1MHz)
DC ACCURACY
(Note 1)
ppm/C
MAX1240/MAX1241
+2.7V, Low-Power,
12-Bit Serial ADCs in 8-Pin SO
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +3.6V (MAX1240); V
DD
= +2.7V to +5.25V (MAX1241); 73ksps, f
SCLK
= 2.1MHz (50% duty cycle); MAX1240--4.7F
capacitor at REF pin, MAX1241--external reference; V
REF
= 2.500V applied to REF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
V
IN
= 0V or V
DD
A
T
A
= +25C
A
100
150
0.01
1
I
IN
SCLK, CS Input Leakage
V
0.2
Input Current
CONDITIONS
SHDN = 0V
A
0.01
10
V
HYST
SCLK, CS Input Hysteresis
SHDN = 0V or V
DD
A
REF Input Current in Shutdown
k
18
25
4.0
SHDN Input Current
Input Resistance
V
0.4
V
SL
SHDN Input Low Voltage
V
(Note 5)
V
DD
- 0.4
V
SH
SHDN Input High Voltage
pF
15
C
IN
V
REF Output Voltage
SCLK, CS Input Capacitance
SHDN = float
nA
SHDN = float
100
SHDN Max Allowed Leakage,
Mid Input
V
V
DD
/2
V
FLT
SHDN Voltage, Floating
V
1.1
V
DD
- 1.1
V
SM
SHDN Input Mid Voltage
I
SINK
= 5mA
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
V
0.4
V
OL
Output Voltage Low
CS = V
DD
(Note 5)
pF
15
C
OUT
Three-State Output Capacitance
CS = V
DD
A
I
SOURCE
= 0.5mA
0.01
10
I
L
Three-State Leakage Current
V
V
DD
- 0.5
V
OH
V
V
DD
3.6V
0.8
V
IL
F
0.1
Capacitive Bypass at REF
SCLK, CS Input Low Voltage
V
2.0
V
IH
SCLK, CS Input High Voltage
Output Voltage High
I
SINK
= 16mA
V
DD
> 3.6V (MAX1241)
0.8
3.0
2.480
2.500
2.520
V
Input Voltage Range
1.00
V
DD
+
50mV
MAX1240AC/BC
ppm/C
REF Temperature Coefficient
30
50
REF Short-Circuit Current
30
MAX1240AE/BE
30
60
MAX1240AM/BM
30
80
0mA to 0.2mA output load
Load Regulation (Note 4)
0.35
mA
F
Capacitive Bypass at REF
4.7
MAX1240C
30
DIGITAL OUTPUT: DOUT
DIGITAL INPUTS: SCLK,
C
CS
S
,
S
SH
HD
DN
N
EXTERNAL REFERENCE
(V
REF
= 2.500V)
INTERNAL REFERENCE
(MAX1240 only)
V
DD
= 3.6V
MAX1240/MAX1241
+2.7V, Low-Power,
12-Bit Serial ADCs in 8-Pin SO
4
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +3.6V (MAX1240); V
DD
= +2.7V to +5.25V (MAX1241); 73ksps, f
SCLK
= 2.1MHz (50% duty cycle); MAX1240--4.7F
capacitor at REF pin, MAX1241--external reference; V
REF
= 2.500V applied to REF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
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 the full-scale range and
offset have been calibrated.
Note 3:
MAX1240--internal reference, offset nulled; MAX1241--external reference (V
REF
= +2.500V), offset nulled.
Note 4:
External load should not change during conversion for specified accuracy.
Note 5:
Guaranteed by design. Not subject to production testing.
Note 6:
Measured as [V
FS
(2.7V) - V
FS
(V
DD(MAX
)].
Note 7:
To guarantee acquisition time, t
ACQ
is the maximum time the device takes to acquire the signal, and is also the minimum
time needed for the signal to be acquired.
SCLK Pulse Width Low
t
CL
200
ns
SCLK Pulse Width High
t
CH
200
ns
SCLK Clock Frequency
f
SCLK
0
2.1
MHz
CS Rise to Output Disable
t
TR
240
ns
SCLK Low to CS Fall Setup Time
t
CS0
50
ns
DOUT Rise to SCLK Rise (Note 5)
t
STR
0
ns
CS Pulse Width
t
CS
240
ns
Figure 2, C
LOAD
= 50pF
CS Fall to Output Enable
t
DV
240
ns
Figure 1, C
LOAD
= 50pF
PARAMETERS
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
Acquisition Time
t
ACQ
1.5
s
CS = V
DD
(Note 6)
TIMING CHARACTERISTICS
(Figure 8)
(V
DD
= +2.7V to +3.6V (MAX1240); V
DD
= +2.7V to +5.25V (MAX1241); T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETERS
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
2.7
3.6
MAX1240
2.7
5.25
MAX1241
V
DD
Supply Voltage
V
0.3
(Note 5)
PSR
Supply Rejection
mV
20
240
SCLK Fall to Output Data Valid
t
DO
20
200
ns
Figure 1,
C
LOAD
= 50pF
MAX124_ _C/E
MAX124_ _M
1.4
2.0
Operating
mode
1.6
2.5
V
DD
= 3.6V
3.5
15
V
DD
= 5.25V
V
DD
= 3.6V
V
DD
= 5.25V
I
DD
1.9
10
Power-down, digital inputs
at 0V or V
DD
1.4
3.5
A
0.9
1.5
V
DD
= 3.6V
MAX1240C
MAX1241A/B
Supply Current
MAX1240A/B
mA
1.6
3.8
V
DD
= 3.6V
V
DD
= 5.25V
0.9
2.8
MAX1241C
POWER REQUIREMENTS
MAX1240/MAX1241
+2.7V, Low-Power,
12-Bit Serial ADCs in 8-Pin SO
_______________________________________________________________________________________
5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2.25
2.75
3.25
3.75
4.25
4.75
5.25
OFFSET ERROR
vs. SUPPLY VOLTAGE
MAX1241-03
SUPPLY VOLTAGE (V)
OFFSET ERROR (LSB)
__________________________________________Typical Operating Characteristics
(V
DD
= 3.0V, V
REF
= 2.5V, f
SCLK
= 2.1MHz, C
L
= 20pF, T
A
= +25C, unless otherwise noted.)
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2
4
3
5
6
OPERATING SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX1241-D
SUPPLY VOLTAGE (V)
OPERATING SUPPLY CURRENT (mA)
R
L
=
CODE = 101010100000
MAX1241
MAX1240
0.8
0.9
1.0
1.1
1.2
1.3
-60
-20
20
60
100
140
SUPPLY CURRENT vs. TEMPERATURE
TEMPERATURE
(C)
SUPPLY CURRENT (mA)
MAX1241-A/NEW
MAX1241
MAX1240
R
LOAD
=
CODE = 10101010000
DOUT
DOUT
6k
DGND
C
LOAD
= 50pF
C
LOAD
= 50pF
6k
DGND
+2.7V
b) High-Z to V
OL
and V
OH
to V
OL
a) High-Z to V
OH
and V
OL
to V
OH
Figure 1. Load Circuits for DOUT Enable Time
DOUT
DOUT
6k
DGND
C
LOAD
= 50pF
C
LOAD
= 50pF
6k
DGND
+2.7V
b) V
OL
to High-Z
a) V
OH
to High-Z
Figure 2. Load Circuits for DOUT Disable Time
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