19-2722; Rev 0; 04/03
420ksps, +5V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
General Description
The MAX1266/MAX1268 low-power, 12-bit analog-to-
digital converters (ADCs) feature a successive-approxi-
mation ADC, automatic power-down, fast wake-up
(2µs), an on-chip clock, +2.5V internal reference, and a
high-speed 12-bit parallel interface. They operate with
a single +5V analog supply.
Power consumption is only 10mW at the maximum sam-
pling rate of 420ksps. Two software-selectable power-
down modes enable the MAX1266/MAX1268 to be shut
down between conversions; accessing the parallel
interface returns them to normal operation. Powering
down between conversions can reduce supply below
10µA at lower sampling rates.
Both devices offer software-configurable analog inputs for
unipolar/bipolar and single-ended/pseudo-differential
operation. In single-ended mode, the MAX1266 has six
input channels and the MAX1268 has two (three input
channels and one input channel, respectively, when in
pseudo-differential mode).
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 demand-
ing power-consumption and space requirements. The
MAX1266 is offered in a 28-pin QSOP package, while the
MAX1268 is available in a 24-pin QSOP. For pin-compati-
ble +3V, 12-bit versions, see the MAX1265/MAX1267.
o
12-Bit Resolution, ±0.5 LSB Linearity
o
Single +5V Operation
o
Internal +2.5V Reference
o
Software-Configurable Analog Input Multiplexer
6-Channel Single Ended/
3-Channel Pseudo-Differential (MAX1266)
2-Channel Single Ended/
1-Channel Pseudo-Differential (MAX1268)
o
Software-Configurable Unipolar/Bipolar
Analog Inputs
o
Low Current
2.8mA (420ksps)
1.0mA (100ksps)
400µA (10ksps)
2µA (Shutdown)
o
Internal 6MHz Full-Power Bandwidth Track/Hold
o
Parallel 12-Bit Interface
o
Small Footprint
28-Pin QSOP (MAX1266)
24-Pin QSOP (MAX1268)
Features
MAX1266/MAX1268
Pin Configurations
TOP VIEW
Applications
Industrial Control Systems
Energy Management
Data-Acquisition Systems
Data Logging
Patient Monitoring
Touch Screens
D9 1
D8 2
D7 3
D6 4
D5 5
24 D10
23 D11
22 V
DD
21 REF
20 REFADJ
Ordering Information
PART
MAX1266ACEI
MAX1266BCEI
MAX1266AEEI
MAX1266BEEI
MAX1268ACEG
MAX1268BCEG
TEMP RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
28 QSOP
28 QSOP
28 QSOP
28 QSOP
24 QSOP
24 QSOP
24 QSOP
24 QSOP
INL
(LSB)
±0.5
±1
±0.5
±1
±0.5
±1
±0.5
±1
D4 6
D3 7
D2 8
D1 9
D0 10
INT 11
RD 12
MAX1268
19 GND
18 COM
17 CH0
16 CH1
15 CS
14 CLK
13 WR
QSOP
Pin Configurations continued at end of data sheet.
Typical Operating Circuits appear at end of data sheet.
MAX1268AEEG -40°C to +85°C
MAX1268BEEG -40°C to +85°C
________________________________________________________________
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.
420ksps, +5V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
MAX1266/MAX1268
ABSOLUTE MAXIMUM RATINGS
V
DD
to GND ..............................................................-0.3V to +6V
CH0–CH5, COM to GND ............................-0.3V to (V
DD
+ 0.3V)
REF, REFADJ to GND.................................-0.3V to (V
DD
+ 0.3V)
Digital Inputs to GND ...............................................-0.3V to +6V
Digital Outputs (D0–D11, INT) to GND.......-0.3V to (V
DD
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
24-Pin QSOP (derate 9.5mW/°C above +70°C)..........762mW
28-Pin QSOP (derate 8.0mW/°C above +70°C)..........667mW
Operating Temperature Ranges
MAX1266_C_ _/MAX1268_C_ _ .........................0°C to +70°C
MAX1266_E_ _/MAX1268_E_ _ ......................-40°C to +85°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
= +5V ±10%, COM = GND, REFADJ = V
DD
, V
REF
= +2.5V, 4.7µF capacitor at REF pin, f
CLK
= 7.6MHz (50% duty cycle),
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
Signal-to-Noise Plus Distortion
Total Harmonic Distortion
(Including 5th-Order Harmonic)
Spurious-Free Dynamic Range
Intermodulation Distortion
Channel-to-Channel Crosstalk
Full-Linear Bandwidth
Full-Power Bandwidth
CONVERSION RATE
External clock mode
Conversion Time (Note 5)
T/H Acquisition Time
Aperture Delay
Aperture Jitter
External Clock Frequency
Duty Cycle
2
f
CLK
t
CONV
t
ACQ
External acquisition or external clock mode
External acquisition or external clock mode
Internal acquisition/internal clock mode
0.1
30
25
<50
<200
7.6
70
External acquisition/internal clock mode
Internal acquisition/internal clock mode
2.1
2.5
3.2
3.0
3.6
3.5
4
400
ns
ns
ps
MHz
%
µs
SINAD
THD
SFDR
IMD
f
IN1
= 49kHz, f
IN2
= 52kHz
f
IN
= 175kHz (Note 4)
SINAD > 68dB
-3dB rolloff
-80
76
-78
350
6
67
(Note 3)
±2.0
±0.2
RES
INL
DNL
MAX126_A
MAX126_B
No missing codes overtemperature
12
±0.5
±1
±1
±4
±4
Bits
LSB
LSB
LSB
LSB
ppm/°C
LSB
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DYNAMIC SPECIFICATIONS
(f
IN(sine wave)
= 50kHz, V
IN
= 2.5V
P-P
, 420ksps, external f
CLK
= 7.6MHz, bipolar input mode)
70
-80
dB
dB
dB
dB
dB
kHz
MHz
_______________________________________________________________________________________
420ksps, +5V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V ±10%, COM = GND, REFADJ = V
DD
, V
REF
= +2.5V, 4.7µF capacitor at REF pin, f
CLK
= 7.6MHz (50% duty cycle),
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
Single Ended and Differential
(Note 6)
Multiplexer Leakage Current
Input Capacitance
INTERNAL REFERENCE
REF Output Voltage
REF Short-Circuit Current
REF Temperature Coefficient
REFADJ Input Range
REFADJ High Threshold
Load Regulation
Capacitive Bypass at REFADJ
Capacitive Bypass at REF
EXTERNAL REFERENCE AT REF
REF Input Voltage Range
REF Input Current
DIGITAL INPUTS AND OUTPUTS
Input Voltage High
Input Voltage Low
Input Hysteresis
Input Leakage Current
Input Capacitance
Output Voltage Low
Output Voltage High
Tri-State Leakage Current
Tri-State Output Capacitance
POWER REQUIREMENTS
Analog Supply Voltage
V
DD
Operating mode,
f
SAMPLE
= 420ksps
Standby mode
Shutdown mode
Power-Supply Rejection
PSR
V
DD
= 5V ±10%, full-scale input
Internal reference
External reference
Internal reference
External reference
4.5
3.3
2.8
1.0
0.5
2
±0.3
5.5
3.6
3.1
1.2
0.8
10
±0.9
µA
mV
mA
V
V
IH
V
IL
V
HYS
I
IN
C
IN
V
OL
V
OH
I
LEAKAGE
C
OUT
I
SINK
= 1.6mA
I
SOURCE
= 1mA
CS
= V
DD
CS
= V
DD
V
DD
- 0.5
±0.1
15
±1
V
IN
= 0 or V
DD
200
±0.1
15
0.4
±1
4.0
0.8
V
V
mV
µA
pF
V
V
µA
pF
V
REF
I
REF
V
REF
= 2.5V, f
SAMPLE
= 420ksps
Shutdown mode
1.0
200
V
DD
+
50mV
300
2
V
µA
4.7
TC
REF
For small adjustments
To power down the internal reference
0 to 0.5mA output load (Note 7)
V
DD
- 1
0.2
0.01
1
10
2.49
2.5
15
±20
±100
2.51
V
mA
ppm/°C
mV
V
mV/mA
µF
µF
C
IN
Unipolar, V
COM
= 0
V
IN
Bipolar, V
COM
= V
REF
/ 2
On-/off-leakage current, V
IN
= 0 or V
DD
0
-V
REF
/2
±0.01
12
V
REF
+V
REF
/2
±1
V
µA
pF
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1266/MAX1268
Positive Supply Current
I
DD
I
DD
_______________________________________________________________________________________
3
420ksps, +5V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
MAX1266/MAX1268
TIMING CHARACTERISTICS
(V
DD
= +5V ±10%, COM = GND, REFADJ = V
DD
, V
REF
= +2.5V, 4.7µF capacitor at REF pin, f
CLK
= 7.6MHz (50% duty cycle),
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
CLK Period
CLK Pulse Width High
CLK Pulse Width Low
Data Valid to
WR
Rise Time
WR
Rise to Data Valid Hold Time
WR
to CLK Fall Setup Time
CLK Fall to
WR
Hold Time
CS
to CLK or
WR
Setup Time
CLK or
WR
to
CS
Hold Time
CS
Pulse Width
WR
Pulse Width
CS
Rise to Output Disable
RD
Rise to Output Disable
RD
Fall to Output Data Valid
RD
Fall to
INT
High Delay
CS
Fall to Output Data Valid
SYMBOL
t
CP
t
CH
t
CL
t
DS
t
DH
t
CWS
t
CWH
t
CSWS
t
CSWH
t
CS
t
WR
t
TC
t
TR
t
DO
t
INT1
t
DO2
(Note 8)
C
LOAD
= 20pF, Figure 1
C
LOAD
= 20pF, Figure 1
C
LOAD
= 20pF, Figure 1
C
LOAD
= 20pF, Figure 1
C
LOAD
= 20pF, Figure 1
CONDITIONS
MIN
132
40
40
40
0
60
40
40
0
100
60
10
10
10
60
40
50
50
100
TYP
MAX
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Note 1:
Tested at V
DD
= +5V, COM = GND, unipolar single-ended input mode.
Note 2:
Relative accuracy is the deviation of the analog value at any code from its theoretical value after offset and gain errors have
been removed.
Note 3:
Offset nulled.
Note 4:
On channel is grounded; sine wave applied to off channels.
Note 5:
Conversion time is defined as the number of clock cycles times the clock period; clock has a 50% duty cycle.
Note 6:
Input voltage range referenced to negative input. The absolute range for the analog inputs is from GND to V
DD
.
Note 7:
External load should not change during conversion for specified accuracy.
Note 8:
When bit 5 is set low for internal acquisition,
WR
must not return low until after the first falling clock edge of the conversion.
V
DD
3kΩ
DOUT
3kΩ
C
LOAD
20pF
DOUT
C
LOAD
20pF
a)
High-Z to V
OH
and V
OL
to V
OH
b)
High-Z to V
OL
and V
OH
to V
OL
Figure 1. Load Circuits for Enable/Disable Times
4
_______________________________________________________________________________________
420ksps, +5V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
Typical Operating Characteristics
(V
DD
= +5V, V
REF
= +2.500V, f
CLK
= 7.6MHz, C
L
= 20pF, T
A
= +25°C, unless otherwise noted.)
MAX1266/MAX1268
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE
MAX1266/68 toc01
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE
MAX1266/68 toc02A
SUPPLY CURRENT vs. SAMPLE FREQUENCY
MAX1266/68 toc02B
0.5
0.4
0.3
0.2
0.5
0.4
0.3
0.2
DNL (LSB)
10,000
WITH INTERNAL REFERENCE
1000
I
DD
(µA)
INL (LSB)
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
0
1000
2000
3000
4000
5000
DIGITAL OUTPUT CODE
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
0
1000
2000
3000
4000
5000
DIGITAL OUTPUT CODE
100
10
WITH EXTERNAL REFERENCE
0
0.1
1
10
100
1k
10k 100k
1M
f
SAMPLE
(Hz)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
R
L
=
∞
CODE = 101010100000
MAX1266/68 toc03
SUPPLY CURRENT vs. TEMPERATURE
MAX1266/68 toc04
STANDBY CURRENT vs. SUPPLY VOLTAGE
MAX1266/68 toc05
2.2
2.3
2.2
2.1
R
L
=
∞
CODE = 101010100000
990
980
STANDBY I
DD
(µA)
970
960
950
940
930
2.1
I
DD
(mA)
2.0
I
DD
(mA)
2.0
1.9
1.9
1.8
1.8
4.50
4.75
5.00
V
DD
(V)
5.25
5.50
1.7
-40
-15
10
35
60
85
TEMPERATURE (°C)
4.50
4.75
5.00
V
DD
(V)
5.25
5.50
STANDBY CURRENT vs. TEMPERATURE
MAX1266/68 toc06
POWER-DOWN CURRENT
vs. SUPPLY VOLTAGE
MAX1266/68 toc07
POWER-DOWN CURRENT
vs. TEMPERATURE
MAX1266/68 toc08
990
980
STANDBY I
DD
(µA)
970
960
950
940
930
-40
-15
10
35
60
3.0
2.2
POWER-DOWN I
DD
(µA)
2.0
POWER-DOWN I
DD
(µA)
4.50
4.75
5.00
V
DD
(V)
5.25
5.50
2.5
2.1
2.0
1.5
1.9
1.0
85
TEMPERATURE (°C)
1.8
-40
-15
10
35
60
85
TEMPERATURE (°C)
_______________________________________________________________________________________
5
