19-1530; Rev 3; 12/02
IT
TION K
VALUA
E
BLE
AVAILA
265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
General Description
Features
♦
12-Bit Resolution, ±0.5 LSB Linearity
♦
+3V Single-Supply Operation
♦
Internal +2.5V Reference
♦
Software-Configurable Analog Input Multiplexer
6-Channel Single-Ended/
3-Channel Pseudo-Differential (MAX1295)
2-Channel Single-Ended/
1-Channel Pseudo-Differential (MAX1297)
♦
Software-Configurable Unipolar/Bipolar
Analog Inputs
♦
Low Current
1.9mA (265ksps)
1.0mA (100ksps)
400µA (10ksps)
2µA (Shutdown)
♦
Internal 3MHz Full-Power Bandwidth Track/Hold
♦
Parallel 12-Bit Interface
♦
Small Footprint
28-Pin QSOP (MAX1295)
24-Pin QSOP (MAX1297)
MAX1295/MAX1297
The MAX1295/MAX1297 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 +2.7V to +3.6V analog supply.
Power consumption is only 5.4mW at the maximum
sampling rate of 265ksps. Two software-selectable
power-down modes enable the MAX1295/MAX1297 to
be shut down between conversions; accessing the par-
allel interface returns them to normal operation.
Powering down between conversions can reduce sup-
ply current below 10µA at lower sampling rates.
Both devices offer software-configurable analog inputs
for unipolar/bipolar and single-ended/pseudo-differen-
tial operation. In single-ended mode, the MAX1295 has
six input channels and the MAX1297 has two (three
input channels and one input channel, respectively,
when in pseudo-differential mode).
Excellent dynamic performance and low power, combined
with ease of use and small package size, make these con-
verters ideal for battery-powered and data-acquisition
applications or for other circuits with demanding power-
consumption and space requirements.
The MAX1295/MAX1297 tri-states
INT
when
CS
goes high.
Refer to MAX1265/MAX1267 if tri-stating
INT
is not desired.
The MAX1295 is offered in a 28-pin QSOP package, while
the MAX1297 comes in a 24-pin QSOP. For pin-compati-
ble +5V, 12-bit versions, refer to the MAX1294/MAX1296
data sheet.
Pin Configurations
TOP VIEW
D9 1
D8 2
D7 3
D6 4
D5 5
D4 6
D3 7
D2 8
D1 9
D0 10
INT 11
RD 12
WR 13
CLK 14
28 D10
27 D11
26 V
DD
25 REF
24 REFADJ
Applications
Industrial Control Systems
Energy Management
Data-Acquisition Systems
Data Logging
Patient Monitoring
Touchscreens
MAX1295
23 GND
22 COM
21 CH0
20 CH1
19 CH2
18 CH3
17 CH4
16 CH5
15 CS
Ordering Information
PART
MAX1295ACEI
MAX1295BCEI
MAX1295AEEI
MAX1295BEEI
MAX1297ACEG
MAX1297BCEG
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
MAX1297AEEG -40°C to +85°C
MAX1297BEEG -40°C to +85°C
QSOP
Pin Configurations continued at end of data sheet.
Typical Operating Circuits appear at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
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.
265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
MAX1295/MAX1297
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 8.00mW/°C above +70°C)........667mW
Operating Temperature Ranges
MAX1295_C_ _ /MAX1297_C_ _ ........................0°C to +70°C
MAX1295_E_ _ /MAX1297_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
= +2.7V to +3.6V, COM = GND, REFADJ = V
DD
, V
REF
= +2.5V, 4.7µF capacitor at REF pin, f
CLK
= 4.8MHz (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 (Note 3)
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)
Track/Hold 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
50
<50
<200
4.8
70
External acquisition/internal clock mode
Internal acquisition/internal clock mode
3.3
2.5
3.2
3.0
3.6
3.5
4.1
625
ns
ns
ps
MHz
%
µs
SINAD
THD
SFDR
IMD
f
IN1
= 49kHz, f
IN2
= 52kHz
f
IN
= 125kHz (Note 4)
SINAD > 68dB
-3dB rolloff
80
76
-78
250
3
67
±2.0
±0.2
RES
INL
DNL
MAX129_A
MAX129_B
No missing codes over temperature
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
, 265ksps, external f
CLK
= 4.8MHz, bipolar input mode)
70
-78
dB
dB
dB
dB
dB
kHz
MHz
_______________________________________________________________________________________
265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +3.6V, COM = GND, REFADJ = V
DD
, V
REF
= +2.5V, 4.7µF capacitor at REF pin, f
CLK
= 4.8MHz (50% duty cycle),
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1295/MAX1297
CONVERSION RATE (continued)
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 (Note 7)
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
Three-State Leakage Current
Three-State Output Capacitance
POWER REQUIREMENTS
Analog Supply Voltage
V
DD
Operating mode,
f
SAMPLE
= 265ksps
Positive Supply Current
I
DD
Standby mode
Shutdown mode
Power-Supply Rejection
PSR
V
DD
= 2.7V to 3.6V, full-scale input
Internal reference
External reference
Internal reference
External reference
2.7
2.5
1.9
0.9
0.5
2
±0.4
3.6
2.8
2.3
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
2.0
0.8
V
V
mV
µA
pF
V
V
µA
pF
V
REF
I
REF
V
REF
= 2.5V, f
SAMPLE
= 265ksps
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
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
V
IN
Unipolar, V
COM
= 0
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
_______________________________________________________________________________________
3
265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
MAX1295/MAX1297
TIMING CHARACTERISTICS
(V
DD
= +2.7V to +3.6V, COM = GND, REFADJ = V
DD
, V
REF
= +2.5V, 4.7µF capacitor at REF pin, f
CLK
= 4.8MHz (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 (Note 8)
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
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
208
40
40
40
0
40
40
60
0
100
60
20
20
20
100
70
70
100
110
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
= +3V, 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
DOUT
6kΩ
C
LOAD
20pF
3kΩ
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
_______________________________________________________________________________________
265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface
MAX1295/MAX1297
Typical Operating Characteristics
(V
DD
= +3V, V
REF
= +2.500V, f
CLK
= 4.8MHz, C
L
= 20pF, T
A
= +25°C, unless otherwise noted.)
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE
MAX1295/7toc01
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE
MAX1295/7toc02
SUPPLY CURRENT
vs. SAMPLE FREQUENCY
MAX1295/7toc02a
0.5
0.4
0.3
0.2
INL (LSB)
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
0
1000
2000
3000
4000
0.5
0.4
0.3
0.2
DNL (LSB)
10,000
WITH INTERNAL REFERENCE
1000
I
DD
(µA)
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
100
10
WITH EXTERNAL REFERENCE
0
0
1000
2000
3000
4000
5000
0.1
1
10
100
1k
10k 100k
1M
DIGITAL OUTPUT CODE
f
SAMPLE
(Hz)
5000
DIGITAL OUTPUT CODE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1295/7 toc03
SUPPLY CURRENT vs. TEMPERATURE
R
L
=
∞
CODE = 101010100000
MAX1295/7 toc04
STANDBY CURRENT vs. SUPPLY VOLTAGE
MAX1295/7 toc05
2.10
2.05
2.00
I
DD
(mA)
1.95
1.90
1.85
1.80
2.7
3.0
R
L
=
∞
CODE = 101010100000
2.2
2.1
2.0
I
DD
(mA)
1.9
1.8
1.7
1.6
930
920
STANDBY I
DD
(µA)
910
900
890
880
-40
-15
10
35
60
85
2.7
3.0
V
DD
(V)
3.3
3.6
TEMPERATURE (°C)
3.3
V
DD
(V)
3.6
STANDBY CURRENT
vs. TEMPERATURE
MAX1295/7 toc06
POWER-DOWN CURRENT
vs. SUPPLY VOLTAGE
MAX1295/7 toc07
POWER-DOWN CURRENT
vs. TEMPERATURE
MAX1295/7 toc08
930
1.50
1.2
920
STANDBY I
DD
(µA)
POWER-DOWN I
DD
(µA)
910
1.00
POWER-DOWN I
DD
(µA)
2.7
3.0
V
DD
(V)
3.3
3.6
1.25
1.1
1.0
900
0.75
890
0.9
880
-40
-15
10
35
60
85
TEMPERATURE (°C)
0.50
0.8
-40
-15
10
35
60
85
TEMPERATURE (°C)
_______________________________________________________________________________________
5
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