General Description
The MAX1491/MAX1493/MAX1495 low-power, 3.5- and
4.5-digit, analog-to-digital converters (ADCs) with inte-
grated liquid crystal display (LCD) drivers operate from a
single 2.7V to 5.25V power supply. They include an inter-
nal reference, a high-accuracy on-chip oscillator, and a
triplexed LCD driver. An internal charge pump generates
the negative supply needed to power the integrated input
buffer for single supply operation. The ADC is config-
urable for either a ±2V or ±200mV input range and it out-
puts its conversion results to an LCD. The MAX1491 is a
3.5-digit (±1,999 count) device, and the MAX1493/
MAX1495 are 4.5-digit (±19,999 count) devices.
The MAX1491/MAX1493/MAX1495 do not require exter-
nal-precision integrating or auto-zero capacitors, crys-
tal oscillators, charge pumps or other circuitry required
with dual slope ADCs (commonly used in panel meter
circuits). These devices also feature on-chip buffers for
the differential signal and reference inputs, allowing
direct interface with high-impedance signal sources. In
addition, the MAX1491/MAX1493/MAX1495 use contin-
uous internal offset calibration, and offer >100dB rejec-
tion of 50Hz and 60Hz line noise. The MAX1493/
MAX1495 perform enhanced offset calibration at
power-up. The MAX1495 also performs enhanced cali-
bration on demand. Other features include data hold
and peak hold, and a user programmable low-battery
monitor.
The MAX1493/MAX1495 come in a 32-pin 7mm
7mm
TQFP package, and the MAX1491 comes in 28-pin
SSOP and 28-pin DIP packages. All devices in this fam-
ily operate over the 0°C to +70°C commercial tempera-
ture range.
Applications
Digital Panel Meters
Hand-Held Meters
Digital Voltmeters
Digital Multimeters
Features
o High Resolution
MAX1495: 4.5 Digits (±19,999 Count)
MAX1493: 4.5 Digits (±19,999 Count)
MAX1491: 3.5 Digits (±1999 Count)
o Sigma-Delta ADC Architecture
No Integrating Capacitors Required
No Autozeroing Capacitors Required
>100dB of Simultaneous 50Hz and 60Hz Rejection
o Operate from a Single 2.7V or 5.25V Supply
o Selectable Input Range of ±200mV or ±2V
o Selectable Voltage Reference: Internal 2.048V or
External
o Internal High-Accuracy Oscillator Needs No
External Components
o Automatic Offset Calibration
o Low Power: Maximum 980µA Operating Current
o Small 32-Pin 7mm
7mm TQFP Package (4.5
Digits), 28-Pin SSOP Package (3.5 Digits), and 28-
Pin DIP Package (3.5 Digits)
o Triplexed LCD Driver
o Evaluation Kit Available (Order MAX1494EVKIT)
MAX1491/MAX1493/MAX1495
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
________________________________________________________________ Maxim Integrated Products
1
TOP VIEW
MAX1493
MAX1495
TQFP
32
28
29
30
31
25
26
27
DV
DD
INTREF
V
NEG
DPON
GND
BP1
BP2
BP3
10
13
15
14
16
11
12
9
DPSET2
HOLD
PEAK
SEG2
SEG1
SEG4
SEG3
SEG5
17
18
19
20
21
22
23 SEG12
24 SEG13
SEG11
SEG10
SEG9
SEG8
SEG7
SEG6
2
3
4
5
6
7
8
DPSET1
RANGE
LOWBATT
REF+
REF-
AIN-
AIN+
1
AV
DD
PART
TEMP
RANGE
PIN-
PACKAGE
RESOLUTION
(DIGITS)
MAX1491CAI*
0
°C to +70°C 28 SSOP
3.5
MAX1491CNI
0
°C to +70°C 28 DIP
3.5
MAX1493CCJ
0
°C to +70°C 32 TQFP
4.5
MAX1495CCJ*
0
°C to +70°C 32 TQFP
4.5
Pin Configurations
Ordering Information
19-3053; Rev 0; 10/03
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.
Pin Configurations continued at end of data sheet.
EVALUATION KIT
AVAILABLE
*Future product--contact factory for availability.
MAX1491/MAX1493/MAX1495
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(AV
DD
= DV
DD
= +2.7V to +5.25V, GND = 0, V
REF+
- V
REF-
= 2.048V (external reference), C
NEG
= 0.1µF. All specifications are T
MIN
to T
MAX
, unless otherwise noted. Typical values are at +25°C, unless otherwise noted.)
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.
AV
DD
to GND............................................................-0.3V to +6V
DV
DD
to GND ...........................................................-0.3V to +6V
AIN+, AIN- to GND ...............................V
NEG
to + (AV
DD
+ 0.3V)
REF+, REF- to GND..............................V
NEG
to + (AV
DD
+ 0.3V)
LOWBATT to GND ...................................-0.3V to (AV
DD
+ 0.3V)
INTREF, RANGE, DPSET1, DPSET2, PEAK,
HOLD to GND ......................................-0.3V to (DV
DD
+ 0.3V)
DPON to GND..........................................-0.3V to (DV
DD
+ 0.3V)
V
NEG
to GND ...........................................-2.6V to (AV
DD
+ 0.3V)
Maximum Current into Any Pin ...........................................50mA
Continuous Power Dissipation (T
A
= +70°C)
32-Pin TQFP (derate 20.7mW/°C above +70°C).....1652.9mW
28-Pin SSOP (derate 9.5mW/°C above +70°C) ...........762mW
28-Pin DIP (derate 14.3mW/°C above +70°C) ........1142.9mW
Operating Temperature Range...............................0°C to +70°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC ACCURACY
MAX1493/MAX1495
-19,999
+19,999
Noise-Free Resolution
MAX1491
-1999
+1999
Count
2.000V range
±1
Integral Nonlinearity (Note 1)
INL
200mV range
±1
Count
Range Change Accuracy
(V
AIN+
- V
AIN-
= 0.100V) on 200mV range /
(V
AIN+
- V
AIN-
= 0.100V) on 2.0V range
10:1
Ratio
Rollover Error
V
AIN+
- V
AIN-
= full scale,
V
AIN-
- V
AIN+
= full scale
±1.0
Count
Output Noise
10
µV
P-P
Offset Error (Zero Input Reading)
Offset
V
IN
= 0 (Note 2)
-0
+0
Reading
Gain Error
(Note 3)
-0.5
+0.5
%FSR
Offset Drift (Zero Reading Drift)
V
IN
= 0
0.1
µV/
°C
Gain Drift
±1
ppm/
°C
INPUT CONVERSION RATE
Conversion Rate
5
Hz
ANALOG INPUTS (AIN+, AIN-) (bypass to GND with 0.1µF or greater capacitors)
RANGE = GND
-2.0
+2.0
Differential (Note 4)
RANGE = DV
DD
-0.2
+0.2
AIN Input Voltage Range
Absolute GND referenced
-2.2V
+2.2V
V
Normal Mode 50Hz and 60Hz
Rejection (Simultaneously)
50Hz and 60Hz ±2%
100
dB
Common-Mode 50Hz and 60Hz
Rejection (Simultaneously)
CMR
For 50Hz ±2% and 60Hz ±2%,
R
SOURCE
< 10k
150
dB
Common-Mode Rejection
CMR
At DC
100
dB
Input Leakage Current
T
A
= +25
°C
10
nA
Input Capacitance
10
pF
Dynamic Input Current
(Note 5)
-20
+20
nA
MAX1491/MAX1493/MAX1495
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(AV
DD
= DV
DD
= +2.7V to +5.25V, GND = 0, V
REF+
- V
REF-
= 2.048V (external reference), C
NEG
= 0.1µF. All specifications are T
MIN
to T
MAX
, unless otherwise noted. Typical values are at +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LOW-BATTERY VOLTAGE MONITOR (LOWBATT)
LOWBATT Trip Threshold
2.048
V
LOWBATT Leakage Current
10
pA
Hysteresis
20
mV
INTERNAL REFERENCE (REF- = GND, INTREF = DV
DD
, bypass REF+ to GND with 4.7µF capacitors)
REF Output Voltage
V
REF
AV
DD
= 5V, T
A
= +25
°C
2.007
2.048
2.089
V
REF Output Short-Circuit Current
T
A
= +25
°C
1
mA
REF Output Temperature
Coefficient
TC
VREF
AV
DD
= 5V
40
ppm/
°C
Load Regulation
I
SOURCE
= 0µA to 300µA,
I
SINK
= 0µA to 30µA, T
A
= +25
°C (Note 6)
6
mV/µA
Line Regulation
50
µV/V
0.1Hz to 10Hz
25
Noise Voltage
10Hz to 10kHz
400
µVp-p
EXTERNAL REFERENCE (INTREF = GND, bypass REF+ and REF- to GND with 0.1µF or greater capacitors)
Differential (V
REF+
- V
REF-
)
2.048
REF Input Voltage
Absolute GND referenced
-2.2
+2.2
V
Normal-Mode 50Hz and 60Hz
Rejection (Simultaneously)
50Hz and 60Hz ±2%
100
dB
Common-Mode 50Hz and 60Hz
Rejection (Simultaneously)
CMR
For 50Hz ±2% and 60Hz ±2%,
R
SOURCE
< 10k
150
dB
Common-Mode Rejection
CMR
At DC
100
dB
Input Leakage Current
T
A
= +25
°C
10
nA
Input Capacitance
10
pF
Dynamic Input Current
(Note 5)
-20
+20
nA
CHARGE PUMP
Output Voltage
V
NEG
-2.6
-2.42
-2.3
V
DIGITAL INPUTS (INTREF, RANGE, PEAK, HOLD, DPSET1, DPSET2, DPON)
Input Current
I
IN
V
IN
= 0 or DV
DD
-10
+10
µA
Input Low Voltage
V
INL
0.3 x
DV
DD
V
Input High Voltage
V
INH
0.7 x
DV
DD
V
Input Hysteresis
V
HYS
DV
DD
= 3.0V
200
mV
MAX1491/MAX1493/MAX1495
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
4
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(AV
DD
= DV
DD
= +2.7V to +5.25V, GND = 0, V
REF+
- V
REF-
= 2.048V (external reference), C
NEG
= 0.1µF. All specifications are T
MIN
to T
MAX
, unless otherwise noted. Typical values are at +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER SUPPLY
AV
DD
Voltage
AV
DD
2.70
5.25
V
DV
DD
Voltage
DV
DD
2.70
5.25
V
Power-Supply Rejection AV
DD
PSRR
A
(Note 7)
80
dB
Power-Supply Rejection DV
DD
PSRR
D
(Note 7)
100
dB
AV
DD
Current
I
AVDD
(Note 8)
660
µA
DV
DD
= 5V
320
DV
DD
Current
I
DVDD
DV
DD
= 3.3V
180
µA
LCD DRIVER
RMS Segment-On Voltage
1.92 x
DV
DD
V
RMS Segment-Off Voltage
1 / 3 x
DV
DD
V
Display Multiplex Rate
107
Hz
LCD Data-Update Rate
2.5
Hz
Note 1: Integral nonlinearity is the derivation of the analog values at any code from its theoretical value after nulling the gain error
and offset error.
Note 2: Offset calibrated.
Note 3: Offset nulled.
Note 4: The input voltage range for the analog inputs is given with respect to the voltage on the negative input of the differential pair.
Note 5: For the range of V
AIN+
or V
AIN-
= -2.2V to +2.2V and V
REF+
or V
REF-
= -2.2V to +2.2V.
Note 6: External load must be constant during conversion for specified accuracy. Guaranteed specification of 2mV/mA is a result of
production test limitations.
Note 7: Measured at DC by changing the power-supply voltage from 2.7V to 5.25V and measuring its effect on the conversion error.
PSRR at 50Hz and 60Hz exceeds 120dB with filter notches of 10, 20, 30, 40, 50, or 60 Hz.
Note 8: Analog power-supply currents are measured with all digital inputs at either GND or DV
DD
. Digital power-supply currents
measured with all digital inputs at either GND or DV
DD
.
MAX1491/MAX1493/MAX1495
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
_______________________________________________________________________________________
5
MAX1493/MAX1495 (
±200mV INPUT RANGE)
INL vs. DISPLAY COUNT
MAX1491/3/5 toc01
DISPLAY COUNT
INL (COUNTS)
10,000
0
-10,000
-0.5
0
0.5
1.0
-1.0
-20,000
20,000
MAX1493/MAX1495 (
±2V INPUT RANGE)
INL vs. DISPLAY COUNT
MAX1491/3/5 toc02
DISPLAY COUNT
INL (COUNTS)
10,000
0
-10,000
-0.5
0
0.5
1.0
-1.0
-20,000
20,000
NOISE DISTRIBUTION
MAX1491/3/5 toc03
NOISE (COUNTS)
PERCENTAGE OF UNITS (%)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-0.1
5
10
15
20
25
0
-0.2
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX1491/3/5 toc04
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (
µ
A)
4.75
4.25
3.75
3.25
100
200
300
400
500
600
700
0
2.75
5.25
ANALOG SUPPLY
DIGITAL SUPPLY
MAX1493/MAX1495
GAIN ERROR vs. SUPPLY VOLTAGE
MAX1491/3/5 toc05
SUPPLY VOLTAGE (V)
GAIN ERROR (% FULL SCALE)
4.75
4.25
3.25
3.75
-0.08
-0.04
-0.06
-0.02
0
0.02
0.04
0.06
0.08
-0.10
2.75
5.25
MAX1493/MAX1495
GAIN ERROR vs. TEMPERATURE
MAX1491/3/5 toc06
TEMPERATURE (
°C)
GAIN ERROR (% FULL SCALE)
60
50
30
40
20
10
-0.09
-0.08
-0.07
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0
-0.10
0
70
Typical Operating Characteristics
(AV
DD
= DV
DD
= 5V, GND = 0, REF+ = 2.048V, REF- = GND, RANGE = DV
DD
, T
A
= +25°C.)
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