19-3053; Rev 2; 5/04
KIT
ATION
EVALU
E
BL
AVAILA
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
General Description
Features
♦
High Resolution
MAX1495: 4.5 Digits (±19,999 Count)
MAX1493: 4.5 Digits (±19,999 Count)
MAX1491: 3.5 Digits (±1999 Count)
♦
Sigma-Delta ADC Architecture
No Integrating Capacitors Required
No Autozeroing Capacitors Required
>100dB of Simultaneous 50Hz and 60Hz Rejection
♦
Operate from a Single 2.7V or 5.25V Supply
♦
Selectable Input Range of ±200mV or ±2V
♦
Selectable Voltage Reference: Internal 2.048V or
External
♦
Internal High-Accuracy Oscillator Needs No
External Components
♦
Automatic Offset Calibration
♦
Low Power: Maximum 980µA Operating Current
♦
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)
♦
Triplexed LCD Driver
♦
Evaluation Kit Available (Order MAX1494EVKIT)
MAX1491/MAX1493/MAX1495
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 (±1999 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, crystal
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 continu-
ous 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 calibration
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.
Pin Configurations
INTREF
DPON
DV
DD
V
NEG
GND
BP1
BP2
26
TOP VIEW
Applications
Digital Panel Meters
Hand-Held Meters
Digital Voltmeters
Digital Multimeters
AV
DD
AIN+
AIN-
REF-
REF+
1
2
3
4
5
6
7
8
32
31
30
29
28
27
BP3
25
24
SEG13
23
SEG12
22
SEG11
21
SEG10
20
SEG9
19
SEG8
18
SEG7
17
SEG6
16
SEG5
MAX1493
MAX1495
Ordering Information
PART
MAX1491CAI
MAX1491CNI
MAX1493CCJ
MAX1495CCJ
TEMP
RANGE
PIN-
PACKAGE
RESOLUTION
(DIGITS)
3.5
3.5
4.5
4.5
LOWBATT
RANGE
DPSET1
0°C to +70°C 28 SSOP
0°C to +70°C 28 DIP
0°C to +70°C 32 TQFP
0°C to +70°C 32 TQFP
9
DPSET2
10
PEAK
11
HOLD
12
SEG1
13
SEG2
14
SEG3
15
SEG4
TQFP
Pin Configurations continued 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.
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
MAX1491/MAX1493/MAX1495
ABSOLUTE MAXIMUM RATINGS
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
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
(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
DC ACCURACY
Noise-Free Resolution
Integral Nonlinearity (Note 1)
Range Change Accuracy
Rollover Error
Output Noise
Offset Error (Zero Input Reading)
Gain Error
Offset Drift (Zero Reading Drift)
Gain Drift
INPUT CONVERSION RATE
Conversion Rate
ANALOG INPUTS (AIN+, AIN-) (bypass to GND with 0.1µF or greater capacitors)
AIN Input Voltage Range
Normal Mode 50Hz and 60Hz
Rejection (Simultaneously)
Common-Mode 50Hz and 60Hz
Rejection (Simultaneously)
Common-Mode Rejection
Input Leakage Current
Input Capacitance
Dynamic Input Current
(Note 5)
-20
CMR
CMR
Differential (Note 4)
RANGE = GND
RANGE = DV
DD
-2.0
-0.2
-2.2V
100
150
100
10
10
+20
+2.0
+0.2
+2.2V
dB
dB
dB
nA
pF
nA
V
5
Hz
Offset
V
IN
= 0 (Note 2)
(Note 3)
V
IN
= 0
-0
-0.5
0.1
±1
INL
MAX1493/MAX1495
MAX1491
2.000V range
200mV range
(V
AIN+
- V
AIN-
= 0.100V) on 200mV range /
(V
AIN+
- V
AIN-
= 0.100V) on 2.0V range
V
AIN+
- V
AIN-
= full scale,
V
AIN-
- V
AIN+
= full scale
-19,999
-1999
±1
±1
10:1
±1.0
10
+0
+0.5
+19,999
+1999
Count
Count
Ratio
Count
µV
P-P
Reading
%FSR
µV/°C
ppm/°C
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Absolute GND referenced
50Hz and 60Hz ±2%
For 50Hz ±2% and 60Hz ±2%,
R
SOURCE
< 10kΩ
At DC
T
A
= +25°C
2
_______________________________________________________________________________________
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
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
LOWBATT Trip Threshold
LOWBATT Leakage Current
Hysteresis
INTERNAL REFERENCE (REF- = GND, INTREF = DV
DD
, bypass REF+ to GND with 4.7µF capacitors)
REF Output Voltage
REF Output Short-Circuit Current
REF Output Temperature
Coefficient
Load Regulation
Line Regulation
Noise Voltage
0.1Hz to 10Hz
10Hz to 10kHz
Differential (V
REF+
- V
REF-
)
Absolute GND referenced
50Hz and 60Hz ±2%
CMR
CMR
For 50Hz ±2% and 60Hz ±2%,
R
SOURCE
< 10kΩ
At DC
T
A
= +25°C
(Note 5)
V
NEG
I
IN
V
INL
V
INH
V
HYS
DV
DD
= 3.0V
0.7 x
DV
DD
200
V
IN
= 0 or DV
DD
-20
-2.6
-10
-2.42
-2.2
100
150
100
10
10
+20
-2.3
+10
0.3 x
DV
DD
TC
VREF
V
REF
AV
DD
= 5V, T
A
= +25°C
T
A
= +25°C
AV
DD
= 5V
I
SOURCE
= 0µA to 300µA,
I
SINK
= 0µA to 30µA, T
A
= +25°C (Note 6)
2.007
2.048
1
40
6
50
25
400
2.048
+2.2
2.089
V
mA
ppm/°C
mV/µA
µV/V
µVp-p
SYMBOL
CONDITIONS
MIN
TYP
2.048
10
20
MAX
UNITS
V
pA
mV
MAX1491/MAX1493/MAX1495
LOW-BATTERY VOLTAGE MONITOR (LOWBATT)
EXTERNAL REFERENCE (INTREF = GND, bypass REF+ and REF- to GND with 0.1µF or greater capacitors)
REF Input Voltage
Normal-Mode 50Hz and 60Hz
Rejection (Simultaneously)
Common-Mode 50Hz and 60Hz
Rejection (Simultaneously)
Common-Mode Rejection
Input Leakage Current
Input Capacitance
Dynamic Input Current
CHARGE PUMP
Output Voltage
Input Current
Input Low Voltage
Input High Voltage
Input Hysteresis
V
µA
V
V
mV
DIGITAL INPUTS (INTREF, RANGE, PEAK, HOLD, DPSET1, DPSET2, DPON)
V
dB
dB
dB
nA
pF
nA
_______________________________________________________________________________________
3
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
MAX1491/MAX1493/MAX1495
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
POWER SUPPLY
AV
DD
Voltage
DV
DD
Voltage
Power-Supply Rejection AV
DD
Power-Supply Rejection DV
DD
AV
DD
Current
DV
DD
Current
LCD DRIVER
RMS Segment-On Voltage
RMS Segment-Off Voltage
Display Multiplex Rate
LCD Data-Update Rate
1.92 x
DV
DD
1/3x
DV
DD
107
2.5
V
V
Hz
Hz
AV
DD
DV
DD
PSRR
A
PSRR
D
I
AVDD
I
DVDD
(Note 7)
(Note 7)
(Note 8)
DV
DD
= 5V
DV
DD
= 3.3V
2.70
2.70
80
100
660
320
180
5.25
5.25
V
V
dB
dB
µA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
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 60Hz.
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
.
4
_______________________________________________________________________________________
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
Typical Operating Characteristics
(AV
DD
= DV
DD
= 5V, GND = 0, REF+ = 2.048V, REF- = GND, RANGE = DV
DD
, T
A
= +25°C.)
MAX1491/MAX1493/MAX1495
MAX1493/MAX1495 (±200mV INPUT RANGE)
INL vs. DISPLAY COUNT
MAX1491/3/5 toc01
MAX1493/MAX1495 (±2V INPUT RANGE)
INL vs. DISPLAY COUNT
MAX1491/3/5 toc02
NOISE DISTRIBUTION
MAX1491/3/5 toc03
1.0
1.0
25
0.5
INL (COUNTS)
0.5
INL (COUNTS)
PERCENTAGE OF UNITS (%)
20
15
0
0
10
-0.5
-0.5
5
-1.0
-20,000
-10,000
0
DISPLAY COUNT
10,000
20,000
-1.0
-20,000
0
-10,000
0
DISPLAY COUNT
10,000
20,000
-0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
NOISE (COUNTS)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX1491/3/5 toc04
MAX1493/MAX1495
GAIN ERROR vs. SUPPLY VOLTAGE
MAX1491/3/5 toc05
MAX1493/MAX1495
GAIN ERROR vs. TEMPERATURE
-0.01
GAIN ERROR (% FULL SCALE)
-0.02
-0.03
-0.04
-0.05
-0.06
-0.07
-0.08
-0.09
-0.10
MAX1491/3/5 toc06
700
600
SUPPLY CURRENT (µA)
500
400
300
200
100
0
2.75
3.25
3.75
4.25
4.75
DIGITAL SUPPLY
ANALOG SUPPLY
0.08
0.06
GAIN ERROR (% FULL SCALE)
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
-0.10
2.75
3.25
3.75
4.25
4.75
0
5.25
5.25
0
10
20
30
40
50
60
70
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
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