19-3053; Rev 0; 10/03
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
General Description
Features
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 ±2±±mV 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.
ꢀ High Resolution
MAX1495: 4.5 Digits ( 19ꢀ999 ꢁountꢂ
MAX1493: 4.5 Digits ( 19ꢀ999 ꢁountꢂ
MAX1491: 3.5 Digits ( 1999 ꢁountꢂ
ꢀ Sigma-Delta ADꢁ Architecture
No Integrating ꢁapacitors Required
No Autozeroing ꢁapacitors 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
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 >1±±dB rejec-
tion of 5±Hz and 6±Hz 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.
ꢀ Selectable Voltage Reference: Internal 2.048V or
External
ꢀ Internal High-Accuracy Oscillator Needs No
External ꢁomponents
ꢀ Automatic Offset ꢁalibration
ꢀ Low Power: Maximum 980µA Operating ꢁurrent
ꢀ Small 32-Pin 7mm ✕ 7mm TQFP Package (4.5
Digitsꢂꢀ 28-Pin SSOP Package (3.5 Digitsꢂꢀ and 28-
Pin DIP Package (3.5 Digitsꢂ
ꢀ Triplexed LꢁD Driver
ꢀ Evaluation Kit Available (Order MAX1494EVKITꢂ
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 ±°C to +7±°C commercial tempera-
ture range.
Pin Configurations
TOP VIEW
32 31 30 29 28 27 26 25
Applications
AV
1
2
3
4
5
6
7
8
24 SEG13
SEG12
23
DD
Digital Panel Meters
Hand-Held Meters
Digital Voltmeters
Digital Multimeters
AIN+
AIN-
22 SEG11
21 SEG10
20 SEG9
19 SEG8
18 SEG7
17 SEG6
REF-
MAX1493
MAX1495
REF+
LOWBATT
RANGE
DPSET1
Ordering Information
TEMP
PIN-
RESOLUTION
(DIGITSꢂ
PART
RANGE
PAꢁKAGE
9
10 11 12 13 14 15 16
MAX1491CAI* 0°C to +70°C 28 SSOP
3.5
3.5
4.5
4.5
MAX1491CNI
0°C to +70°C 28 DIP
0°C to +70°C 32 TQFP
MAX1493CCJ
TQFP
MAX1495CCJ* 0°C to +70°C 32 TQFP
Pin Configurations continued at end of data sheet.
*Future product—contact factory for availability.
________________________________________________________________ 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.