MAX1491CAI+T Maxim Integrated Products, MAX1491CAI+T Datasheet - Page 17
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MAX1491CAI+T
Manufacturer Part Number
MAX1491CAI+T
Description
IC ADC W/LCD DRIVER 28-SSOP
Manufacturer
Maxim Integrated Products
Datasheet
1.MAX1491CAI.pdf
(25 pages)
Specifications of MAX1491CAI+T
Display Type
LCD
Configuration
7 Segment + 2 Annunciators
Digits Or Characters
A/D 3.5 Digits
Current - Supply
980µA
Voltage - Supply
2.7 V ~ 5.25 V
Operating Temperature
0°C ~ 70°C
Mounting Type
Surface Mount
Package / Case
28-SSOP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Interface
-
Lead Free Status / Rohs Status
Details
If ghosting is present on the LCD, the RMS OFF voltage
is too high. Choose an LCD with a higher RMS OFF
voltage or decrease DV
The MAX1491/MAX1493/MAX1495 allow for full deci-
mal-point control and feature leading-zero suppression.
Use DPON, DPSET1, and DPSET2 to set the value of
the decimal point. Tables 2 and 3 show the truth tables
of the DPON, DPSET1, and DPSET2 that determine
which decimal point is used.
The MAX1491/MAX1493/MAX1495 reference sets the
full-scale range of the ADC transfer function. With a
nominal 2.048V reference, the ADC full-scale range is
±2V with RANGE equal to GND. With RANGE equal to
DV
erence voltage decreases full-scale range (see the
Transfer Functions section).
The MAX1491/MAX1493/MAX1495 accept either an
external reference or an internal reference. The INTREF
input selects the reference mode.
For internal reference operation, connect INTREF to
DV
GND with a 4.7µF capacitor. The internal reference pro-
vides a nominal 2.048V source between REF+ and
GND. The internal reference temperature coefficient is
typically 40ppm/°C.
Table 2. Decimal-Point Control Table (MAX1493/MAX1495)
Table 3. Decimal-Point Control Table (MAX1491)
DD
DD
DPSET1
DPON
, the full-scale range is ±200mV. A decreased ref-
, connect REF- to GND, and bypass REF+ to
0
0
0
0
1
1
1
1
0
0
1
1
______________________________________________________________________________________
DPSET1
DD
DPSET2
0
0
1
1
0
0
1
1
.
0
1
0
1
Decimal Point Control
DPSET2
0
1
0
1
0
1
0
1
Reference
3.5- and 4.5-Digit, Single-Chip
DISPLAY OUTPUT
1 8 8.8
1 8.8 8
1.8 8 8
1 8 8 8
DISPLAY OUTPUT
Connect INTREF to GND to use the external reference.
The external reference inputs, REF+ and REF-, are fully
differential. For a valid external reference input, V
must be greater than V
with a 0.1µF or greater capacitor to GND in external ref-
erence mode.
Figure 13 shows the MAX1493/MAX1495 operating with
an external differential reference. In this mode, REF- is
connected to the top of the strain gauge and REF+ is
connected to the midpoint of the resistor-divider on the
supply.
At power-on, the digital filter and modulator circuits
reset. The MAX1493/MAX1495 allow 6s for the refer-
ence to stabilize before performing enhanced offset
calibration. During these 6s, the MAX1493/MAX1495
display 1.2V to 1.5V when a stable reference is detect-
ed. If a valid reference is not found, the MAX1493/
MAX1495 time out after 6s and begin enhanced offset
calibration. Enhanced offset calibration typically lasts
2s. The MAX1493/MAX1495 begin converting after
enhanced offset calibration.
The MAX1491/MAX1493/MAX1495 offer on-chip offset
calibration. The MAX1491/MAX1493/MAX1495 calibrate
offset during every conversion cycle. The MAX1495
ADCs with LCD Drivers
1 8 8.8 8
1 8.8 8 8
1 8 8 8 8
1 8 8 8 8
1 8 8 8 8
1 8 8 8 8
1 8 8 8.8
1.8 8 8 8
Applications Information
ZERO INPUT READING
REF-
. Bypass REF+ and REF-
ZERO INPUT READING
0.000
0.00
Offset Calibration
000
0.0
0.0000
0.000
0.00
0.0
0
0
0
0
Power-On
REF+
17