MAX1491CAI+T Maxim Integrated Products, MAX1491CAI+T Datasheet - Page 20
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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
Power up AV
input and external reference voltage to the device. If
this is not possible, limit the current into these inputs to
50mA. Isolate the digital supply from the analog supply
with a low-value resistor (10Ω) or ferrite bead when the
analog and digital supplies come from the same
source. For best performance, ground the MAX1491/
MAX1493/MAX1495 to the analog ground plane of the
circuit board.
Avoid running digital lines under the device, because
these may couple noise onto the die. Run the analog
ground plane under the MAX1491/MAX1493/MAX1495
to minimize coupling of digital noise. Make the power-
supply lines to the MAX1491/MAX1493/MAX1495 as
wide as possible to provide low-impedance paths and
reduce the effects of glitches on the power-supply line.
Shield fast-switching signals, such as clocks, with digital
ground to avoid radiating noise to other sections of the
board. Avoid running clock signals near the analog
inputs. Avoid crossover of digital and analog signals.
Running traces that are on opposite sides of the board at
right angles to each other reduces feedthrough effects.
Good decoupling is important when using high-resolu-
tion ADCs. Decouple the supplies with 4.7µF and 0.1µF
ceramic capacitors to GND. Place these components
as close to the device as possible to achieve the
best decoupling.
Refer to the MAX1494 evaluation kit manual for the rec-
ommended layout. The evaluation board package
includes a fully assembled and tested evaluation board.
3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers
Figure 17. MAX1491 Transfer Function ±200mV Range
20
- 1 - - -
LCD
1 - - -
-1999
______________________________________________________________________________________
1999
- 0
- 1
- 2
2
1
0
DD
Supplies, Layout, and Bypassing
-200mV
and DV
DD
ANALOG INPUT VOLTAGE
-100µV 100µV
before applying an analog
0
+200mV
Integral nonlinearity (INL) is the deviation of the values
on an actual transfer function from a straight line. This
straight line is either a best-straight-line fit or a line
drawn between the end points of the transfer function,
once offset and gain errors have been nullified. INL for
the MAX1491/MAX1493/MAX1495 is measured using
the end-point method.
Differential nonlinearity (DNL) is the difference between
an actual step width and the ideal value of one count. A
DNL error specification of less than one count guarantees
no missing counts and a monotonic transfer function.
Rollover error is defined as the absolute value differ-
ence between a near-positive full-scale reading and
near-negative full-scale reading. Rollover error is tested
by applying a full-scale positive voltage, swapping
AIN+ and AIN-, and then adding the results.
Ideally, with AIN+ connected to AIN-, the MAX1491/
MAX1493/MAX1495 display a zero. Zero input reading
is the measured deviation from the ideal zero and the
actual measured point.
Figure 18. MAX1491 Transfer Function ±2V Range
- 1 - - -
LCD
1 - - -
-1999
1999
- 0
- 1
- 2
2
1
0
-2V
ANALOG INPUT VOLTAGE
-1mV
Zero Input Reading
0
1mV
Rollover Error
Definitions
+2V
DNL
INL