MAX1494CCJ+T Maxim Integrated Products, MAX1494CCJ+T Datasheet - Page 29

IC ADC W/LCD DRIVER 32-TQFP

MAX1494CCJ+T

Manufacturer Part Number
MAX1494CCJ+T
Description
IC ADC W/LCD DRIVER 32-TQFP
Manufacturer
Maxim Integrated Products
Datasheet

Specifications of MAX1494CCJ+T

Display Type
LCD
Configuration
7 Segment + 2 Annunciators
Interface
Serial
Digits Or Characters
A/D 4.5 Digits
Current - Supply
960µA
Voltage - Supply
2.7 V ~ 5.25 V
Operating Temperature
0°C ~ 70°C
Mounting Type
Surface Mount
Package / Case
32-LQFP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
best performance, ground the MAX1492/MAX1494 to
the analog ground plane of the circuit board.
Avoid running digital lines under the device because
they can couple noise onto the device. Run the analog
ground plane under the MAX1492/MAX1494 to mini-
mize coupling of digital noise. Make the power-supply
lines to the MAX1492/MAX1494 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 0.1µF and 4.7µF
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 kit includes a fully
assembled and tested evaluation board.
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 endpoints of the transfer function,
once offset and gain errors have been nullified. INL for
the MAX1492/MAX1494 is measured using the end-
point method.
Differential nonlinearity (DNL) is the difference between
an actual step width and the ideal value of 1 LSB. A
DNL error specification of less than 1 LSB guarantees
no missing codes and a monotonic transfer function.
______________________________________________________________________________________
3.5- and 4.5-Digit, Single-Chip ADCs
Definitions
DNL
INL
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 near full-scale positive voltage, swapping
AIN+ and AIN-, and then adding the results.
Ideally, with AIN+ connected to AIN- the MAX1492/
MAX1494 LCD is 0 or -0. Zero input reading is the mea-
sured deviation from the ideal 0 and the actual mea-
sured point.
Gain error is the amount of deviation between the mea-
sured full-scale transition point and the ideal full-scale
transition point.
Common-mode rejection (CMR) is the ability of a
device to reject a signal that is common to both input
terminals. The common-mode signal can be either an
AC or a DC signal or a combination of the two. CMR is
often expressed in decibels.
Normal-mode rejection is a measure of how much out-
put changes when a 50Hz and 60Hz signal is injected
into only one of the differential inputs. The MAX1492/
MAX1494 sigma-delta converter uses its internal digital
filter to provide normal-mode rejection to both 50Hz
and 60Hz power-line frequencies simultaneously.
Power-supply rejection ratio (PSRR) is the ratio of the
input-supply change (in volts) to the change in the con-
verter output (in volts). It is typically measured in decibels.
Normal-Mode 50Hz and 60Hz Rejection
with LCD Drivers
Power-Supply Rejection Ratio
Common-Mode Rejection
Zero Input Reading
(Simultaneously)
Rollover Error
Gain Error
29

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