LTC2413IGN#TR Linear Technology, LTC2413IGN#TR Datasheet - Page 36

• Manufacturer Part Number: LTC2413IGN#TR
• Description: IC ADC 24BIT 50/60HZ MPWR 16SSOP
• Manufacturer: Linear Technology

Specifications of LTC2413IGN#TR

• Number Of Bits: 24
• Sampling Rate (per Second): 6.8
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 2
• Power Dissipation (max): 1mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
LTC2413
For those applications that cannot be fulfilled by the
LTC2413 alone, compensating for error in external ampli-
fication can be done effectively due to the “no latency”
feature of the LTC2413. No latency operation allows
samples of the amplifier offset and gain to be interleaved
with weighing measurements. The use of correlated double
sampling allows suppression of 1/f noise, offset and
thermocouple effects within the bridge. Correlated double
sampling involves alternating the polarity of excitation and
dealing with the reversal of input polarity mathematically.
Alternatively, bridge excitation can be increased to as
much as 10V, if one of several precision attenuation
techniques is used to produce a precision divide operation
on the reference signal. Another option is the use of a
reference within the 5V input range of the LTC2413 and
developing excitation via fixed gain, or LTC1043 based
voltage multiplication, along with remote feedback in the
excitation amplifiers, as shown in Figures 48 and 50.
Figure 43 shows an example of a simple bridge connec-
tion. Note that it is suitable for any bridge application
where measurement speed is not of the utmost impor-
tance. For many applications where large vessels are
weighed, the average weight over an extended period of
time is of concern and short term weight is not readily
determined due to movement of contents, or mechanical
resonance. Often, large weighing applications involve load
36
U
U
BRIDGE
R1 AND R2 CAN BE USED TO INCREASE TOLERABLE AC COMPONENT ON REF SIGNALS
350
W
R1
R2
Figure 43. Simple Bridge Connection
U
3
4
5
6
REF
REF
IN
IN
+
–
LTC2413
+
–
V
GND
REF
2
1, 7, 8, 9,
10, 15, 16
SDO
SCK
cells located at each load bearing point, the output of
which can be summed passively prior to the signal pro-
cessing circuitry, actively with amplification prior to the
ADC, or can be digitized via multiple ADC channels and
summed mathematically. The mathematical summation
of the output of multiple LTC2413’s provides the benefit of
a root square reduction in noise. The low power consump-
tion of the LTC2413 makes it attractive for multidrop
communication schemes where the ADC is located within
the load-cell housing.
A direct connection to a load cell is perhaps best incorpo-
rated into the load-cell body, as minimizing the distance to
the sensor largely eliminates the need for protection
devices, RFI suppression and wiring. The LTC2413 exhib-
its extremely low temperature dependent drift. As a result,
exposure to external ambient temperature ranges does
not compromise performance. The incorporation of any
amplification considerably complicates thermal stability,
as input offset voltages and currents, temperature coeffi-
cient of gain settling resistors all become factors.
The circuit in Figure 44 shows an example of a simple
amplification scheme. This example produces a differen-
tial output with a common mode voltage of 2.5V, as
determined by the bridge. The use of a true three amplifier
instrumentation amplifier is not necessary, as the LTC2413
CS
F
O
11
14
12
13
+
LT1019
2413 F43
sn2413 2413fs