LTC2410 Linear Technology, LTC2410 Datasheet - Page 32

• Manufacturer Part Number: LTC2410
• Description: 24-Bit No Latency ADC with Differential Input and Differential Reference
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
LTC2410
BRIDGE APPLICATIONS
Typical strain gauge based bridges deliver only 2mV/Volt
of excitation. As the maximum reference voltage of the
LTC2410 is 5V, remote sensing of applied excitation
without additional circuitry requires that excitation be
limited to 5V. This gives only 10mV full scale, which can
be resolved to 1 part in 10000 without averaging. For many
solid state sensors, this is still better than the sensor. For
example, averaging 64 samples however reduces the
noise level by a factor of eight, bringing the resolving
power to 1 part in 80000, comparable to better weighing
systems. Hysteresis and creep effects in the load cells are
typically much greater than this. Most applications that
require strain measurements to this level of accuracy are
measuring slowly changing phenomena, hence the time
required to average a large number of readings is usually
32
SDO
SCK
CS1
CS2
CS3
CS4
CONTROLLER
U
SDO
SCK
CS1
CS2
CS3
CS4
U
V
REF
REF
IN
IN
GND
CC
+
LTC2410
–
+
–
#1
31 OR LESS
CLOCK PULSES
SDO
SCK
CS
F
O
W
Figure 45. Actual Frequency Rate LTC2410 System
V
REF
REF
IN
IN
GND
CC
U
+
LTC2410
–
+
–
#2
SDO
SCK
CS
F
O
not an issue. For those systems that require accurate
measurement of a small incremental change on a signifi-
cant tare weight, the lack of history effects in the LTC2400
family is of great benefit.
For those applications that cannot be fulfilled by the
LTC2410 alone, compensating for error in external ampli-
fication can be done effectively due to the “no latency”
feature of the LTC2410. 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
V
REF
REF
IN
IN
GND
CC
+
–
LTC2410
+
–
#3
SDO
SCK
CS
F
O
V
REF
REF
IN
IN
GND
CC
+
–
LTC2410
+
–
#4
SDO
SCK
CS
F
O
V
V
EXTERNAL OSCILLATOR
(153,600HZ)
REF
REF
+
–
2410 F45