INA253 データシート(Datasheet) 9 Page - Texas Instruments
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SLOS954 – MAY 2018
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Feature Description (continued)
addition to the initial adjustment, the calibration procedure is not effective. The user must account for the
temperature-induced changes. One of the primary benefits of the low temperature coefficient of the INA250
(including both the integrated current-sensing resistor and current-sensing amplifier) is ensuring that the device
measurement remains accurate, even when the temperature changes throughout the specified temperature
range of the device.
For the integrated current-sensing resistor, the drift performance is shown in Figure 3. Although several
temperature ranges are specified in the table, applications operating in ranges other than those described can
use Figure 3 to determine how much variance in the shunt resistor value can be expected. As with any resistive
element, the tolerance of the component varies when exposed to different temperature conditions.
current-sensing resistor integrated in the INA250, the resistor does vary slightly more when operated in
temperatures ranging from –40°C to 0°C than when operated from 0°C to 125°C. Even in the –40°C to 0°C
temperature range, the drift is still low at 25 ppm/°C.
Figure 3. Sensing Resistor vs Temperature
An additional aspect to consider is that when current flows through the current-sensing resistor, power is
dissipated across this component. This dissipated power results in an increase in the internal temperature of the
package, including the integrated sensing resistor. This resistor self-heating effect results in an increase of the
resistor temperature helping to move the component out of the colder, wider drift temperature region.
8.3.4 Enhanced PWM Rejection Operation
The enhanced PWM rejection feature of the INA253 provides increased attenuation of large common-mode
ΔV/Δt transients. Large ΔV/Δt common-mode transients associated with PWM signals are employed in
applications such as motor or solenoid drive and switching power supplies. Traditionally, large ΔV/Δt common-
mode transitions are handled strictly by increasing the amplifier signal bandwidth, which can increase chip size,
complexity and ultimately cost. The INA253 is designed with high common-mode rejection techniques to reduce
large ΔV/Δt transients before the system is disturbed as a result of these large signals. The high AC CMRR, in
conjunction with signal bandwidth, allows the INA253 to provide minimal output transients and ringing compared
with standard circuit approaches.
8.3.5 Input Signal Bandwidth
The INA253 input signal, which represents the current being measured, is accurately measured with minimal
disturbance from large ΔV/Δt common-mode transients as previously described. For PWM signals typically
associated with motors, solenoids, and other switching applications, the current being monitored varies at a
significantly slower rate than the faster PWM frequency.
The INA253 bandwidth is defined by the –3-dB bandwidth of the current-sense amplifier inside the device, see
Specifications. The device bandwidth provides fast throughput and fast response required for the rapid detection
and processing of overcurrent events. Without the higher bandwidth, protection circuitry may not have adequate
response time and damage may occur to the monitored application or circuit.
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