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Features
No external sense element required
PWM output indicates the current magnitude and direction
PWM output can be interfaced with microprocessors
Precision ΔΣ current-sense technique
Low temperature sensitivity
Internal filtering rejects false trips
Internal Power-On-Reset (POR)
Description The
LM3814/LM3815 Current Gauges provide easy to use precision current measurement with virtually zero insertion loss (typically 0.004Ω). The
LM3814 is used for high-side sensing and the
LM3815 is used for low-side sensing.
A Delta Sigma analog to digital converter is incorporated to precisely measure the current and to provide a current averaging
function. Current is averaged over 6 msec time periods in order to provide immunity to current spikes. The ICs have a pulse-width
modulated (PWM) output which indicates the current magnitude and direction. The shutdown pin can be used to inhibit false
triggering during start-up, or to enter a low quiescent current mode.
The
LM3814 and
LM3815 are factory-set in two different current options. The sense range is −1A to +1A or −7A to +7A. The user specifies a particular
part number to match the current range for a given application. The sampling interval for these parts is 6ms. If larger
sampling interval is desired for better accuracy, please refer to the data sheets for the part numbers LM3812 and LM3813.
Key Specification
Ultra low insertion loss (typically 0.004Ω)
2V to 5.25V supply range
±3.5% accuracy at room temperature (includes accuracy of the internal sense element) (
LM3814-1.0,
LM3815-1.0)
Low quiescent current in shutdown mode (typically 2.5 µA)
6 msec sampling interval
Applications
Battery charge/discharge gauge
Motion control diagnostics
Power supply load monitoring and management
Resettable smart fuse
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