LM3814  Product Folder

The LM3814/LM3815 Current Gauges provide easy to use precision current measurement with virtually zero insertion loss (typically 0.004 Ohm). 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.

• No external sense element required
• PWM output indicates the current magnitude and direction
• PWM output can be interfaced with microprocessors
• Precision [DELTA][Sigma] current-sense technique
• Low temperature sensitivity
• Internal filtering rejects false trips
• Internal Power-On-Reset (POR)

• Ultra low insertion loss (typically 0.004 Ohm)
• 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

• Battery charge/discharge gauge
• Motion control diagnostics
• Power supply load monitoring and management
• Resettable smart fuse