LM3813  Product Folder

The LM3812/LM3813 Current Gauges provide easy to use precision current measurement with virtually zero insertion loss (typically 0.004 Ohm). The LM3812 is used for high-side sensing and the LM3813 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 50 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 LM3812 and LM3813 are factory-set in two different current options. The sense range is -1A to +1A or -7A to +7A. The sampling interval for these parts is 50ms. If faster sampling is desired, please refer to the data sheets for the part numbers LM3814 and LM3815.

• 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
• ±2% accuracy at room temperature (includes accuracy of the internal sense element) (LM3812-1.0, LM3813-1.0)
• Low quiescent current in shutdown mode (typically 2.5 µA)
• 50 msec sampling interval

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