LM3812

LM3812/LM3813 Precision Current Gauge IC with Ultra Low Loss Sense Element and PWM Output June 1999 LM3812/LM3813 Precision Current Gauge IC with Ultra Low Loss Sense Element and PWM Output General Description The LM3812/LM3813 Current Gauges provide easy to use precision current measurement with virtually zero insertion loss (typically 0.004Ω). 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. Key Specifications n Ultra low insertion loss (typically 0.004Ω) n 2V to 5.25V supply range n ± 2% accuracy at room temperature (includes accuracy of the internal sense element) (LM3812-1.0, LM3813-1.0) n Low quiescent current in shutdown mode (typically 2.5 µA) n 50 msec sampling interval Features n No external sense element required n PWM out...