LM3822 National Semiconductor, LM3822 Datasheet
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LM3822
Manufacturer Part Number
LM3822
Description
Precision Current Gauge IC with Internal Zero Ohm Sense Element and PWM Output
Manufacturer
National Semiconductor
Datasheet
1.LM3822.pdf
(12 pages)
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© 2000 National Semiconductor Corporation
LM3822
Precision Current Gauge IC with Internal Zero Ohm
Sense Element and PWM Output
General Description
The LM3822 Current Gauge provides easy to use precision
current measurement with virtually zero insertion loss (typi-
cally 0.003 ). The LM3822 is used for high-side sensing.
A Delta Sigma analog to digital converter is incorporated to
precisely measure the current and to provide a current aver-
aging function. Current is averaged over 50 msec time peri-
ods 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 LM3822 is factory-set in two different current options.
The sense range is −1.0A to +1.0A or −2.0A to +2.0A. The
sampling interval for this part is 50ms. If faster sampling is
desired, please refer to the data sheet for the part number
LM3824.
Connection Diagram
DS101249
LM3822 for High-Side Sensing
Top View
Key Specifications
n Ultra low insertion loss (typically 0.003 )
n 2V to 5.5V supply range
n
n Low quiescent current in shutdown mode (typically
n 50 msec sampling interval
n In MSOP-8 Package
Features
n No external sense element required
n PWM output indicates the current magnitude and
n PWM output is easily interfaced with microprocessors
n Precision
n Low temperature sensitivity
n Internal filtering rejects false trips
n Internal Power-On-Reset (POR)
n DC Offset is less than 1 mA for 1A part
Applications
n Battery charge/discharge gauge
n Motion control diagnostics
n Power supply load monitoring and management
n Resettable smart fuse
(includes accuracy of the internal sense element)
1.8 µA)
direction
and controllers
±
2% accuracy at room temperature for the 1A device
DS101249-1
current-sense technique
www.national.com
July 2000