BU21050FS Datasheet, PDF (6/8 Pages) Rohm – Capacitive Sensor Switch Control IC

BU21050FS
Technical Note
【Filter selection】
The noise filter effect can be selected If “Strong” is selected, noise will get down, but the reaction time will be longer.
Sensor ON threshold
FILTER =”L”: filter effect → under
delay time → small
FILTER =”L”: filter effect → strong
delay time → big
Switch detect time
●Setting method
1)Please for the first time in a minimum gain.
2)THOFF = 0V, and, THON 1/2VDD voltage as a guideline for whether or not to switch ON, and gain selection to
please the rough.
Note: ON gain to a minimum, you gain more precision amended to increase the impact too, so please take note.
●Operation Mode
This IC has several modes, called detection mode, calibration mode, and shut-down mode. Each modeis described as follow
【Detection Mode】
This is normal operation mode of this IC. In this mode, IC detects the sensor capacitance continually.
【Calibration Mode】
Under detection mode when no operation has been detected for sometime, Sensor offset calibration will be done.
And the interval between each calibration is fixed
Detection mode and Calibration mode are switched automatically.
【Shutdown Mode】
When SDN pin is set to “L”, IC will be shut-down and all internal circuits will stop working. IC will work again
when SDN pin is set to “H”.
●Power Supply ON Sequence
This IC has two power input pins AVDD and DVDD. Power ON sequence must be whether set DVDD firstor set the two at
one time. Since internal reset circuit is monitoring AVDD, wrong power ON sequencemay cause initialization error.
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2009.04 - Rev.B