Capacitive Sensor Control IC Series
Capacitive Sensor Switch
Control IC
BU21051FS
●Description
BU21051FS are the capacitive sensor controller with 2ch respectively.
The IC has the port interface and easy to replace the point of switch to this controller.
●Features
1) Port output interface
2) Few software control
3) 2ch GPIO outputs
4) 5V power supply voltage available
5) Integrated 10bit AD converter, clock and reset
6) Package SSOP-A16
●Applications
It is possible to use it widely as a switch such as home electric appliance.
●Absolute Maximum Ratings (Ta=25℃)
PARAMETER SYMBOL
MIN MAX
AVD D -0.3 7. 0
Applied voltage
DVDD -0.3 7.0
RATING
UNIT
V
V
-0.3 AVDD + 0.3
Input voltage
Storage temperature
range T
Power dissipation Pd 500 mW
Ambient temperature reduces a permission loss by 5mW per case more than 25 degrees Celsius, 1 degree Celsius
AIN
V
-0.3 DVDD + 0.3
DIN
-55 125 ℃
stg
V
Jan. 2009
●Recommended Operating conditions
PARAMETER SYMBOL
RATING
UNIT
MIN TYP MAX
Applied voltage
AVDD 4.5 5.0 5.5 V
DVDD 4.5 5.0 5.5 V
Operating temperature
T
-40 25 85 ℃
range
opr
●Electrical characteristics(Especially, Topr=25℃ and AVDD=DVDD=0 as long as it doesn't specify it.)
RATING
PARAMETER SYMBOL
UNIT Condition
MIN TYP MAX
DC characteristics
Input“H”voltage V
Input“L”voltage V
Output“H”voltage VOL GND - DVDD x 0.2 V I
Output“L”voltage I
Input leakage current I
DVDD x 0.9 - DVDD + 0.2 V
IHIO
GND – 0.2 - DVDD x 0.1 V
ILIO
-1 - 1 μA
IZ
-1 - 1 μA
OZ
= -2[mA]. Overshoot is excluded.
OH
Output leakage current IST - - 2 μA Shutdown (SDN=“L”)
Standby current I
- 500 - uA
DD
●A/D Converter
RATING
PARAMETER SYMBOL
UNIT Condition
MIN TYP MAX
Resolution - 10 - bit
Analog Input voltage V
Change clock frequency f
Change time f
Zero scale voltage - - GND + 0.07 V
Full scale voltage AVDD - 0.07 - - V
Differential non line accurate DNL - - ±3 LSB
Integrate non line accurate INL - - ±3 LSB
●CR Oscillator characteristic
PARAMETER SYMBOL
Oscillation Frequency f
GND - AVDD V
AIN
0.2 - 1.0 MHz
adck
- 13 - μsec f
tim
adck
RATING
UNIT Condition
MIN TYP MAX
0.9 1.6 2.5 MHz
cr
= 1[MHz]
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●Block Diagram, Pin configuration
AVDD
TST
THON
THOFF
GAIN[1]
GAIN[0]
FILTER
PO1
DVDD
GND
SREF
SIN1
SDN
PO2
N.C.
SIN2
●Sensor I/F CV Conversion Circuit:
This part selects target sensor and converts its capacitance to a voltage signal. Specifically, alleight
sensors are selected one-by-one and their capacity is compared to a common referencecapacity. Each
difference value is converted to a certain voltage signal.
●AD Conversion
The voltage signal derived from CV conversion is further converted to digital value by this block.
●Conversion Sequence Control
This block controls the process of CV conversion and generates timing of selecting target sensors.
●Noise Filter
The GND level difference between appliance and human body will cause noises to the CV conversion
●Compare threshold
CV converted to sensor data On / Off compared with a threshold, the switch converts the signal.
●Calibration
When the capacitance change do not exceed the threshold for a certain period, this blockstarts-up
calibration process.
●Reset Generation
This is internal reset circuit. Reset is initialized by external SDN signal.
●Clock Generation
Clock from internal RC oscillation circuit is used as system clock.
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