ROHM BU21051FS Technical data

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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