ROHM BU21050FS Technical data

Capacitive Sensor Control IC Series

Capacitive Sensor Switch Control IC

BU21050FS

●Description

BU21050FS are the capacitive sensor controller with 8ch 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) 4bit Binary outputs or 8GPIO outputs

4) 5V power supply voltage available

5) Integrated 10bit AD converter, clock and reset

6) Package SSOP-A32

●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

-0.3 AVDD + 0.3

V

Input voltage

Storage temperature range T

Power dissipation Pd 760 mW

Ambient temperature reduces a permission loss by 7.6mW 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

Item Symbol

Unit Condition

Min Typ Max

DC characteristics

Input“H”voltage V

Input“L”voltage V

Output“H”voltage V

IHIO

ILIO

OHIO

DVDD x 0.9 - DVDD + 0.2 V

GND – 0.2 - DVDD x 0.1 V

DVDD x 0.8 - DVDD V IOH = -2[mA]。Overshoot is excluded。

Output“L”voltage VOL GND - DVDD x 0.2 V IOL = 2[mA]。Undershoot is excluded。

Input leakage current IIZ -1 - 1 μA

Output leakage current IOZ - - 1 μA

Standby current IST - - 2 μA Shutdown (SDN=“L”)

Operation current IDD - 550 - uA

●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

GND - AVDD V

AIN

0.2 - 2.0 MHz

adck

- 13 - μsec f

tim

adck

= 1[MHz]

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

RATING

PARAMETER SYMBOL

UNIT Condition

MIN TYP MAX

Frequency

Oscillation fcr 0.8 1.6 2.5 MHz

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●Block Diagram, Pin configuration

・Sensor I/F CV Conversion Circuit

This part selects target sensor and converts its capacitance to a voltage signal. Specifically,

all eight sensors are selected one-by-one and their capacity is compared to a common reference

capacity. Each difference value is converted to a certain voltage signal.

0

0 T

T

T S

S

TST3

TST1

TST2

TST1

TST2

TST1

TST2

TST1

TST2

GND

SDN

DVDD

PO2

PO1

T

F

F E

E

E R

R

SIN1

SIN2

SIN1

SIN2

SIN1

S

PO5

PO4

PO6

PO5

PO4

PO6

PO5

PO4

PO6

PO5

PO4

PO3

SIN3

PO6

PO7

PO8

SIN5

SIN6

SIN8

SIN6

SIN8

SIN6

SIN8

SIN6

SIN8

SIN6

SIN8

SIN6

SIN8

SIN6

SIN4

SIN8

SIN7

INSEL

IFSEL

GAIN[1]

THON

IFSEL

GAIN[0]

AVDD

THOFF

FILTER

THOFF

FILTER

THOFF

FILTER

THOFF

FILTER

THOFF

FILTER

THOFF

FILTER

THOFF

FILTER

・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 circuit. This block eliminates these noises.

・Compare threshold

CV converted to sensor data On / Off compared with a threshold, the switch converts the signal.

・Interface Selection

By setting this block, output mode can be set to either 8-bit PIO mode or 4-bit binary mode.

・Calibration

When the capacitance change do not exceed the threshold for a certain period, this block

starts-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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