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

2/7

●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.

3/7

●Pin Description

Pin No.

10 SIN6 Ain Sensor input 6 - AVDD “Hi-Z” ③

11 SIN7 AIn Sensor input 7 - AVDD “Hi-Z” ③

12 SIN8 AIn Sensor input 8 - AVDD “Hi-Z” ③

13 THON AIn

14 THOFF AIn

15 AVDD Power Analog part Power supply - -

16 FILTER In Filter selection

17 IFSEL In Sensor output selection

18 INSEL In simultaneous push selection

19 GAIN[0] In

20 GAIN[1] In DVDD ①

21 PO8 22 PO7 23 PO6

24 PO5 Out sensor output5 - DVDD “Hi-Z” “L” ②

25 PO4 26 PO3 27 PO2 28 PO1 Out sensor output1/BIN[0] DVDD “Hi-Z” “L” ② 29 TST0 In digital part test input0 Usually tide to “L” DVDD ① 30 TST1 In digital part test input1 Usually tide to “L” DVDD ① 31 TST2 In digital part test input2 Usually tide to “L” DVDD ① 32 TST3 In digital part test input3 Usually tide to “L” DVDD ①

Name I/O Function Note Supply Reset Level I/O Pad

1 SDN In Shutdown input

2 DVDD Power Digital part Power supply Digital part Power supply - 3 GND Ground Ground - - 4 SREF AIn Standard capacitor input - AVDD “Hi-Z” ③ 5 SIN1 AIn Sensor input1 - AVDD “Hi-Z” ③ 6 SIN2 AIn Sensor input 2 - AVDD “Hi-Z” ③ 7 SIN3 AIn Sensor input 3 - AVDD “Hi-Z” ③ 8 SIN4 AIn Sensor input 4 - AVDD “Hi-Z” ③ 9 SIN5 AIn Sensor input 5 - AVDD “Hi-Z” ③

Sensor ON threshold voltage input Sensor OFF threshold voltage input

Gain level selection

Out

sensor output8 - DVDD “Hi-Z”*2 “L”*3 ②

Out

sensor output7 - DVDD “Hi-Z” “L” ②

Out

sensor output6 - DVDD “Hi-Z” “L” ②

Out

sensor output4/BIN[3]

Out

sensor output3/BIN[2] DVDD “Hi-Z” “L” ②

Out

sensor output2/BIN[1] DVDD “Hi-Z” “L” ②

“H” : state of operation “L” halt condition

- AVDD “Hi-Z” ③

AVDD “Hi-Z” ③

“H”: Filter effect: strong “L”: Filter effect: Weak

“H” :ON : L-Active,

OFF : Nch Open Drain

“L”: 4bit Binary Mode

H-Active, L

“H” : simultaneous push banned “L” : 8 outputs setting

GAIN[1:0] = 00 : Strong GAIN[1:0] = 01 : GAIN[1:0] = 10 :

GAIN[1:0] = 11 : Week

INSEL=“L”: Binary Mode

0000 = Button OFF 0001 = SIN1 ON

1000 = SIN8 ON

※*1 Initial State ①When internal organs power-on reset

※2 “Hi-Z” when PIO Mode ※3 “L” when Binary Mode

Gain

:

DVDD ①

DVDD “Hi-Z” “L” ②

is effective

②When SDN=”L”

4/7

●I/O Circuit ①CMOS INPUT ②CMOS 3state output ③CMOS 3state output with analog switch

CIN

PAD

【IFSEL: Output interface format】

IFSEL Mode Output format H 8ch PIO L-active, Nch Open Drain L 4bit Binary H-active, L

INSEL = H : 8GPIOs output mode Initial status PO[8:1] = Hi-Z

INSEL = L : 4bit Binary output mode

Initial Status PO[4:1] = L

Button PO[4:1] Button OFF 0000 SIN1 0001 SIN2 0010 SIN3 0011 SIN4 0100 SIN5 0101 SIN6 0110 SIN7 0111 SIN8 1000

Only the first sensor input was effective in terms of button ON judgment when more than one input has occurred.

Next judgment would be done after all the button is OFF.

【INSEL : Simultaneous push judgment control】

This setting is effective when IFSEL = “H”

INSEL Function Note

OEN

PADI

AIN

ASW

PAD

H

Simultaneous push

banned

Simultaneous push

L

effective

【THON: Button OFF→ON threshold value judge】

【THOFF: Button ON→OFF threshold value judge】

Setting the threshold value of electrostatic Sensor Switches. By applying voltages can be set. As an example, 1/2VDD applied to the entire range of the sensor output 1 / 2 to set the threshold value. In fact, the voltage setting resistance to the partial pressure is recommended to us.

【GAIN Selection】

Sensor gain can be set in 4 stages

GAIN[1:0] = 00 (x92) GAIN[1:0] = 01 (x69) GAIN[1:0] = 10 (x46) GAIN[1:0] = 11 (x1)

Only the dominant button will output

when more than 2 buttons were pressed

Every button that was pressed will output

5/7

【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 value

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 mode is 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 first or set the two at one time. Since internal reset circuit is monitoring AVDD, wrong power ON sequence may cause initialization error.

6/7

●Ordering part number

123

B

U

Part No.

Part No

SSOP-A32

Dimension〉

〈

BU21050FS

1 2 5 E 20

F

0 S

Package

FS ：SSOP-A32

〈Tape and Reel information〉

Tape

Quantity

Direction

Embossed carrier tape

2000pcs

E2

The direction is the 1pin of product is at the upper left when you hold

(

reel on the left hand and you pull out the tape on the right hand)

Reel

Packaging and forming specification

E2：Embossed tape and reel

1234

1Pin

1234

Direction of feed

1234

(Unit:mm)

1st 2009, January

※When you order , please order in times the amount of package quantity.

7/7

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Appendix-Rev4.0

ROHM BU21050FS Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual