BU21009MUV Datasheet, PDF (3/14 Pages) Rohm – Capacitive Sensor Switch Control IC

BU21009MUV
●Block Diagram, Pin configuration
Technical Note
SREF
SIN[15:0]
CS
SCL
SDA/TXD
RXD
SDN
CLK_EXT
AVDD
DVDD
Sensor I/F、
CV translate
ADC
circuit
Data correction and
making to format
Conversion
sequence control
Data register
Reset
generation
Power
on
Reset
Clock
generation
CR
oscill
ation
host I/F
Power
management
AVSS
DVSS
INT
MODE[1:0]
DVSS
DVDD
AVDD
SREF
SIN[0]
SIN[1]/LED[0]
SIN[2]
SIN[3]/LED[1]
MODE[1]
MODE[0]
AVSS
TSTA
SIN[15]/LED[7]
SIN[4]
SIN[13]/LED[6]
SIN[12]
・Sensor I/F CV translate circuit
This module selects between sensor inputs. The selection sequences between all 16 channels.
・AD Conversion
The voltage into which CV is converted is converted into a digital value.
Conversion is 10 bit and full scale corresponds to AVDD.
・Conversion sequence control
Performs timing generation for the analogue circuitry and a sequencer circuit for selection of the sensor channel for conversion.
・Data correction and making to format
This module provides the digital intelligence of the sensor.
The block includes, amongst other things, scaling, adding offsets and input filtering for de-bouncing.
Registers are formatted to simplify usage by the softwareapplication.
The block implements auto-calibration to manage drift in temperature, process variation, voltage variation and aging effects.
・Data register
This stores the results for the software application. Please refer to the register map for details.
・HOST I/F
2 wire serial interface.
・Power management
The power management block provides smart power control.
When the sensors are not in use, the Controller automatically transitions into a low-power mode.
When a sensor is touched, then the device automatically wakes up and enters its normal operation.
The chip drives an INT pin for alerting the controller device in this case.
・Reset generation
The circuit is initialized by a either a soft reset command or by the external SDN pin.
・Clock generation
The device has an internal oscillator.
Provision is also made if the application would like to make use of an external clock input.
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2009.04 - Rev.B