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CAP1128-1-BP-TR 参数 Datasheet PDF下载

CAP1128-1-BP-TR图片预览
型号: CAP1128-1-BP-TR
PDF下载: 下载PDF文件 查看货源
内容描述: [LED Driver]
分类和应用: 驱动接口集成电路
文件页数/大小: 88 页 / 585 K
品牌: SMSC [ SMSC CORPORATION ]
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8 Channel Capacitive Touch Sensor with 2 LED Drivers  
Datasheet  
4.5.2.1  
Manual Recalibration  
The Calibration Activate Registers (Section 5.11, "Calibration Activate Register") force recalibration of  
selected sensor inputs. When a bit is set, the corresponding capacitive touch sensor input will be  
recalibrated (both analog and digital). The bit is automatically cleared once the recalibration routine  
has finished.  
Note: During this recalibration routine, the sensor inputs will not detect a press for up to 200ms and  
the Sensor Base Count Register values will be invalid. In addition, any press on the  
corresponding sensor pads will invalidate the recalibration.  
4.5.2.2  
4.5.2.3  
4.5.2.4  
Automatic Recalibration  
Each sensor input is regularly recalibrated at a programmable rate (see Section 5.17, "Recalibration  
Configuration Register"). By default, the recalibration routine stores the average 64 previous  
measurements and periodically updates the base “not touched” setting for the capacitive touch sensor  
input.  
Note: Automatic recalibration only works when the delta count is below the active sensor input  
threshold. It is disabled when a touch is detected.  
Negative Delta Count Recalibration  
It is possible that the device loses sensitivity to a touch. This may happen as a result of a noisy  
environment, an accidental recalibration during a touch, or other environmental changes. When this  
occurs, the base untouched sensor input may generate negative delta count values. The  
NEG_DELTA_CNT bits (see Section 5.17, "Recalibration Configuration Register") can be set to force  
a recalibration after a specified number of consecutive negative delta readings.  
Note: During this recalibration, the device will not respond to touches.  
Delayed Recalibration  
It is possible that a “stuck button” occurs when something is placed on a button which causes a touch  
to be detected for a long period. By setting the MAX_DUR_EN bit (see Section 5.6, "Configuration  
Registers"), a recalibration can be forced when a touch is held on a button for longer than the duration  
specified in the MAX_DUR bits (see Section 5.8, "Sensor Input Configuration Register").  
Note: Delayed recalibration only works when the delta count is above the active sensor input  
threshold. If enabled, it is invoked when a sensor pad touch is held longer than the MAX_DUR  
bit setting.  
4.5.3  
4.5.4  
Proximity Detection  
Each sensor input can be configured to detect changes in capacitance due to proximity of a touch.  
This circuitry detects the change of capacitance that is generated as an object approaches, but does  
not physically touch, the enabled sensor pad(s). When a sensor input is selected to perform proximity  
detection, it will be sampled from 1x to 128x per sampling cycle. The larger the number of samples  
that are taken, the greater the range of proximity detection is available at the cost of an increased  
overall sampling time.  
Multiple Touch Pattern Detection  
The multiple touch pattern (MTP) detection circuitry can be used to detect lid closure or other similar  
events. An event can be flagged based on either a minimum number of sensor inputs or on specific  
sensor inputs simultaneously exceeding an MTP threshold or having their Noise Flag Status Register  
bits set. An interrupt can also be generated. During an MTP event, all touches are blocked (see  
Section 5.15, "Multiple Touch Pattern Configuration Register").  
Revision 1.32 (01-05-12)  
SMSC CAP1128  
DATA3S4HEET