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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  
4.5.5  
4.5.6  
Low Frequency Noise Detection  
Each sensor input has an EMI noise detector that will sense if low frequency noise is injected onto the  
input with sufficient power to corrupt the readings. If this occurs, the device will reject the corrupted  
sample and set the corresponding bit in the Noise Status register to a logic ‘1’.  
RF Noise Detection  
Each sensor input contains an integrated RF noise detector. This block will detect injected RF noise  
on the CS pin. The detector threshold is dependent upon the noise frequency. If RF noise is detected  
on a CS line, that sample is removed and not compared against the threshold.  
4.6  
ALERT# Pin  
The ALERT# pin is an active low (or active high when configured) output that is driven when an  
interrupt event is detected.  
Whenever an interrupt is generated, the INT bit (see Section 5.1, "Main Control Register") is set. The  
ALERT# pin is cleared when the INT bit is cleared by the user. Additionally, when the INT bit is cleared  
by the user, status bits are only cleared if no touch is detected.  
4.6.1  
Sensor Interrupt Behavior  
The sensor interrupts are generated in one of two ways:  
1. An interrupt is generated when a touch is detected and, as a user selectable option, when a release  
is detected (by default - see Section 5.6). See Figure 4.3.  
2. If the repeat rate is enabled then, so long as the touch is held, another interrupt will be generated  
based on the programmed repeat rate (see Figure 4.2).  
When the repeat rate is enabled, the device uses an additional control called MPRESS that determines  
whether a touch is flagged as a simple “touch” or a “press and hold”. The MPRESS[3:0] bits set a  
minimum press timer. When the button is touched, the timer begins. If the sensor pad is released  
before the minimum press timer expires, it is flagged as a touch and an interrupt is generated upon  
release. If the sensor input detects a touch for longer than this timer value, it is flagged as a “press  
and hold” event. So long as the touch is held, interrupts will be generated at the programmed repeat  
rate and upon release (if enabled).  
APPLICATION NOTE: Figure 4.2 and Figure 4.3 show default operation which is to generate an interrupt upon  
sensor pad release and an active-low ALERT# pin.  
APPLICATION NOTE: The host may need to poll the device twice to determine that a release has been detected.  
SMSC CAP1128  
Revision 1.32 (01-05-12)  
DATA3S5HEET