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EPC110 参数 Datasheet PDF下载

EPC110图片预览
型号: EPC110
PDF下载: 下载PDF文件 查看货源
内容描述: 完全集成的可配置的光障的驱动程序和接收器 [Fully integrated configurable light barrier driver & receiver]
分类和应用: 驱动
文件页数/大小: 27 页 / 588 K
品牌: EPC [ ESPROS PHOTONICS CORP ]
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epc110  
Pulse Modulated Operation (e.g. OUTNint to OUTN)  
The epc110 chip operates the LED and the receiver path on a pulse modulated concept. Thus, the LED is operated with short pulses whereas  
the receiver channel does synchronous demodulation of the received light pulses by reading the current pulses of the photo diode. This  
concept allows a very high sensitivity, high speed operation, and a high suppression of input ambient or foreign light (DC currents) generated  
by sunlight or other DC light sources like light bulbs. The pulse length is set by the parameter TPULSE.  
In the standalone mode the whole system is clocked by the scan period defined by the programmed parameter TPER. In the controlled mode  
the timing is propagated from the external signal EN (positive edge, synchronized on the internal clock).  
In order to eliminate interference caused by modulated light, e.g. a flashing light or by other light barriers, the input signal from the photodiode  
is amplified, filtered, and processed by an integrated signal processor. If the photo diode signal meets the required frequency, pattern and  
amplitude, the output(s) are triggered. The following timing diagram shows the basic concept.  
t
t
Cycle  
Pulse  
on  
off  
Emitter LED  
yes  
no  
Beam interrupted  
Photo diode current I  
OUTN or OUTH  
PD  
n
n
2
1
2
1
V
M
INT  
INT  
[V]  
OUTN or OUTH  
t
t
F
R
Release time  
Response time  
missing pulses  
valid (non-missing) pulses  
Figure 6: Pulse modulation concept  
It is in fact a digital filter which counts missing and non-missing pulses to change the ou tput state of OUTN or OUTH.  
Working principle of the digital filter e.g. for the signal OUTNint to OUTN Filter:  
The aim of this programmable filter is to suppress single pulses, so they cannot trigger the output and generate a false signals.  
This filter is based on a counter, which is counting up (increment) the valid pulses and counting down (decrement) the missing pulses in a  
weighted manner. Separate weighting factors can be selected for valid pulses (parameter INC) and missing pulses (parameter DEC). If the  
counter reaches the upper limit (maximum count, response time), the signal OUTN is set to LOW. Similar in the opposite direction, if the  
counter reaches zero, the lower limit (minimum count, release time), the signal OUTN is put to HIGH. With the parameters INC and DEC the  
filter has the advantage of individual selectable gradients of the slopes. Counter will never exceed maximum nor minimum limit. In between it  
acts as an integrator of both parameters.  
IF Pulse then  
IF Pulse = valid then  
Counter = Counter + (INC * 1024 for INC > 0 and 32 * 1024 for INC = 0)  
IF counter > 215 (maximum limit) then Counter = maximum limit  
IF counter = maximum limit then OUTN = 0  
IF Pulse = missing then  
Counter = Counter - (2DEC  
)
IF counter < 0 (minimum limit) then Counter = minimum limit  
IF counter = minimum limit then OUTN = 1  
ELSE wait for Pulse  
Lets assume that the photo diode does not receive light pulses for a long time: This means the light beam is interrupted. Then OUTN is at high  
level. If the light beam is not anymore interrupted, the photodiode receives light pulses which are strong enough to trigger the OUTNINT  
threshold and the internal pulse evaluation unit (designated in Figure 5 with 'Pulse evaluation') starts to count the receiving pulses. If the  
number of received pulses reach the set level nV, the output OUTN turns to low level. Thus, single pulses cannot trigger the output and  
generate a false signal.  
The same procedure is used when a beam changes from not interrupted to interrupted. The internal pulse evaluation unit counts the missing  
pulses. If the number of missing pulses reaches the set level n M, OUTN is turned to high level.  
© 2011 ESPROS Photonics Corporation  
Characteristics subject to change without notice  
8
Datasheet epc110 - V2.1  
www.espros.ch  
 
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