LM1872

Manufacturer Part NumberLM1872
DescriptionRadio Control Receiver/Decoder
ManufacturerNational Semiconductor
LM1872 datasheet
 


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Applications
(Continued)
Where only one of the two available analog channels needs
conversion to a digital format the LM555 approach offers
simplicity combined with up to 150 mA of output drive (Fig-
ure 14) The trailing edge of CH 1’s output pulse is used to
reset the timer in preparation for comparing CH 2’s pulse
width to the time constant (1 1 ms) set by the internal 10k
resistor and C1 For CH 2 pulse widths greater than 1 1 ms
C1 ramps to threshold setting an internal latch in the
FIGURE 13 Conversion of an Analog Channel
FIGURE 14 Simple Conversion of an Analog to a Digital Channel
LM555 and causing the load to be energized Due to the
timing of the reset pulse however the LM555 output will go
high again for 1 1 ms during the next pulse comparison cy-
cle thus producing an ON state duty cycle of about 95%
For most commonly encountered loads such as motors so-
lenoids lamps and horns this is of little consequence The
OFF state duty cycle is 100%
to a Digital (On Off) Channel
17
TL H 7912 – 25
TL H 7912 – 26