Resistor da Kofa: Me ke ta ce?
Mishe ne Pull-Down Resistor?
Pull-down resistor ake amfani da ita a cikin tashar logiki na kawo ainiyoyi don tabbatar da halayen bayanai. Ana yi shi da sauraro da transistors da koguna don tabbatar da tsari ya dace da ground zuwa Vcc yana gudanar da koguna ta fuskantar (kamar pull-up resistor).
Wannan zaka iya zama mafi karfi a karamin lokacin, saboda haka za a bayar misal.
Tashar digital na nisa masu uku masu halayen bayanai; High (1), Low (0), da floating (mai ba a tabbata). Amma tashar digital na biyo ke yi a kan halayen high ko low.
A cikin halayen floating, tashar digital suna iya yanayi a kan high da low. Resisters suna amfani da su don kawo karfi a cikin tashar.
Kunna tashar digital wanda ke yi a kan 5 V. Idan voltage voltage ya dace a kan 2 zuwa 5 V, halayen bayanai na tashar ke high. Da idan voltage ya fi 0.8 V, halayen bayanai ke low.
Idan voltage ya dace a kan 0.9 zuwa 1.9 V, tashar zaka iya yanayi a kan halaye.
Pull-down ko pull-up resistors suna amfani da su a cikin tashar digital don kawo wannan yanayi. A cikin halayen floating, pull-down resisters suna kawo halayen bayanai a kan zero volts idan babu tashar mai gudanar da ita.
Yadda Pull-Down Resistor Yake Gudanar da Ita?
Pull-down resistor an kofa da ground, kamar yadda aka baka a cikin hoton.
Pull Down Resistor Working
Idan koguna mechanical ta fuskantar, voltage na input ya kofa zuwa zero (low). Pin digital ya tabbatar da halayen low.
Idan koguna mechanical ta kammalar, voltage na input ya kofa zuwa high. A cikin kyau, pin digital ya tabbatar da halayen high.
Tsarin pull-down resistor ya kamata ake da tsari mai yawa da impedance na tashar. Idan ba ake da tsari mai yawa, ba zan iya kofa current, da adadu voltage ana iya kasance a pin input.
Tashar zaka iya yi a kan halayen floating a cikin kyau, idan koguna ta fuskantar ko kammalar.
Haɗaƙar Pull-Down Resistors
Tsari da ke bukata don pull-down resistors an haɗaƙe ta da Ohm’s law.
Hoton da ake amfani da ita don haɗaƙar pull-down resistance shine;
![\[ R_{pull-down} = \frac{V_{L(max)} - 0}{I_{source}} \]](https://www.electrical4u.com/wp-content/ql-cache/quicklatex.com-bb48317c1a196bc163ae8378712c71bd_l3.png?ezimgfmt=rs:196x41/rscb38/ng:webp/ngcb38 "Rendered by QuickLaTeX.com")
Idan,
VLmax shine voltage mai yawa da ake buƙata a kan halayen low,
Isource shine gate-source current.
Misali, voltage mai yawa da ake buƙata don kofar tashar shine 0.8 V. Da gate source current shine 0.5 mA.
![\[ R_{pull-down} = \frac{0.8 - 0}{0.5 \times 10^-3} \]](https://www.electrical4u.com/wp-content/ql-cache/quicklatex.com-3899ddf6102ac9499566ca13481c189a_l3.png?ezimgfmt=rs:189x36/rscb38/ng:webp/ngcb38 "Rendered by QuickLaTeX.com")
![\[ R_{pull-down} = 1.6 k \Omega \]](https://www.electrical4u.com/wp-content/ql-cache/quicklatex.com-c731f263eb4e7ea8326c76959ebf3d4a_l3.png?ezimgfmt=rs:149x18/rscb38/ng:webp/ngcb38 "Rendered by QuickLaTeX.com")
A cikin kyau, za a iya zaba tsari mai yawa da pull-down resistance shine 1.6 kΩ. Amma ba za a iya amfani da tsari mai yawa da wannan.
Saboda tsari mai yawa tana da juyin voltage mai yawa, wanda tana da ganin gate input voltage zuwa faɗa mai yawa.
Saboda haka, za a zaba pull-down resistor a kan juyin voltage mai yawa da 0.4-0.5 V. Sannan za a zaba tsari mai yawa da pull-down resistance a kan
