[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-670871-105":59,"doc-detail-670871-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","ne555-and-ne556-applications-an170-application-note","NE555 and NE556 applications - AN170 - Application note","","AN170 provides an application-note introduction to the Philips 555 timer and its dual 556 counterpart, describing why these devices became widely used. It explains the internal architecture using voltage comparators, a bistable flip-flop, a discharge transistor, and a resistor divider reference. The document covers one-shot and oscillator operation, typical timing accuracy and drift, trigger/threshold behavior, and the overall “totem-pole” output stage suitable for sink or source capability. It also begins detailing circuit functions such as the reset mechanism.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":30,"@type":76,"position":81},"https://docshare.wps.com/document/technology/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/ne555-and-ne556-applications-an170-application-note/670871/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/ne555-and-ne556-applications-an170-application-note/670871.png","ImageObject",300,407,{"name":92,"@type":93},"Levi","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-11-02","2026-11-01",true,{"@type":102,"interactionType":103,"userInteractionCount":19},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What internal blocks make up the 555 timer described in AN170?","Question",{"text":112,"@type":113},"The document describes two voltage comparators, a bistable flip-flop, a discharge transistor, and a resistor divider reference network that sets comparator levels.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How does the timer decide when to set or reset during an RC timing cycle?",{"text":117,"@type":113},"When the trigger voltage falls below one third of the supply, the trigger comparator sets the flip-flop and drives the output high; when the capacitor voltage exceeds two thirds of the supply, the threshold comparator resets the flip-flop and drives the output low.",{"name":119,"@type":110,"acceptedAnswer":120},"What are the differences between using the timer as a one-shot versus an oscillator?",{"text":121,"@type":113},"For one-shot operation, only resistance and capacitance are needed as external components; for oscillator operation, one additional resistor is required for generating repeated cycles and adjustable duty cycles.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},670871,1793572437,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":29,"category_name":30,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":19,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":56,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":129,"read_time":143},7971461740909,"https://ap-avatar.wpscdn.com/davatar_155a257f0dc6eb9ab79c44ca47cae57d","INTEGRATED CIRCUITS  \n\n| | |\n| --- | --- |\n| AN170\u003Cbr>NE555 and NE556 applications |  |\n\n1988 Dec  \n􀀁􀀆􀀇􀀈􀀇􀀌􀀎  \n􀀂􀀅􀀉􀀇􀀃􀀋􀀊􀀄􀀐􀀃􀀏􀀋􀀍􀀎  \nPhilips Semiconductors Application note  \n\n| NE555 and NE556 applications | AN170 |\n| --- | --- |\n\nINTRODUCTION  \nIn mid 1972, Philips Semiconductors introduced the 555 timer, a unique functional building block that has enjoyed unprecedented popularity. The timer’s success can be attributed to several inherent characteristics foremost of which are versatility, stability and low cost. There can be no doubt that the 555 timer has altered the course of the electronics industry with an impact not unlike that of the IC operational amplifier.  \nThe simplicity of the timer, in conjunction with its ability to produce long time delays in a variety of applications, has lured many designers from mechanical timers, op amps, and various discrete circuits into the ever increasing ranks of timer users.  \nDESCRIPTION  \nThe 555 timer consists of two voltage comparators, a bistable flip-flop, a discharge transistor, and a resistor divider network. To understand the basic concept of the timer let’s first examine the timer in block form as in Figure 1.  \nThe resistive divider network is used to set the comparator levels. Since all three resistors are of equal value, the threshold comparator is referenced internally at 2/3 of supply voltage level and the trigger comparator is referenced at 1/3 of supply voltage. The outputs of the comparators are tied to the bistable flip-flop. When the trigger voltage is moved below 1/3 of the supply, the comparator changes state and sets the flip-flop driving the output to a high state. The threshold pin normally monitors the capacitor voltage of the RC timing network. When the  \nOUTPUT  \nFLIP  \nFLOP  \nV CC  \nDISCHARGE  \nCONTROL  \nVOLTAGE  \nTHRESHOLD  \nOUTPUT  \nTRIGGER  \nCOMP  \nCOMP  \nRESET  \nSL00954  \nFigure 1. 555/556 Timer Functional Block Diagram  \ncapacitor voltage exceeds 2/3 of the supply, the threshold comparator resets the flip-flop which in turn drives the output to a low state. When the output is in a low state, the discharge transistor is “on”, thereby discharging the external timing capacitor. Once the capacitor is discharged, the timer will await another trigger pulse, the timing cycle having been completed.  \nThe 555 and its complement, the 556 Dual Timer, exhibit a typical initial timing accuracy of 1% with a 50ppm/C timing drift with temperature. To operate the timer as a one-shot, only two external components are necessary; resistance & capacitance. For an  \noscillator, only one additional resistor is necessary. By proper selection of external components, oscillating frequencies from one cycle per half hour to 500kHz can be realized. Duty cycles can be adjusted from less than one percent to 99 percent over the frequency spectrum. Voltage control of timing and oscillation functions is also available.  \nTimer Circuitry  \nThe timer is comprised of five distinct circuits: two voltage comparators; a resistive voltage divider reference; a bistable flip-flop; a discharge transistor; and an output stage that is the“totem-pole” design for sink or source capability. Q10-Q13 comprise a Darlington differential pair which serves as a trigger comparator. Starting with a positive voltage on the trigger, Q10 and Q11 turn on when the voltage at Pin 2 is moved below one third of the supply voltage. The voltage level is derived from a resistive divider chain consisting of R7 , R8 and R9. All three resistors are of equal value (5kΩ) . At 15V supply, the triggering level would be 5V.  \nWhen Q10 and Q11 turn on, they provide a base drive for Q15 , turning it on. Q16 and Q17 form a bistable flip-flop. When Q15 is saturated, Q16 is ”off’ and Q17 is saturated. Q16 and Q17 will remain in these states even if the trigger is removed and Q15 is turned ”off’. While Q17 is saturated, Q20 and Q14 are turned off.  \nThe output structure of the timer is a “totem-pole” design, with Q22 and Q24 being large","cbCaif07s84IaAS2","https://ap.wps.com/l/cbCaif07s84IaAS2","pdf",364363,"English","# Introduction\n# Description\n## Timer circuitry\n# Output\n# Reset Function","[{\"question\":\"What internal blocks make up the 555 timer described in AN170?\",\"answer\":\"The document describes two voltage comparators, a bistable flip-flop, a discharge transistor, and a resistor divider reference network that sets comparator levels.\"},{\"question\":\"How does the timer decide when to set or reset during an RC timing cycle?\",\"answer\":\"When the trigger voltage falls below one third of the supply, the trigger comparator sets the flip-flop and drives the output high; when the capacitor voltage exceeds two thirds of the supply, the threshold comparator resets the flip-flop and drives the output low.\"},{\"question\":\"What are the differences between using the timer as a one-shot versus an oscillator?\",\"answer\":\"For one-shot operation, only resistance and capacitance are needed as external components; for oscillator operation, one additional resistor is required for generating repeated cycles and adjustable duty cycles.\"}]","NE555 and NE556 applications - AN170 - Application note | PDF",48]