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th e p o w e r su p p ly c irc u it su s ta in s th e o ff sta te a s lo n g a s c u rre n t o f 5 0 0

m in im u m flo w s to V in te rm in a l

fro m a sta rt u p re s is to r.
In o rd e r to p re v e n t a m a lfu n ctio n to b e ca u s e d b y a no ise an d so o n , d ela y tim e is p ro vid e d b y C 1

in c o rp ora te d in th e IC a n d, th e re fo re , th e la tc h c irc uit o p e ra te s w h e n th e O V P or T S D c irc uit is in o p e ra tio n ,

o r a n e xte rn a l sig na l in p u t is p ro vide d fo r a b o u t 1 0

o r lo n g e r.

In a d d itio n , e v e n a fte r th e la tch circ u it sta rt op e ra tin g, th e c o n sta n t vo lta g e re g u la to r c ircu it is in o p e ra tio n

a n d th e c ircu it c u rre n t is a t h ig h le ve l.
A s a re s ult, V in te rm in a l v o lta g e ra p id ly d e cre a s es .

W h e n V in te rm in a l v olta g e b e c o m e s lo w e r th an th e sh u td ow n vo lta g e , V IN (O F F ) (4 .9 V ty p ic al), it s ta rts

in c re a sin g a s th e c irc u it cu rre nt is b e lo w 5 0 0

W h e n it re a c h e s th e O N -s ta te v o lta g e , V IN (O N ) (8 V typ ica l), V in te rm in a l v o lta g e s ta rts d e c rea s in g be c a u se
th e c ircu it c u rre n t in c re a s e s a g a in .

W h e n th e la tch circ u it is o n , Vin te rm ina l v o lta g e in c re a se s a n d d e c re a se s w ith in th e ra n g e fro m 4 .9 V ty p ica l
to 8 V ty p ic a l a n d is p rev e n te d fro m a b no rm a lly risin g .

C a lib ra tio n o f th e la tc h is d o n e b y d e c re a sin g Vin term in a l v o lta g e b elo w 3 .3 V.
T h e p o w e r su p p ly c a n b e re s ta rte d a fter d isc o n n e ctin g a n A C inp u t to th e p o w e r su p p ly o n c e .

7 . T h e rm a l sh u td o w n circ u it

It is a c ircu it to trig ge r th e la tc h c irc u it w h e n th e fra m e te m p era tu re o f th e IC e x ce e d s 1 5 0

(typ ica l).

A lth o u g h th e te m p e ra tu re is a c tu a lly se n s e d a t th e co n tro l c h ip , it w o rk s a g a in st o v e rh e a tin g o f the

p o w e r tra n s isto r a s the p o w er tra n sis tor a n d th e co n tro l IC a re m o u n te d o n the sa m e le a d fra m e .

8 . O v er-v olta g e p ro te c tio n c irc u it

It is a c ircu it to trig ge r th e la tc h c irc u it w h e n V in te rm in a l vo lta g e e x ce e d s 11 V (typ ic a l).
A lth ro u g h it b a s ic ally fu n c tio n s a s p ro tec tio n s a s p ro te ctio n o f V in te rm in a l ag a ins t o v er-v o lta g e ,

s in c e V in te rm in a l is u su a lly s u p p lie d fro m th e d riv e w in d in g o f th e tra n s fo rm e r a n d th e v o lta ge is p ro p o r
a tio n a l to the o u tp u t v o lta g e , it a ls o fun c tio n s a ga in st the o ve r-vo lta g e o f s e co n d a ry o u tp u t w h ich ca u s e s

w h e n th e c o n tro l c ircu it o p e n s o r in s o m e o th e r e ve n ts.

7-15. Stand-by Mode TOP210

T h is IC (T O P 2 1 0 ) is u se d fo r lo w -p o w e r c o n c u m p tio n w he n rec e iv e r is o p e ra tin g in s ta n d -b y m o d e .

1 . D R A IN P IN (pin 5 )

O u tp u t M O S F E T d ra in c o nn e c tio n. P ro vid e s in te rn a l b ia s c u rre n t d u rin g s ta rt-u p o p e ra tio n via a n in te rn a l

s w itc h e d h ig h vo lta g e c u rre n t so u rc e . In te rn a l cu rren t s e n se p o in t.

2 . C O N T R O L P IN (p in 4 )

E rro r a m p lifie r a nd fe e d b a c k cu rre n t in p ut p in fo r d u ty c yc le c o n tro l.
In te rn a l b ia s c u rre n t d u rin g n o rm a l o p e ra tio n .

It is a ls o u s ed a s th e su p p ly b y p a ss a n d a u to -re s ta rt/c o m p e n sa tio n c a p a cito r c o n ne c tio n p o in t.