1 data sheet STC705-706/706p-707-708-708t/s/r-813l p supervisor circuits -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- stc ver1.0 features ? precision supply-voltage monitor - 4.63v (stc706l/705, 813l, 708l/707) - 4.38v (stc706m/706, 813m, 708m/708) - 3.08v (stc706t, 813t, 708t) - 2.93v (stc706s, 813s, 708s) - 2.63v (stc706r, 813r/706p, 708r) - 2.32v (stc706z, 813z, 708z) - 2.20v (stc706y, 813y, 708y) 200ms reset pulse width debounced ttl/cmos-compatible manual- reset input independent watchdog timer 1.6sec time-out (not available for stc707/708/708t/708s/r/z/y) reset output signal: - active-low only (STC705/706/706t/s/r/z/y) - active-high only (stc813l/m/t/s/r/706p) - active-high and active-low (707/708/708t/s/r) voltage monitor for power-fail or low battery warning guaranteed reset/reset valid at v cc = 1.2v introduction the stc706x/813x/708x family microprocessor (p) supervisory circuits are targeted to improve reliability and accuracy of power-supply circuitry in p systems. these devices reduce the complexity and number of components required to monitor power- supply and battery functions. the main functions are: 1. asserting reset output during power-p, power- down and brownout conditions for p system; 2. detecting power failure or low-battery conditions with a 1.25v threshold detector; 3. w atchdog functions (not for stc708x). applications power-supply circuitry in p systems
2 data sheet STC705-706/706p-707-708-708t/s/r-813l p supervisor circuits -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- stc ver1.0 contents features ............................................................................................................................... ........................ 1 block diagram .................................................................................................................. .......................... 1 introduction ............................................................................................................................... .................. 1 pin information ................................................................................................................ ........................... 4 pin configuration .............................................................................................................. ................ 4 pin description ................................................................................................................ .................. 4 functional description ......................................................................................................... ....................... 5 reset output ................................................................................................................... ................... 5 watchdog timer ................................................................................................................. ............... 5 manual reset ................................................................................................................... .................. 5 power-fail comparator .......................................................................................................... ........... 5 function reference table ....................................................................................................... ........... 6 detailed specifications ........................................................................................................ ........................ 7 absolute maximum ratings ....................................................................................................... ....... 7 recommended operation condition ................................................................................................ .7 dc electrical characteristics .................................................................................................. ........... 8 ac electrical characteristics .................................................................................................. ........... 9 ordering information ........................................................................................................... ..................... 10 mechanical information ......................................................................................................... ................... 11 notes .......................................................................................................................... ............................... 12
3 data sheet STC705-706/706p-707-708-708t/s/r-813l p supervisor circuits -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- stc ver1.0 reset generator mr vcc pfi pfo reset 1.25v v rst vcc 250ua reset figure 2. block diagram of stc708x / 707 block diagram figure 1. block diagram of stc706x/707, stc813x/706p v cc 250ua v rst 1.25v watchdog transition detector watchdog timer wdi wdo timebase for reset & watchdog reset generator mr vcc pfi reset *706x (reset *813x,706p) pfo
4 data sheet STC705-706/706p-707-708-708t/s/r-813l p supervisor circuits -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- stc ver1.0 pin information pin configuration figure 3. pin configuration top view 1 2 3 4 8 7 6 5 m r v cc gnd pfi wdo reset wdi pfo stc706l/m/t/s/resa stc706l/m/t/s/repa 8-pin soic/8-pin pdip 1 2 3 4 8 7 6 5 mr v cc gnd pfi wdo reset wdi pfo stc813l/m/t/s/r/706pesa stc813l/m/t/s/r/706pepa 8-pin soic/8-pin pdip 1 2 3 4 8 7 6 5 mr v cc gnd pfi reset reset nc pfo stc708l/m/t/s/resa stc708l/m/t/s/repa 8-pin soic/8-pin pdip pin description table 1. pin description e m a n n i pe m a n n i p e m a n n i p e m a n n i pe m a n n i pe p y te p y t e p y t e p y te p y tn o i t p i r c s e dn o i t p i r c s e d n o i t p i r c s e d n o i t p i r c s e dn o i t p i r c s e d r mi : t e s e r - l a u n a m: t e s e r - l a u n a m : t e s e r - l a u n a m : t e s e r - l a u n a m: t e s e r - l a u n a m 0 5 2 l a n r e t n i n a s a h t i . w o l e v i t c a , v 8 . 0 w o l e b d e l l u p n e h w e s l u p t e s e r a s r e g g i r t a a h t i w d n u o r g o t d e t r o h s s a l l e w s a e n i l c i g o l s o m c r o l t t a m o r f n e v i r d e b d n a t n e r r u c p u - l l u p . h c t i w s c c vr e w o p y l p p u s r e w o py l p p u s r e w o p y l p p u s r e w o p y l p p u s r e w o py l p p u s r e w o p d n gd n u o r g e c n e r e f e r d n u o r ge c n e r e f e r d n u o r g e c n e r e f e r d n u o r g e c n e r e f e r d n u o r ge c n e r e f e r d n u o r gs l a n g i s l l a r o f i f pi u p n i r o t i n o m e g a t l o v l i a f - r e w o pu p n i r o t i n o m e g a t l o v l i a f - r e w o p u p n i r o t i n o m e g a t l o v l i a f - r e w o p u p n i r o t i n o m e g a t l o v l i a f - r e w o pu p n i r o t i n o m e g a t l o v l i a f - r e w o p o t i f p t c e n n o c . w o l s e o g o f p , v 5 2 . 1 n a h t s s e l s i i f p n e h w : t . d e s u t o n n e h w c c v r o d n g o f po : t u p t u o l i a f - r e w o p: t u p t u o l i a f - r e w o p : t u p t u o l i a f - r e w o p : t u p t u o l i a f - r e w o p: t u p t u o l i a f - r e w o p s y a t s o f p e s i w r e h t o ; v 5 2 . 1 n a h t s s e l s i i f p n e h w t n e r r u c s k n i s d n a w o l s t e g t i . h g i h i d wi u p n i g o d h c t a wu p n i g o d h c t a w u p n i g o d h c t a w u p n i g o d h c t a wu p n i g o d h c t a w d n a t u o s n u r r e m i t g o d h c t a w l a n r e t n i e h t , c e s 6 . 1 r o f w o l r o h g i h s n i a m e r i d w f i : t s e l b a s i d r e f f u b e t a t s - e e r h t e c n a d e p m i - h g i h a o t i d w g n i t c e n n o c r o i d w g n i t a o l f . w o l s e o g o d w - e e r h t s i i d w . d e t r e s s a s i t e s e r r e v e n e h w s r a e l c r e m i t g o d h c t a w l a n r e t n i e h t . e r u t a e f g o d h c t a w e h t . e g d e g n i l l a f r o g n i s i r a s e e s i d w r o , d e t a t s c nt c e n n o c o n t e s e ro : s e s l u p t u p t u o t e s e r: s e s l u p t u p t u o t e s e r : s e s l u p t u p t u o t e s e r : s e s l u p t u p t u o t e s e r: s e s l u p t u p t u o t e s e r t e s e r e h t w o l e b s i c c v r e v e n e h w w o l s y a t s d n a , d e r e g g i r t n e h w s m 0 0 2 r o f w o l w o l m o r f s e o g r m r o d l o h s e r h t t e s e r e h t e v o b a s e s i r c c v r e t f a s m 0 0 2 r o f w o l s n i a m e r t i . d l o h s e r h t . r m o t d e t c e n n o c s i o d w s s e l n u t e s e r r e g g i r t t o n l l i w t u o e m i t g o d h c t a w a . h g i h o t o d wo t u p t u o g o d h c t a wt u p t u o g o d h c t a w t u p t u o g o d h c t a w t u p t u o g o d h c t a wt u p t u o g o d h c t a w s e o d d n a t n u o c c e s 6 . 1 s t i s e h s i n i f r e m i t g o d h c t a w l a n r e t n i e h t n e h w w o l s l l u p : . s n o i t i d n o c e n i l - w o l g n i r u d w o l s e o g o s l a o d w . d e r a e l c s i g o d h c t a w e h t l i t n u n i a g a h g i h o g t o n s e o d o d w , t e s e r e k i l n u , r e v e w o h ; w o l s y a t s o d w , d l o h s e r h t t e s e r e h t w o l e b s i c c v r e v e n e h w h g i h s e o g o d w , d l o h s e r h t t e s e r e h t e v o b a s e s i r c c v s a n o o s s a . h t d i w e s l u p m u m i n i m e v a h t o n . y a l e d o n h t i w t e s e ro e s e r f o e s r e v n i e h te s e r f o e s r e v n i e h t e s e r f o e s r e v n i e h t e s e r f o e s r e v n i e h te s e r f o e s r e v n i e h t. w o l s i t e s e r , h g i h s i t e s e r r e v e n e h w . h g i h e v i t c a : t
5 data sheet STC705-706/706p-707-708-708t/s/r-813l p supervisor circuits -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- stc ver1.0 functional description the stcxxx family can assert reset output during power-up, power-down and brownout conditions for up system, detect power failure or low-battery conditions with a 1.25v threshold detector and have watchdog functions. refer to table 2 for their individual features. the typical application see figure 4. reset output the supervisory circuits can assert reset for a microprocessor during power-up, power-down and brownout to prevent code execution errors. on power-up, once v cc reaches about 1.2v, reset is a guaranteed logic low of 0.4v or less. as v cc rises, reset stays low. when v cc rises above the reset threshold, an internal timer releases reset after about 200ms. reset pulses low whenever v cc drops below the reset threshold (brownout condition). if brownout occurs in the middle of a previously initiated reset pulse, the pulse continues for at least another 140ms. on power-down, once v cc falls below the reset threshold, reset stays low and is guaranteed to be 0.4v or less until vcc drops below 1v. the stc813x and stc706p active-high reset output is simply the complement of the reset output, and is guaranteed to be valid with v cc down to 1.2v. some ps, such as intel ? s 80c51, require an active-high reset pulse. watchdog timer the watchdog circuit monitors the p ? s activity. if the p does not toggle the watchdog input (wdi) within 1.6sec and wdi is not in high impedance, wdo goes low. as long as reset is asserted or the wdi input is in high impedance, the watchdog timer will stay cleared and will not count. as soon as reset is released and wdi is driven high or low, the timer will start counting. pulses as short as 50ns can be detected. typically, wdo will be connected to the non-maskable interrupt input (nmi) of a p. when v cc drops below the reset threshold, wdo will go low whether or not the watchdog timer has timed out yet. normally this would trigger an nmi interrupt, but reset goes low simultaneously, and thus overrides the nmi interrupt. if wdi is left unconnected, wdo can be used as a low-line output. since floating wdi disables the internal timer, wdo goes low only when v cc falls below the reset threshold, thus functioning as a low-line output. manual reset the manual-reset input (mr) allows reset to be triggered by a push-button switch. the switch is effectively debounced by the 140ms minimum reset pulse width. mr is ttl/cmos logic compatible, so it can be driven by any logic reset output. power-fail comparator the power-fail comparator will send out a low signal once detects a voltage lowered than 1.25v. it can be used for various purposes because its output and non-inverting input are not internally connected. the inverting input is internally connected to a 1.25v reference. figure 4. typical application circuit dc linear regulator vcc supervisory pfi circuit wdi p vcc reset i/o line nmi interrupt in out reset wdo pfo mr p
6 data sheet STC705-706/706p-707-708-708t/s/r-813l p supervisor circuits -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- stc ver1.0 function reference table table 2. function table of pt7a75xx family stc706l/705 4.63v low 200 1.6 1.25v detector yes stc813l 4.63v high 200 1.6 1.25v detector yes stc7 08l/707 4.63v low, high 200 unavailable 1.25v detector yes stc706m/706 4.38v low 200 1.6 1.25v detector yes stc813m 4.38v high 200 1.6 1.25v detector yes stc708m/708 4.38v low, high 200 unavailable 1.25v detector yes stc706t 3.08v low 200 1.6 1.25v detector yes stc813t 3.08v high 200 1.6 1.25v detector yes stc708t 3.08v low, high 200 unavailable 1.25v detector yes stc706s 2.93v low 200 1.6 1.25v detector yes stc813s 2.93v high 200 1.6 1.25v detector yes stc708s 2.93v low, high 200 unavailable 1.25v detector yes stc706r 2.63v low 200 1.6 1.25v detector yes stc813r/706p 2.63v high 200 1.6 1.25v detector yes stc708r 2.63v low, high 200 unavailable 1.25v detector yes stc706z 2.32v low 200 1.6 1.25v detector yes stc813z 2.32v high 200 1.6 1.25v detector yes stc708z 2.32v low, high 200 unavailable 1.25v detector yes stc706y 2.20v low 200 1.6 1.25v detector yes stc813y 2.20v high 200 1.6 1.25v detector yes stc708y 2.20v low, high 200 unavailable 1.25v detector yes nom. watch dog time (sec), t wd power fail comp. manual reset input part no. reset threshold reset active low or high nom. reset time (ms), t rs
8 data sheet STC705-706/706p-707-708-708t/s/r-813l p supervisor circuits -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- stc ver1.0 mechanical information figure 7. 8-pin soic
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