mitsumi system reset (with battery back-up) pst620, 621 system reset (with battery back-up) monolithic ic pst620, 621 outline features 1. low current consumption 2. capacitors (super capacitor, large capacity chemical capacitor) are used for back-up power supply, lowering system cost 3. stable 1-chip microcomputer crystal oscillator rise time maintained with the built-in pulse shaver. 4. in addition to power outage detection for main power supply (+5v), there are built-in pins to detect ac power supply and +5v power supply primary side 5. reset signal output by back-up power supply (super capacitor, large capacity chemical capacitor) detection applications 1. vcr 2. audio equipment 3. communications equipment 4. rice cookers, etc. pin assignment pin description 14 32 85 67 pst620 pin no. pin name function 1 v ac has +2.0v detection voltage to detect ac power supply and stable power supply primary side, for quick power outage detection. 2 v cc1 +5v main power supply 3 v cc2 back-up power supply (back-up capacitor connected) 4 tc pulse width setting pin for pulse shaver (capacitor and resistor connected) 5 re reset output 6 ps cont pulse shaver on/off switching high : off low : on 7 ce chip enable signal output 8 gnd gnd package dip-8b (pst620ddb, PST621DDB) sop-8c (pst620dft, pst621dft) these ics are part of the regular series of back-up ics, and use capacitors (super capacitor, large capacity chemical capacitor) as back-up power supply. they control 1-chip microcomputer high-speed, low-speed, and stand-by modes (mni control). these ics also are capable of controlling data save in eprom and other nonvolatile memories during power outage. products to be discontinued
mitsumi system reset (with battery back-up) pst620, 621 pst621 pin no. pin name function 1 v ac has +2.0v detection voltage to detect ac power supply and stable power supply primary side, for quick power outage detection. 2 v cc 1 +5v main power supply 3 v cc 2 back-up power supply (back-up capacitor connected) 4 t c pulse width setting pin for pulse shaver (capacitor and resistor connected) 5 re --------------------------------------------------------------- reset output 6 mode switches 1-chip microcomputer mode with pulse shaver output signal 7 ce chip enable signal output (power outage detection signal) 8 gnd gnd block diagram pst620 pst621 absolute maximum ratings (ta=25 c) item symbol rating storage temperature t stg - 40~+125 c operating temperature t opr - 20~+70 c power supply voltage v cc max. - 0.3~+10v tc input input voltage v c max. v cc 1+0.3v allowable loss pd 450mw products to be discontinued
mitsumi system reset (with battery back-up) pst620, 621 electrical characteristics (ta=25 c) note 1 : * 1 connect tc pin to gnd. note 2 : except where noted otherwise, vac=5v, vc=open. item symbol measurement conditions min. typ. max. units detection voltage 1 v s 1r l 1=47k ce output, v cc 1=l h * 1 4.00 4.20 4.40 detection pst620 v s 2 r l 2=47k , re output 2.00 2.15 2.30 v voltage 2 pst621 v cc 2=h l * 1 2.90 3.10 3.30 detection voltage 3 v s 3r l 1=47k, ce output, v ac =h l * 1 1.85 2.00 2.15 hysteresis voltage 1 v s 1r l 1=47k, ce output, v cc 1=l h l 75 150 300 hysteresis voltage 2 v s 2r l 2=47k, ce output, v cc 2=l h l 25 50 100 mv hysteresis voltage 3 v s 3r l 1=47k ce output, v ac =l h l 45 90 180 detection voltage v s / t r l 1=47k , ce output 0.01 temperature coefficient 1 detection voltage v s / t r l 2=47k , re output 0.02 %/ c temperature coefficient 2 detection voltage v s / t r l 1=47k , ce output 0.01 temperature coefficient 3 low-level output voltage 1 v ol 1 v cc 1=v s 1 min. - 0.05v, r l 1=47k ce output 0.1 0.2 low-level output voltage 2 v ol 2 v cc 2=v s 2 min. - 0.05v, r l 2=47kz re output 0.1 0.4 v low-level output voltage 3 v ol 3 v cc 1=0v, v cc 2=v s2 typ./0.85 r l 1=47k , ce output 0.2 0.4 operation limit voltage 1 v op 1r l 1=47k, v ol 1 < = 0.4v ce output 0.8 1.0 v operation limit voltage 2 v op 2r l 2=47k , v ol 2 < = 0.4v re output 0.8 1.0 consumption current 1 i cc 1v cc 1=v cc 2=v s 1/0.85 5.0 8.5 i cc 2r l 1=r l 2= 2.0 3.5 consumption current 2 i cc 1v cc 1=v cc 2=v s 1 min. - 0.05v 8.0 14.5 a i cc 2r l 1=r l 2= 2.0 3.5 consumption current 3 i cc 1v cc 1=v cc 2=v s 2 min. - 0.05v 8.0 14.5 i cc 2r l 1=r l 2= 4.0 7.0 consumption current 4 i cc 2 v cc 1=0v r l 1=r l 2=, v cc 2=v s1t typ./0.85 2.0 3.5 a consumption current 5 i cc 2 v cc 1=0v r l 1=r l 2= v cc 2=v s 2 min. - 0.05v 4.0 7.0 output current while on 1 i ol 1v cc 1=v s 1 min. - 0.05v, r l 1=0 ce output 2 ma output current while on 2 i ol 2v cc 2=v s 2 min. - 0.05v, r l 2=0 re output 2 transport delay time 1 t plh 1 v cc 1=v s 1 typ.0.4v, r l 2=47k ce output 10 transport delay time 2 t plh 2 v cc 2=v s 2 typ.0.4v, r l 2=47k re output 50 s transport delay time 3 t plh 3 v cc 1=v s 1 typ.0.4v, r l 2=47k ce output 40 transport delay time 4 t plh 4 v cc 2=v s 2 typ.0.4v, r l 2=47k re output 80 ac pin input resistance r acin 0.5 1.0 m one-shot pulse width t pd cd=0.47f rd=100k, v cc 1=v s 1 typ.0.4v 61421ms one-shot output voltage v tol v cc 1=v s1 typ./0.85, r l 1=47k re output, * 1 0.1 0.4 v tc pin threshold voltage v cth r l 1=47k, v c =l h 2.0 v tc input input current i cin v cc 1=v s 1 typ./0.85, vc=5.0v 1 a ps pin input h level voltage v psh 2.0 v ps pin input l level voltage v psl 0.6 v ps pin input h level current i psh v psh =2.0v 10 a products to be discontinued
mitsumi system reset (with battery back-up) pst620, 621 characteristics (pst620, 621 series. however, vs2 in pst620 series only.) i cc 1 ( a) 15.00 i cc 1 (a) 15.00 .0000 .0000 .0000 10.00 1.500/div 1.500/div 1.000/div v cc 1(v) current consumption (v) 4.400 (v) 4.400 .0000 .0000 .0000 10.00 .4400/div .4400/div .0900/div v cc 1 (v) v s 1 (v) 2.300 .0000 2.100 .2300/div (v) 2.300 .0000 2.300 .2300/div v cc 1 (v) .0200/div v s 2 cs (v) 10.00 rest (v) 10.00 .0000 .0000 .0000 10.00 1.000/div 1.000/div 1.000/div v cc 1 (v) v ol 10 5 0 - 250 255075 pulse width (ms) temperature ( c) 1 shot pulse width-temperature 4.30 4.20 4.10 - 25 0 25 50 75 vs1 detection voltage (v) temperature ( c) vs1 detection voltage-temperature 2.20 2.10 2.00 - 25 0 25 50 75 vs2 detection voltage (v) temperature ( c) vs2 detection voltage-temperature 2.10 2.00 1.90 - 250 255075 vs3 detection voltage (v) temperature ( c) vs3 detection voltage-temperature products to be discontinued
mitsumi system reset (with battery back-up) pst620, 621 timing chart v cc 1 v cc 2 ce tc re ce 4.2v 2.15v v tx delay delay note : connect v ac pin to v cc when not using. ac power supply ac rectifier or regulator primary side note 1: vth is set at 2.0v and hysteresis voltage at 90mv. 1. use a resistor to divide the detected voltage so that it equals v th when monitoring regulator primary side power supply. 2. when monitoring ac voltage rectified as in the application circuit, set so that it equals v th by lowering the constant and dividing with a resistor. refer to application circuit diagram. note 2: vac input and vs1 are or, so either signal makes ce low when power outage is detected. pst620 pst621 ac v cc 1 ce mode v cc 2 reset 4.2v 3.1v application circuits v ac input : power supply transformer secondary voltage detection products to be discontinued
mitsumi system reset (with battery back-up) pst620, 621 1. connection 1. +5v power supply to v cc 1 (pin 2). 2. connect back-up capacitor to v cc 2 (pin 3). 3. connect a diode between v cc 1 (pin 2) and v cc 2 (pin 3). 4. connect pulse width setting resistor and capacitor to pc (pin 4) when using pulse shaver. 5. re output (pin 5) is reset signal output and is output when v cc is less than 2.15v. 6. when using pulse shaver, p scont (pin 6) is high level. 7. ce output (pin 7) is for chip enable signal and goes low when power outage is detected. 2. theory of operation 1. when +5v power is supplied normally, it is charged to the back-up capacitor via a diode. 2. the back-up capacitor starts back-up if +5v power supply voltage drops for some reason and v cc 1 goes below 4.2v, and at the same time the ce --------------------------------------------------- signal switches the 1-chip microcomputer to standby mode, so that it operates on low current consumption. 3. when +5v power supply recovers and goes over 4.2v, an re output signal of a certain width is output, and this signal resets the 1-chip microcomputer. at the same time normal mode starts and the time until crystal oscillator output stabilizes is reset. 4. if +5v power supply does not recover, and back-up capacitor voltage goes below 2.15v, reset is carried out by the re output signal to prevent the microcomputer from running wild. 3. setting ac power supply power outage detection 1. theory of operation for detecting ac voltage ac voltage is rectified and smoothed by the capacitor. this voltage is divided and set at vac input detection voltage, +2v. at this time the smoothing capacitor and dividing resistor time constants are used to set ac voltage missing waveform. 2. vac voltage setting (r1, r2) set resistor ratio at the midpoint between r1 and r2 so that the voltage to be detected is +2v. impressed ac voltage there is are no limitations on ac voltage as it is divided by r1 and r2 and applied to pst620. 3. setting time constants to detect ac voltage (c4, r1+r2) for impressed ac voltage of 5vrms, and c4 and r1+r2 time constant of 60ms, set so that ac voltage detects power outage when approximately 2 waveforms are missed. the time constants can be set to detect missing ac waveforms. application circuits vac input : stable power supply primary voltage detection products to be discontinued
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