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ds04-27402-3e fujitsu semiconductor data sheet assp power-voltage monitoring ic with watchdog timer MB3793-42 n n n n description the mb3793 is an integrated circuit to monitor power voltage; it incorporates a watchdog timer. a reset signal is output when the power is cut or falls abruptly. when the power recovers normally after resetting, a power-on reset signal is output to microprocessor units (mpus). an internal watchdog timer with two inputs for system operation diagnosis can provide a fail-safe function for various application systems. there is also a mask option that can detect voltages of 4.9 to 2.4v in 0.1-v steps. the model number and package code are as shown below. n n n n features ? precise detection of power voltage fall: 2.5% ? detection voltage with hysteresis ? low power dispersion: i cc = 27 m a (reference) ? internal dual-input watchdog timer ? watchdog timer halt function (by inhibition terminal) ? independently-set watchdog and reset times ? mask option for detection voltage (4.9 to 2.4 v, 0.1-v steps) n n n n packages model no. package code detection voltage MB3793-42 3793-a 4.2 v 8-pin plastic dip 8-pin plastic sop 8-pin plastic sol (dip-8p-m01) (fpt-8p-m01) (fpt-8p-m02)
MB3793-42 2 n n n n pin assignment n n n n pin description pin no. symbol description pin no. symbol description 1 reset outputs reset 5 v cc power supply 2 ctw sets monitoring time 6 inh inhibits watchdog timer function 3 ctp sets power-on reset hold time 7 ck2 inputs clock 2 4 gnd ground 8 ck1 inputs clock 1 reset ctw ctp gnd ck1 ck2 inh v cc (dip-8p-m01) (fpt-8p-m01) (fpt-8p-m02) (top view) 1 2 3 4 8 7 6 5
MB3793-42 3 n nn n block diagram ctp reset inh ctw ck1 ck2 v cc gnd comp. o i 1 @ 3 m ai 2 @ 30 m a r 1 @ 590 k w q rsff2 q s r q rsff1 q s r comp. s - + v s v ref @ 1.24 v r 2 @ 240 k w + - 3 1 6 2 8 7 4 5 to v cc of all blocks output buffer p u l se generator 1 p u l se generator 2 to gnd of all blocks watchdog timer reference voltage generator
MB3793-42 4 n n n n block functions 1. comp. s comp. s is a comparator with hysteresis to compare the reference voltage with a voltage (v s ) that is the result of dividing the power voltage (v cc ) by resistors r 1 and r 2 . when v s falls below 1.24 v, a reset signal is output. this function enables the mb3793 to detect an abnormality within 1 m s when the power is cut or falls abruptly. 2. comp. o comp. o is a comparator to control the reset signal (reset ) output and compares the threshold voltage with the voltage at the ctp terminal for setting the power-on reset hold time. when the voltage at the ctp terminal exceeds the threshold voltage, resetting is canceled. 3. reset output buffer since the reset (reset ) output buffer has cmos organization, no pull-up resistor is needed. 4. pulse generator the pulse generator generates pulses when the voltage at the ck1 and ck2 clock terminals changes to high from low level (positive-edge trigger) and exceeds the threshold voltage; it sends the clock signal to the watchdog timer. 5. watchdog timer the watchdog timer can monitor two clock pulses. short-circuit the ck1 and ck2 clock terminals to monitor a single clock pulse. 6. inhibition terminal the inhibition (inh) terminal forces the watchdog timer on/off. when this terminal is high level, the watchdog timer is stopped. 7. flip-flop circuit the flip-flop circuit rsff1 controls charging and discharging of the power-on reset hold time setting capacity (c tp ). the flip-flop circuit rsff2 switches the charging accelerator for charging c tp during resetting on/off. this circuit only functions during resetting and does not function at power-on reset.
MB3793-42 5 n n n n absolute maximum ratings *: the power voltage is based on the ground voltage (0 v). warning: semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings. do not exceed these ratings. n n n n recommended operating conditions warning: the recommended operating conditions are required in order to ensure the normal operation of the semiconductor device. all of the devices electrical characteristics are warranted when the device is operated within these ranges. always use semiconductor devices within their recommended operating condition ranges. operation outside these ranges may adversely affect reliability and could result in device failure. no warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet. users considering application outside the listed conditions are advised to contact their fujitsu representatives beforehand. (ta = + 25 c) parameter symbol rating unit min. max. power voltage* v cc - 0.3 + 7v input voltage* ck1 v ck1 - 0.3 + 7v ck2 v ck2 inh v inh reset output voltage (direct current) reset i ol i oh - 10 + 10 ma power dissipation (ta +85 c) p d ? 200 mw storage temperature tstg - 55 + 125 c parameter symbol value unit min. typ. max. power supply voltage v cc 1.2 5.0 6.0 v reset (reset ) output current i ol i oh - 5 ?+ 5ma power-on reset hold time setting capacity c tp 0.001 0.1 10 m f watchdog timer monitoring time setting capacity c tw 0.001 0.1 1 m f watchdog timer monitoring time t wd 0.1 ? 1500 ms operating ambient temperature ta - 40 + 25 + 85 c
MB3793-42 6 n n n n electrical characteristics 1. dc characteristics *1: at clock input terminals ck1 and ck2, the pulse input frequency is 1 khz and the pulse amplitude is 0 v to v cc . *2: inhibition input is at high level. (v cc = + 5 v , ta = + 25 c) parameter symbol conditions value unit min. typ. max. power current i cc1 watchdog timer operation* 1 ? 27 50 m a i cc2 watchdog timer halt* 2 ? 25 45 detection voltage v sl v cc falling ta = + 25 c 4.10 4.20 4.30 v ta = - 40 to + 85 c 4.05 4.20 4.35 v sh v cc rising ta = + 25 c 4.20 4.30 4.40 v ta = - 40 to + 85 c 4.15 4.30 4.45 detection voltage hysteresis difference v shys v sh - v sl 50 100 150 mv ck input threshold voltage v cih ? (1.4) 1.9 (2.5) v v cil ? (0.8) 1.3 (1.8) v ck input hysteresis v chys ? (0.4) 0.6 (0.8) v inh input voltage v iih ? 3.5 ? v cc v v iil ? 000.8v input current (ck1,ck2,inh) i ih v ck = v cc ? 01.0 m a i il v ck = 0 v - 1.0 0 ?m a reset output voltage v oh i reset = - 5 ma 4.5 4.75 ? v v ol i reset = + 5 ma ? 0.12 0.4 v reset-output minimum power voltage v ccl i reset = + 50 m a ? 0.8 1.2 v
MB3793-42 7 2. ac characteristics *: the voltage range is 10% to 90% at testing the reset output transition time. (v cc = + 5 v , ta = + 25 c) parameter symbol conditions value unit min. typ. max. power-on reset hold time t pr c tp = 0.1 m f 80 130 180 ms watchdog timer monitoring time t wd c tw = 0.01 m f c tp = 0.1 m f 7.5 15 22.5 ms watchdog timer reset time t wr c tp = 0.1 m f 5 10 15 ms ck input pulse duration t ckw ? 500 ?? ns ck input pulse cycle t ckt ? 20 ??m s reset (reset ) output transition time rising tr* c l = 50pf ?? 500 ns falling tf* c l = 50pf ?? 500 ns
MB3793-42 8 n n n n timing diagram 1. basic operation (positive clock pulse) ctp reset inh ctw ck1 ck2 v sh v cc v sl v ccl v th v h v l (1) (2) (3) (4) (5) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) t pr t wd t pr t wr t ckw
MB3793-42 9 2. basic operation (negative clock pulse) ctp reset inh ctw ck1 ck2 v sh v cc v sl v ccl v th v h v l t pr t wd t pr t wr t ckw (1) (2) (3) (4) (5) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)
MB3793-42 10 3. single-clock input monitoring (positive clock pulse) ctp reset ctw ck1 v th v h v l ck2 t wr t ckw t ckt t wd note: the mb3793 can monitor only one clock. the mb3793 checks the clock signal at every other input pulse. therefore, set watchdog timer monitor time t wd to the time that allows the mb3793 to monitor the period twice as long as the input clock pulse.
MB3793-42 11 4. inhibition operation (positive clock pulse) ctp reset inh ctw ck1 ck2 v sh v cc v sl v ccl v th v h v l t pr t wd t pr t wr t ckw (1) (2) (3) (4) (5) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)
MB3793-42 12 5. clock pulse input (positive clock pulse) 6. inhibition input rising and falling time ctw ck1 ck2 v h v l *1 *2 note: the mb3793 watchdog timer monitors clock 1 (ck1) and clock 2 (ck2) pulses al- ternately. when a ck2 pulse is detected after detecting a ck1 pulse, the monitor- ing time setting capacity (c tw ) switches to charging from discharging. when two consecutive pulses occur on one side of this alternation before switch- ing, the second pulse is ignored. in the above figure, pulses *1 and *2 are ignored. inh 90 % 10 % 90 % 10 % v cc 0 v t fi t ri
MB3793-42 13 n nn n operation sequence the operation sequence is explained by using n timing diagram 1. basic operation (positive clock pulse). the following item numbers correspond to the numbers in n timing diagram 1. basic operation (positive clock pulse). (1) when the power voltage (v cc) reaches about 0.8 v (v ccl ), a reset signal is output. (2) when v cc exceeds the rising-edge detection voltage (v sh ), charging of power-on reset hold time setting capacitance (c tp ) is started. v sh is about 4.3 v. (3) when the voltage at the ctp terminal setting the power-on reset hold time exceeds the threshold voltage (v th ), resetting is canceled and the voltage at the reset terminal changes to high level to start charging of the watchdog timer monitoring time setting capacitance (c tw ). vth is about 3.6 v. the power-on reset hold time (t pr ) can be calculated by the following equation. t pr (ms) ? a c tp ( m f) where, a is about 1300. (4) when the voltage at the ctw terminal setting the monitoring time reaches high level (v h ), c tw switches to discharging from charging. v h is about 1.24 v (reference value). (5) when clock pulses are input to the ck2 terminal during c tw discharging after clock pulses are input to the ck1 terminalpositive-edge trigger, c tw switches to charging. (6) if clock pulse input does not occur at either the ck1 or ck2 clock terminals during the watchdog timer monitoring time (t wd ), the ctw voltage falls below low level (v l ), a reset signal is output, and the voltage at the reset terminal changes to low level. v l is about 0.24 v. t wd can be calculated from the following equation. t wd (ms) ? b c tw ( m f) + c c tp ( m f) where, b is about 1500. c is about 3; it is much smaller than b. hence, when c tp / c tw 10, the calculation can be simplified as follows: t wd (ms) ? b c tw ( m f) (7) when the voltage of the ctp terminal exceeds v th again as a result of recharging c tp , resetting is canceled and the watchdog timer restarts monitoring. the watchdog timer reset time (t wr ) can be calculated by the following equation. t wr (ms) ? d c tp ( m f) where, d is about 100. (8) when v cc falls below the rising-edge detection voltage (v sl ), the voltage of the ctp terminal falls and a reset signal is output, and the voltage at the reset terminal changes to low level. v sl is about 4.2 v. (9) when v cc exceeds v sh , c tp begins charging. (10)when the voltage of the ctp terminal exceeds v th , resetting is canceled and the watchdog timer restarts. (11)when an inhibition signal is input (inh terminal is high level), the watchdog timer is halted forcibly. in this case, v cc monitoring is continued without the watchdog timer. the watchdog timer does not function unless this inhibition input is canceled. (12)when the inhibition input is canceled (inh terminal is low level), the watchdog timer restarts. (13)when the v cc voltage falls below v sl after power-off, a reset signal is output. (14)when the power voltage (v cc ) falls below about 0.8 v (v ccl ) , a reset signal is released. similar operation is also performed for negative clock-pulse input ( n timing diagram 2. basic operation (negative clock pulse)). short-circuit the clock terminals ck1 and ck2 to monitor a single clock. the basic operation is the same but the clo c k pulses are monitored at e v e r y other pulse ( n timing dia g r am 3. single - clo c k input monito r i ng).
MB3793-42 14 n n n n typical characteristics 40 35 30 25 20 15 10 MB3793-42 c tw c tp v inh v cc 0.01 m f 0.1 m f 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 (v inh = 0 v) (v cc < v sh ) ta = + 25 c ta = + 85 c ta = - 40 c 0 012345678910 100 200 300 400 500 v reset i reset ta r on 98 mv + 5 ma - 40 c 19.6 w 135 mv + 25 c 27 w 167 mv + 85 c 33.4 w 4.0 - 20 - 40 0 20406080100 4.1 4.2 4.3 4.4 4.5 v sh v sl ta = + 25 c ta = + 85 c ta = - 40 c 4.0 0 - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 v reset i reset ta r on 4.800 v - 5 ma - 40 c 40 w 4.750 v + 25 c 50 w 4.707 v + 85 c 58.6 w power current - power voltage power current i cc ( m a) power voltage v cc (v) watchdog timer monitoring watchdog timer stopping (v inh = v cc ) reset inhibited detection voltage - ambient temperature detection voltage v sh and v sl (v) ambient temperature ta ( c) reset output current i reset (ma) reset output voltage v reset (v) reset output voltage - reset output current (p-mos side) reset output voltage - reset output current (n-mos side) reset output voltage v reset (mv) reset output current i reset (ma) f = 1 khz duty = 10 % v l = 0 v v h = v cc
MB3793-42 15 7 6 5 4 3 2 1 0 012 34 56 7 ta = + 85 c ta = + 25 c ta = - 40 c - 40 - 20 0 2 0 4 0 6 0 8 0 100 0 20 40 60 80 100 120 140 160 180 200 220 240 260 - 40 - 20 0 2 0 4 0 6 0 8 0 100 0 2 4 6 8 10 12 14 16 18 20 22 24 26 - 40 - 20 0 2 0 4 0 6 0 8 0 100 0 2 4 6 8 10 12 14 16 18 20 22 24 26 reset output voltage - power voltage power voltage v cc (v) reset output voltage v reset (v) pull-up resistance: 100 k w r eset-on reset time - ambient temperature (when v cc rising) ambient temperature ta ( c) power-on reset time t pr (ms) watchdog timer reset time - ambient temperature (when monitoring) watchdog timer monitoring time - ambient temperature ambient temperature ta ( c) ambient temperature ta ( c) watchdog timer reset time t wr (ms) watchdog timer monitoring time t wd (ms)
MB3793-42 16 10 4 10 3 10 2 10 1 1 10 - 1 10 - 4 10 - 3 10 - 2 10 - 1 110 1 10 2 ta = - 40 c ta = + 25 c ta = + 85 c 10 3 10 2 10 1 1 10 - 1 10 - 4 10 - 3 10 - 2 10 - 1 110 1 10 2 10 - 2 ta = - 40 c ta = + 25 c ta = + 85 c 10 3 10 2 10 1 1 10 - 1 10 - 4 10 - 3 10 - 2 10 - 1 110 1 10 - 5 ta = - 40 c ta = + 25 c ta = + 85 c 10 4 10 3 10 2 10 1 1 10 - 1 10 - 4 10 - 3 10 - 2 10 - 1 110 1 10 - 5 c tp = 0.01 m f c tp = 0.1 m f c tp = 1 m f power-on reset time - c tp capacitance reset time - c tp capacitance power-on reset time t pr (ms) power-on reset time setting capacitance c tp ( m f) power-on reset time setting capacitance c tp ( m f) watchdog timer monitoring time - c tw capacitance (under ta condition) watchdog timer monit o ring time - c tw capacitance watchdog timer monitoring time t wd (ms) watchdog timer monitoring time setting capacitance c tw ( m f) watchdog timer monitoring time setting capacitance c tw ( m f) watchdog timer monitoring time t wd (ms) reset time t wr (ms)
MB3793-42 17 n n n n standard connection equation of time-setting capacitances (c tp and c tw ) and set time t pr (ms) ? a c tp ( m f) t wd (ms) ? b c tw ( m f) + c c tp ( m f) however, when c tp /c tw 10, t wd (ms) ? b c tw ( m f) t wr (ms) ? d c tp ( m f) value of a, b, c and d (example) when c tp = 0.1 m f and c tw = 0.01 m f, t pr ? 130 [ms] t wd ? 15 [ms] t wr ? 10 [ms] a b c d remark 1300 1500 3 100 v cc v cc c tw c tp ctw ctp ck1 ck2 inh gnd reset reset v cc ck gnd reset v cc ck gnd mb3793 3 5 1 6 4 2 8 7 micro- processor 1 micro- processor 2
MB3793-42 18 n n n n application example 1. monitoring single clock 2. watchdog timer stopping v cc v cc c tw c tp ctw ctp ck1 ck2 inh gnd reset reset v cc ck gnd mb3793 5 1 8 7 4 6 3 2 micro- processor v cc v cc c tw c tp ctw ctp ck1 ck2 gnd reset reset v cc ck gnd reset v cc ck gnd mb3793 5 1 8 7 4 6 3 2 inh halt halt micro- processor1 micro- processor2
MB3793-42 19 n n n n ordering information part number package remarks MB3793-42p 8-pin plastic dip (dip-8p-m01) MB3793-42pf 8-pin plastic sop (fpt-8p-m01) MB3793-42pnf 8-pin plastic sol (fpt-8p-m02)
MB3793-42 20 n n n n package dimensions (continued) 8-pin plastic dip (dip-8p-m01) dimensions in mm (inches) c 1994 fujitsu limited d08006s-2c-3 0.89 +0.35 ?.30 ?.30 +0.40 9.40 ? 0.99 1.52 +0.30 ? +.014 ?012 .035 .370 ?012 +.016 .060 ? +.012 +.012 ? .039 4.36(.172)max 3.00(.118)min 2.54(.100) typ 0.46?.08 (.018?003) 0.25?.05 (.010?002) 0.51(.020)min 7.62(.300) typ 15?ax 1 pin index 6.20?.25 (.244?010) +0.30
MB3793-42 21 (continued) 8-pin plastic sop (fpt-8p-m01) dimensions in mm (inches) c 2000 fujitsu limited f08002s-4c-5 0.13(.005) m "a" 0.68(.027)max 0.18(.007)max 0.20(.008) 0.50(.020) details of "a" part 0.45?.10 0.05(.002)min 7.80?.40 5.30?.30 0.50?.20 (.020?008) (stand off) (.018?004) (.209?012) (.307?016) .250 ?008 +.010 ?.20 +0.25 6.35 .006 ?001 +.002 ?.02 +0.05 0.15 .268 ?008 +.016 ?.20 +0.40 6.80 index typ 1.27(.050) 3.81(.150)ref 2.25(.089)max (mounting height) 0.10(.004)
MB3793-42 22 (continued) 8-pin plastic sol (fpt-8p-m02) dimensions in mm (inches) c 2000 fujitsu limited f08004s-2c-5 1.27(.050)typ 0.42?.10 0.20?.05 0.15?.10 3.90?.30 6.00?.40 0.50?020 5.00?.30 0.40(.016) 3.81(.150)ref .199 ?008 +.010 ?.20 +0.25 5.05 0.13(.005) m (.017?004) (.008?002) (.154?012) (.236?016) (.197?012) (.006?004) "a" 0.65(.026)max 0.18(.007)max 0.40(.016) 0.20(.008) details of "a" part (.020?008) (stand off) 45 1.55?.20(.061?008) (mounting height) 0.10(.004)
MB3793-42 fujitsu limited f o r fur t her inf o r m ation please contact: japan fujitsu limited marketing division electronic devices shinjuku dai-ichi seimei bldg. 7-1, nishishinjuku 2-chome, shinjuku-ku, tokyo 163-0721, japan tel: +81-3-5322-3353 fax: +81-3-5322-3386 http://ede v ice . fujitsu.com/ north and south america fujitsu microelectronics, inc. 3545 north first street, san jose, ca 95134-1804, u.s.a. tel: +1-408-922-9000 fax: +1-408-922-9179 customer response center mon. - f r i.: 7 am - 5 pm (pst) tel: +1-800-866-8608 fax: +1-408-922-9179 http://www . fujitsumicro . com/ europe fujitsu microelectronics europe gmbh am siebenstein 6-10, d-63303 dreieich-buchschlag, germany tel: +49-6103-690-0 fax: +49-6103-690-122 http://www . fujitsu-fme .com/ asia pacific fujitsu microelectronics asia pte. ltd. #05-08, 151 lorong chuan, new tech park, singapore 556741 tel: +65-281-0770 fax: +65-281-0220 http://ww w . fma l . fuj it su . com / korea fujitsu microelectronics korea ltd. 1702 kosmo tower, 1002 daechi-dong, kangnam-gu,seoul 135-280 korea tel: +82-2-3484-7100 fax: +82-2-3484-7111 f0106 ? fujitsu limited printed in japan all rights reserved. the contents of this document are subject to change without notice. customers are advised to consult with fujitsu sales representatives before ordering. the information and circuit diagrams in this document are presented as examples of semiconductor device applications, and are not intended to be incorporated in devices for actual use. also, fujitsu is unable to assume responsibility for infringement of any patent rights or other rights of third parties arising from the use of this information or circuit diagrams. the products described in this document are designed, and manufactured as contemplated for general use, including without limitation, ordinary industrial use, general office use, personal use, and household use, but are not designed, developed and manufactured as contemplated (1) for use accompanying fatal risks or dangers that, unless extremely high safety is secured, could have a serious effect to the public, and could lead directly to death, personal injury, severe physical damage or other loss (i.e., nuclear reaction control in nuclear facility, aircraft flight control, air traffic control, mass transport control, medical life support system, missile launch control in weapon system), or (2) for use requiring extremely high reliability (i.e., submersible repeater and artificial satellite). please note that fujitsu will not be liable against you and/or any third party for any claims or damages arising in connection with above-mentioned uses of the products. any semiconductor devices have inherently a certain rate of failure. you must protect against injury, damage or loss from such failures by incorporating safety design measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current levels and other abnormal operating conditions. if any products described in this document represent goods or technologies subject to certain restrictions on export under the foreign exchange and foreign trade control law of japan, the prior authorization by japanese government should be required for export of those products from japan.

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