1 of 4 041002 features automatically restarts microprocessor after power failure maintains reset for 350 ms after v cc returns to an in-tolerance condition reduces need for discrete components precision temperature-compensated voltage reference and voltage sensor low-cost to-92 package or surface mount 8-pin soic packages available internal 5 k pullup resistor compatible with motorola 68xxx series and hc16 microprocessors pin function compatible with the motorola mc33064, mc34064, mc33164, and mc34164 operating temperature of -40c to +85c pin assignment 1 2 3 pin descriptions to-92 1 rst - active low reset output 2 v cc - power supply 3 gnd - ground 8-pin soic rst - active low reset output v cc - power supply nc - no connect gnd - ground description the ds1233m econoreset uses a precis ion temperature-compensated reference and comparator circuit to monitor the status of the power supply (v cc ). when an out-of-tolerance condition is detected, an internal power-fail signal is generated which forces reset to the active (low) state. when v cc returns to an intolerance condition, the reset sign al is kept in the active state fo r approximately 350 ms to allow the power supply and processor to stabilize. ds1233m econoreset www.maxim-ic.com _ _ _ rst v cc n c gnd n c n c n c n c 1 2 3 4 8 7 6 5 ds1233m 8-pin soic (150mil) see mech. drawings section on website bottom vie w to-92 package see mech. drawings section on website 1 2 3 dallas ds1233 econo reset
ds1233m 2 of 4 operation - power monitor the ds1233m provides the functions of detecting out-o f-tolerance power supply conditions and warning a processor-based system of impending power failure. when v cc is detected as out-of-tolerance, as defined by the tolerance of the part selected, the rst signal is asserted. on power-up, rst is kept active for approximately 350 ms after the power supply has re ached the selected tolerance. this allows the power supply and microprocessor to stabilize before rst is released. block diagram figure 1 application example figure 2
ds1233m 3 of 4 timing diagram: power-up figure 3 voltage trip levels parameter symbol min typ max units notes voltage high trip level v htl 4.75 v ds1233m-5, ds1233m-55 voltage low trip level v ltl 4.00 v ds1233m-5, ds1233m-55 voltage high trip level v htl 3.14 v ds1233m-3 voltage low trip level v ltl 2.48 v ds1233m-3 timing diagram: power-down figure 4
ds1233m 4 of 4 absolute maximum ratings* voltage on v cc pin relative to ground -0.5v to +7.0v voltage on i/o relative to ground -0.5v to v cc + 0.5v operating temperature -40c to +85c storage temperature -55c to +125c soldering temperature 260c for 10 seconds this is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the oper ation sections of this specifica tion is not implied. exposure to absolute maximum rating conditions for extended periods of time may affect reliability. recommended dc operating conditions (-40c to +85c) parameter symbol min typ max units notes supply voltage v cc 1.2 5.5 v 1 dc electrical characteristics (-40c to +85c; v cc = 1.2v to 5.5v) parameter symbol min typ max units notes output voltage @ -500 a v oh v cc -0.5v v cc -0.1v v 1 output current @ 0.4v i ol +8 ma 2,3 operating current i cc 50 a 4 v cc trip point (ds1233m-5) v cctp 4.25 4.375 4.49 v 1 v cc trip point (ds1233m-55) v cctp 4.5 4.625 4.75 v 1 v cc trip point (ds1233m-3) v cctp 2.64 2.72 2.8 v 1 output capacitance c out 10 pf internal pullup resistor r p 3.75 5 6.50 k ac electrical characteristics (-40c to +85c; v cc = 1.2v to 5.5v) parameter symbol min typ max units notes reset active time t rst 200 350 500 ms v cc detect to rst t rpd 210 s v cc slew rate (v htl - v ltl ) t f 300 s v cc slew rate (v ltl - v htl )t r 0ns v cc detect to rst t rpu 200 350 500 ms 5 notes: 1. all voltages are referenced to ground. 2. measured with v cc 2.7v. 3. a 1 k external resistor may be required in some applications for proper operation of the microprocessor reset control circuit. 4. measured with outputs open. 5. t r = 5 s.
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