1 of 5 041002 features automatically restarts a microprocessor after power failure maintains reset for 150ms after v cc returns to an in-tolerance condition reduces need for discrete components precision temperature-compensated voltage reference and voltage sensor accurate 5%, 10% or 20% power monitoring low-cost to-92 or space saving surface- mount sot-23 packages available push-pull output for low current operation operating temperature -40 c to +85 c pin assignment pin description to-92 1 rst active low reset output 2 v cc power supply 3 gnd ground sot-23 1 rst active low reset output 2 v cc power supply 3 gnd ground description the ds1815 econoreset uses a precisi on temperature 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 state. when v cc returns to an in-tolerance condition, the reset signal is kept in the active state fo r approximately 150ms to allow the power supply and processor to stabilize. ds1815 3.3v econoreset with push-pull output www.maxim-ic.com 12 3 top view sot-23 package see mech. drawings section on website 1 2 3 1 2 3 bottom view to-92 package see mech. drawings section on website dallas ds1815 econo reset downloaded from: http:///
ds1815 2 of 5 operation power monitor the ds1815 provides the functions of detecting out-o f-tolerance power supply conditions and warning a processor-based system of imp ending power failure. when v cc is detected as out of tolerance, the rst signal is asserted. on power-up, rst is kept active for approximately 150ms after the power supply has reached the selected tolerance. this allows the power supply and microprocessor to stabilize before rst is released. block diagram (cmos output) figure 1 application example figure 2 application diagram: rst valid to 0 volts v cc on the ds1815 figure 3 downloaded from: http:///
ds1815 3 of 5 timing diagram: power-up figure 4 timing diagram: power-down figure 5 downloaded from: http:///
ds1815 4 of 5 absolute maximum ratings* voltage on v cc pin relative to ground -0.5v to +7.0v voltage on rst relative to ground -0.5v to +5v 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 operation sections of this specification is not implied. exposure to absolute maximum rating conditions for extended periods of time may affect reliability. recommended dc operating conditions (-40 c to +85 c) parameter symbol min typ max units notes supply voltage v cc 0.0 5.5 v 1 dc electrical characteristics (-40 c to +85 c; 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 v1 output current @ 2.4v i oh 350 a 2 output current @ 0.4v i ol +10 ma 2 operating current v cc < 5.5 i cc 28 35 a 3 v cc trip point (ds1815-5) v cctp 2.98 3.06 3.15 v 1 v cc trip point (ds1815-10) v cctp 2.80 2.88 2.97 v 1 v cc trip point (ds1815-20) v cctp 2.47 2.55 2.64 v 1 output capacitance c out 10 pf ac electrical characteristics (-40 c to +85 c; v cc = 1.2v to 5.5v) parameter symbol min typ max units notes reset active time t rst 100 150 250 ms 4 v cc detect to rst t rpd 25 s v cc slew rate (v cctp (max) to v cctp (min)) t f 300 s 6 v cc slew rate (v cctp (min) to v cctp (max)) t r 0n s v cc detect to rst t rpu 100 150 250 ms 4, 5 downloaded from: http:///
ds1815 5 of 5 notes:1. all voltages are referenced to ground. 2. measured with v cc 2.7v. 3. measured with rst output open. 4. measured with 2.7v v cc 3.3v. 5. t r = 5 s. 6. the t f value is for reference in defining values for t rpd and should not be considered a requirement for proper operation or use of the device. part marking codes a, b, &c represent the device type. 810 . . . . ds1810811 . . . . ds1811 812 . . . . ds1812 813 . . . . ds1813 815 . . . . ds1815 816 . . . . ds1816 817 . . . . ds1817 818 . . . . ds1818 d represents the device tolerance. a . . . . . . 5% b . . . . . . 10% c . . . . . . 15% d . . . . . . 20% downloaded from: http:///
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