1 of 5 rev: 022306 general description the ds1813 econoreset uses a precision 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 conditi on, the reset signal is kept in the active stat e for approximately 150ms to allow the power s upply and processor to stabilize. the ds1813 also monitors a pushbutton on the reset output. if the reset line is pulled low, a reset is generated upon release a nd will be held in reset output low for typically 150ms. features automatically restarts a microprocessor after power failure monitors pushbutton for external override maintains reset for typically 150ms 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 or space-saving surface- mount sot-23 packages available efficient open-drain output with internal 5.5k ? pullup resistor -40 c to +85 c operating temperature pin configurations pin description pin to-92 sot-23 name function 1 1 rst active-low reset output 2 2 v cc power supply 3 3 gnd ground ds1813 5v econoreset with pushbutton www.maxim-ic.com 12 3 top view sot-23 package see mech. drawings section on website 1 2 3 1 2 3 bottom vie w to-92 package see mech. drawings section on website dallas ds1813 econo reset downloaded from: http:///
ds1813 2 of 5 operationpower monitor the ds1813 provides the functions of detecting out-of-tolerance power-supply conditions and warning a processor-based system of im pending 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. operationpush button reset the ds1813 provides for a pushbutton switch for manual reset control. when the ds1813 is not in a reset cycle, a pushbutton reset can be generated by pulling the rst pin low for at least 1s. when the pushbutton is held low, the rst is forced active low and will remain active low for about 150ms after the pushbutton is released. see figure 2 for an applica tion example and figure 3 for the timing diagram. figure 1. block diagram (open-drain output) figure 2. application example downloaded from: http:///
ds1813 3 of 5 figure 3. timing diagram: pushbutton reset figure 4. timing diagram: power-up figure 5. timing diagram: power-down downloaded from: http:///
ds1813 4 of 5 absolute maxi mum ratings voltage range on v cc pin relative to ground...-0.5v to +7.0v voltage range on rst relative to ground..-0.5v to (v cc +0.5v) operating temperature range-40c to +85c storage temperature range.-55c to +125c soldering temperature.see ip c/jedec j-std-020 specification this is a stress rating only and functional ope ration of the device at these or any ot her conditions above those indicated in t he operation sections of this specification is not implied. exposure to absolute maximum ra ting conditions for extended periods of time may affect reliability. recommended dc oper ating conditions (t a = -40 c to +85 c) parameter symbol min typ max units notes supply voltage v cc 0 5.5 v 1 dc electrical characteristics (v cc = 1.2v to 5.5v, t a = -40 c to +85 c.) parameter symbol min typ max units notes output current at 0.4v i ol 10 ma 2, 3 voltage input low v il 0.4 v 1 voltage input high v ih 0.7 x v cc v 1 operating current v cc < 5.5 i cc 30 40 a 4 ds1813-5 4.50 4.62 4.75 ds1813-10 4.25 4.35 4.49 v cc trip point ds1813-15 v cctp 4.00 4.13 4.24 v 1 internal pullup resistor r p 3.50 5.5 7.5 k ? 6 output capacitance c out 10 pf ac electrical characteristics (v cc = 1.2v to 5.5v, t a = -40 c to +85 c.) parameter symbol min typ max units notes reset active time t rst 100 150 300 ms v cc detect to rst t rpd 2 5 s v cc slew rate (v cctp ( max ) - v cctp(min) ) t f 300 s 7 v cc slew rate (v cctp(min) - v cctp(max) ) t r 0 ns v cc detect to rst t rpu 100 150 300 ms 5 pushbutton detect to rst t pb 1 s pushbutton reset t pbrst 100 150 300 ms downloaded from: http:///
ds1813 5 of 5 maxim/dallas semiconductor cannot assume res ponsibility for use of any circuitry other than circuitry entirely embodied in a ma xim/dallas semiconductor product. no circuit patent licenses are implied. maxi m/dallas semiconductor reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ? 2006 maxim integrated products ? printed usa the maxim logo is a registered trademark of maxim integrated products, inc. the dallas logo is a registered trademark of dallas semiconductor corporation. notes: 1) all voltages are referenced to ground. 2) measured with v cc 2.7v. 3) a 1k ? external resistor may be required in some applications for proper operation of the microprocessor reset control circuit. 4) measured with rst output open. 5) t r = 5 s. 6) v oh and i oh are a function of the value of r p and the associated output load conditions. 7) this value is for referenc e in defining values for t rpd and should not be consid ered a requirement for proper operation or us e of the device. part marking codes a, b, and c represent the device type. 810 . . . . ds1810 811 . . . . 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:///
|
