benefits and features ? improves reliability of processor operation o temperature -compensated voltage monitor for precise, automated power- fail detection o automatically restarts a microprocessor after power failure o maintains reset for 150ms after v cc ret urns to tolerance for processor stabilization o monitors pushbutton for external over ride o active -low reset output ? efficient open - drain output with internal 5.5k pullu p resistor saves power and space o 35a (m ax) quiescent c urrent ? allows for easy design with no complicated settings o fixed 3.3v reset threshold o 5%, 10%, and 20% tolerance versions available ? operates in most commercial and ind ustrial environments o -40c to +85c operating temperature range ? mxd1818 offers improved performance over the ds1818 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 ds1818 econoreset uses a precision 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 state. when v cc returns to an in - tolerance condition, the reset signal is kept in the active state for approximately 150 ms to allow the power supply and processor to stabilize. the ds1818 also monitors a pushbutton on the reset output. if the reset line is pulled low, a re set is generated upon release and the ds1818 output will be held in reset output low for typically 150 m s. ds1818 3.3v econoreset with pushbutton 1 2 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 ds1818 econo reset 1 of 5 19-7559 ; rev 1; 3/15 downloaded from: http:///
ds1818 operation - power monitor the ds1818 provides the functions of detecting out -of- tolerance power supply conditions and warning a processor- based system of impending power failures. when v cc is detected as out -of- tolerance, the rst signal is asserted. on power -up, rst is kept active for approximately 150 ms after the power supply has reached the selected tolerance. this allows the power supply and microprocessor to stabilize before rst is released. block diagram (open - drain output) figure 1 application example figure 2 operation - pushbutton reset the ds1818 provides a pushbutton switch for manual reset control. when the ds1818 is not in a re set cycle, a pushbutton reset can be generated by pulling the rst pin low for at least 1 s. when the pushbutton is held low, the rst is forced active low and will remain active low for about 150 ms after the pushbutton is released. see figure 2 for an application example and figure 3 for the t iming diagram. timing diagram: pushbutton reset figure 3 2 of 6 downloaded from: http:///
ds1818 timing diagram: power - up figure 4 timing diagram: power - down figure 5 3 of 6 downloaded from: http:///
ds1818 absolute maximum ratings* voltage on v cc pin relative to gr ound -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. expos ure to absolute maximum rating conditions for extended periods of time may affec t reliability. recommended dc operating conditions (- 40 c to +85 c) parameter symbol min typ max units notes supply voltage v cc 1.0 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 current @ 0.4 v i ol +10 ma 2, 3 voltage input low v il 0.4 v 1 voltage input high v ih 0.7 *v cc v 1 operating current v cc < 5.5v i cc 28 35 a 4 v cc trip point (ds1818-5) v cctp 2.98 3.06 3.15 v 1 v cc trip point (ds1818-10) v cctp 2.80 2.88 2.97 v 1 v cc trip point (ds1818-20) v cctp 2.47 2.55 2.64 v 1 internal pull-up resistor r p 3.50 5.5 7.5 k ? 7 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 5 v cc detect to rst t rpd 2 5 s v cc slew rate (v cctp (max) to v cctp (min)) t f 300 s 8 v cc slew rate (v cctp (min) to v cctp (max)) t r 0 ns v cc detect to rst t rpu 100 150 250 ms 5, 6 pushbutton detect to rst t pb 1 s pushbutton reset t pbrst 100 150 250 ms 5 4 of 6 downloaded from: http:///
ds1818 notes: 1. all voltages are referenced to ground. 2. measured with v cc 2.7v. 3. a 1 k ? external pull - up resistor may be required in some applications for proper operation of the microprocessor reset control circuit. 4. measured with rst output open. 5. measured with 2.7v v cc 3.3v. 6. t r = 5 s. 7. v oh and i oh are a function of the value of r p and the associated output load conditions. 8. 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 - 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% 5 of 6 downloaded from: http:///
ds1818 revision history revision number revision date description pages changed 1 3/15 updated benefits and features section 1 for pricing, delivery, and ordering information, please contact maxim di rect at 1 -888-629- 4642, or visit maxim integrateds website at www.maximintegrated.com . maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit pat ent licenses are implied. maxim integrated reserves the right to change the circuitry and specifications without notice at any time. the parametric values (mi n and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of m axim integrated products, inc. ? 2015 maxim integrated products, inc. 6 of 6 downloaded from: http:///
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