DS1813 5v econoreset with pushbutton DS1813 050798 1/5 features ? automatically restarts a microprocessor after power failure ? monitors pushbutton for external override ? maintains reset for typically 150 ms after v cc returns to an intolerance condition ? reduces need for discrete components ? precision temperaturecompensated voltage reference and voltage sensor ? lowcost to92 or space saving surfacemount sot23 packages available ? efficient opendrain output with internal 5.5k w pullup resistor ? operating temperature 40 c to +85 c pin assignment 1 23 to92 package see mech. drawings section 12 3 sot23 package 123 pin descriptions to92 1 rst active low reset output 2v cc power supply 3 gnd ground sot23 1 rst active low reset output 2v cc power supply 3 gnd ground description the DS1813 econoreset uses a precision temperature reference and comparator circuit to monitor the status of the power supply (v cc ). when an outoftolerance condition is detected, an internal powerfail signal is generated which forces reset to the active state. when v cc returns to an intolerance condition, the reset sig- nal is kept in the active state for approximately 150 ms to allow the power supply 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 and will be held in reset output low for typi- cally 150 ms.
DS1813 050798 2/5 operation power monitor the DS1813 provides the functions of detecting outof tolerance power supply conditions and warning a pro- cessorbased system of impending power failure. when v cc is detected as outoftolerance, the rst signal is asserted. on powerup, 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 re- leased. operation pushbutton 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 1 m s. when the pushbutton is held low, the reset 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 timing diagram. block diagram (opendrain output) figure 1 vcc tolerance t.c. reference 150 ms ground reset rst monitor delay and bias 5.5k w v cc + application example figure 2 DS1813 microprocessor rst reset v cc
DS1813 050798 3/5 timing diagram: pushbutton reset figure 3 rst v ih t rst v il t pb timing diagram: power up figure 4 t r t rpu v oh v cc rst v cctp v cctp (max) v cctp (min) timing diagram: power down figure 5 v ol t rpd t f v cctp v cc rst v cctp (max) v cctp (min)
DS1813 050798 4/5 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 40 c to +85 c storage temperature 55 c to +125 c soldering temperature 260 c 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 current @ 0.4 volts 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 < 5.5 i cc 30 40 m a 4 v cc trip point (DS18135) v cctp 4.50 4.62 4.75 v 1 v cc trip point (DS181310) v cctp 4.25 4.35 4.49 v 1 v cc trip point (DS181315) 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 ( 40 c to +85 c ; v cc = 1.2v to 5.5v) parameter symbol min typ max units notes reset active time t rst 100 150 300 ms v cc detect to rst t rpd 2 5 m s v cc slew rate (v cctp (max) v cctp (min)) t f 300 m 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 m s pushbutton reset t pbrst 100 150 300 ms notes: 1. all voltages are referenced to ground. 2. measured with v cc > 2.7 volts. 3. a 1k w external resistor may be required in some applications for proper operation of the microprocessor reset control circuit.
DS1813 050798 5/5 4. measured with rst output open. 5. t r = 5 m 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 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 12 3 abcd aao, abo, &aco represent the device type. ado represents the device tolerance. 810 ds1810 . . . . 811 ds1811 . . . . 812 ds1812 . . . . 813 DS1813 . . . . 815 ds1815 . . . . 816 ds1816 . . . . 817 ds1817 . . . . 818 ds1818 . . . . a5% . . . . . . b 10% . . . . . . c 15% . . . . . . d 20% . . . . . .
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