1 of 7 111899 features ? halts and restarts an out-of-control microprocessor ? holds microprocessor in check during power transients ? automatically restarts microprocessor after power failure ? monitors pushbutton for external override ? accurate 5% or 10% microprocessor power supply monitoring ? eliminates the need for discrete components ? space-saving, 8-pin mini-dip ? optional 16-pin soic surface mount package ? industrial temperature -40c to +85c available, designated n pin assignment pin description pbrst - pushbutton reset input td - time delay set tol - selects 5% or 10% v cc detect gnd - ground rst - reset output (active high) rst - reset output (active low, open drain) st - strobe input v cc - +5 volt power nc - no connections description the ds1232 micromonitor? chip monitors three vita l conditions for a micropr ocessor: power supply, software execution, and external override. first, a precision temperature-compensated reference and comparator circuit monitors the status of v cc . when an out-of-tolerance c ondition occurs, an internal power fail signal is generated which for ces reset to the active state. when v cc returns to an in-tolerance condition, the reset signals are kept in the active stat e for a minimum of 250 ms to allow the power supply and processor to stabilize. ds1232 micromonitor chip www.maxim-ic.com ds1232s 16-pin soic (300-mil) see mech. drawings section nc pbrst nc td nc tol nc gnd nc vcc nc st nc rst nc rst 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 pbrst ds1232 8-pin dip (300-mil) see mech. drawings section td tol gnd vcc st rst 1 2 3 4 8 7 6 5 rst micromonitor is a trademark of dallas semiconductor.
ds1232/ds1232s 2 of 7 the second function the ds1232 performs is pus hbutton reset control. the ds1232 debounces the pushbutton input and guarantees an active reset pulse width of 250 ms minimum. the third function is a watchdog timer. the ds1232 has an internal timer that fo rces the reset signals to the active state if the strobe input is not driven low pr ior to timeout. the watchdog timer f unction can be set to operate on timeout settings of approximate ly 150 ms, 600 ms, and 1.2 seconds. operation - po wer monitor the ds1232 detects out-of-tolerance power supply conditions and warn s a processor-based system of impending power failure. when v cc falls below a preset level as defined by tol (pin 3), the v cc comparator outputs the signals rst (pin 5) and rst (pin 6). when tol is connected to ground, the rst and rst signals become active as v cc falls below 4.75 volts. when tol is connected to v cc , the rst and rst signals become active as v cc falls below 4.5 volts. the rst and rst are excellent control signals for a microprocessor, as processing is stopped at the la st possible moments of valid v cc . on power-up, rst and rst are kept active for a minimum of 250 ms to allow the power supply and processor to stabilize. operation - push button reset the ds1232 provides an input pin for direct connec tion to a pushbutton (figur e 2). the pushbutton reset input requires an active low signal. internally, this input is deboun ced and timed such that rst and rst signals of at least 250 ms minimum are generated. the 250 ms dela y starts as the pushbutton reset input is released from low level. operation - watchdog timer a watchdog timer function forces rst and rst signals to the active state when the st input is not stimulated for a predetermined time period. the time pe riod is set by the td input to be typically 150 ms with td connected to ground, 600 ms with td left unconnected, and 1.2 seconds with td connected to v cc . the watchdog timer starts timing out from the set time period as soon as rst and rst are inactive. if a high-to-low transition occurs on the st input pin prior to timeout, the watchdog timer is reset and begins to timeout again. if the watchdog timer is allowed to timeout, then the rst and rst signals are driven to the active state for 250 ms minimum. the st input can be derive d from microprocessor address signals, data signals, a nd/or control signals. when the mi croprocessor is functioning normally, these signals would, as a matter of routine, cause the watchdog to be reset prior to timeout. to guarantee that the watchdog timer does not timeout, a high-to-low tr ansition must occur at or less than the minimum shown in table 1. a typical circuit example is shown in figure 3.
ds1232/ds1232s 3 of 7 micromonitor block diagram figure 1 pushbutton reset figure 2 watchdog timer figure 3
ds1232/ds1232s 4 of 7 timing diagram: pushbutton reset figure 4 timing diagram: strobe input figure 5 watchdog timeouts table 1 time-out td pin min typ max gnd 62.5 ms 150 ms 250 ms float 250 ms 600 ms 1000 ms v cc 500 ms 1200 ms 2000 ms
ds1232/ds1232s 5 of 7 timing diagram: power-down figure 6 timing diagram: power-up figure 7
ds1232/ds1232s 6 of 7 absolute maxi mum 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 0c to 70c operating temperature (industrial version) -40c to +85c storage temperature -55c to +125c soldering temperature 260c for 10 seconds * this is a stress rating only and functional operati on of the device at these or any other conditions above those indicated in the opera tion sections of this specifica tion is not implied. exposure to absolute maximum rating conditions for extende d periods of time may affect reliability. recommended dc operating condit ions (0 c to 70 c) parameter symbol min typ max units notes supply voltage v cc 4.5 5.0 5.5 v 1 st and pbrst input high level v ih 2.0 v cc +0.3 v 1 st and pbrst input low level v il -0.3 +0.8 v 1 dc electrical characteristics (0 c to 70 c; v cc =4.5 to 5.5v) parameter symbol min typ max units notes input leakage i il -1.0 +1.0 a 3 output current @ 2.4v i oh -8 -10 ma 5 output current @ 0.4v i ol 8 10 ma low level @ rst v ol 0.4 v 1 output voltage @ -500 a v oh v cc -0.5v v cc -0.1v v 1, 7 operating current i cc 0.5 2.0 ma 2 v cc trip point (tol=gnd) v cctp 4.50 4.62 4.74 v 1 v cc trip point (tol=v cc ) v cctp 4.25 4.37 4.49 v 1 capacitance (t a =25 c) parameter symbol min typ max units notes input capacitance c in 5 pf output capacitance c out 7 pf
ds1232/ds1232s 7 of 7 ac electrical characteristics (0 c to 70 c; v cc =5v 10%) parameter symbol min typ max units notes pbrst = v il t pb 20 ms reset active time t rst 250 610 1000 ms st pulse width t st 20 ns 6, 8 v cc fail detect to rst and rst t rpd 100 175 s v cc slew rate 4.75v to 4.25v t f 300 s v cc detect to rst and rst transition t rpu 250 610 1000 ms 4 v cc slew rate 4.25v to 4.75v t r 0 5 s pbrst stable low to rst and rst t pdly 20 ms notes: 1. all voltages referenced to ground. 2. measured with outputs open. 3. pbrst is internally pulled up to v cc with an internal im pedance of 10k typical. 4. t r = 5 s. 5. rst is an open-drain output. 6. must not exceed t td minimum. see table 1. 7. rst remains within 0.5v of v cc on power-down until v cc drops below 2.0v. rst remains within 0.5v of gnd on power-down until v cc drops below 2.0v. 8. watchdog can not be disabled. it mu st be strobed to avoid resets.
e nglish ? ???? ? ??? ? ??? what's ne w p roducts solutions de sign ap p note s sup p ort buy comp any me mbe rs ds1232 part number table notes: see the ds1232 quickview data sheet for further information on this product family or download the ds1232 full data sheet (pdf, 140kb). 1. other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales . 2. didn't find what you need? ask our applications engineers. expert assistance in finding parts, usually within one business day. 3. part number suffixes: t or t&r = tape and reel; + = rohs/lead-free; # = rohs/lead-exempt. more: see full data sheet or part naming c onventions . 4. * some packages have variations, listed on the drawing. "pkgc ode/variation" tells which variation the product uses. 5. part number notes free sample buy direct package: type pins size drawing code/var * temp rohs/lead-free? materials analysis ds1232 ibm c at i pdip;8 pin;300 dwg: 56-g5005-000a (pdf) use pkgcode/variation: p8-1 * 0c to +70c rohs/lead-free: no materials analysis ds1232 pdip;8 pin;300 dwg: 56-g5005-000a (pdf) use pkgcode/variation: p8-1 * 0c to +70c rohs/lead-free: no materials analysis ds1232+ pdip;8 pin;300 dwg: 56-g5005-000a (pdf) use pkgcode/variation: p8+1 * 0c to +70c rohs/lead-free: yes materials analysis ds1232n+ pdip;8 pin;300 dwg: 56-g5005-000a (pdf) use pkgcode/variation: p8+1 * -40c to +85c rohs/lead-free: yes materials analysis ds1232n pdip;8 pin;300 dwg: 56-g5005-000a (pdf) use pkgcode/variation: p8-1 * -40c to +85c rohs/lead-free: no materials analysis ds1232s-ibm soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * 0c to +70c rohs/lead-free: no materials analysis ds1232s/t&r/c 01 soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * 0c to +70c rohs/lead-free: no materials analysis
ds1232s/t&r/c 06 soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * 0c to +70c rohs/lead-free: no materials analysis ds1232s/t&r/c 05 soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * 0c to +70c rohs/lead-free: no materials analysis ds1232s/t&r/c 11 soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * 0c to +70c rohs/lead-free: no materials analysis ds1232s/t&r/c 13 soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * 0c to +70c rohs/lead-free: no materials analysis ds1232s+ soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16+11 * 0c to +70c rohs/lead-free: yes materials analysis ds1232s+t&r t&r qty 1000/reel soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16+11 * 0c to +70c rohs/lead-free: yes materials analysis ds1232s/t&r t&r qty 1000/reel soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * 0c to +70c rohs/lead-free: no materials analysis ds1232s soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * 0c to +70c rohs/lead-free: no materials analysis ds1232sn+ soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16+3 * -40c to +85c rohs/lead-free: yes materials analysis ds1232sn soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * -40c to +85c rohs/lead-free: no materials analysis ds1232sn+t&r t&r qty 1000/reel soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16+11 * -40c to +85c rohs/lead-free: yes materials analysis ds1232sn/t&r t&r qty 1000/reel soic ;16 pin;300 dwg: 56-g4009-001b (pdf) use pkgcode/variation: w16-11 * -40c to +85c rohs/lead-free: no materials analysis didn't find what you need? c ontac t us: send us an email c opyright 2 0 0 7 by m axim i ntegrated p roduc ts , dallas semic onduc tor ? legal n otic es ? p rivac y p olic y
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