DS1239 micromanager chip DS1239 022698 1/4 features ? provides necessary control for start up and shutdown of power supply from keyboard ? holds microprocessor in check during power transients ? halts and restarts an out-of-control microprocessor ? monitors push button for external override ? warns microprocessor of an impending power failure ? converts cmos sram into nonvolatile memory ? unconditionally write-protects memory when power supply is out of tolerance ? consumes less than 100 na of battery current ? controls external power switch for high current applications ? accurate 10% power supply monitoring ? optional 5% power supply monitoring designated DS1239-5 ? provides orderly shutdown in nonvolatile microprocessor applications ? supplies necessary control for low-power astop modeo in battery operate hand-held applications ? standard 16-pin dip or space-saving 16-pin soic ? optional industrial temperature range -40 c to +85 c pin assignment in vbat vcco vcc gnd pf pso pf wc/sc psi rst pbrst cei ceo st nmi DS1239 16-pin dip (300 mil) see mech drawings section 1 11 12 13 14 2 3 4 5 6 7 89 10 15 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 vbat vcco vcc gnd pf pf wc/sc psi pso rst pbrst cei ceo st nmi in DS1239 16-pin soic (300 mil) see mech. drawings section pin description v bat +3 volt battery input v cco switched sram supply output v cc +5 volt power supply input gnd ground pf power fail (active high) pf power fail (active low) wc/sc wake-up control (sleep) psi power supply control input in early warning input nmi non-maskable interrupt st strobe input ceo chip enable output cei chip enable input pbrst pushbutton reset input rst reset output (active low) pso power supply control outputs description the DS1239 micromanager provides all the necessary functions for power supply control and monitoring, reset control, and memory backup in microprocessor-based systems. using the DS1239, an ac power switch is no longer required for microprocessor-based systems. a keyboard control system for power supply start up and shutdown is provided through the use of the power sup- ply control input and output. in other respects, the DS1239 is functionally identical to a ds1236 in the nmos mode. for a complete description of the other DS1239 features, refer to the ds1236 data sheet. pin-out of the DS1239 is identical to the ds1236 with two exceptions. the rc and rst pins have been re- placed with psi and pso, respectively. other pins and functions operate exactly as the ds1236 in nmos mode.
DS1239 022698 2/4 power supply control the DS1239 facilitates the power-up and power down sequencing of a main power supply from a keyboard or pushbutton. the power supply control input (psi ) and power supply control output (pso) are used for this purpose. prior to establishing a voltage on v cc (+5v), the psi is internally held at a high level at all times with the v bat supply. when psi is forced low via a key pad or other source, the pso is connected to the v bat to pro- vide a high level. as shown in figure 1, this active high signal can be wired directly to an optically isolated scr to initiate an ac to dc power-up sequence. this in turn will provide the supply voltage for v cc . the timing is il- lustrated in figure 2. holding the psi input low, the pso output will supply a connection to the v bat pin until the v cc reaches v bat , or a maximum of 500 ms. if the sup- ply voltage on v cc rises above the v bat level before the t psi time-out, the pso pin will remain high and track the v cc input. if v cc does not rise above v bat before either t psi or psi is allowed to return to a high level, the pso output will return to tristate. once the pso output and v cc are set at a high level, a subsequent falling edge on psi will tristate pso to initiate a shut down condition. the 10 microamp current supplied by the psi pin allows the use of a 0.1 m f capacitor as a simple pushbutton de- bounce circuit. the battery size for this application must be selected to provide the scr on-current for the power supply response time and is consequently applica- tion-specific. power supply control figure 1 120v ac input 5v dc r1 r2 c2 p1 moc3012 2 3 5 6 battery r3 gnd pso 1 2 3 4 5 6 7 89 10 11 12 13 14 15 16 +3v 1 4 c1 = 0.1 uf DS1239 dc power supply 120 v 60 hz v cc v bat psi
DS1239 022698 3/4 power supply control timing figure 2 v cc v cc = v bat v cc = v cctp v cc = 0 v psi = v ohl pso = v ohl pso = tri-state psi = v cc pso slews with v cc pso = tristate 4.5 4.25 t f t psi v il t pst t pso psi = v ohl t psp t pso power supply failure
DS1239 022698 4/4 absolute maximum 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 0 c to 70 c operating temperature (industrial version) 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. these specifications reflect the power supply control feature of the DS1239. for complete electrical specifications, refer to the ds1236 data sheet. dc electrical characteristics (0 c to 70 c; v cc = 4.5v to 5.5v) parameter symbol min typ max units notes psi output current i psi 3 m a pso output current i pso 10 ma 3 ac electrical characteristics (0 c to 70 c; v cc = 4.5v to 5.5v) parameter symbol min typ max units notes psi to valid v cc t psi 200 ms 1 psi to pso tri-state t pst 20 ns psi to valid pso t pso 100 ns pso pulse width t psp 200 500 ms 2 notes: 1. minimum turn-on response time for ac-to-dc power supply. 2. pso pulse width for v cc held below v bat . 3. pso will typically source 1.5 ma at 1.5v with v cc = 0v, v bat = 3v.
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