3, 4 and 8 pin automatic shut-off timers january 2002 description the basic ASOT is a cmos integrated circuit timer that can be mask programmed from 2.5 minutes to 32 hours as shown in table 1. the output of the ic is used to turn on a 12v relay and has a duty cycle which can be mask programmed from 5% to 37.5% in 2.5% steps as shown in table 2. the duty cycle can be selected to optimize operation for a particular relay coil. there are 5 different versions of the ic. the ASOT is a 3-pin version housed in a to-92 package. the application schematic is shown in figure 2. when latching switch s1 is closed, the output turns on energizing relay l1 and keeping switch s1 closed. when the programmed time-out expires, the output turns off deenergizing relay l1 and causing switch s1 to open. the ASOTr is a 4-pin version as shown in figure 3. the out- put turns on in the same manner as in the 3-pin version. if momentary switch s2 is closed, the timer resets and starts timing out again. the s2 input has an internal pull-up resistor. every subsequent momentary switch closure resets the timer. as in the 3-pin version, the output remains on until the timeout expires. the ASOTt is also a 4-pin version as shown in figure 4. in this version contacts c1 replace switch s1 and are not accessible. the application of power caused by closing lsi/csi lsi computer systems, inc. 1235 walt whitman road, melville, ny 11747 (631) 271-0400 fax (631) 271-0405 ASOT ASOTr ASOTr1 ASOTt ASOTt1 u l a3800 1 2 3 4 8 5 6 7 v dd gnd out in nc nc nc duty cycle in v dd gnd out in v dd gnd out figure 1. package options dip/soic to-92 sip 8-pin version 4-pin version 3-pin version 1 2 3 4 ASOTr1 and ASOTt1 ASOT ASOTr and ASOTt the momentary switch s2 causes the output to toggle on as in the 3-pin version. if the momentary switch is closed again, the output toggles off causing contact c1 to open and power to be removed. the r2 input has an internal pull-up resistor. the default operaton of the output produces a double duty cycle for the first 10 milliseconds of output activation to increase the pull-in torque of the relay. the option to remove this feature is factory selectable in the ASOT (3-pin), ASOTr (4-pin) and ASOTt (4-pin) versions. there are also two 8-pin versions available which allow the user to change this feature. the ASOTr1 is the 8-pin version used in the figure 3 application and the ASOTt1 is the 8-pin version used in the figure 4 application. in both cases, the duty cycle input has an internal pull-up resistor. tying the input to vss removes the double duty cycle feature. advance information features: ? minimizes external components and power consumption ? factory calibrated timer ? mask programmable from 2.5 minutes to 32 hours applications control of household appliances, heaters, lighting and ac motors. timeout numbers auto shut-off times 01 - 10 0h 0h 0h 0h 0h 0h 0h 0h 0h 0h 2.5m 5m 7.5m 10m 12.5m 15m 17.5m 20m 22.5m 25m 11 - 20 0h 0h 0h 0h 0h 0h 0h 1h 1h 1h 30m 35m 37.5m 40m 45m 50m 52.5m 0m 10m 15m 21 - 30 1h 1h 1h 1h 2h 2h 2h 2h 3h 3h 20m 30m 40m 45m 0m 20m 30m 40m 0m 20m 31 - 40 3h 4h 4h 5h 5h 6h 6h 7h 8h 9h 30m 0m 40m 0m 20m 0m 40m 0m 0m 0m 41 - 50 9h 10h 10h 12h 14h 16h 20h 24h 28h 32h 20m 0m 40m 0m 0m 0m 0m 0m 0m 0m duty cycle numbers duty cycle percentages 01 - 07 5 7.5 10 12.5 15 17.5 20 08 - 14 22.5 25 27.5 30 32.5 35 37.5 table 1 table 2 7214-011702-1
absolute maximum ratings: (all voltages referenced to v ss ) symbol value unit maximum v dd +85 v input v in +5 to v ss - 0.3 v operating temperature t a 0 to +85 ? storage temperature t stg -65 to +150 ? 7214-011702-2 electrical characeristics: (all voltages referenced to vss) parameter symbol min typ max unit condition shunt regulator voltage v dd 70 75 80 v - regulator sink current i sk - - 10 ma - supply current i dd - - 370 ? v dd = 48v power-on-reset v por 32 37 42 v - por hysteresis v hys 7 - 12 v - output driver - on i o 70 - - ma vo = 5v i o 50 - - ma vo = 3v output driver - off i o - - 50 ? vo = v dd output frequency f o 20.5 21.8 23.11 khz - switch on delay s od - 47 - ms v dd > v por input switching voltage v sw - - 2.5 v ASOTr, ASOTt source current i sc - 20 - ? ASOTr @v in = 0v positive clamp voltage v pc - - 4 v ASOTt @input sink current = 350? negative clamp voltage v nc - - 1 v ASOTt @input sink current = 350? duty cycle select i dc - 20 - ? ASOTr1, ASOTt1 source current @v in = 0v v dd l o a d vss out c1 d2 d1 r1 figure 2. ASOT v dd l o a d vss out c1 d2 d1 r1 in l1 l1 s1 s1 s2 ac ac duty cycle * figure 3. ASOTr, ASOTr1 * this input available only for ASOTr1 v dd l o a d vss out c1 d3 d1 r1 in l1 s1 ac duty cycle * figure 4. ASOTt, ASOTt1 * this input available only for ASOTt1 d2 c1 r2 the information included herein is believed to be accurate and reliable. however, lsi computer systems, inc. assumes no responsibilities for inaccuracies, nor for any infringements of patent rights of others which may result from its use.
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