Am555 Precision Timer Distinctive Characteristics Timing from microseconds through hours 200mA output sink current Variable duty cycle @ TTL output compatibility Temperature stability of 0.005%/C @ 100% reliability assurance testing in compliance with MIL-STD-883 The Am555 ts a highly stable tring device used to provide accurate time delays or to build precision oscillators. When the device is used as a monostable, the time ts precisely con- trolled using one external resistor and one external capaci- tor. When the device 1s used as a precision oscillator, the frequency and duty cycle are controlled by two external resistors and one external capacitor. For monostable operation, a HIGH-to-LOW transition is applied to the trigger input. The device is triggered when the input trigger voltage reaches 1/3 Voc. Once the circuit is triggered, st will remain in the triggered FUNCTIONAL DESCRIPTION state until the set time has elapsed, even if it ts triggered again, The output pulse width 1s equal to 1.1 RaC. For continuous oscillation, two external resistors are used such that the external capacitor charges and discharges be- tween 1/3 Vcc and 2/3 Vcc. The charge time is given by tcharge = 0.693 (Ra + Re)C while the discharge time ts discharge = 0.693 Rec. The device also features a direct reset that overrides all other inputs. When the reset 1s LOW the output 1s LOW re- gardiess of the other inputs. SCHEMATIC DIAGRAM LOGIC SYMBOL g CONTROL Vee 0% 1 5] VOLTAGE . 5k S 3 Be A THRESHOLDO-] coMPARATOR wonreee 2 THRESHOLD q9kR COMPARATOR TRIGGER 8 Sun 3 Sk OUTPUT J 10k2 x, MR] | THIGeER 2 a PUT O ouTpuT 4 aeser 4 2200 Ou oo DRIVER FLIP FLOP -O RESET DISCHARGE Pe DISCHARGE 7 1902 atk GNDO- ' {00 > Sk al = + = srs +z it i + + yan . = Pin 1= GND ORDERING INFORMATION CONNECTION DIAGRAMS Package Temperature Order Vee Type Range Number v snoL yt ef] vce GND YY QDISCHARGE el ve to Poe NELeeY TRIGGER [_] 2 7 Joiscuance TO-5 tot Dice 0C to +70C AMS555XC output] 3 6 7] tHresHouo TRIGGERS) 2 & OTHRESHOLO TOS 85C to +125C SE555T reser (| 4 5 LJ yocTack oureund ofcontaon Dice 55C to +125C AM555XM VOLTAGE Note Pin 7 1s marked for orientation 81Am 555 MAXIMUM RATING (Above which the useful life may be impaired) Storage Temperature Temperature (Ambient) Under Bias Military Grade 65C to +150C 55C to +125C Commercial Grade OC to +70C Supply Voltage to Ground Potential +18V Power Dissipation 6OOmW Lead Temperature (Soldering 60 seconds} +300C ELECTRICAL CHARACTERISTICS (Ta = 25C Vcc =+5V to +15V Unless Otherwise Noted) Military Commercial Parameter Test Conditions Min Typ Max Nin Typ Max Units Supply Voltage 45 18 45 16 Vv Supply Current {LOW State) Veo =8V RL == 3 5 3 8 mA Voc = 15V RL = & (Note 1) 10 12 10 18 Thresheld Voltage 2/3 2/3 XVcc Vec = 15V 48 5 52 5 Trigger Voltage Vv Vc = 5V 145 167 19 167 Trigger Current 05 05 uA Reset Voltage 04 QO? 10 04 o7 10 Vv Reset Current 01 01 mA Threshold Current (Note 3) 01 25 01 25 BA Vec = 15V 96 10 104 90 10 11 Control Voltage Level Vv Voc =5V 29 333 38 26 333 4 ISINK = 10mA 01 015 01 25 Vee = 15V sik = Sema 04 05 04 75 v Output Voltage SINK mA 20 22 20 25 (Low) tsink = 200mA 25 25 Vee =5V ISINK = 8mA 01 025 Isink =SmA 25 35 Output Voltage Veco =15V | lsource =200mA 125 125 (HIGH) Voc = 18V | yg = 100A 130 133 12 75 133 V Voc =5V 30 33 275 33 Timing Error (Monostable) Initial Accuracy Ra, = 1k& to 100k2 05 2 1 % Drift with Temp C= 0 uF (Note 2) 30 100 50 ppm/c Orift with Sup Volt 005 02 o1 %/Volt Rise Time of Output 100 100 nsec Fall Time of Output 100 100 Notes +t Supply current when output HIGH typically tmA tess 2 Tasted at Veg = SV and Voc ~ 15V 3 > Determines the maximum value of Ra + Rg For 15V operation tha max total R = 20m2 82Am555 Minimum Pulse Width Required for Triggering MUN(MUM PULSE WIDTH nsec. +70C + oO oO at 02 03 o4 LOWEST VOLTAGE LEVEL OF TRIGGER PULSE XVc Low Output Voltage Versus Output Sink Current Vout VOLTS 10 10 100 Isimk ~ mA Delay Time Versus Supply Voltage 1015 2 3 1005 1000 NORMALIZED DELAY TIME o 8 a 0990 0985 0 5 10 15 20 SUPPLY VOLTAGE VOLTS TYPICAL CHARACTERISTICS Supply Current Versus High Output Voltage Versus Supply Voltage Output Source Current 100 < < 80 +25C {|_| e , 5 8 3 60 te | ira +128C & oc > 3 $ 40 p > 55C | a yy = B 20 SVS Vee 15V 0 0 50 10 15 10 10 400 SUPPLY VOLTAGE VOLTS Isource 4 Low Output Voltage Versus Low Output Voltage Versus Output Sink Current Output Sink Current 10 10 Yoo = 10V Voc = 15V o 5 10 5 10 $ $ i 0, +125C: & Ha5G > 2 fat 2 oo1 oot 001 10 10 100 10 10 100 Isiwk MA 'sink mA Propagation Delay Versus Delay Time Versus Voltage Level of Temperature Trigger Pulse 1015 g = 1010 @ e 1 > % 1005 s zd Ww Ss a 2 1000 & N = = 0995 & = < 8 ogo = - +70C 0985 -50 -25 0 25 50 75 100 125 o 01 02 03 04 AMBIENT TEMPERATURE C LOWEST VOLTAGE LEVEL OF TRIGGER PULSE XV 8-3Am555 APPLICATIONS MONOSTABLE OPERATION When the timer is operated as a monostable multivibrator, one external capacitor, C, and one external resistor, Ra, are used as shown tn Figure 1. When the trigger input ts re- duced below 1/3 Vec, the timer internal flip-flop is set. This releases the short circuit across the external capacitor and the Q output goes HIGH. The voltage across the ca- Pacitor begins to rise exponeniially with the time constant RaC. When the capacitor voltage reaches 2/3 Vec, the in- ternal comparator resets the flip-flop and the external capacitor, C, 1s rapidly discharged provided the trigger voltage 1s returned above 1/3 Voc. The output ts now in LOW state and a new timing cycle may be initiated. The time that the output ts in the HIGH state ts given by 1.1 RaC or can be taken directly from Figure 2. Both the charge rate and internal threshold are directly proportional to the Vcc supply voltage. Thus, the timer output pulse width 1s independent of the power supply voltage If a LOW Is applied to the reset input, the output is forced LOW and the external capacitor discharged regardiess of the other Inputs. Vec RESET |, 24] av RI g ce TRIGGE THRESHOLD Ra DISCHARGE 2/3 Vee AmS55 THRESHOLD g OUTPUT ~ Fig. 1. Monostable Operation of the Am555. 100 t= 11AQC 10 a ' 4 10 Fy Zz -< x S 01 < < o oo 001 10-100 1 ue usec 100 1 10 usec msec msec msec sec see TIME DELAY {OUTPUT HIGH) Fig. 2. Monostable Pulse Width. ASTABLE OPERATION When the timer ts operated tn the astable mode, two ex- ternal resistors, Ra and Rg, and one external capacitor, C, are used as shown in Figure 3, With this connection scheme, the external capacitor, C, charges and discharges between 1/3 Voc and 2/3 Voc. The charge time (output HIGH} ts tap = 0.693 (Ra + Rg) C The discharge time (output LOW) ts tg = 0 693 Rec The total period for one cycle of output HIGH and output LOW is T=tag ttg = 0 693 (Ra +2Re)C The frequency for this period, T, 1s 1 1 faze 0 693 (Ra + 2Rg) C The astable free running frequency can also be found from the graph shown in Figure 4 The duty cycle, time the output is LOW divided by the period, ts given by tg Rg tap t+tp = Ra +2Rp Yee Ra reser DISCHARGE 2/8 Vee AmS55 THRESHOLD Re oureut 4J 14 Veg THRESHOLD 1 O1pF Fig. 3. Astable Operation of the Am555. HAF 4 ' 144 (Ay + 2Rp) C o1 CAPACITANCE ~ uF 001 Rat 2Rg 0001 01 10 10 100 1k 10k FREE RUNNING FREQUENCY Hz 100k Fig. 4. Astable Free Running Frequency. Metallization and Pad Layout GND TRIGGER OUTPUT Vec DISCHARGE THRESHOLD CONTROL RESET DIE SIZE 0040 X 0060" VOLTAGE 84