NE555 SA555 - SE555 GENERAL PURPOSE SINGLE BIPOLAR TIMERS .. .. . .. . LOW TURN OFF TIME MAXIMUM OPERATING FREQUENCY GREATER THAN 500kHz TIMING FROM MICROSECONDS TO HOURS OPERATES IN BOTH ASTABLE AND MONOSTABLE MODES HIGH OUTPUT CURRENT CAN SOURCE OR SINK 200mA ADJUSTABLE DUTY CYCLE TTL COMPATIBLE TEMPERATURE STABILITY OF 0.005% PERoC DESCRIPTION The NE555 monolithic timing circuit is a highly stable controller capableof producing accuratetime delays or oscillation. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor.For a stableoperation as an oscillator, the free running frequency and the duty cycle are both accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output structure can source or sink up to 200mA. The NE555 is available in plastic and ceramic minidip package and in a 8-lead micropackage and in metal can package version. N DIP8 (Plastic Package) D SO8 (Plastic Micropackage) ORDER CODES Part Number NE555 Package Temperature Range N D 0oC, 70oC • • o o • • o o • • SA555 –40 C, 105 C SE555 –55 C, 125 C PIN CONNECTIONS (top view) July 1998 1 8 2 7 3 6 4 5 1 2 3 4 5 6 7 8 - GND - Trigger - Output - Reset - Control voltage - Threshold - Discharge - VCC 1/10 NE555/SA555/SE555 BLOCK DIAGRAM VCC+ 5kΩ COMP THRESHOLD CONTROL VOLTAGE DISCHARGE R FLIP-FLOP Q 5kΩ COMP OUT TRIGGER S INHIBIT/ RESET 5kΩ S RESET S - 808 6 SCHEMATIC DIAGRAM CONTROL VOLTAGE OUTPUT THRESHOLD COMPARATOR 5 VCC R2 830Ω R1 4.7kΩ R12 6.8kΩ R4 R8 1kΩ 5kΩ R3 4.7kΩ Q21 Q5 Q6 Q7 Q8 Q19 Q9 Q20 Q22 Ρ13 3.9kΩ R11 5kΩ THRESHOLD Q1 Q2 Q23 Q3 R9 5kΩ Q11 Q12 TRIGGER 2 D2 RES ET 4 R14 220Ω Q24 Q13 Q10 Q16 DISCHARGE 3 D1 R17 4.7kΩ Q4 Q18 R16 100Ω R15 4.7kΩ Q15 7 Q17 Q14 R5 10kΩ R6 100kΩ R7 100kΩ R10 5kΩ 1 G ND TRIGGER COMPARATOR FLIP FLOP ABSOLUTE MAXIMUM RATINGS Symbol Vcc Toper Tj Tstg 2/10 Parameter Value Supply Voltage Operating Free Air Temperature Range Junction Temperature Storage Temperature Range 18 for NE555 for SA555 for SE555 Unit V 0 to 70 –40 to 105 –55 to 125 o 150 o –65 to 150 o C C C NE555/SA555/SE555 OPERATING CONDITIONS Symbol VCC Vth, Vtrig, Vcl, Vreset Parameter Supply Voltage Maximum Input Voltage SE555 NE555 - SA555 Unit 4.5 to 18 4.5 to 18 V VCC VCC V ELECTRICAL CHARACTERISTICS T amb = +25oC, VCC = +5V to +15V (unless otherwise specified) Symbol ICC VCL Vth Ith Vtrig Itrig Parameter SE555 Min. Max. 3 10 2 Timing Error (monostable) (RA = 2k to 100kΩ, C = 0.1µF) Initial Accuracy - (note 2) Drift with Temperature Drift with Supply Voltage 0.5 30 0.05 Timing Error (astable) (RA, RB = 1kΩ to 100kΩ, C = 0.1µF, VCC = +15V) Initial Accuracy - (note 2) Drift with Temperature Drift with Supply Voltage 1.5 90 0.15 Supply Current (RL ∞) (- note 1) Low State VCC = +5V VCC = +15V High State VCC = 5V Max. 5 12 3 10 2 6 15 2 100 0.2 1 50 0.1 3 0.5 2.25 150 0.3 9 2.6 10 3.33 11 4 Threshold Voltage VCC = +15V VCC = +5V 9.4 2.7 10 3.33 10.6 4 8.8 2.4 10 3.33 11.2 4.2 0.1 0.25 0.1 0.25 5 1.67 5.2 1.9 5 1.67 5.6 2.2 0.5 0.9 0.5 2.0 0.7 1 0.7 1 V V Threshold Current - (note 3) µA V 4.8 1.45 Trigger Current (Vtrig = 0V) Reset Current % ppm/°C %/V % ppm/°C %/V 10.4 3.8 Trigger Voltage VCC = +15V VCC = +5V Unit mA 10 3.33 Reset Voltage - (note 4) 0.4 4.5 1.1 0.4 µA V mA 0.1 0.4 0.4 1 0.1 0.4 0.4 1.5 Low Level Output Voltage VCC = +15V, IO(sink) = 10mA IO(sink) = 50mA IO(sink) = 100mA IO(sink) = 200mA VCC = +5V, IO(sink) = 8mA IO(sink) = 5mA 0.1 0.4 2 2.5 0.1 0.05 0.15 0.5 2.2 0.1 0.4 2 2.5 0.3 0.25 0.25 0.75 2.5 High Level Output Voltage VCC = +15V, IO(source) = 200mA IO(source) = 100mA VCC = +5V, IO(source) = 100mA 12.5 13.3 3.3 Vreset = +0.4V Vreset = 0V Notes : Typ. 9.6 2.9 Ireset VOH Min. Control Voltage level VCC = +15V VCC = +5V Vreset VOL NE555 - SA555 Typ. V 0.25 0.2 0.4 0.35 V 13 3 12.75 2.75 12.5 13.3 3.3 1. Supply current when output is high is typically 1mA less. 2. Tested at VCC = +5V and VCC = +15V. 3. This will determine the maximum value of RA + RB for +15V operation the max total is R = 20MΩ and for 5V operation the max total R = 3.5MΩ. 3/10 NE555/SA555/SE555 ELECTRICAL CHARACTERISTICS (continued) Symbol Parameter SE555 Min. NE555 - SA555 Typ. Max. 20 100 Min. Typ. Max. 20 100 Idis (off) Discharge Pin Leakage Current (output high) (Vdis = 10V) Vdis(sat) Discharge pin Saturation Voltage (output low) - (note 5) VCC = +15V, Idis = 15mA VCC = +5V, Idis = 4.5mA 180 80 480 200 180 80 480 200 Output Rise Time Output Fall Time 100 100 200 200 100 100 300 300 Turn off Time - (note 6) (Vreset = VCC) 0.5 tr tf toff Notes : Unit nA mV 0.5 ns µs 5. No protection against excessive Pin 7 current is necessary, providing the package dissipation rating will not be exceeded. 6. Time mesaured from a positive going input pulse from 0 to 0.8x VCC into the threshold to the drop from high to low of the output trigger is tied to treshold. Figure 1 : Minimum Pulse Width Required for Trigering Figure 2 : Supply Current versus Supply Voltage Figure 3 : Delay Time versus Temperature Figure 4 : Low Output Voltage versus Output Sink Current 4/10 NE555/SA555/SE555 Figure 5 : Low Output Voltage versus Output Sink Current Figure 6 : Low Output Voltage versus Output Sink Current Figure 7 : High Output Voltage Drop versus Output Figure 8 : Delay Time versus Supply Voltage Figure 9 : Propagation Delay versus Voltage Level of Trigger Value 5/10 NE555/SA555/SE555 APPLICATION INFORMATION Figure 11 MONOSTABLE OPERATION In the monostable mode, the timer functions as a one-shot. Referring to figure 10 the external capacitor is initially held discharged by a transistor inside the timer. Figure 10 t = 0.1 ms / div INPUT = 2.0V/div OUTPUT VOLTAGE = 5.0V/div VCC = 5 to 15V Reset R1 4 7 The circuit triggers on a negative-going input signal when the level reaches 1/3 Vcc. Once triggered, the circuit remains in this state until the set time has elapsed, even if it is triggered again during this interval.The duration of the output HIGH stateis given by t = 1.1 R1C1 and is easily determined by figure 12. Notice that since the charge rate and the threshold level of the comparator are both directly proportional to supply voltage, the timing interval is independent of supply. Applying a negativepulse simultaneously to the reset terminal (pin 4) and the trigger terminal (pin 2) during the timing cycle discharges the external capacitor and causes the cycle to start over. The timing cycle now starts on the positive edge of the reset pulse. During the time the reset pulse in applied, the output is driven to its LOW state. When a negativetrigger pulse is applied to pin 2, the flip-flop is set, releasing the short circuit across the external capacitor and driving the output HIGH. The voltage across the capacitor increases exponentially with the time constantτ = R1C1. When the voltage across the capacitor equals 2/3 Vcc, the comparatorresets the flip-flop which then discharge the capacitor rapidly and drivers the output to its LOW state. Figure 11 shows the actual waveforms generatedin this mode of operation. When Reset is not used, it should be tied high to avoid any possibly or false triggering. 6/10 Figure 12 C (µF) 10 1.0 0.1 0.01 0.001 10 µs Ω 0.01 µF R1 = 9.1kΩ, C1 = 0.01µF, RL = 1kΩ Ω 1 Control Voltage CAPACITOR VOLTAGE = 2.0V/div 10 M 5 3 C1 Ω 10 0k 1M Ω Output 6 1k Ω NE555 10 k 2 R 1= Trigger 8 100 µs 1.0 ms 10 ms 100 ms 10 s (t d ) ASTABLE OPERATION When the circuit is connected as shown in figure 13 (pin 2 and 6 connected)it triggers itself and free runs as a multivibrator. The external capacitor charges through R1 and R2 and discharges through R2 only. Thus the duty cycle may be precisely set by the ratio of these two resistors. In the astable mode of operation, C1 charges and discharges between 1/3 Vcc and 2/3 Vcc. As in the triggeredmode, the chargeand discharge times and therefore frequency are independent of the supply voltage. NE555/SA555/SE555 Figure 13 Figure 15 : Free Running Frequency versus R1, R2 and C1 VCC = 5 to 15V R1 4 Output 8 7 3 NE555 Control Voltage 0.01 µF R2 1 2 1.0 R1 + 0.1 6 5 C (µF) 10 R2 1M = C1 0.01 Figure 14 shows actual waveforms generatedin this mode of operation. The charge time (output HIGH) is given by : t1 = 0.693 (R1 + R2) C1 and the discharge time (output LOW) by : t2 = 0.693 (R2) C1 Thus the total period T is given by : T = t1 + t2 = 0.693 (R1 + 2R2) C1 The frequency ofoscillation is them : 1 1.44 f= = T (R1 + 2R2) C1 and may be easily found by figure 15. The duty cycle is given by : R2 D= R1 + 2R2 0.001 0.1 1 10 Ω 10 M 1k Ω 10 kΩ 0k Ω Ω 10 100 1k 10k f o (Hz) PULSE WIDTH MODULATOR When the timer is connected in the monostable mode and triggered with a continuous pulse train, the output pulse width can be modulated by a signal applied to pin 5. Figure 16 shows the circuit. Figure 16 : Pulse Width Modulator. VCC RA 8 4 Figure 14 Trigger 7 2 t = 0.5 ms / div NE555 6 Modulation Input OUTPUT VOLTAGE = 5.0V/div Output 3 5 C 1 CAPACITOR VOLTAGE = 1.0V/div R1 = R2 = 4.8kΩ, C1= 0.1µF, RL = 1kΩ 7/10 NE555/SA555/SE555 LINEAR RAMP When the pullup resistor, RA, in the monostable circuit is replaced by a constant current source, a linear ramp is generated. Figure 17 shows a circuit configuration that will perform this function. Figure 17. VCC RE Thus the frequency of oscillation is f = 1 t1 + t2 Note that this circuit will not oscillate if RB is greater 8 4 Trigger R1 50% DUTY CYCLE OSCILLATOR For a 50% duty cycle the resistors RA and RE may beconnected as in figure19. The time preriod for the output high is the same as previous, t1 = 0.693 RA C. For the output low it is t2 = RB − 2RA [(RARB) ⁄ (RA + RB)] CLn 2RB − RA Figure 19 : 50% Duty Cycle Oscillator. 7 2 NE555 2N4250 or equiv. VCC 6 VCC C Output 3 5 0.01µF R2 RA 51kΩ 1 4 8 RB 7 2 22kΩ NE55 Figure 18 shows waveforms generator by the linear ramp. The time interval is given by : (2/3 VCC RE (R1+ R2) C T= VBE = 0.6V R1 VCC − VBE (R1+ R2) Figure 18 : Linear Ramp. Out 6 5 3 1 0.01µF C 0.01µF than 1/2 RA because the junction of RA and RB cannot bring pin 2 down to 1/3 VCC and trigger the lower comparator. ADDITIONAL INFORMATION Adequate power supply bypassing is necessary to protect associated circuitry. Minimum recommended is 0.1µF in parallel with 1µF electrolytic. VCC = 5V Time = 20µs/DIV R 1 = 47kΩ R 2 = 100kΩ R E = 2.7kΩ C = 0.01µF 8/10 Top trace : input 3V/DIV Middle trace : output 5V/DIV Bottom trace : output 5V/DIV Bottom trace : capacitor voltage 1V/DIV NE555/SA555/SE555 PM-DIP8.EPS PACKAGE MECHANICAL DATA 8 PINS - PLASTIC DIP A a1 B b b1 D E e e3 e4 F i L Z Min. Millimeters Typ. 3.32 0.51 1.15 0.356 0.204 Max. 1.65 0.55 0.304 10.92 9.75 7.95 Min. 0.020 0.045 0.014 0.008 Max. 0.065 0.022 0.012 0.430 0.384 0.313 2.54 7.62 7.62 3.18 Inches Typ. 0.131 0.100 0.300 0.300 6.6 5.08 3.81 1.52 0.125 0260 0.200 0.150 0.060 DIP8.TBL Dimensions 9/10 NE555/SA555/SE555 PM-SO8.EPS PACKAGE MECHANICAL DATA 8 PINS - PLASTIC MICROPACKAGE (SO) A a1 a2 a3 b b1 C c1 D E e e3 F L M S Min. Millimeters Typ. 0.1 0.65 0.35 0.19 0.25 Max. 1.75 0.25 1.65 0.85 0.48 0.25 0.5 Min. Inches Typ. 0.026 0.014 0.007 0.010 Max. 0.069 0.010 0.065 0.033 0.019 0.010 0.020 0.189 0.228 0.197 0.244 0.004 o 45 (typ.) 4.8 5.8 5.0 6.2 1.27 3.81 3.8 0.4 0.050 0.150 4.0 1.27 0.6 0.150 0.016 0.157 0.050 0.024 o 8 (max.) SO8.TBL Dimensions 1998 STMicroelectronics – Printed in Italy – All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Italy - Japan - Korea - Malaysia - Malta - Mexico - Morocco The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdo m - U.S.A. 10/10 ORDER CODE : Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this pub lication are subject to change without notice. This publication supersedes and replaces all information previously supplied. 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