NE555 SA555 - SE555 General purpose single bipolar timers Features ■ 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% per °C N DIP8 (Plastic package) D SO8 (Plastic micropackage) Description The NE555 monolithic timing circuit is a highly stable controller capable of producing accurate time delays or oscillation. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For a stable operation as an oscillator, the free running frequency and the duty cycle are both accurately controlled with two external resistors and one capacitor. Pin connections (top view) The circuit may be triggered and reset on falling waveforms, and the output structure can source or sink up to 200mA. 1 8 2 7 3 6 4 5 1 - GND 2 - Trigger 3 - Output 4 - Reset March 2007 Rev 4 5 - Control voltage 6 - Threshold 7 - Discharge 8 - VCC 1/20 www.st.com 20 Contents NE555 - SA555 - SE555 Contents 1 Schematic diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Absolute maximum ratings and operating conditions . . . . . . . . . . . . . 4 3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1 Monostable operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.2 Astable operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.3 Pulse width modulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.4 Linear ramp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.5 50% duty cycle oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.6 Additional information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 5 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 6 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2/20 NE555 - SA555 - SE555 1 Schematic diagrams Schematic diagrams Figure 1. Block diagram VCC+ 5kΩ COMP THRESHOLD CONTROL VOLTAGE DISCHARGE R FLIP-FLOP 5kΩ Q COMP OUT TRIGGER S INHIBIT/ RESET 5kΩ S RESET S - 8086 Figure 2. Schematic diagram CONTROL VOLTAGE OUTPUT THRESHOLD COMPARATOR 5 VCC R2 830W R1 4.7kW R4 R8 1kW 5kW R3 4.7kW R12 6.8kW Q21 Q5 Q6 Q7 Q8 Q19 Q9 Q22 Q20 R13 3.9kW R11 5kW THRESHOLD Q1 Q2 Q3 Q11 Q12 TRIGGER 2 Q23 R9 5kW D2 RESET Q10 4 R14 220W Q24 Q18 R16 100W R15 4.7kW Q15 7 Q17 Q14 GND 3 Q13 Q16 DISCHARGE D1 R17 4.7kW Q4 R5 10kW R6 100kW R7 100kW R10 5kW 1 TRIGGER COMPARATOR FLIP FLOP 3/20 Absolute maximum ratings and operating conditions 2 Absolute maximum ratings and operating conditions Table 1. Absolute maximum ratings Symbol Parameter VCC Tj Table 2. Value Unit Supply voltage 18 V Junction temperature 150 °C -65 to 150 °C Value Unit 4.5 to 16 4.5 to 16 4.5 to 18 V VCC V Storage temperature range Tstg Operating conditions Symbol VCC Parameter Supply voltage NE555 SA555 SE555 Vth, Vtrig, Vcl, Vreset Maximum input voltage Toper 4/20 NE555 - SA555 - SE555 Operating free air temperature range NE555 SA555 SE555 0 to 70 -40 to 105 -55 to 125 °C NE555 - SA555 - SE555 Electrical characteristics 3 Electrical characteristics Table 3. Tamb = +25°C, VCC = +5V to +15V (unless otherwise specified) SE555 Symbol Unit Min. ICC NE555 - SA555 Parameter Typ. Max. 3 10 2 Timing error (monostable) (RA = 2k to 100kΩ, C = 0.1μF) Initial accuracy (1) 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 - (1) Drift with temperature Drift with supply voltage 1.5 90 0.15 Supply current (RL = ∝) Low stage VCC = +5V VCC = +15V High state VCC = 5V Min. Typ. Max. 5 12 3 10 2 6 15 2 100 0.2 1 50 0.1 3 0.5 2.25 150 0.3 mA % ppm/°C %/V % ppm/°C %/V VCL Control voltage level VCC = +15V VCC = +5V 9.6 2.9 10 3.33 10.4 3.8 9 2.6 10 3.33 11 4 V Vth 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 V Ith Threshold current (2) 0.1 0.25 0.1 0.25 µA 5 1.67 5.2 1.9 5 1.67 5.6 2.2 V 0.5 0.9 0.5 2.0 µA 0.7 1 0.7 1 V mA Vtrig Trigger voltage VCC = +15V VCC = +5V Itrig Trigger current (Vtrig = 0V) (3) 4.8 1.45 Vreset Reset voltage Ireset Reset current Vreset = +0.4V Vreset = 0V 0.1 0.4 0.4 1 0.1 0.4 0.4 1.5 VOL 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 VOH High level output voltage VCC = +15V IO(sink) = 200mA IO(sink) = 100mA VCC = +5V IO(sink) = 100mA 0.4 4.5 1.1 13 3 12.5 13.3 3.3 0.4 0.25 0.2 12.75 2.75 12.5 13.3 3.3 V 0.4 0.35 V 5/20 Electrical characteristics Table 3. NE555 - SA555 - SE555 Tamb = +25°C, VCC = +5V to +15V (unless otherwise specified) SE555 Symbol NE555 - SA555 Parameter Unit Min. Typ. Max. 20 Min. Typ. Max. 100 20 100 Idis(off) Discharge pin leakage current (output high) Vdis = 10V Vdis(sat) Discharge pin saturation voltage (output low) (4) 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 (5) (Vreset = VCC) 0.5 tr tf toff nA mV 0.5 1. Tested at VCC = +5V and VCC = +15V. 2. This will determine the maximum value of RA + RB for 15V operation. The maximum total (RA + RB) is 20MΩ for 15V operation and 3.5MΩ for +5V operation. 3. Specified with trigger input high. 4. No protection against excessive pin 7 current is necessary, providing the package dissipation rating is not exceeded. 5. Time measured from a positive pulse (from 0V to 0.8xVCC) on the Threshold pin to the transition from high to low on the Output pin. Trigger is tied to Threshold. 6/20 ns µs NE555 - SA555 - SE555 Electrical characteristics Figure 3. Minimum pulse width required for triggering Figure 4. Supply current versus supply voltage Figure 5. Delay time versus temperature Figure 6. Low output voltage versus output sink current Figure 7. Low output voltage versus output sink current Figure 8. Low output voltage versus output sink current 7/20 Electrical characteristics Figure 9. High output voltage drop versus output Figure 11. Propagation delay versus voltage level of trigger value 8/20 NE555 - SA555 - SE555 Figure 10. Delay time versus supply voltage NE555 - SA555 - SE555 Application information 4 Application information 4.1 Monostable operation In the monostable mode, the timer generates a single pulse. As shown in Figure 12, the external capacitor is initially held discharged by a transistor inside the timer. Figure 12. Typical schematics in monostable operation VCC = 5 to 15V Reset R1 8 4 Trigger 7 2 NE555 Output 6 5 3 1 C1 Control Voltage 0.01μF 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 state is given by t = 1.1 R1C1 and is easily determined by Figure 14. Note that because 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 negative pulse 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 is applied, the output is driven to its LOW state. When a negative trigger pulse is applied to pin 2, the flip-flop is set, releasing the shortcircuit across the external capacitor and driving the output HIGH. The voltage across the capacitor increases exponentially with the time constant t = R1C1. When the voltage across the capacitor equals 2/3 VCC, the comparator resets the flip-flop which then discharges the capacitor rapidly and drives the output to its LOW state. Figure 13 shows the actual waveforms generated in this mode of operation. When Reset is not used, it should be tied high to avoid any possibility of unwanted triggering. 9/20 Application information NE555 - SA555 - SE555 Figure 13. Waveforms in monostable operation t = 0.1 ms / div INPUT = 2.0V/div OUTPUT VOLTAGE = 5.0V/div CAPACITOR VOLTAGE = 2.0V/div R1 = 9.1kΩ, C1 = 0.01μF, RL = 1kΩ Figure 14. Pulse duration versus R1C1 0.01 0.001 10 μs 4.2 Ω 10 M 0.1 10 k R 1= 1.0 Ω 10 0k Ω 1M Ω 1k Ω C (μF) 10 100 μs 1.0 ms 10 ms 100 ms 10 s (t d ) Astable operation When the circuit is connected as shown in Figure 15 (pin 2 and 6 connected) it triggers itself and free runs as a multi-vibrator. The external capacitor charges through R1 and R2 and discharges through R2 only. Thus the duty cycle can be set accurately by adjusting 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 triggered mode, the charge and discharge times and, therefore, frequency are independent of the supply voltage. 10/20 NE555 - SA555 - SE555 Application information Figure 15. Typical schematics in astable operation VCC = 5 to 15V R1 8 4 Output 3 7 NE555 Control Voltage R2 6 5 0.01μF 1 2 C1 Figure 16 shows the actual waveforms generated in 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 of oscillation is then: 1 1.44 f = --- = -------------------------------------T ( R1 + 2R2 )C1 It can easily be found from Figure 17. The duty cycle is given by: R2 D = ------------------------R1 + 2R2 11/20 Application information NE555 - SA555 - SE555 Figure 16. Waveforms in astable operation t = 0.5 ms / div OUTPUT VOLTAGE = 5.0V/div CAPACITOR VOLTAGE = 1.0V/div R1 = R2 = 4.8kΩ, C1= 0.1μF, RL = 1kΩ Figure 17. Free running frequency versus R1, R2 and C1 C (μF) 10 1.0 R 1 1k Ω 10 kΩ + 0.1 0.01 0.001 0.1 12/20 1 R2 1M = 10 M 10 10 0k Ω Ω Ω 100 1k 10k f o (Hz) NE555 - SA555 - SE555 4.3 Application information 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 18 shows the circuit. Figure 18. Pulse width modulator VCC RA 8 4 Trigger 7 2 NE555 6 Modulation Input 5 3 Output C 1 4.4 Linear ramp When the pull-up resistor, RA, in the monostable circuit is replaced by a constant current source, a linear ramp is generated. Figure 19 shows a circuit configuration that will perform this function. Figure 19. Linear ramp VCC RE 8 4 Trigger R1 7 2 NE555 2N4250 or equiv. 6 C Output 5 3 0.01μF R2 1 13/20 Application information NE555 - SA555 - SE555 Figure 20 shows the 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 20. Linear ramp VCC = 5V Time: 20µs/DIV R1 + 47kΩ R2 = 100kΩ RE = 2.7kΩ C = 0.01µF 4.5 Top trace: input 3V/DIV Middle trace: output 5V/DIV Bottom trace: output 5V/DIV Bottom trace: capacitor voltage 1V/DIV 50% duty cycle oscillator For a 50% duty cycle, the resistors RA and RE can be connected as in figure 19. The time period for the output high is the same as for astable operation (see Section 4.2 on page 10): t1 = 0.693 RA C For the output low it is RB – 2RA t 2 = [(R. RB)/(RA+RB)].C.Ln --------------------------2RB – RA Thus the frequency of oscillation is: 1 f = ---------------t1 + t2 14/20 NE555 - SA555 - SE555 Figure 21. Application information 50% duty cycle oscillator VCC VCC RA 51kΩ 4 8 RB 7 2 22kΩ NE55 Out 6 5 3 1 0.01μF C 0.01μF Note that this circuit will not oscillate if RB is greater 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. 4.6 Additional information Adequate power supply by passing is necessary to protect associated circuitry. The minimum recommended is 0.1µF in parallel with 1µF electrolytic. 15/20 Package information 5 NE555 - SA555 - SE555 Package information In order to meet environmental requirements, STMicroelectronics offers these devices in ECOPACK® packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an STMicroelectronics trademark. ECOPACK specifications are available at: www.st.com. 16/20 NE555 - SA555 - SE555 Package information Figure 22. DIP8 package mechanical data Dimensions Ref. Millimeters Min. Typ. A Inches Max. Min. Typ. 5.33 Max. 0.210 A1 0.38 0.015 A2 2.92 3.30 4.95 0.115 0.130 0.195 b 0.36 0.46 0.56 0.014 0.018 0.022 b2 1.14 1.52 1.78 0.045 0.060 0.070 c 0.20 0.25 0.36 0.008 0.010 0.014 D 9.02 9.27 10.16 0.355 0.365 0.400 E 7.62 7.87 8.26 0.300 0.310 0.325 E1 6.10 6.35 7.11 0.240 0.250 0.280 e 2.54 0.100 eA 7.62 0.300 eB L 10.92 2.92 3.30 3.81 0.430 0.115 0.130 0.150 17/20 Package information NE555 - SA555 - SE555 Figure 23. SO8 package mechanical data Dimensions Ref. Millimeters Min. Typ. A Max. Min. Typ. 1.75 0.25 Max. 0.069 A1 0.10 A2 1.25 b 0.28 0.48 0.011 0.019 c 0.17 0.23 0.007 0.010 D 4.80 4.90 5.00 0.189 0.193 0.197 H 5.80 6.00 6.20 0.228 0.236 0.244 E1 3.80 3.90 4.00 0.150 0.154 0.157 e 0.004 0.010 0.049 1.27 0.050 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k 1° 8° 1° 8° ccc 18/20 Inches 0.10 0.004 NE555 - SA555 - SE555 6 Ordering information Ordering information Table 4. Order codes Part number Temperature range Package Packing Marking DIP8 Tube NE555N SO8 Tube or tape & reel NE555 DIP8 Tube SA555N SO8 Tube or tape & reel SA555 DIP8 Tube SE555N SO8 Tube or tape & reel SE555 NE555N 0°C, +70°C NE555D/DT SA555N -40°C, +105°C SA555D/DT SE555N -55°C, + 125°C SE555D/DT 7 Revision history Date Revision 1-Jun-2003 1 2004-2006 2-3 15-Mar-2007 4 Changes Initial release. Internal revisions Expanded order code table. Template update. 19/20 NE555 - SA555 - SE555 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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