Precision Timer NE555 Connection Diagram FUNCTION TABLE SO-8 NE555M OUTPUT DISCHARGE SWITCH Low On RESET TRIGGER VOLTAGE THRESHOLD VOLTAGE Low Irrelevant Irrelevant High <1/3VDD High High High >1/3V DD >2/3VDD Low High >1/3VDD <2/3V DD Off On As previously established DIP-8 NE555N General Description Features The NE555 is a highly stable device for generating accurate time delays or oscillation. Additional terminals are provided for triggering or resetting if desired. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For astable operation as an oscillator, the free running frequency and duty cycle are accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output circuit can source or sink up to 200mA or drive TTL circuits. n n n n n n Direct replacement for SE555/NE555 Timing from microseconds through hours Operates in both astable and monostable modes Adjustable duty cycle Output can source or sink 200 mA Output and supply TTL compatible n Normally on and normally off output Applications n n n n n n n Wing Shing Computer Components Co., (H.K.)Ltd. Homepage: http://www.wingshing.com Precision timing Pulse generation Sequential timing Time delay generation Pulse width modulation Pulse position modulation Linear ramp generator Tel:(852)2341 9276 Fax:(852)2797 8153 E-mail: [email protected] 1 NE555 ELECTRICAL CHARACTERISTICS (TA = 25˚C, VCC = +5V to +15V, unless othewise specified) Parameter Conditions Limits Min Supply Voltage Supply Current Note 4 Typ 4.5 = 5V, RL = ∞ OUTPUT LOW = 15V, RL = ∞ OUTPUT LOW Units Max 16 V mA VCC VCC Vcc=5V,No load OUTPUT HIGH 3 10 2 6 15 5 1 3 RA = 1k to 100kΩ, 50 Timing Error, Monostable Initial Accuracy Drift with Temperature % ppm/˚C C = 0.1µF, (Note 5) Accuracy over Temperature 1.5 Drift with Supply 0.1 % 0.5 %/V Timing Error, Astable Initial Accuracy Drift with Temperature RA, RB = 1k to 100kΩ, 2.25 % 150 ppm/˚C 3.0 % C = 0.1µF, (Note 5) Accuracy over Temperature Drift with Supply 0.30 %/V Threshold Voltage 0.667 x VCC Trigger Voltage VCC = 15V 4.5 5 VCC = 5V Trigger at 0V 1.1 Trigger Current 1.67 0.5 Reset Voltage Reset Current Threshold Current Control Voltage Level 0.3 Reset at Vcc (Note 6) VCC = 15V VCC = 5V 9 2.6 Pin 7 Leakage Output High 5.6 2.2 V 2 uA V 1 V 0.1 30 0.4 250 mA 10 3.33 20 1 11 4 V 100 nA 200 mV 0.7 nA Pin 7 Sat (Note 7) Output Low VCC = 15V, I7 = 15mA 180 Output Low VCC = 4.5V, I7 = 4.5mA 80 2 mV NE555 Electrical Characteristics (Notes 1, 2) (Continued) (TA = 25˚C, VCC = +5V to +15V, unless othewise specified) Parameter Conditions Limits Min Output Voltage Drop (Low) Units Typ Max ISINK = 10mA 0.1 0.25 ISINK = 50mA 0.4 0.75 V ISINK = 100mA 2 2.5 V ISINK = 200mA 2.5 VCC = 15V V V VCC = 5V Output Voltage Drop (High) ISINK = 8mA 0.15 0.4 ISINK = 5mA 0.1 0.25 0.35 ISOURCE = 200mA, VCC = 15V 12.5 ISOURCE = 100mA, VCC = 15V VCC = 5V V V V 12.75 13.3 V 2.75 3.3 V Rise Time of Output 100 300 ns Fall Time of Output 100 300 ns Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified. Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device performance. Note 3: For operating at elevated temperatures the device must be derated above 25˚C based on a +150˚C maximum junction temperature and a thermal resistance 170˚C/W (S0-8), junction to ambient. Note 4: Supply current when output high typically 9mA and MAX. is 13mA at Vcc=15V. Note 5: Tested at VCC = 5V and VCC = 15V. . Note 6: This will determine the maximum value of RA + RB for 15V operation. The maximum total (RA + RB) is 20MΩ. Note 7: No protection against excessive pin 7 current is necessary providing the package dissipation rating will not be exceeded. RECOMMENDED OPERATING CONDITIONS MIN 4.5 Supply voltage ,Vcc MAX. UNIT 16 V Input voltage (control,reset,threshold, and trigger ) Vcc + - Output current 200 mA o Operating free-air temperature, TA 0 3 70 0 C NE555 Applications Information MONOSTABLE OPERATION In this mode of operation, the timer functions as a one-shot (Figure 1). The external capacitor is initially held discharged by a transistor inside the timer. Upon application of a negative trigger pulse of less than 1/3 VCC to pin 2, the flip-flop is set which both releases the short circuit across the capacitor and drives the output high. NOTE: In monostable operation, the trigger should be driven high before the end of timing cycle. FIGURE 3. Time Delay FIGURE 1. Monostable ASTABLE OPERATION If the circuit is connected as shown in Figure 4 (pins 2 and 6 connected) it will trigger itself and free run as a multivibrator. The external capacitor charges through RA + RB and discharges through RB. Thus the duty cycle may be precisely set by the ratio of these two resistors. The voltage across the capacitor then increases exponentially for a period of t = 1.1 RA C, at the end of which time the voltage equals 2/3 VCC. The comparator then resets the flip-flop which in turn discharges the capacitor and drives the output to its low state. Figure 2 shows the waveforms generated in this mode of operation. Since the charge and the threshold level of the comparator are both directly proportional to supply voltage, the timing internal is independent of supply. FIGURE 4. Astable VCC = 5V TIME = 0.1 ms/DIV. RA = 9.1kΩ C = 0.01µF Top Trace: Input 5V/Div. Middle Trace: Output 5V/Div. Bottom Trace: Capacitor Voltage 2V/Div. In this mode of operation, the capacitor charges and discharges between 1/3 VCC and 2/3 VCC. As in the triggered mode, the charge and discharge times, and therefore the frequency are independent of the supply voltage. FIGURE 2. Monostable Waveforms During the timing cycle when the output is high, the further application of a trigger pulse will not effect the circuit so long as the trigger input is returned high at least 10µs before the end of the timing interval. However the circuit can be reset during this time by the application of a negative pulse to the reset terminal (pin 4). The output will then remain in the low state until a trigger pulse is again applied. When the reset function is not in use, it is recommended that it be connected to VCC to avoid any possibility of false triggering. Figure 3 is a nomograph for easy determination of R, C values for various time delays. 4 NE555 Physical Dimensions inches (millimeters) unless otherwise noted NE555M Pad locatin DISCHARGE 7 8 Vcc GND 1 6 CONTROL VOLTAGE 5 THRESHOLD 4 RESET 95 95 2 TRIGGER 3 OUTPUT Chip Size: 1.02x 1.07 mm Pad N 1 2 3 4 Coordinates mkm X Y 95 313 115 126 Pad Name GND TRIGGER OUTPUT RESET 5 THRESHOLD 6 7 8 CONTROL VOLTAGE DISCHARGE 590 810 Vcc 5 810 126 451 635 780 829 420 125 893 492