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N74F269DR Datasheet Additional Hysteresis If additional hysteresis is desired, this can be done with the addition of three resistors using positive feedback, as shown in Figure 2. The positive feedback method slows the com- parator response time. Calculate the resistor values as fol- lows: 1) Select R3. The current through R3 should be greater than the input bias current to minimize errors. The current through R3 (IF) at the trip point is (VREF - VOUT) /R3. Consider the two possible output states when solving for R3, and use the smaller of the two resulting resistor values. The two formulas are: R3 = VREF/IF (when VOUT = 0) R3 = Vcc - VREF /IF (VOUT = VCC) 2) Choose a hysteresis band required (VHB). 3) Calculate Rl, where Rl = R3 X(VHBNCC) 4) Choose the trip point for VIN rising. This is the threshold voltage (VTHR) at which the comparator switches from low to high as VIN rises about the trip point. 5) Calculate R2 as follows: N74F269DR Price IPSW - Bit 6 Interrupt switch - When set to a logic l, ~NTA iS the Time ofDay Alarm and ~N-I-BI(INTB) is the Watchdog Alarm. When set to logic 0, this bit reverses the output pins. INTA iS now the Watchdog Alarm output and INTB /(INTB) is the Time of Day Alarm output. N74F269DR on stock Noise performance is optimized for 2.5 Gb/s operation, with a calculated rms noise based sensitivity of -26 dBm for 10-'0 bit error rate. achieved using a detector with 0.5 pF capacitance and a responsivity of 0.9 NW, with an infinite extinction ratio source.
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