Overview

Product details

    XL551 is a single chip timing circuit manufactured by the LinCMOS7.1 process. The timer is fully compatible with CMOS, TTL and MOS logic and operates at frequencies up to 2 MHZ. Compared to the XL555 timer, the device uses a smaller timing capacitance due to its high input impedance. Therefore, more precise time delays and oscillations are possible. Low power consumption across the entire supply voltage range. The XL551 has a trigger level of about one-third of the supply voltage and a threshold level of about two-thirds of the supply voltage. These levels can be changed by using the Control Voltage terminal (CONT). When the trigger input (TRIG) is lower than the trigger level, the trigger is set and the output becomes higher. If the trigger is higher than the trigger level and the threshold input (THRES) is higher than the threshold level, the trigger resets and the output is low. The reset input overrides all other inputs and can be used to start a new timing loop. If reset low: The trigger is reset, the output is low when the output is low, and a low impedance path is provided between DISCH and GND. All unused inputs should be bound to the appropriate logic level to prevent error triggering. While the CMOS output is capable of sinking over 100 mA and the source over 10 mA, the XL551 shows significantly reduced power current spikes during output conversion. This minimizes the need for the large decoupling capacitors required by the XL555. The XL551 features a range from 0°C to 70°C.