XL551

XD551 and XL551 are monolithic timing circuit ICs. These timers are fully compatible with CMOS, TTL, and MOS logic, operating at frequencies up to 2MHz. Due to their high input impedance, these devices use smaller timing capacitors, enabling more precise time delays and oscillation. Power consumption is low across the entire supply voltage range. The trigger level of the XD551 and XL551 is approximately one-third of the supply voltage, and the threshold level is approximately two-thirds of the supply voltage. These levels can be modified using the control voltage terminal (CONT). When the trigger input (TRIG) falls below the trigger level, the flip-flop is set and the output goes high. If TRIG is above the trigger level and the threshold input (THRES) is above the threshold level, the flip-flop is reset and the output goes low. The reset input (RESET) overrides all other inputs and can be used to initiate a new timing cycle. When RESET is low, the flip-flop is reset and the output goes low. Whenever the output is low, a low-impedance path is provided between DISCH and GND. All unused inputs should be connected to the appropriate logic level to prevent false triggering.

Applications

• Astable multivibrator applications

Key features

• Ultra-low power consumption: 170μA at VDD = 5V
• Astable mode operation capable
• High output current capability: 100mA sink (max), 10mA source (typical)
• Output fully compatible with CMOS, TTL, and MOS
• Low supply current reduces spikes during output transitions
• Single supply 2V to 15V operation
• ESD protection exceeds 1500V (per MIL-STD-883C, Method 3015.2)
• Operating temperature range: 0°C to 70°C
• Package options: DIP8 (XD551) and SOP8 (XL551)