Low Power LinCMOS™ Timer

The TLC555 is a CMOS monolithic timing circuit.

The timer is fully compatible with CMOS, TTL, and MOS logic and operates at

frequencies up to 2MHz. Because of a high input impedance, this device supports

smaller timing capacitors than those supported by the NE555 or LM555. As a result,

more accurate time delays and oscillations are possible. Power consumption is low

across the full range of power-supply voltage.

Like the NE555, the

TLC555 has a trigger level equal to approximately one-third of the supply voltage

and a threshold level equal to approximately two-thirds of the supply voltage. These

levels can be altered by use of 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 is low. The

reset input (RESET) can override all other inputs and can be used to initiate a new

timing cycle. If RESET is low, the flip-flop is reset and the output is low.

Whenever the output is low, a low-impedance path is provided between the discharge

terminal (DISCH) and GND. All unused inputs must be tied to an appropriate logic

level to prevent false triggering.