Abstract :
An I/SUP 2/L timing circuit without external components is presented, which makes use of some specific I/SUP 2/L properties-operation at low power levels, light sensitivity, variable delay, and long maximum delay times. The circuit comprises 45 gates on a chip area of 0.3 mm/SUP 2/. It produces pulses from below 1 ms to more than 10 s which are inversely proportional to a single supply current. For this purpose, new methods for current splitting and amplification with I/SUP 2/L circuits are used. The temperature dependence of the output pulse width is better than 0.8 percent/K. If the circuit is irradiated by light, it produces pulses with a pulse width inversely proportional to the light intensity. For example, it can be used as an integrated exposure meter for all kinds of photographic applications.
