CMOS Programmable Timer

CD4541B programmable Timer consists of a 16-stage binary Counter an Oscillator that is controlled by external R-C components (2 resistors and a capacitor), an Automatic power-on reset circuit, and output control Logic The Counter increments on positive-edge Clock transitions and CAN also be reset via the MASTER RESET input.
The output from this Timer is the Q or Q output from the 8th, 10th, 13th, or 16th Counter stage. The desired stage is chosen using time-select inputs A and B (see Frequency Select Table).
The output is available in either of two modes selectable via the MODE input, pin 10 (see Truth Table). When this MODE input is a Logic "1", the output will be a continuous square wave having a frequency equal to the Oscillator frequency divided by 2N. With the MODE input set to Logic "0" and after a MASTER RESET is initiated, the output (assuming Q output has been selected) changes from a low to a high state after 2N-1 counts and remains in that state until another MASTER RESET pulse is applied or the MODE input is set to a Logic "1".
Timing is initialized by setting the AUTO RESET input (pin 5) to Logic "0" and turning power on. If pin 5 is set to Logic "1", the AUTO RESET circuit is disabled and counting will not start until after a positive MASTER RESET pulse is applied and returns to a low level. The AUTO RESET consumes an appreciable amount of power and should not be used if low-power operation is desired. For reliable Automatic power-on reset, VDD should be greater than 5V.
The RC Oscillator shown in Figure 2, oscillates with a frequency determined by the RC network and is calculated using:
Where f is between 1kHz and 100kHz and RS 10k and 2RTC.
By Texas Instruments