The SN74LV8154 is a dual 16 bit binary counter with 3-state output registers, designed for 2-V to 5.5-V VCC operation.
This 16 bit counter (A or B) feeds a 16 bit storage register and each storage register is further divided into an upper byte and lower byte. The GAL, GAU, GBL, and GBU inputs are used to select the byte that needs to be output at Y0-Y7. CLKA is the clock for A counter and CLKB is the clock for B counter. RCLK is the clock for the A and B storage registers. All three clock signals are positive-edge triggered.
A 32 bit counter can be realized by connecting CLKA and CLKB together and by connecting RCOA to CLKBEN.
To ensure the high-impedance state during power up or power down, GAL, GAU, GBL, and GBU should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down.