The 74HC193-Q100; 74HCT193-Q100 is a 4-bit synchronous binary up/down counter.
Separate up/down clocks, CPU and CPD respectively, simplify operation. The outputs
change state synchronously with the LOW-to-HIGH transition of either clock input. If the
CPU clock is pulsed while CPD is held HIGH, the device counts up. If the CPD clock is
pulsed while CPU is held HIGH, the device counts down. Only one clock input can be held
HIGH at any time to guarantee predictable behavior. The device can be cleared at any
time by the asynchronous master reset input (MR). It may also be loaded in parallel by
activating the asynchronous parallel load input (PL). The terminal count up (TCU) and
terminal count down (TCD) outputs are normally HIGH. When the circuit has reached the
maximum count state of 15, the next HIGH-to-LOW transition of CPU causes TCU to go
LOW. TCU remains LOW until CPU goes HIGH again, duplicating the count up clock.
Likewise, the TCD output goes LOW when the circuit is in the zero state and the CPD
goes LOW. The terminal count outputs duplicate the clock waveforms and can be used as
the clock input signals to the next higher-order circuit in a multistage counter. Multistage
counters are not fully synchronous, since there is a slight delay time difference added for
each stage that is added. The counter may be preset by the asynchronous parallel load
capability of the circuit. Information on the parallel data inputs (D0 to D3), is loaded into
the counter. This information appears on the outputs (Q0 to Q3) regardless of the
conditions of the clock inputs when the parallel load (PL) input is LOW. A HIGH level on
the master reset (MR) input disables the parallel load gates. It overrides both clock inputs
and sets all outputs (Q0 to Q3) LOW. If one of the clock inputs is LOW during and after a
reset or load operation, the next LOW-to-HIGH transition of that clock is interpreted as a
legitimate signal and it is counted. Inputs include clamp diodes that enable the use of
current limiting resistors to interface inputs to voltages in excess of VCC.
This product has been qualified to the Automotive Electronics Council (AEC) standard
Q100 (Grade 1) and is suitable for use in automotive applications.