CMOS同步可编程4位计数器 CMOS Synchronous Programmable 4-Bit Counters
CD40160B, CD40161B, CD40162B, and CD40163B are 4-bit synchronous programmable counters. The CLEAR function of the CD40162B and CD40163B is synchronous and a low level at the CLEAR\ input sets all four outputs low on the next positive CLOCK edge. The CLEAR function of the CD40160B and CD40161B is asynchronous and a low level at the CLEAR\ input sets all four outputs low regardless of the state of the CLOCK, LOAD\, or ENABLE inputs. A low level at the LOAD\ input disables the counter and causes the output to agree with the setup data after the next CLOCK pulse regardless of the conditions of the ENABLE inputs.
The carry look-ahead circuitry provides for cascading counters for n-bit synchronous applications without additional gating. Instrumental in accomplishing this function are two count-enable inputs and a carry output COUT. Counting is enabled when both PE and TE inputs are high. The TE input is fed forward to enable COUT. This enabled output produces a positive output pulse with a duration approximately equal to the positive portion of the Q1 output. This positive overflow carry pulse can be used to enable successive cascaded stages. Logic transitions at the PE or TE inputs may occur when the clock is either high or low.
The CD40160B types are supplied in 16-lead hermetic dual-in-line ceramic packages F3A suffix. The CD40161B types are supplied in 16-lead hermetic dual-in-line ceramic packages F3A suffix, 16-lead dual-in-line plastic packages E suffix, 16-lead small-outline packages NSR suffix, and 16-lead thin shrink small-outline packages PW and PWR suffixes.
The CD40160B through CD40163B types are functionally equivalent to and pin-compatible with the TTL counter series 74LS160 through 74LS163 respectively.