SN54ALS193A

Supply voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Input voltage, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 V
Operating free-air temperature range, TA: SN54ALS193A . . . . . . . . . . . .55°C to 125
                                          SN74ALS193A . . . . . . . . . . . . . . . . . 0to 70
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....65to 150

†Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

The SN54ALS193A are synchronous, reversible, 4-bit up/down binary counters. Synchronous counting operation is provided by having all flip-flops clocked simultaneously so that the outputs change coincident with each other when instructed by the steering logic. SN54ALS193A of operation eliminates the output counting spikes normally associated with asynchronous (rippleclock)
counters.

The outputs of the four flip-flops SN54ALS193A are triggered on a low-to-high-level transition of either count/clock (UP or DOWN) input. The direction of the count SN54ALS193A is determined by which count input is pulsed while the other count input is high.

All four counters are fully programmable; that is, each output of SN54ALS193A may be preset to either level by placing a low on the load (LOAD) input and entering the desired data at the data inputs. The output changes to agree with the data inputs independently of the count pulses. SN54ALS193A feature allows the counters to be used as modulo-N dividers by simply modifying the count length with the preset inputs.

A high level applied to the clear (CLR) input forces all outputs of SN54ALS193A to the low level. The clear function is independent of the count and LOAD inputs. The UP, DOWN, and LOAD inputs of SN54ALS193A are buffered to lower the drive requirement, which significantly reduces the loading on, or current required by, clock drivers, etc., for long parallel words.

These counters are designed to be cascaded without the need for external circuitry. The borrow (BO) output produces a low-level pulse while the count is zero (all Q outputs low) and the DOWN input is low. Similarily, the carry (CO) output produces a low-level pulse while the count is 9 or 15 (all Q outputs high) and the UP input is low. The counters can then be easily cascaded by feeding BO and CO to the count-down and count-up inputs, respectively, of the succeeding counter.

The SN54ALS193A is characterized for operation over the full military temperature range of 55to 125. The SN74ALS193A is characterized for operation from 0to 70.