SN54/74LS147

The SN54/74LS147 and SN54/74LS148 are Priority Encoders. SN54/74LS147 and SN54/74LS148  provide priority decoding of the inputs to ensure that only the highest order data line is encoded. Both devices have data inputs and outputs which are active at the low logic level.

The SN54/74LS147 and SN54/74LS148  encode nine data lines to four-line (8-4-2-1) BCD. The implieddecimal zero condition does not require an input condition because zero is encoded when all nine data lines are at a high logic level.The LS148 encodes eight data lines to three-line (4-2-1) binary (octal). By providing cascading circuitry (Enable Input EI and Enable Output EO) octalexpansion is allowed without needing external circuitry.The SN54/ 74LS748 is a proprietary Motorola part incorporating a built-in deglitcher network which minimizes glitches on the GS output. The glitch occurs on the negative going transition of the EI input when data inputs 07 are at logical ones.

The only dc parameter differences between theSN54/74LS147 and SN54/74LS148  are that (1) Pin 10 (input 0) has a fan-in of 2 on the LS748 versus a fan-in of 1 on the LS148; (2) Pins 1, 2, 3, 4, 11, 12 and 13 (inputs 1, 2, 3, 4, 5, 6, 7) have a fan-in of 3 on the LS748 versus a fan-in of 2 on the LS148.The only ac difference is that tPHL from EI to EO is changed from 40 to 45 ns.

Motorola reserves the right to make changes without further notice to any SN54/74LS147 and SN54/74LS148  products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit,and specifically disclaims any and all liability, including without limitation consequential or incidental damages. "Typical" parameters can and do vary in different applications. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. Motorola does not convey any license under its patent rights nor the rights of others.