======================================================================== 74F538 1-OF-8 DECODER (3-STATE OUTPUTS) ======================================================================== Family: Fairchild FAST (Advanced Schottky TTL) Source: 1980 Fairchild FAST Data Book, pages 4-115 ... 4-117 Status: PRELIMINARY -- page 4-115 carries a "Preliminary" watermark. Ratings: Vcc = +5.0 V +/-5%, TA = 0 to +70 deg C DESCRIPTION ----------- The 'F538 decoder/demultiplexer accepts three Address (A0 - A2) input signals and decodes them to select one of eight mutually exclusive outputs. A polarity control input (P) determines whether the outputs are active-LOW or active-HIGH. A HIGH signal on either of the active-LOW Output Enable (/OE) inputs forces all outputs to the high impedance state. Two active-HIGH and two active-LOW input enables are available for easy expansion to 1-of-32 decoding with four packages, or for data demultiplexing to one of eight or one of 16 destinations. o OUTPUT POLARITY CONTROL o DATA DEMULTIPLEXING CAPABILITY o MULTIPLE ENABLES FOR EXPANSION o 3-STATE OUTPUTS CONNECTION DIAGRAM (20-pin DIP) -------------------------------- Pin Function Pin Function --- ------------------------------- --- ------------------------------- 1 O2 Output 2 20 Vcc 2 O1 Output 1 19 O3 Output 3 3 O0 Output 0 18 O4 Output 4 4 /OE1 Output Enable (active LOW) 17 A2 Address input 2 5 /OE2 Output Enable (active LOW) 16 /E1 Enable input (active LOW) 6 A0 Address input 0 15 /E2 Enable input (active LOW) 7 A1 Address input 1 14 E3 Enable input (active HIGH) 8 O5 Output 5 13 E4 Enable input (active HIGH) 9 O6 Output 6 12 P Polarity Control input 10 GND 11 O7 Output 7 TRUTH TABLE ----------- H = HIGH voltage level; L = LOW voltage level; X = immaterial; Z = high impedance state. Function /OE1 /OE2 /E1 /E2 E3 E4 A2 A1 A0 O0 O1 O2 O3 O4 O5 O6 O7 -------------- ---- ---- --- --- -- -- -- -- -- -- -- -- -- -- -- -- -- High Impedance H X X X X X X X X Z Z Z Z Z Z Z Z High Impedance X H X X X X X X X Z Z Z Z Z Z Z Z Disable L L H X X X X X X Outputs Equal P Input Disable L L X H X X X X X Outputs Equal P Input Disable L L X X L X X X X Outputs Equal P Input Disable L L X X X L X X X Outputs Equal P Input Active-HIGH L L L L H H L L L H L L L L L L L Output L L L L H H L L H L H L L L L L L (P = L) L L L L H H L H L L L H L L L L L L L L L H H L H H L L L H L L L L L L L L H H H L L L L L L H L L L L L L L H H H L H L L L L L H L L L L L L H H H H L L L L L L L H L L L L L H H H H H L L L L L L L H Active-LOW L L L L H H L L L L H H H H H H H Output L L L L H H L L H H L H H H H H H (P = H) L L L L H H L H L H H L H H H H H L L L L H H L H H H H H L H H H H L L L L H H H L L H H H H L H H H L L L L H H H L H H H H H H L H H L L L L H H H H L H H H H H H L H L L L L H H H H H H H H H H H H L INPUT LOADING / FAN-OUT ------------------------ Pin Names Description U.L. HIGH/LOW ----------- -------------------------------- ------------- A0 - A2 Address Inputs 0.5 / 0.375 /E1, /E2 Enable Inputs (Active LOW) 0.5 / 0.375 E3, E4 Enable Inputs (Active HIGH) 0.5 / 0.375 /OE1, /OE2 Output Enable Inputs (Active LOW) 0.5 / 0.375 P Polarity Control Input 0.5 / 0.375 O0 - O7 3-State Outputs 25 / 12.5 DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE ----------------------------------------------------- Symbol Parameter Min Typ Max Units ------ -------------------------------------- --- --- --- ----- ICC Power Supply Current (All Outputs OFF) 38 mA Conditions: A0 - A2, /E1, /E2 = Gnd; /OE1, /OE2, E3, E4, P = HIGH. AC CHARACTERISTICS ------------------ Symbol Parameter Min Typ Max Units ------ ------------------------------------ --- ---- --- ----- tPLH Propagation Delay An to On -- 12.5 -- ns tPHL Propagation Delay An to On -- 11.5 -- ns tPLH Propagation Delay /E1 or /E2 to On -- 11.5 -- ns tPHL Propagation Delay /E1 or /E2 to On -- 11 -- ns tPLH Propagation Delay E3 or E4 to On -- 14 -- ns tPHL Propagation Delay E3 or E4 to On -- 14.5 -- ns tPLH Propagation Delay P to On -- 13 -- ns tPHL Propagation Delay P to On -- 12 -- ns tPZH Output Enable Time /OE1 or /OE2 -- 5.0 -- ns tPZL Output Enable Time /OE1 or /OE2 -- 5.5 -- ns tPHZ Output Disable Time (1) /OE1 or /OE2 -- 5.0 -- ns tPLZ Output Disable Time (1) /OE1 or /OE2 -- 5.5 -- ns (1) Disable times measured with CL = 5.0 pF.