AC138 ACT138 54ACI/74AC138 54ACTI74ACT138 1-of-8 Decoder/Demultiplexer Description The ACPACT138 is a high-speed 1-of-8 decoder/demultiplexer. This device is ideally suited for high-speed bipolar memory chip select address decoding. The multiple input enables allow parailel expansion to a 1-of-24 decoder using just three *AC/ACT138 devices or a 1-of-32 decoder using four AC/ACT138 devices and one inverter. Demultiplexing Capability Multiple Input Enable for Easy Expansion Active LOW Mutually Exclusive Outputs * Outputs Source/Sink 24 mA * ACT138 has TTL-Compatible inputs Ordering Code: See Section 6 Logie Symbol [tid S| Ay Ay Ag , E, E, Oy 9; Oy O03 Og Os Og 0; TPT IT? Pin Names Ao - A2 Address Inputs E; - Ea Enable Inputs E3 Enable Input Go - 67 Outputs 5-34 Connection Diagrams 4 f Ao in ~ 16] Voc Ai (21 [15] Go Az [I [14] 5; Bf 13] G2 e. (| 12] 33 es [6] 1a] 6: 37 ra] 5s Gp [6] [9] Os Pin Assignment for DIP, Flatpak and SOIC (xo! (218 fay! | & Bl wa GND [10, eA NC [14] [tr NC Os f13} al Voc 0s 13] fig] Oo fg 63) fe fo fe d Os nc & & Pin Assignment for LCCAC138 ACT138 Functional Description The 'AC/'ACT138 high-speed 1-of-8 decoder/demultiplexer accepts three binary weighted inputs (Ao, A1, A2) and, when enabled, provides eight mutually exclusive active-LOW outputs (Oo - 67). The 'AC/ACT138 features three Enable inputs, two active-LOW (E1, E2) and one active-HIGH (E3). Ali outputs will be HIGH unless E; and E2 are LOW and Es is HIGH. This multiple enabled function allows easy parallel expansion of the device to a 1-of-32 (6 lines to 32 lines) decoder with just four AC/ACT138 devices and one inverter (See Figure a). The 'AC/ACT138 can be used as an 8-output demultiplexer by using one of the active LOW Enable inputs as the data input and the other Enable inputs as strobes. The Enabie inputs which are not used must be permanently tied to their appropriate active-HIGH or active-LOW state. Truth Table inputs Outputs E: | E2 | Es | Ao | Ai | A2 | Oo | Oi | G2 | O3 | Ga | Gs | Os | Or H x xX x Xx x H H H H H H H H Xx H x x Xx xX H H H H H H H H X X L x x x H H H H H H H H L L H L L L L H H H H H H H L L H H L L H L H H H H H H L L H L H L H H L H H H H H L L H H H L H H H L H H H H L L H L L H H H H H L H H H L L H H L H H H H H H L H H H=HIGH Voltage Level L L H L H H H H H H H H L H L=LOW Voltage Level L L H H H H H H H H H H H L X= Immaterial Logic Diagram Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays. -35AC138 ACT138 Figure a: Expansion to 1-of-32 Decoding A A "4 A- [Do Az a | 123 ~ Ac oA AL ALA E Ac Ar A> E Ai Az Qo O1 On O Oz Qs O5 Os O O: 01 O2 03 Os O5 Ose OF Oo O1 Oz 03 Oa Os Os OF TYPryryy Oy, Too toreto owe wanenscwawanascomaceccerarensnonceccrcaeeremecccwoueeccceeae nen On DC Characteristics (unless otherwise specified) Symbol Parameter 54AC/ACT T4ACIACT Units Conditions VIN = Vcc or Maximum Quiescent Ground, lec Supply Current 160 80 HA Voc =5.5 V, Ta = Worst Case VIN = Vcc or Maximum Quiescent Ground, Ice Supply Current 8.0 8.0 BA Voc =5.5 V, TA= 25C . wg VIN=Voc2.1 V Maximum Additional \oct ; 16 15 mA Vec=5.5 V, Icc/Input (ACT138) Ta =Worst Case 5-36AC138 ACT138 AC Characteristics 74AC 54AC 74AC Ta= 55C | Ta= - 40C oO Symbol Parameter vect| A= $288 to +125C | to +85C | Units | Fig. a) =r CL=50 pF | CL=50 pF No. Min Typ Max | Min Max | Min Max Propagation Delay 3.3 1.0 85 13.0 1.0 16.0 1.0 15.0 tu An to On 50/10 65 95/10 120] 10 105] " | 36 Propagation Delay 3.3 1.0 8.0 12.5 1.0 15.0 1.0 14.0 tPHL An to On 50} 10 60 90/10 115] 10 105] " | 36 tPLH Propagation Delay 3.3 1.0 11.0 15.0 1.0 16.5 1.0 16.0 ns 36 E: or E2 to On 5.0 | 1.0 80 110} 10 130] 10 12.0 tPHL Propagation Delay 3.3 1.0 95 13.5 1.0 15.5 1.0 15.0 ns 36 E; or E2 to On 5.0 | 1.0 7.0 95 | 10 120] 10 105 Propagation Delay 3.3 1.0 11.0 156.5 1.0 17.0 1.0 16.5 tPLH E3 to On 50/10 80 110|10 135/140 125] 8 | 36 Propagation Delay 3.3 1.0 8.5 13.0 1.0 15.0 1.0 14.0 tPHL Es to On 50/10 60 80/10 110] 10 95 | S | 36 *Voltage Range 3.3 is 3.3 V+0.3 V Voltage Range 5.0 is 5.0 V+0.5V AC Characteristics 74ACT 54ACT 74ACT Ta= 55C | Ta= 40C _ 3 Symbol Parameter Vec* oute to + 125C to +85C | Units | Fig. a) =p CL=50 pF | CL=50 pF No. Min Typ Max |] Min Max | Min Max tL Propagation Delay 501/140 70 105] 10 125/10 115] ns | 36 An to On tPHL Propagation Delay 50] 10 65 105] 10 125/140 115] ns | 36 An to On Propagation Delay \ tPLH Es or Eo to On 5.0 | 1.0 80 115 | 10 135 1 10 12.5 ns 3-6 Propagation Delay tPHL Es or Ez to On 5.0 | 1.0 75 1145/10 125] 10 12.5 ns 3-6 tPLH Propagation Delay 50] 10 80 120] 10 140] 10 130| ns | 36 E3 to On tPHL Propagation Delay 50] 10 65 105| 10 120] 10 115 | ns | 36 E3 to On *Voltage Range 5.0 is 5.0 V+0.5 V Military parameters given herein are for general references only. For current military specifications and subgroup testing information please request Fairchilds Table | data sheet from your Fairchild sales engineer or account representative. -37AC138 ACT138 Capacitance 54I74ACIACT Symbol Parameter Units Conditions Typ CIN Input Capacitance 45 pF Vcc =5.5 V Cpp Power Dissipation 60.0 pF Voc=5.5 V Capacitance 5-38