TECHNICAL DATA IN74LS138 3-to-8-Line Decoder/Demultiplexer This schottky-clamped TTL MSI circuit is designed to be used in high-performance memory-decording or data-routing applications requiring very short propagation delay time. In high-performance memory systems this decode can be used to minimize the effects of system decoding. When employed with high-speed memories utilizing a fast enable circuit the delay times of this decorder and the enable time of the memory are usually less than the typical access times of the memory. This means that the effective system delay introduced by the schottky-clampled system decoder is negligible. * Designed Specifically for High Speed Memory Decoders and Data Transmission Systems * Incorporate 3 Enabler Inputs to Simplify Cascading AND/OR Data Reception * Schottky Clamped for High Performance ORDERING INFORMATION IN74LS138N Plastic IN74LS138D SOIC TA = 0 to 70 C for all packages PIN ASSIGNMENT LOGIC DIAGRAM FUNCTION TABLE Inputs PIN 16 =VCC PIN 8 = GND Outputs CS1 CS2 CS3 A2 A1 A0 Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 X X H X H X L X X X X X X X X X X X H H H H H H H H H H H H H H H H H H H H H H H H H H H H L L L L L L L L L L L L L L H H L H L H L H H H H L H H H H L H H H H L H H H H H H H H H H H H H H H H H H H H L L L L L L L L H H H H L L H H L H L H H H H H H H H H H H H H H H H H L H H H H L H H H H L H H H H L H = high level (steady state) L = low level (steady state) X = don't care 1 IN74LS138 MAXIMUM RATINGS* Symbol Parameter Value Unit VCC Supply Voltage 7.0 V VIN Input Voltage 7.0 V VOUT Output Voltage 5.5 V Tstg Storage Temperature Range -65 to +150 C * Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the Recommended Operating Conditions. RECOMMENDED OPERATING CONDITIONS Symbol Parameter Min Max Unit 5.25 V VCC Supply Voltage 4.75 VIH High Level Input Voltage 2.0 VIL Low Level Input Voltage 0.8 V IOH High Level Output Current -0.4 mA IOL Low Level Output Current 8.0 mA TA Ambient Temperature Range +70 C 0 V DC ELECTRICAL CHARACTERISTICS over full operating conditions Guaranteed Limit Symbol Parameter Test Conditions Min Max Unit -1.5 V VIK Input Clamp Voltage VCC = min, IIN = -18 mA VOH High Level Output Voltage VCC = min, IOH = -0.4 mA VOL Low Level Output Voltage VCC = min, IOL = 4 mA 0.4 VCC = min, IOL = 8 mA 0.5 VCC = max, VIN = 2.7 V 20 A VCC = max, VIN = 7.0 V 0.1 mA -0.4 mA -100 mA 10 mA IIH High Level Input Current IIL Low Level Input Current VCC = max, VIN = 0.4 V IO Output Short Circuit Current VCC = max, VO = 0 V (Note 1) ICC Supply Current VCC = max Outputs enabled and open 2.7 -20 V V Note 1: Not more than one output should be shorted at a time, and duration should not exceed one second. 2 IN74LS138 AC ELECTRICAL CHARACTERISTICS (TA=25C, VCC = 5.0 V, CL = 15 pF, RL = 2 k, tr =15 ns, tf = 6.0 ns) Symbol tPLH Parameter Level Maximum Propagation Delay, Input A to Output Y tPHL Maximum Propagation Delay, Input A to Output Y tPLH Maximum Propagation Delay, Input A to Output Y tPHL Maximum Propagation Delay, Input A to Output Y tPLH Maximum Propagation Delay , CS1 to Output Y Unit 20 ns 41 ns 27 ns 39 ns 26 ns 38 ns 18 ns 32 ns 3 3 Maximum Propagation Delay , CS1 to Output Y tPLH Maximum Output Transition Time , CS2 or CS3 to Output Y Maximum Output Transition Time , CS2 or CS3 to Output Y Figure 1. Switching Waveforms Max 2 tPHL tPHL Min 2 Figure 2. Switching Waveforms NOTES A. CL includes probe and jig capacitance. B. All diodes are 1N916 or 1N3064. Figure 3. Switching Waveforms Figure 4. Test Circuit 3