Details

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BUY 74LS138 https://www.utsource.net/itm/p/12608392.html

Pin Number	Pin Name	Description
1	A0	Address Input 0
2	A1	Address Input 1
3	A2	Address Input 2
4	Y3	Output 3 (Active Low)
5	Y2	Output 2 (Active Low)
6	Y1	Output 1 (Active Low)
7	Y0	Output 0 (Active Low)
8	GND	Ground
9	Y7	Output 7 (Active Low)
10	Y6	Output 6 (Active Low)
11	Y5	Output 5 (Active Low)
12	Y4	Output 4 (Active Low)
13	G2B	Inhibit Input B (Active High)
14	G1	Enable Input (Active High)
15	G2A	Inhibit Input A (Active High)
16	VCC	Power Supply (5V)

Instructions for Using 74LS138:

1. Power Supply:

   • Connect pin 16 (VCC) to +5V.
   • Connect pin 8 (GND) to ground.

2. Enable and Inhibit Inputs:

   • The device is enabled when G1 is high and both G2A and G2B are low.
   • If any of these conditions are not met, all outputs will be high (inactive).

3. Address Inputs:

   • A0, A1, and A2 are the address inputs that determine which output is active.
   • The active output corresponds to the binary value of A2A1A0.

4. Output States:

   • The outputs (Y0 to Y7) are active low, meaning they go low (0V) when selected and high (5V) when not selected.
   • Only one output is active at a time based on the address inputs.

5. Truth Table:

   • The following truth table shows the relationship between the address inputs and the active output:

   A2	A1	A0	G1	G2A	G2B	Output Active (Low)
   0	0	0	H	L	L	Y0
   0	0	1	H	L	L	Y1
   0	1	0	H	L	L	Y2
   0	1	1	H	L	L	Y3
   1	0	0	H	L	L	Y4
   1	0	1	H	L	L	Y5
   1	1	0	H	L	L	Y6
   1	1	1	H	L	L	Y7

6. Handling:

   • Ensure proper handling to avoid static damage.
   • Use decoupling capacitors near the power pins to reduce noise.

7. Applications:

   • The 74LS138 is commonly used in digital circuits for memory addressing, multiplexing, and demultiplexing.

(For reference only)