Details

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BUY DM74LS138N https://www.utsource.net/itm/p/183382.html
Decoder/Demultiplexer

Parameter	Symbol	Conditions	Min	Typ	Max	Unit
Supply Voltage	VCC	Operating	4.75	5.0	5.25	V
Input Voltage (High)	VIH	IIH = 20 μA	2.0	-	5.5	V
Input Voltage (Low)	VIL	IIL = -0.4 mA	0.0	-	0.8	V
Output Voltage (High)	VOH	IOH = -0.4 mA	2.4	-	5.0	V
Output Voltage (Low)	VOL	IOL = 16 mA	0.0	-	0.5	V
Propagation Delay Time	tpd	VCC = 5V, TA = 25°C	-	22	-	ns
Power Dissipation	PD	Maximum	-	-	100	mW

Instructions for Using DM74LS138N

1. Pin Configuration:

   • 1, 2, 3: Address inputs A, B, C
   • 4, 5, 6, 7, 9, 10, 11, 12: Active low outputs Y0 to Y7
   • 8: Ground (GND)
   • 13: Output enable (G1)
   • 14, 15: Chip select inputs (G2A, G2B)
   • 16: Power supply (V_CC)

2. Operation:

   • The DM74LS138N is a 3-to-8 line decoder/demultiplexer.
   • It has three address inputs (A, B, C) that select one of eight outputs (Y0 to Y7).
   • The chip select inputs (G2A, G2B) and the output enable input (G1) must be active low for the decoder to function.
   • When all chip select and enable inputs are low, the selected output corresponding to the address inputs will be low, and all other outputs will be high.

3. Power Supply:

   • Connect V_CC to +5V and GND to 0V.
   • Ensure the power supply voltage remains within the specified range to avoid damage to the device.

4. Addressing Outputs:

   • The address inputs A, B, and C determine which output is activated.
   • For example, if A = 0, B = 1, and C = 1, then Y3 will be low, and all other outputs will be high.

5. Chip Select and Enable:

   • G1, G2A, and G2B must all be low for the decoder to be active.
   • If any of these inputs are high, all outputs will be high, regardless of the address inputs.

6. Propagation Delay:

   • The propagation delay time (t_pd) is the time it takes for a change in the input to affect the output. It is typically 22 ns at 5V and 25°C.

7. Power Dissipation:

   • The maximum power dissipation is 100 mW. Ensure proper heat management if operating near this limit.

8. Handling:

   • Handle the device with care to avoid static discharge, which can damage the internal circuits.
   • Use appropriate ESD protection when handling and soldering the device.

(For reference only)