Details

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BUY 74LS21 https://www.utsource.net/itm/p/12608813.html

Parameter	Symbol	Conditions	Min	Typical	Max	Unit
Supply Voltage	VCC	Operating	4.75	-	5.25	V
Input Low Voltage	VIL	Input Low	0.0	-	0.8	V
Input High Voltage	VIH	Input High	2.0	-	5.0	V
Output Low Voltage	VOL	IOL = 16 mA	0.0	0.4	0.5	V
Output High Voltage	VOH	IOH = -0.4 mA	2.7	3.4	5.0	V
Propagation Delay Time	tpd	VCC = 5V, TA = 25掳C	12	-	22	ns
Power Dissipation	PD	Per Package	-	-	100	mW
Operating Temperature Range	TA	-	-40	-	85	掳C

Instructions for Using 74LS21:

1. Supply Voltage (V_CC):

   • Ensure the supply voltage is within the range of 4.75V to 5.25V to avoid damage to the IC.

2. Input Voltages:

   • For a logic low input, ensure the voltage is between 0V and 0.8V.
   • For a logic high input, ensure the voltage is between 2.0V and 5.0V.

3. Output Voltages:

   • When the output is low, the voltage should not exceed 0.5V under a load of 16mA.
   • When the output is high, the voltage should be at least 2.7V under a load of -0.4mA.

4. Propagation Delay Time (t_pd):

   • The propagation delay time is the time it takes for the output to change state after the input changes. It should be between 12ns and 22ns at room temperature (25掳C) with a 5V supply.

5. Power Dissipation (P_D):

   • The maximum power dissipation for the entire package is 100mW. Ensure proper heat dissipation if operating near this limit.

6. Operating Temperature (T_A):

   • The IC can operate in temperatures ranging from -40掳C to 85掳C. Ensure the operating environment is within these limits to prevent thermal stress.

7. Handling:

   • Handle the IC with care to avoid static discharge, which can damage the internal circuits. Use proper ESD protection when handling the IC.

8. Mounting:

   • Ensure the IC is securely mounted on the PCB and all pins are properly soldered to avoid poor connections.

9. Testing:

   • Before final assembly, test the IC in a controlled environment to ensure it meets the specified parameters.

10. Storage:

    • Store the IC in a dry, cool place away from direct sunlight and sources of heat.

(For reference only)