Details

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BUY LM2678T -5.0 https://www.utsource.net/itm/p/12610669.html

Below is the parameter table and instructions for the LM2678T-5.0, a 3A Step-Down Voltage Regulator.

Parameter Table

Parameter	Symbol	Min	Typ	Max	Unit
Input Voltage Range	VIN	4.5	-	40	V
Output Voltage	VOUT	-	5.0	-	V
Output Current	IOUT	-	3.0	-	A
Switching Frequency	fSW	-	150	-	kHz
Efficiency (at 5V, 3A)	畏	-	90	-	%
Dropout Voltage (at 3A)	VDROPOUT	-	1.2	-	V
Quiescent Current	IQ	-	5	-	mA
Shutdown Current	ISD	-	50	-	渭A
Thermal Resistance (胃JA)	-	-	50	-	掳C/W
Operating Temperature Range	TJ	-40	-	125	掳C
Storage Temperature Range	TSTG	-65	-	150	掳C

Instructions

1. Component Description:

   • The LM2678T-5.0 is a high-efficiency, step-down voltage regulator capable of delivering up to 3A of output current.
   • It operates over an input voltage range from 4.5V to 40V and provides a fixed 5.0V output.

2. Circuit Design:

   • Input Capacitor (CIN):
     • Use a 10渭F ceramic capacitor with low ESR to filter the input voltage.
     • Place it as close as possible to the VIN and GND pins.
   • Output Capacitor (COUT):
     • Use a 22渭F tantalum or ceramic capacitor to stabilize the output voltage.
     • Place it close to the VOUT and GND pins.
   • Inductor (L):
     • Choose an inductor with a value between 10渭H and 47渭H.
     • Ensure it has a saturation current rating higher than the maximum output current (3A).
   • Feedback Resistor (RFB):
     • The feedback resistor is not required for the fixed 5.0V version, but if using an adjustable version, refer to the datasheet for the appropriate resistor values.

3. Thermal Management:

   • Ensure adequate heat dissipation by using a heatsink or thermal pad.
   • The thermal resistance (胃JA) is 50掳C/W, so calculate the power dissipation and ensure the device does not exceed its maximum operating temperature of 125掳C.

4. Shutdown Function:

   • The shutdown function can be activated by pulling the SHDN pin low.
   • The shutdown current is typically 50渭A.

5. Layout Considerations:

   • Keep the layout compact and minimize trace lengths, especially for high-frequency signals.
   • Use wide traces for power and ground to reduce resistance and inductance.

6. Testing and Troubleshooting:

   • Verify the input and output voltages with a multimeter.
   • Check the output ripple with an oscilloscope.
   • If the output voltage is unstable, check the values of CIN, COUT, and L, and ensure they meet the recommended specifications.

By following these guidelines, you can effectively design and implement a circuit using the LM2678T-5.0 voltage regulator.

(For reference only)