Details

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BUY LM3478MMX/NOPB https://www.utsource.net/itm/p/12610859.html

Parameter	Symbol	Min	Typ	Max	Unit
Input Voltage	VIN	4.5	-	42	V
Output Voltage	VOUT	-	1.23	-	V
Switching Frequency	fSW	100	500	750	kHz
Duty Cycle Range	D	0.3	-	0.9	-
Quiescent Current	IQ	-	1.1	-	mA
Shutdown Current	ISD	-	1	-	渭A
Reference Voltage	VREF	1.21	1.23	1.25	V
Reference Voltage Tempco	TCVREF	-	35	-	ppm/掳C
Thermal Shutdown	TSD	-	160	-	掳C
Operating Temperature	TOPR	-40	-	125	掳C
Storage Temperature	TSTG	-65	-	150	掳C

Instructions for Use:

1. Input Voltage (VIN):

   • Ensure the input voltage is within the range of 4.5V to 42V.
   • Use appropriate input capacitors to filter out noise and provide stable operation.

2. Output Voltage (VOUT):

   • The output voltage is set by the feedback network connected to the FB pin.
   • For a typical application, use the formula ( V_ = 1.23 times left(1 + fracright) ) to calculate the resistor values.

3. Switching Frequency (fSW):

   • Set the switching frequency using an external resistor connected to the RT pin.
   • The typical range is from 100kHz to 750kHz.

4. Duty Cycle Range (D):

   • The duty cycle should be between 30% and 90% for optimal performance.
   • Avoid operating at the extremes of this range to prevent instability.

5. Quiescent Current (IQ):

   • The quiescent current is typically 1.1mA. This is the current consumed by the IC when it is active but not driving a load.

6. Shutdown Current (ISD):

   • When the SHDN pin is pulled low, the shutdown current is approximately 1渭A.
   • Use this feature to conserve power in battery-operated applications.

7. Reference Voltage (VREF):

   • The reference voltage is nominally 1.23V and is used to set the output voltage.
   • Ensure the reference voltage is stable and accurate for precise regulation.

8. Reference Voltage Tempco (TCVREF):

   • The temperature coefficient of the reference voltage is 35ppm/掳C, indicating minimal drift over temperature changes.

9. Thermal Shutdown (TSD):

   • The IC will automatically shut down if the junction temperature exceeds 160掳C to prevent damage.
   • Ensure adequate heat dissipation and thermal management in high-power applications.

10. Operating Temperature (TOPR):

    • The operating temperature range is from -40掳C to 125掳C.
    • Ensure the ambient temperature and thermal design allow the IC to operate within this range.

11. Storage Temperature (TSTG):

    • The storage temperature range is from -65掳C to 150掳C.
    • Store the IC in a dry, temperature-controlled environment to maintain reliability.

Additional Notes:

• Always refer to the datasheet for detailed information and specific application circuits.
• Use proper PCB layout techniques to minimize noise and ensure stable operation.
• For high-frequency applications, pay attention to parasitic inductances and capacitances.

(For reference only)