Details

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BUY 3845B https://www.utsource.net/itm/p/12611346.html

Parameter	Description
Part Number	3845B
Type	Power Management IC
Function	DC-DC Converter Controller
Input Voltage	4.5V to 28V
Output Voltage	Adjustable, typically 1.23V to 26V
Switching Frequency	100kHz to 400kHz (Adjustable)
Current Limit	Programmable with an external resistor
Protection Features	Overcurrent Protection, Thermal Shutdown, Undervoltage Lockout
Package	SOIC-8
Operating Temperature	-40掳C to +125掳C
Storage Temperature	-65掳C to +150掳C

Instructions for Use

1. Circuit Design:

   • Ensure that the input voltage is within the specified range of 4.5V to 28V.
   • Use an external feedback resistor network to set the desired output voltage.
   • Choose an appropriate inductor and capacitor for the output filter based on the switching frequency and load requirements.

2. Component Selection:

   • Inductor: Select an inductor with a saturation current higher than the maximum expected load current.
   • Capacitors: Use low ESR capacitors for both input and output filtering to minimize ripple and improve transient response.
   • Feedback Resistor: Calculate the value of the feedback resistor using the formula ( V_ = 1.23 times (1 + frac) ).

3. Layout Considerations:

   • Place the input and output capacitors as close as possible to the IC to reduce noise and improve stability.
   • Keep the ground plane solid and wide to ensure good thermal dissipation and reduce ground bounce.

4. Programming Current Limit:

   • Connect a resistor between the current limit (ILIM) pin and ground to set the current limit. The current limit can be calculated using the formula provided in the datasheet.

5. Thermal Management:

   • Ensure adequate heat sinking if the IC will operate at high power levels or in high ambient temperatures.
   • Monitor the temperature of the IC and take necessary actions to prevent overheating.

6. Testing and Validation:

   • Test the circuit under various load conditions to ensure stable operation and proper regulation.
   • Verify the output voltage and current limits using a multimeter and oscilloscope.

7. Safety Precautions:

   • Always follow standard safety guidelines when handling electronic components.
   • Avoid short circuits and overvoltage conditions to prevent damage to the IC and other components.

(For reference only)