Details

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BUY UC2856N https://www.utsource.net/itm/p/12444389.html

Parameter	Symbol	Min	Typ	Max	Unit	Description
Input Voltage	Vcc	10	15	35	V	Supply voltage range
Start-Up Current	Istart	-	0.5	1.0	mA	Typical start-up current
Operating Current	Icc	2.5	3.5	4.5	mA	Typical operating current
Oscillator Frequency	fosc	200	500	700	kHz	Adjustable oscillator frequency
Duty Cycle	D	0.2	0.5	0.8		Adjustable duty cycle range
Error Amplifier Gain	Aea	50	100	150	V/μA	Error amplifier gain
Soft-Start Time	Tss	1	2	3	ms	Soft-start time
Overcurrent Protection	Iocp	0.1	0.2	0.3	A	Overcurrent protection threshold
Thermal Shutdown	Tsd	140	150	160	°C	Thermal shutdown temperature
Storage Temperature	Tstg	-40	-	125	°C	Storage temperature range
Operating Temperature	Topr	-40	-	125	°C	Operating temperature range

Instructions for UC2856N

1. Power Supply:

   • Ensure the input voltage (Vcc) is within the specified range (10V to 35V).
   • Connect the supply voltage to the Vcc pin and ground to the GND pin.

2. Oscillator Configuration:

   • Set the oscillator frequency (fosc) using an external resistor and capacitor connected to the RT/CT pins.
   • The typical range for the oscillator frequency is 200kHz to 700kHz.

3. Duty Cycle Control:

   • Adjust the duty cycle (D) by configuring the feedback network connected to the FB pin.
   • The typical range for the duty cycle is 0.2 to 0.8.

4. Error Amplifier:

   • Use the error amplifier (EA) to regulate the output voltage.
   • Connect the compensation network to the COMP pin to stabilize the control loop.

5. Soft-Start:

   • Implement soft-start by connecting a capacitor to the SS pin.
   • The soft-start time (Tss) can be adjusted to prevent inrush currents during startup.

6. Overcurrent Protection:

   • The overcurrent protection (OCP) is activated when the current through the power switch exceeds the threshold (Iocp).
   • Ensure the power switch is properly rated to handle the maximum current.

7. Thermal Management:

   • Monitor the device temperature to ensure it does not exceed the thermal shutdown temperature (Tsd).
   • Use appropriate heat sinks or cooling methods if necessary.

8. Storage and Operating Conditions:

   • Store the device in an environment with temperatures between -40°C and 125°C.
   • Operate the device within the specified operating temperature range (-40°C to 125°C).

9. Layout Considerations:

   • Keep high-frequency traces short and away from sensitive analog signals.
   • Use a ground plane to minimize noise and improve stability.

10. Testing and Debugging:

    • Verify all connections and component values before applying power.
    • Use an oscilloscope to monitor key signals such as the oscillator frequency, duty cycle, and output voltage.
    • Adjust component values as needed to achieve the desired performance.

(For reference only)