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Below is the parameter table and instructions for the UC2845BN, a fixed frequency current mode controller designed for high-performance off-line and DC-DC converters.

UC2845BN Parameter Table

Parameter	Symbol	Min	Typ	Max	Unit
Supply Voltage	Vcc	10	16	30	V
Start-Up Current	Istart	-	0.6	1.2	mA
Operating Current	Iop	-	2.5	4.0	mA
Under-Voltage Lockout	UVLO	9.0	10.5	12.0	V
Oscillator Frequency	fosc	100	500	1000	kHz
Current Limit Threshold	ILIM	1.0	1.5	2.0	V
Error Amplifier Gain	Aea	50	75	100	V/渭A
Soft-Start Time	Tss	100	500	1000	渭s
Maximum Duty Cycle	Dmax	0.5	0.8	0.9	-
Thermal Shutdown Temperature	TSD	140	150	160	掳C
Storage Temperature Range	Tstg	-40	25	125	掳C
Operating Temperature Range	Topr	-40	25	125	掳C

UC2845BN Instructions

1. Power Supply Connection:

   • Connect the Vcc pin to the power supply.
   • Ensure the power supply voltage is within the specified range (10V to 30V).
   • Use a bypass capacitor (typically 0.1渭F) between Vcc and GND to filter out noise.

2. Under-Voltage Lockout (UVLO):

   • The IC will not operate if the Vcc voltage falls below the UVLO threshold (9.0V to 12.0V).
   • Once Vcc rises above the UVLO threshold, the IC will start operating.

3. Oscillator Configuration:

   • Set the oscillator frequency by connecting an external resistor (RT) and capacitor (CT) between the RT/CT pin and GND.
   • The frequency can be calculated using the formula: ( f_ = frac{1.1}{R_T cdot C_T} ).

4. Current Limiting:

   • The current limit threshold is set by the voltage on the CS pin.
   • Connect a current-sensing resistor (Rs) in series with the power switch to monitor the current.
   • The current limit is triggered when the voltage across Rs exceeds the ILIM threshold (1.0V to 2.0V).

5. Error Amplifier:

   • Connect the error amplifier feedback (FB) pin to the output voltage divider.
   • The error amplifier compares the FB voltage to an internal reference (typically 2.5V) and adjusts the duty cycle to maintain the desired output voltage.

6. Soft-Start:

   • The soft-start function limits the initial inrush current by gradually increasing the duty cycle.
   • The soft-start time can be adjusted by connecting a capacitor (CSS) between the SS pin and GND.

7. Thermal Protection:

   • The IC includes thermal shutdown protection that activates if the internal temperature exceeds 150掳C.
   • Ensure proper heat dissipation and avoid prolonged operation at high temperatures.

8. Output Stage:

   • The UC2845BN drives the gate of the power MOSFET through the OUT pin.
   • Ensure the gate drive capability of the UC2845BN matches the requirements of the power MOSFET.

9. Layout Considerations:

   • Keep the high-frequency and high-current paths as short as possible to minimize parasitic inductance and capacitance.
   • Use wide traces for power and ground connections to reduce resistance and improve thermal performance.

10. Testing and Debugging:

    • Use an oscilloscope to monitor the waveforms at key points (e.g., Vcc, FB, CS, OUT) during testing.
    • Verify that the output voltage and current are within the expected ranges.
    • Check for any signs of overheating or instability.

By following these instructions, you can ensure the UC2845BN operates reliably in your power supply design.

(For reference only)