Details

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BUY UC3843N https://www.utsource.net/itm/p/12597598.html

Parameter	Symbol	Min	Typical	Max	Unit	Description
Supply Voltage	Vcc	10	15	30	V	Operating supply voltage range
Start-Up Current	Icc(start)	-	1.0	-	mA	Quiescent current during start-up (Vcc = 15V)
Operating Current	Icc(op)	-	3.5	-	mA	Quiescent current during operation (Vcc = 15V)
Output Current	Iout	100	200	300	mA	Maximum output current
Oscillator Frequency Range	fosc	100	-	500	kHz	Frequency range of internal oscillator
Reference Voltage	Vref	5.0	5.1	5.2	V	Internal reference voltage
Error Amplifier Transconductance	gm	0.4	0.5	0.6	mS	Transconductance of error amplifier
Compensation Pin Current	Icomp	-	1.0	-	μA	Maximum compensation pin current
Minimum ON Time	ton(min)	0.8	-	1.2	μs	Minimum pulse width
Maximum Duty Cycle	D(max)	-	99	-	%	Maximum duty cycle
Thermal Shutdown Temperature	Tsd	150	160	170	°C	Thermal shutdown temperature
Storage Temperature	Tstg	-40	-	125	°C	Operating storage temperature range

Instructions for Using UC3843N:

1. Power Supply:

   • Ensure the supply voltage (Vcc) is within the specified range of 10V to 30V.
   • Use a bypass capacitor (typically 0.1μF) between Vcc and ground to filter out noise.

2. Start-Up and Operation:

   • The IC draws a lower current during start-up (1.0mA) compared to normal operation (3.5mA).
   • Ensure the supply voltage is stable before enabling the IC.

3. Output Current:

   • The maximum output current (Iout) is 300mA. Ensure the external components can handle this current.

4. Oscillator Configuration:

   • Set the oscillator frequency using an external resistor (Rt) and capacitor (Ct). The formula for calculating the frequency is: [ f_ = frac{1.8}{R_t cdot C_t} ]
   • Choose values that fall within the 100kHz to 500kHz range.

5. Error Amplifier:

   • Connect the error amplifier to the compensation network and feedback loop to maintain regulation.
   • Use the transconductance (gm) value to design the compensation network.

6. Compensation Pin:

   • The compensation pin (COMP) should be connected to a compensation network to stabilize the control loop.
   • The maximum current through this pin is 1.0μA.

7. Minimum ON Time:

   • Ensure the minimum ON time (ton(min)) is at least 0.8μs to avoid issues with pulse width modulation.

8. Duty Cycle:

   • The maximum duty cycle (D(max)) is 99%. Avoid exceeding this limit to prevent over-driving the output.

9. Thermal Management:

   • Monitor the thermal shutdown temperature (Tsd) to ensure the IC does not overheat.
   • Use appropriate heat sinking if necessary.

10. Storage and Handling:

    • Store the IC in a temperature range of -40°C to 125°C.
    • Handle the IC with care to avoid static damage.

(For reference only)