Details

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BUY UC3843 SOP8 https://www.utsource.net/itm/p/12609636.html

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Supply Voltage	Vcc	8	16	35	V
Start-up Current	Istrt		1.2		mA	Vcc = 16V
Operating Current	Icc		4		mA	Vcc = 16V
Reference Voltage	Vref	4.97	5.0	5.03	V
Error Amplifier Transconductance	Gm	4	5	6	mS
Compensation Pin Leakage Current	Ilc		20		nA	Vcomp = 0 to Vcc
Maximum Duty Cycle	Dmax		94		%	fsw = 100kHz, ILIMIT pin grounded
Switching Frequency Range	fsw	100		500	kHz
Leading Edge Blanking	tLEB	150		250	ns
Current Limit Threshold	VILIM	1	1.2	1.4	V
Minimum Off Time	toff	500			ns
Minimum On Time	ton	500			ns

Instructions for UC3843 SOP8

1. Power Supply Connection:

   • Connect the supply voltage (Vcc) between 8V and 35V to pin 8 and ground to pin 4.

2. Startup and Operating Current:

   • Ensure that the startup current does not exceed 1.2mA at Vcc = 16V.
   • The operating current should be around 4mA at Vcc = 16V.

3. Reference Voltage:

   • Use the reference voltage of 5V for setting up the feedback loop.

4. Error Amplifier Configuration:

   • Configure the error amplifier with a transconductance of 5mS for optimal performance.

5. Compensation Network:

   • Design the compensation network considering the leakage current of 20nA from the compensation pin.

6. Duty Cycle Control:

   • Set the maximum duty cycle to no more than 94% for stable operation at 100kHz switching frequency with the ILIMIT pin grounded.

7. Switching Frequency Setting:

   • Adjust the resistor connected to the RT/CT pin to set the desired switching frequency within the range of 100kHz to 500kHz.

8. Leading Edge Blanking:

   • Account for a leading edge blanking time between 150ns and 250ns to prevent false triggering due to noise.

9. Current Limiting:

   • Set the current limit threshold between 1V and 1.4V for protection against overcurrent conditions.

10. Minimum Off and On Times:

    • Ensure the minimum off and on times are both at least 500ns to avoid issues with the switching mechanism.

These parameters and instructions are essential for correctly configuring and using the UC3843 in an application circuit.

(For reference only)