Can anyone point me to a datasheet for a 6 pin smd IC labeled 281123, which by location in the circuit appears to be a pwm controller for a SMPS? Pin 1 is ground, Pin 6 is MOSFET gait driver output. No mfg marking on chip.
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\$\begingroup\$ edit the post ... don't write a comment \$\endgroup\$– jsotolaCommented Feb 18, 2023 at 5:24
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1\$\begingroup\$ A picture might help to give more context. As written, your question is way too broad. If it were a SOT23-6 package, I’d doubt they could fit all the numbers on it. \$\endgroup\$– KartmanCommented Feb 18, 2023 at 6:33
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1\$\begingroup\$ Any more details about the SMPS? AC TO DC? Vout estimation? \$\endgroup\$– raaymaanCommented Feb 18, 2023 at 8:04
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2 Answers
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The markings match with a Qualpwr (库博电子) MS2281 PWM controller.
Please note that there are variants from other manufacturers available, like the OB2281A or U2281.
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Closest I can find is the TSM2611 from Taiwan Semiconductor, which is a Dual N-channel MOSFET in an SOT-26 outline. Would that fit ?
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\$\begingroup\$ I found a reference calling it "a power management IC" without any further info. So it may be something else. So it may help to try to understand what the part does in the circuit. You could add top and bottom photos of the whole PCB to your question. \$\endgroup\$ Commented Feb 18, 2023 at 10:16
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\$\begingroup\$ The SMPS is AC to +/-5Vdc. The chip in question is definitely a PWM MOSFET/Transistor driver IC. It received the output of a TL431 voltage reference (monitoring the +Vout via an optoisolator, to either increase the pulse width if Vout is low or decrease pulse width if Vout is high. I want the datasheet so I can possibly convert from +/-5Vdc to +/-15Vdc. When I adjust resistors values around the TL431, I can raise Vout to 12V at which point the PS fails to run continuously, and I am wondering if the IC in question's bootstrap V is getting too high (beyond recommended range). \$\endgroup\$ Commented Feb 19, 2023 at 0:15