any equivalent to LQ1216 PWM IC - Page 1
Forum section: electronics / repair

author: 800908
author_rank: Contributor
timestamp: December 26, 2020, 07:09:44 am
content: HiI searched the internet about the LQ1216 but I found nothing about it.it is PWM IC and control the mosfet in primary side if power supply.Pin 1 is Vcc and pin 8 is Gnd.Pin 2,6,7 not been used.thanks.

author: asis
author_rank: Frequent Contributor
timestamp: December 26, 2020, 09:22:42 am
content: Hi,Maybe NCP1216 after all?https://datasheetspdf.com/pdf-file/473297/ON/NCP1216/1

author: 800908
author_rank: Contributor
timestamp: December 26, 2020, 01:12:17 pm
content: actually I checked that but NCP1216 pinout is different.

author: asis
author_rank: Frequent Contributor
timestamp: December 26, 2020, 05:48:45 pm
content: You give the image of the PCB on both sides.It may be possible to adapt.

author: fzabkar
author_rank: Super Contributor
timestamp: December 27, 2020, 02:15:50 am
content: This thread has a hand drawn circuit:https://mysku.ru/blog/china-stores/34369.htmlHowever, the pin numbering in that circuit looks like a mirror image of yours (as if one of you has numbered the pins from the underside of the PCB).

author: 800908
author_rank: Contributor
timestamp: December 27, 2020, 06:05:50 am
content: this board was fine except the IC that I took from it and put it on the another important board and the board is not worthy of time but I want to know how to adapt another IC to it so in the future I do it myself.I have UC3843 and it show up on Google results for LQ1216 so if it possible I want to adapt this IC to my board.I added the picture of the board.

author: fzabkar
author_rank: Super Contributor
timestamp: December 27, 2020, 07:30:49 am
content: The difference between your IC and others is that yours relies on an external totem pole (Q4 & Q5) to drive the MOSFET chopper (Q1). Other PWM controller ICs have a built-in totem pole and are able to drive the MOSFET directly.How old is your unit? Can you see any date codes on the capacitors or other chips?

author: 800908
author_rank: Contributor
timestamp: December 27, 2020, 08:02:21 am
content: Quote from: fzabkar on December 27, 2020, 07:30:49 amI seen lot of power supply that use two small transistor to drive the mosfet and most of them use UC38xx IC.date on the board is 2018.8

author: Ian.M
author_rank: Super Contributor
timestamp: December 27, 2020, 09:33:15 am
content: Before you can even *THINK*of a substitute, you've got to know the operating frequency. If you know how to do so safely, measure it at the LQ1216 output (pin 5) on the working unit, under load. If you are unsure how to measure frequency safely on the primary side of a SMPSU, or don't have appropriate test equipment, scope the transformer end of one of the rectifier diodes on the secondary side. Getting the frequency seriously wrong will drastically reduce the output current, and may result in explosive failure of the MOSFET and control circuit!You can *probably* substitute a UC384x series chip but its going to need several circuit changes including extra parts for the timing network, and either some track cuts and patch wires or a PNP current mirror to convert the opto output to pull up towards Vref rather than down towards ground, so a daughterboard is going to be essential to carry the extra parts and to wrangle the UC384x pinout to match. TI'sUCx84x datasheetis particularly helpful, especially Figure 25. Typical Application Design Example Schematic.Unless the PSU is expensive, it probably isn't worth the effort, so measure the frequency and its Vcc voltage, and *hope* someone recognizes it from them and the partial pinout:Code:LQ1216 DIP-8 SMPS controllerPin Function---+--------1 Vcc2 ? (N/C)3 Voltage Feedback (pulldown by opto)4 Output5 Current Sense (from MOSFET drain)6 ? (N/C)7 ? (N/C)8 0V 'Gnd'

author: amyk
author_rank: Super Contributor
timestamp: December 27, 2020, 09:36:15 am
content: It seems more like the actual name of this IC is BP2302LT or BF2302LT, and the LQ1216 is actually a datecode/batch (12th week of 2016.)...of which I cannot find a match either.At leasthttp://sztgm.cn.makepolo.com/product/101013329138.htmlseems to have some very brief info on LQ1216.

author: electronium
author_rank: Newbie
timestamp: December 04, 2022, 11:43:36 pm
content: Date and correction of LQ1216 rare IC circuit shemaic and pin by me is as followsPin 1=VccPin 2=x (no connect)Pin 3=FbPin 4=sensePin 5 = gate(base of two transistor small-oscillator)Pin 6 = x (no connect)Pin 7 = x (no connect)Pin 8 = Gnd (hot ground)