Is this the correct application? (LED Driver AP3032) - Page 1
Forum section: electronics / projects

author: Fcolor04
author_rank: Contributor
timestamp: April 07, 2022, 10:20:40 am
content: I'm asking for help with correct application of AP3032 (U2), but I won't be mad if anyone helps to verify the whole circuit, the design is battery operated desktop lamp, it is supposed to drive 1W led but I'm unsure if anything is correct. Please help!Specs:USB C poweredBattery - Li Pol 500mAhDriving bright ledAs cheap as possibleI suppose the output current is changed by changing R10the datasheet really confuses me, they say for dimming functionality you need only DC -R11- but its also possible by providing 25kHz+ pwm on CTRL?Edit:I should provided datasheet link in OP, sorryU1https://lcsc.com/product-detail/Battery-Management-ICs_BL-Shanghai-Belling-BL4054B-42TPRN_C83783.htmlU2https://lcsc.com/product-detail/LED-Drivers_Diodes-Incorporated-AP3032KTR-G1_C264086.html

author: robzy
author_rank: Regular Contributor
timestamp: April 08, 2022, 12:50:44 am
content: It looks like R11 is the biggest change you've made from the datasheet, right?The datasheet calls for either an analoge voltage into the other side of R6 (the 90k resistor), and you are using a potentiometer (R11) to generate the voltage.Using resistors as a voltage divider has issues depending on the load. The load itself can pull the voltage divider away from the desired value. Resulting in a non-linear adjustment.

author: .rpv
author_rank: Contributor
timestamp: April 08, 2022, 12:59:36 am
content: Hi, so, you're trying to use this with a 3v vF led?... using a boost converter to power something that will be under the boost converter vin it is a bad idea. If you see your schematic the led will be connected to the battery with the inductor (will act just as a low value resistor), schottky diode and the 1Ω resistor in series, this mean that when the battery it's above 4v your led can receive 1A or more (depending on the dc resistance of your inductor and the vf of the schottky diode and led used) and the boost converter can't do anything about it. So if you were using this circuit for 2 leds in series can be OK, or using a buck converter led driver, but also will have some issues with the vin voltage being close to the vf+fb voltage.The OV voltage in this boost converter it's 27v, it should be connected directly to the vout.For dimming, the IC supports using DC or PWM, one of the other depending on what is your application needs.

author: Fcolor04
author_rank: Contributor
timestamp: April 08, 2022, 02:47:45 pm
content: I guess you're right, I don't have much budget so It's great that I asked thenpossible solution for the voltage is to put schottky in series with the led? They're 1A rated and pennies to getAlso I'll buffer the output of the pot (R11) with an op amp, big thanks for help!

author: Fcolor04
author_rank: Contributor
timestamp: April 08, 2022, 03:59:21 pm
content: Possibly better design?Edit: instantly after posting, I noticed missing connection from opamp to battery, imagine it's there!

author: robzy
author_rank: Regular Contributor
timestamp: April 09, 2022, 01:34:03 am
content: Quote from: Fcolor04 on April 08, 2022, 02:47:45 pmI don't know if that's required or not. Hopefuly someone smarter than me can answer.

author: Fcolor04
author_rank: Contributor
timestamp: April 26, 2022, 07:39:31 pm
content: Now that I think of my circuit, could these dropout diodes possibly be replaced by a single zener? Wouldn't that be better solution?

author: f618x
author_rank: Newbie
timestamp: January 17, 2023, 01:09:24 pm
content: How did you go with AP3032?I'm thinking of using it for a current project