Products Mentioned

LT3591 Production
The LT3591 is a fixed frequency step-up DC/DC converter speci?cally designed to drive up to ten white LEDs in series from a Li-Ion cell. Series connection...
Datasheet
LT3591 on Analog.com

LTC3490 Production
The LTC3490 provides a constant current drive for 1W LED applications. It is a high efficiency boost converter that operates from 1 or 2 NiMH or alkaline...
Datasheet
LTC3490 on Analog.com

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LT3591 LED in parallel

oliver.wang

on Dec 10, 2020

Dear Sir,

Is it possible to use one LTC3490 to driver LEDs in 3 parallel 3 series LED/ total LED current is 60mA?

(I use LTSpice to simulation is ok, but customer test in PCBA circuit is failure)

Thanks.

Mikee_Lacson_00

on Dec 10, 2020 2:33 AM
0
Hi

Do you know what is the part number of the LED's being driven ?

Regards
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oliver.wang
on Dec 10, 2020 2:46 AM in reply to Mikee_Lacson_00
0
Dear Mikee,

LED part number: 01. JT.CB426WS ,

VIn:5V, Vo: 16.5V~19.2V(LED: 3S3P), Io: 60mA

Thanks.
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oliver.wang
on Dec 10, 2020 4:47 AM in reply to Mikee_Lacson_00
0
Dear Mikee,

The LED part number is "01. JT.CB426WS", Vf:6V, If: 20mA

Vin: 2.5V~4.6V

Thanks.
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Mikee_Lacson_00

on Dec 10, 2020 7:44 PM in reply to oliver.wang
0
Hi

LTC3490 would not be able to handle the configuration as it is limited to 4V

LTC3491 should be able to handle the requirements.

Can you provide wave forms on the SW, VIn, Cap and LED nodes ?

For the mean time, please check the connections on the board and the orientation of the inductor in the circuit

Regards
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oliver.wang
on Dec 10, 2020 8:40 PM in reply to Mikee_Lacson_00
0
Dear Mikee,

If LTC3491 Vin voltage is 5V, is it should be able to handle the requirements?

Thanks.
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Mikee_Lacson_00

on Dec 12, 2020 4:34 AM in reply to oliver.wang
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Hi

Rough computation for the Pk inductor current with the given conditions using LTC3491 would be about 250mA. Which should allow the LED driver with the given conditions.

Please provide the waveforms requested in order to check what might be the cause of the problem

Regards
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LT3591 LED in parallel