Category: Hardware
Product Number: LTC3892-1, LTC3892
Hi,
We have implemented the design from the last page of LTC3892: 60V Low IQ, Dual, 2-Phase Synchronous Step-Down DC/DC Controller
While testing 3 boards we have discovered that the LTC3892 IC in all 3 examples that pins 19 & 21 have become shorted to ground (pin 29).
In 2 examples pins 18 & 22 also became shorted to ground and in 1 example pins 16 and 17 also became shorted to ground.
Input voltage was always between 30 and 60V.
We are supplying the circuit from a bench power supply.
We are currently using the circuit with minimal load (driving only an LM7805 which outputs to a PIC16F628A).
We are currently using the circuit with minimal load (driving only an LM7805 which outputs to a PIC16F628A).
The differences from the reference design are:
- On Vin, 2 x 1uF and 1 x 2.2uF instead of 1 x 1uF and 5 x 2.2uF
- On Vout, 2 x 22uF instead of 2 x 150uF with the addition of 2 x 1uF, 2 x 1nF, and 2 x 2200uF
- Inductors are SRP2313AA-100M (https://www.bourns.com/docs/Product-Datasheets/SRP2313AA.pdf, SRP2313AA Series – Shielded Power Inductors)
The inductors (SRP2313AA-100M) we are using are/have:
10uH, 20% tolerance, Q (Min.) @100kHz/V of 40, Typ. SRF of 7 MHz, Typ. DCR of 3.8 mOhm, Max. DCR of 4.15 mOhm,
Typ. Irms of 30A and Typ. Isat of 20A
The inductors used in the reference design (SER2900 Shielded Power Inductors) are/have:
10uH, 10% tolerance, Typ. SRF of 20 MHz, Nom. DCR of 2.60 mOhm, Max DCR of 2.86 mO,
20/40°C rise in temp. of 20/28A, and Isat 10/20/30% drop of 28/31.2/32.1A
I'm wondering if this issue is related to:
Any suggestions, please
Regards,
Peter
Edit Notes
Additional info[edited by: electron1979 at 10:35 PM (GMT -4) on 28 May 2025]