Hi,
I've a circuit using a MT3640 which is I suspect a clone of the TLV61048, at least it's pin compatible. TLV61048 is preferred but long lead times and not in stock anywhere means I had no choice.
XI'''AN Aerosemi Tech | XI'''AN Aerosemi Tech MT3608 | DC-DC Converters - LCSC.COM
I'm boosting 5V to +/-14V. I've noticed that lower than about 6.5V efficiency drops massively. I've tried:
Inductors from 1.5 to 5.6uH (Coilcraft XEL4030 so well within current saturation)
8x 10uF X7R (4x on the PCB but doubled for a test)
Without any success. Looks like's it's the MT3640 and the 2A current limit is *******. Anything else look amiss?
For reference most the current draw is 12x NE5534's.
I've a circuit using a MT3640 which is I suspect a clone of the TLV61048, at least it's pin compatible. TLV61048 is preferred but long lead times and not in stock anywhere means I had no choice.
XI'''AN Aerosemi Tech | XI'''AN Aerosemi Tech MT3608 | DC-DC Converters - LCSC.COM
I'm boosting 5V to +/-14V. I've noticed that lower than about 6.5V efficiency drops massively. I've tried:
Inductors from 1.5 to 5.6uH (Coilcraft XEL4030 so well within current saturation)
8x 10uF X7R (4x on the PCB but doubled for a test)
Without any success. Looks like's it's the MT3640 and the 2A current limit is *******. Anything else look amiss?
For reference most the current draw is 12x NE5534's.
Attachments
How do you think the negative output works ?
Should it not be a mirror image of the positive ?
The way it is drawn, D2 dumps most of the positive output energy directly to ground.
I think, D2 should be in parallel with D1 and oriented the same as D1.
And gnd should not connect to the coupling cap at all.
Should it not be a mirror image of the positive ?
The way it is drawn, D2 dumps most of the positive output energy directly to ground.
I think, D2 should be in parallel with D1 and oriented the same as D1.
And gnd should not connect to the coupling cap at all.
D2 only conducts current once, on the very first positive going edge. D2 clamps the voltage on C51's top plate to +0.3V. Thereafter, C51's top plate swings between -11.7V and +0.3V ... and D2 never conducts current, ever again.
It's similar to a "DC level restoration" diode in black and white video circuits.
It's similar to a "DC level restoration" diode in black and white video circuits.