I am trying to make a high-power audio amplifier circuit consisting of the TPS55340 as a boost converter IC to boost a battery's voltage from 14.4 (12-16.6 V) to ~19 V, to allow higher output power from the audio amplifier and keep a steady voltage throughout the total battery discharge cycle.
However, I cannot pull more than 1.4 A from the battery before the output voltage on the TPS55340 begins to drop significantly (~16.2 V where Vin = 15.52 V). The effect is even worse as the battery discharges more.
Requirements for the boost converter design:
- 19 V Vout
- 3 A peak output current
- Smallest PCB footprint design and layout
- Lowest possible ripple on Vout
The battery is a custom made 4S/1P 21700 pack consisting of the Samsung 50E cells. The associated BMS is able to output 6 A of continuous and 8 A non-continuous current, confirmed using low-value resistor loads. The cutoff voltage for overdischarge is 12 V and the cutoff for overcharge is 16.6 V. I'm certain that this battery pack is not the issue. I've even used a bench power supply rated up to 30 V, 6 A on Vin and the voltage drop on Vout still persists.
I've cleaned the PCB from flux and other residue using IPA alcohol, as I was informed that this could have an impact on the circuit performance. Sadly, Vout still drops significantly.
I've attempted to increase the C10 capacitor value, all the way up to 2200 μF and still no luck.
- All other parts are generic. All the capacitors are rated for at least 25 V and are low ESR. The ceramic caps have XR7 quality. The resistors are all within 1% of their rated values. Both resistors and ceramic caps are 0603 (imperial) packaging.
PCB layout (C9 footprint is open and not used in this design):
After countless hours of head-scratching, I feel that I screwed up what appears to be a simple and straightforward boost converter design. Any help is much appreciated.