TPS92543-Q1: TPS92543-Q1 Boost does not start, LGBST active but HGBST no output, reference design based

Part Number: TPS92543-Q1

Hi TI team,

We are evaluating TPS92543-Q1 using the reference design. The schematic is attached.

UART communication is working correctly, and register read/write with readback has been verified.

Current BOOST configuration:

• BSTREF = 14V
• BSTFSW = 250kHz
• BSTILIMP = 00
• BSTISLOPE = 101
• BSTOVTH = 11
• BOOST Enable (SYSCFG1 = 0x44)

Current initialization sequence:

1. Disable driver
2. Clear status registers
3. Configure BOOST registers
4. Enter RUN mode
5. Enable BOOST
6. Verify register readback
7. Read STATUS1 / BSTSTATUS / BCK1STATUS

Current register status:

• STATUS1 = 0x00
• BSTSTATUS = 0x00
• BCK1STATUS = 0x00

Observed behavior:

• LGBST outputs switching pulses.
• HGBST has no switching waveform.
• SWBST only shows a ringing/sinusoidal waveform instead of normal switching.
• After installing Q1/Q2, switching disappears almost immediately.
• VBCK remains approximately equal to VIN (~12V), so BOOST never reaches the expected 14V output.

To isolate the problem, we removed Q1/Q2 and supplied VBCK externally. The BUCK and LED driver could operate, but PWM behavior was still not as expected.

We also noticed that our schematic includes two additional 1nF capacitors from ISP and ISN to GND, while the reference schematic does not.

Could you please help confirm:

1. Is our initialization sequence correct?
2. Should BOOST be enabled before entering RUN mode?
3. Are there any mandatory initialization steps not described in the datasheet?
4. Is there an official TPS92543-Q1 initialization example or demo available?
5. Could the additional 1nF capacitors on ISP/ISN affect BOOST startup?

Thank you.