Other Parts Discussed in Thread: TPS63700
Hi,
I have designed a -5V negative supply using TPS6735ID. Attached circuit image of the same.The device is battery powered. U18 input is from a Vbat to 5V boost regulator. L24 inductor specs: .
When LCD is powered on, there is an audible resonant noise from the inductor L24. When the battery is dead and charger is connected for hours, the device still shows a dead battery. When root caused this issue, it came down to TPS6735ID regulator and LCD. When the battery is dead and charging, the regulator is enabled and providing an output of 3.92V. But the LCD is not on, meaning there is no actual load for the regulator. This is causing a ground bounce at the board ground through L24. Attached images of probed signals. When this regulator section is isolated, the battery charging is stabilized and device is powering up. Is this the problem caused by the TPS6735ID regulator or the topology of my design? Please help me out here.
Thank you!