Hello,
in a handheld measurement equipment the TPS61222 is used for battery power supply, but also to produce a clean 5 Volt signal if power is used from 2 other sources (USB and LM1117 regulated higher voltages). Due to it's design the measurement equipment draws currents (mainly due to relays) between 30 mA and 180 mA. The issue is that the output voltage of the TPS61222 gets unstable at the higher output currents and drops down to 4.x Volt with strong oscillations. My observation is that the issue can be decreased by very much higher bypassing capacitors (200uF - 300uF) instead of the recommendet 10 uF capacitor, but not fully avoided. Questions:
1. Is the TPS61222 able to provide output currents up to 200 mA? Figure 1 of the datasheet states it should be.
2. Is there any recommandation how to best fix this behaviour without moving to a different device?
The attached files show the circuit diagram, the PCB layout and also the oscillating output voltage starting when output current increases.
Thanks for your advice
Michael Knitter
