Other Parts Discussed in Thread: TPS61220, TPS61220EVM-319
I'm trying to incorporated a TPS61221 boost regulator with a fixed 3.3 V output into an embedded design to keep the supply voltage above 3 V as the battery drains. My design turns on and off. But, when it is on it draws a lot of current: 75 mA. I'm having trouble maintaining the 3.3 V output at the 75 mA of current. I've wired the device per the circuit diagram in the datasheet using 10 uF capacitors for C1 and C2 and a 4.7 uH inductor. When I connect the TPS61221 to a power supply and do not connect it to a load it's output voltage is 3.3 V, but when loaded with my circuit it can only sources about 50 mA and the output voltage drops to 2.8 V or so. Looking at Figure 1 in the datasheet I think that the output current should be in the 150-200 mA range for the range of input voltages that I plan on using: 2.2 - 3.7 V. I'm clearly missing something, but I can't figure out exactly what. Does anyone have any suggestions? Thanks!