Does the spice model of the ADP2303 operate in a inverting buck-boost application?
I used the ADP230x BuckBostInvert spread sheet to design a simple 5 V to -12 V power supply.
To test some input and output filters I wanted to run some simulation in LTspice. I opened the ADP2303 test jig and modified it to match the inverting buck-boost design above.
When I run this simulation the switcher never comes into regulation. The FB input voltage rises to about 900 mV above the GND pin (the output voltage). The output voltage rises about -13.5 V after 30 ms, with no signs of stopping.
I suspect the model may not support the inverting buck-boost topology. Can anyone confirm if it does or does not work in this mode? Or, if you you spot an error in my LTspice circuit, please let me know.
I'm afraid that the ADP2303 LTSpice model doesn't support inverting configuration simulation, although the actual part can work under this configuration.
Well that's a shame. Why not make a simulation model that matches the part so users can check transient response etc before building a board? As a result I will be using another part for this project.
Please refer to LT1956 datasheet page 25 as example POS to NEG circuit.