Hi All,
I'm designing a buck converter using TPS40090 as the controller. This buck converter need to be a programmable one which means that i can control the output voltage based on the program voltage. This IC has a internal 0.7 voltage reference which can be disconnected. This is where i can connect my program voltage value.
TPS40090 has internal error amplifier. My objective is to convert this internal error amp as a buffer (to bypass the internal error amp) and using external error amp with compensation.
The reason why i want to use external error amp is because i have 3 control mode which is constant voltage, constant current and constant power which has its own compensation value. so i need to have 3 external error amp instead of one and feed it back to the internal buffer (which is the internal error amp converted to buffer) .
I have tried doing this but the whole simulation is not working. I believe there is influence from SS pin and Idroop pin which in the diagram are also connected to the internal error amp, therefore the internal amp cannot be converted into pure buffer.
Appreciate if you guys able to give some ideas regarding this issues.
