Hi Group,
I am going to demonstrate that the specification that Batteriser is trying to achieve is not physically possible. There is no need to consider the IC at all.
Battery MeasurementFirst I used my HPIB controlled Load and DMMs to characterise a AA Cell. I used a Duracell Procell. This is a top tier battery.
Here is a picture of the equipment:
The discharging was interrupted periodically to measure the Open Circuit Voltage and the ESR of the battery.
This data is consistent with data published by various battery manufacturers.
LTspice ModelThe data from the battery measurements was transferred to an LTspice model. The model includes tables for OCV and ESR.
I have arranged the model to step from 90% charged to 10% charged in 20% steps. At each step I have swept the load resistance from 2 Ohms to 0.1 Ohms. I have plotted a graph that shows peak power in Watts that can be obtained from the cell. (I use the word charged even though the alkaline battery is a primary cell. Think of the cell as being chemically charged.)
Maximum Power TheoremThe Maximum Power Theorem states that the maximum power will be delivered to the load when the load resistance (impedance) is equal in magnitude to the source resistance (impedance). In this case this happens when the load resistance is equal to the ESR. And at that point half the power is dissipated in the ESR and half in the load.
ObservationIn order to get 1.5W from the cell, the cell must have greater than 70% of capacity left.
Regards,
Jay_Diddy_B