Si10xx-DK

6

Rev. 0.1

Since supply current is typically dependent on supply voltage, the discharge profile editor provides two columns for

supply current. The V2 and V1 voltages at the top of the two columns specify the voltages at which the current

measurements were taken. The Battery Life Estimator creates a linear approximation based on the input data and

is able to feed the simulation engine with an approximate supply current demand for every input voltage.

The minimum system operating voltage input field allows the system operating time to stop increasing when the

simulated battery voltage drops below a certain threshold. This is primarily to allow operating time estimates for

systems that cannot operate down to 1.8 V, which is the voltage of two fully drained single-cell batteries placed in

series.

The wakeup frequency box calculates the period of a single iteration through the four power modes and displays

the system wake up frequency. This is typically the "sample rate" in low power analog sensors.

Once the battery type and discharge profile is specified, the user can click the "Simulate" button to start a new

simulation. The simulation engine calculates the estimated battery life when using one single-cell battery, two

single-cell batteries in series, and two single-cell batteries in parallel. Figure 5 shows the simulation output window.

Figure 5. Battery Life Estimator Utility Simulation Results Form

The primary outputs of the Battery Life Estimator are an estimated system operating time and a simulated graph of

battery voltage vs. time. Additional outputs include estimated battery capacity, average current, self-discharge

current, and the ability to export graph data to a comma delimited text file for plotting in an external graphing

application.