Description

STEVAL-ISV012V1

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Doc ID 018897 Rev 2

1

Description

The STEVAL-ISV012V1 demonstration board is based on the SPV1040 solar voltage boost

converter and the L6924D single cell Li-ion battery charger.

The SPV1040 device is a high efficiency, low power, low voltage, monolithic step-up

converter with an input voltage range from 0.3 V to 5.5 V, and is capable of maximizing the

energy generated by even a single solar cell (or fuel cell), where low input voltage handling

capability is extremely important.

Thanks to the embedded MPPT algorithm, even under varying environmental conditions

(such as irradiation, dirt, temperature) the SPV1040 offers maximum efficiency in terms of

power harvested from the cells and transferred to the output.

The SPV1040 protects itself and other application devices by stopping the PWM switching if

either the maximum current threshold (up to 2 A) is reached or the maximum temperature

limit (up to 155 °C) is exceeded.

The L6924D device is a fully monolithic battery charger dedicated to single cell Lithium-

ion/Lithium-ion polymer battery packs. It is the ideal solution for space-limited applications

such as PDAs, handheld equipment, cellular phones, and digital cameras.

The L6924D normally works as a linear charger when powered from an external voltage

regulated adapter. The device can also work in “quasi-pulse” charger mode when powered

from a current limited adapter like that of a solar panel. To work in this condition, the

charging current of the device should be set to a level higher than the solar panel maximum

peak current.

Thanks to the L6924D’s very low minimum input voltage (down to 2.5 V), during the fast-

charge phase the output voltage of the solar panel drops down to the battery voltage plus

the voltage drop across the power MOSFET of the charger.

The main advantage of the quasi-pulse charging mode is that it shares the simplicity of the

linear approach, where the power dissipated is dramatically reduced, thereby maximizing

the charge rate from the solar panel.

The Li-ion battery solar charger with embedded (MPPT) and quasi-pulse charging mode is

“best-in-class” in terms of system efficiency, allowing battery charging while maximizing

available solar panel power.

In the STEVAL-ISV012V1 demonstration board, the L6924D is supplied by the output stage

of the SPV1040, which is supplied by a 400 mW PV panel.