/a>Solar battery charging” title=”Solar battery charging”>Solar battery charging” title=”Solar battery charging”>Solar battery charger, input voltage 0.3V to 5.5V, internal integrated 140 mΩ synchronous rectifier, 120 mΩ power Switch, 100kHz fixed PWM frequency, duty cycle is controlled by MPPT algorithm, output voltage has voltage regulation, over-current and over-temperature protection, mainly used in smart phones and GPS systems, wireless mobile phones, small appliances and sensors, handheld media players (PMP), digital cameras, toys and hand-held health care equipment. This article introduces the SPV1040 main features, block diagram, typical application circuit, output parallel and series connection diagrams, and solar battery charger STEVAL-ISV006V2 circuit diagram and bill of materials and PCB layout.

High efficiency solar battery charger with embedded MPPT

The SPV1040 is a high efficiency, low power and low voltage monolithic step-up converter that operates over a 0.3 V to 5.5 V input voltage range which allows providing power supply to products using even down to one photovoltaic cell or fuel cells where the capability of Handling low input voltages is of utmost importance.

Despite the variation of several conditions over the day (like irradiation, dirt, temperature, etc.) the SPV1040 allows to achieve the maximum efficiency in terms of power harvested from the cells and transferred to the output thanks to the embedded MPPT algorithm.

It employs an input voltage regulation loop, which fixes the charging battery voltage, set with a resistor divider and a maximum output current set with a current sense resistor according to charging current constraints.

The SPV1040 guarantees safety of application devices and of the converter itself stopping the PWM switching in case either of reached maximum input current peak threshold set up to 1.8 A or maximum temperature limit set up to 155 ℃.

As additional feature the IC build-in an input source reverse polarity protection which prevents damaging in case of reverse connection of solar Panel at the input.

Main features of SPV1040:

■ 0.3 V to 5.5 V operating input voltage

■ 140 mΩ internal synchronous rectifier

■ 120 mΩ internal power active switch

■ 100 kHz fixed PWM frequency

■ Duty cycle controlled by MPPT algorithm

■ Output voltage regulation, overcurrent and overtemperature protection

■ Input source reverse polarity protection

■ Built in soft-start

■ Up to 95% efficiency

■ 3 mm x 4.4 mm TSSOP8 package

SPV1040 Application:

■ Smart phones and GPS systems

■ Wireless headsets

■ Small appliances, sensors

■ Portable media players

■ Digital still cameras

■ Toys and portable healthcare

Figure 1. SPV1040 block diagram

Figure 2. SPV1040 Simplified Application Circuit Diagram

Figure 3. SPV1040 output parallel connection diagram

Figure 4. SPV1040 output series connection diagram

Solar battery charger STEVAL-ISV006V2 with SPV1040

STEVAL-ISV006V2: solar battery charger using the SPV1040

The SPV1040 is a high efficiency, low power and low voltage DC-DC converter that provides a single output voltage up to 5.2 V. Startup is guaranteed at 0.3 V and the device operates down to 0.45 V when coming out from MPPT mode. It is a 100 kHz fixed frequency PWM step-up (or boost) converter able to maximize the energy generated by few solar cells (polycrystalline or amorphous). The duty cycle is controlled by an embedded unit running an MPPT algorithm with the goal of maximizing the power generated from the panel by continuously tracking its output voltage and current.

The SPV1040 guarantees the safety of overall application and of converter itself by stopping the PWM switching in the case of an overcurrent or overtemperature condition.

The IC integrates a 120 mΩ N-channel MOSFET power switch and a 140 mΩ P-channel
MOSFET synchronous rectifier.

Figure 5. Typical Application Circuit Using SPV1040

Figure 6. Outline Drawing of Solar Battery Charger STEVAL-ISV006V2

Figure 7. STEVAL-ISV006V2 circuit diagram

Solar Battery Charger STEVAL-ISV006V2 Bill of Materials:



Figure 8. STEVAL-ISV006V2 PCB Layout
For details, see:
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00287506.pdf
and
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00292052.pdf