SPV1040 operation description

AN4050

4/19

DocID022816 Rev 2

1

SPV1040 operation description

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. If combined with the L6924D, it provides the ideal

solution for charging lithium battery packs by harvesting energy from a very small solar

panel.

The SPV1040 is a 100 kHz fixed frequency PWM step-up converter able to maximize the

energy harvested by few solar cells. thanks to the embedded MPPT algorithm which

maximizes the power generated from the panel by continuously tracking its output voltage

and current. The converter guarantees the safety of the overall application and its own by

stopping the PWM switching in case of an overvoltage, overcurrent or overtemperature

condition. The IC integrates a 120 m

Ω N-channel MOSFET power switch and a 140 mΩ P-

channel MOSFET synchronous rectifier.

Figure 2. Typical application circuit

The SPV1040 acts as an impedance adapter between the PV module and the output load.

In fact, the equivalent circuit can be seen below:

Figure 3. SPV1040 equivalent circuit

The MPPT algorithm properly sets up the DC working point by guaranteeing Z

in

= Z

m

(assuming Z

m

is the impedance of the supply source). In this way, the power extracted from

the supply source (P

in

= V

in

* I

in

) is maximum (P

m

= V

m

* I

m

).

The voltage-current curve shows all the available working points of the PV panel at a given

solar irradiation. The voltage-power curve is derived from the voltage-current curve by

AM11733v1

Lx

R

S

L

V

BATT

XSHUT

GND

MPP SET

V

PV

R

1

R

3

C

OUT

R

F1

R

F2

C

F

MPP

R

2

C

INsns

C

OUTsns

C

IN

D

OUT

I

CTRL_MINUS

I

CTRL_PLUS

V

CTRL

V

OUT