SPV1040 operation
AN4050
4/17
DocID022816 Rev 3
1
SPV1040 operation
device is a low power, low voltage, monolithic step-up converter with an
input voltage range from 0.3 V to 5.5 V, capable of maximizing the energy generated by a
single solar cell (or fuel cell), where low input voltage handling capability is important.
When combined with the
, it provides an ideal solution for charging lithium battery
packs with energy harvested from a very small solar panel.
The SPV1040 is a 100 kHz, fixed-frequency pulse width modulation (PWM) step-up
converter able to maximize the energy harvested by a few solar cells. It employs a
maximum power point tracking (MPPT) algorithm which continuously tracks its output
voltage and current. The converter guarantees the safety of the overall application and its
own by stopping PWM switching in case of an overvoltage, 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 2: Typical application circuit
The SPV1040 acts as an impedance adapter between the PV module and the output load.
The equivalent circuit is shown below.
Figure 3: SPV1040 equivalent circuit
The MPPT algorithm sets up the correct DC working point by ensuring 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
).
Lx
R
S
L
V
BATT
XSHUT
GND
MPP-SET
V
PV
R
1
R
3
C
OUT
R
F1
C
F
R
F2
R
2
C
INsns
C
OUTsns
C
IN
D
OUT
I
CTRL_MINUS
I
CTRL_PLUS
V
CTRL
V
OUT
SPV1040
I
I
R
C
I
V
V
gm V
C
I
Z DC
R
V
V
PV
Panel
IN
IN
IN
IN
OUT
OUT
OUT
OUT
