STMicroelectronics STEVAL-ISV021V1 energy harvesting system, SPV1050 ULP energy harvester energy harvester Application note

AN4396
Application note
STEVAL-ISV021V1, energy harvesting system based on SPV1050,
PV panel and battery
Domenico Ragonese
Introduction
The STEVAL-ISV021V1 is a demonstration kit which consists of a complete energy
harvesting module based on the SPV1050 ULP energy harvester and battery charger,
having the purpose to show the electrical performance of the power converter and many
other fundamental electrical quantities related to the overall system.
The SPV1050 power manager is configured as a buck-boost converter, fitting the electrical
characteristics of the mounted PV panel and battery.
A power monitoring board along with a software GUI are used to monitor and to graph both
of the PV panel and battery voltage and current, and system performances, like MPPT
accuracy and conversion efficiency.
The STEVAL-ISV021V1 represents the standalone harvesting module that can be
interfaced with a wireless sensor node to provide the microcontroller, transmitter and
sensors with the energy scavenged and stored into the battery.
Furthermore, the STEVAL-ISV021V1 harvesting module embeds an extension connector
to interface and to monitor of some of the SPV1050 input and output signals through
a microcontroller based board.
The complete STEVAL-ISV021V1 kit is shown in Figure 1.
Figure 1. Power monitoring board (left) and harvesting module (right), top view
June 2014
DocID025514 Rev 1
1/19
www.st.com
Contents
AN4396
Contents
1
Schematic and bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2
Harvesting module layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3
Harvesting module connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4
Jumpers and switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5
Harvesting module and power monitoring board . . . . . . . . . . . . . . . . 14
6
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2/19
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1
Schematic and bill of material
Schematic and bill of material
The schematic, bill of material and gerber files can be downloaded from the Design
resources tab of the STEVAL-ISV021V1 product folder on www.st.com.
DocID025514 Rev 1
3/19
19
Schematic and bill of material
4/19
Figure 2. Harvesting module schematic
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Sect. Item Qty.
1
1
Battery
Ref.
Part/value
BT1
Support for
Li-Ion
battery
2
1
J6
SMD
jumper
3
2
U3
Flexible PV
panel
1
J4
SMD
jumper
SMD
Pitch
100 mils
Pitch
100 mils
Keystone
Manufacturer code
More information
3008
SMD
FCI
95293-101-03LF
This jumper allows the
connection of the STORE
pin to the voltage regulator
U4 in case the external
sampling is OFF
SMD
SANYO
AM-1801
2 PV panels connected in
series
95293-101-03LF
This jumper disconnects
the PV panel U3 in case
an alternative supply is
required and connected to
CN1
SMD
FCI
Supply
DocID025514 Rev 1
5
Tolerance Voltage
Technol.
Watt
Package Manufacturer
(%)
current
info.
AN4396
Table 1. Harvesting module BOM
6
1
J5
3-way
switch
Pitch
100 mils
SMD
FCI
95293-101-03LF
This jumper allows the
connection of the source
to the harvester U1 in
case the external
sampling is OFF
7
1
CN1
2-way
conn.
Pitch
100 mils
SMD
FCI
95293-101-03LF
Input connector for
external PV panel or TEG
Schematic and bill of material
5/19
Sect. Item Qty.
Ref.
Part/value
Tolerance Voltage
Technol.
Watt
Package Manufacturer
(%)
current
info.
MPPT section
1
U2
SPV1050
9
1
C6
1 µF
15%
10
1
Rmpp
10 M
1%
11
1
Rmpps
680 k
1%
12
1
Rin
3 M
0.01
13
1
C34
10 nF
15%
14
LDO1
DocID025514 Rev 1
Harvester/DC-DC controller section
8
1
L1
22 µH
15
1
SW1
3-way
switch
16
1
C5
100 nF
LDO2
17
1
SW2
3-way
switch
18
1
C4
100 nF
Manufacturer code
Harvester and thin film
battery manager
ST
25 V
16 V
X5R
0603
Murata
GRM188R61E105KA12D
Input capacitance
0.1
0603
VISHAY
CRCW060310M0FKEA
Resistor partitioning for
MPP track
0.1
0603
TE
Connectivity
CRG0603F680K
Resistor partitioning for
MPP setting
0603
VISHAY
CRCW06033M00FKEA
Input resistor partitioning
0603
Murata
GRM188R71C103KA01D
Voltage sampling time
constant capacitance
Coilcraft
LPS4018-223ML_
LPS5010-223ML_
XFL2006-223ME_
DC-DC inductor
Close 1 - 2, LDO1 is
disabled
Close 2 - 3, LDO1
controlled by external
signal
X7R
20%
10%
10%
6.3 V
6.3 V
More information
Pitch
100 mils
SMD
FCI
95293-101-04LF
X5R
0402
AVX
04026D104KAT2A
Pitch
100 mils
SMD
FCI
95293-101-04LF
X5R
0402
AVX
04026D104KAT2A
Schematic and bill of material
6/19
Table 1. Harvesting module BOM (continued)
Close 1 - 2, LDO2 is
disabled
Close 2 - 3, LDO2
controlled by external
signal
AN4396
Sect. Item Qty.
Ref.
Part/value
Tolerance Voltage
Technol.
Watt
Package Manufacturer
(%)
current
info.
Manufacturer code
More information
Battery management section
2
C9,
C10
47 µF
20%
6.3 V
X5R
0805
KEMET
C0805C476M9PAC7800
Capacitor on STORE net
21
1
Cuvp
470 nF
15%
10 V
X5R
0603
Murata
GRM188R71A474KA61D
UVP voltage sampling
delay time constant
capacitance
22
1
Ruvp
6.8 M
1%
0603
VISHAY
CRCW06036M80FKEA
23
1
Reoc
0.75 M
1%
0603
VISHAY
CRCW0603750KFKEA
24
1
Rout
3 M
1%
0603
VISHAY
CRCW06033M00FKEA
Ambient light
25
1
U7
SFH5711
SMD
OSRAM
SFH 5711
26
1
R12
80 k
0603
VISHAY
CRCW060382K0FKEA
27
1
J7
SMD
jumper
SMD
FCI
95293-101-03LF
External supply from USB
DocID025514 Rev 1
19
28
1
U8
STLQ50CR
SOT3235L
ST
STLQ50C-R
29
1
SB49
5.36 k
0.1
0603
Panasonic
ERA3AEB5361V
30
1
SB50
2.05 k
±1%
0.1
0603
VISHAY
CRCW06032K05FKEA
31
2
C14,
C15
1 µF
15%
X5R
0603
Murata
GRM188R61E105KA12D
33
1
J23
SMD
jumper
Pitch
100 mils
SMD
FCI
95293-101-03LF
1%
0.1
Pitch
100 mils
VEOC = 4.15 V
VUVP = 3.75 V
Ambient light sensor:
place on the same solder
side of the PV panel (U3)
Disable charging from
USB
7/19
Schematic and bill of material
25 V
AN4396
Table 1. Harvesting module BOM (continued)
Sect. Item Qty.
Ref.
Part/value
External connections
DocID025514 Rev 1
Spacers + nuts
34
1
J28
Micro-USB
35
1
J25
16-pin
conn.
36
1
J27
16-pin
conn.
37
4
Screw
support
Tolerance Voltage
Technol.
Watt
Package Manufacturer
(%)
current
info.
Manufacturer code
More information
SMD
Molex
47346-0001
External charge from USB
2.54 mm
SDM
Samtec
SMH-108-02-G-D
Connector for future
extensions
2.54 mm
SMD
Samtec
SMH-108-02-G-D
Connector for power
monitoring board
RS
325-687 and 525-701
Schematic and bill of material
8/19
Table 1. Harvesting module BOM (continued)
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2
Harvesting module layout
Harvesting module layout
Figure 3 and Figure 4 show the component placement and the layout (top and bottom
views) of the harvesting module.
Figure 3. Harvesting module - top view
Figure 4. Harvesting module - bottom view
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Harvesting module layout
AN4396
In order to ensure a proper noise rejection that could impact the SPV1050 device
performance, the following indications must be followed in the PCB routing:
10/19

The exposed pad and the pins PGND and GND must be connected to the same ground
plane.

The capacitor on the STORE pin must be placed as closest as possible to the related
pin.

The capacitors on the LDO1 and LDO2 pins must be placed as closest as possible to
the related pins.
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3
Harvesting module connectors
Harvesting module connectors
The STEVAL-ISV021V1 provides a set of connectors for the input sources which are
described below:

CN1 (2-pin connector)
This connector is provided to supply the SPV1050 device by a supply source alternative to
the on-board PV panel.
Table 2. CN1 connector
CN1 pin number
Signal
1
2
SOURCE +
SOURCE -
The J4 must be open before an external source is connected to the CN1. For the proper
selection of the external source, please refer to the datasheet of the SPV1050 device.

J25 (16-pin extension connector).
It can be used to connect the harvesting module to an external load such as a wireless
sensor node module.
Table 3. J25 connector
J25 pin number
1-2
3-4
5-6
SPV1050 LDO1_EN LDO2_EN
BATT_CHG
pin signal CONTROL CONTROL

7-8
9 - 10
11 - 12
13 - 16
BATT_CONN
LDO2
LDO1
GND
–
LDO1_EN CONTROL (input): it provides the connection to an external signal that
controls the LDO1_EN pin. In this case the SW1 must be left open. If the LDO1 is
not used, the LDO1_EN pin has to be connected to ground.
–
LDO2_EN CONTROL (input): it provides the connection to an external signal that
controls the LDO2_EN pin. In this case the SW2 must be left open. If the LDO2 is
not used, the LDO2_EN pin has to be connected to ground.
–
BATT_CHG (output): battery charge status pin.
This is an open drain pin that has to be pulled up by a resistor (10 M typical) to
VSTORE voltage rail.
–
BATT_CONN (output): battery connection status pin.
This is an open drain pin that has to be pulled up by a resistor (10 M typical) to
VSTORE voltage rail.
–
LDO2: LDO2 (3.3 V) output voltage pin.
–
LDO1: LDO1 (1.8 V) output voltage pin.
–
GND: ground pin of the extension board.
J27 (16-pin monitoring connector)
It provides the connection to the power monitoring board.
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Harvesting module connectors
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Table 4. J27 connector
J27 pin number
1-2
Signal
12/19
3-4
SOURCE PV+
5-6
7-8
Vbatt+ VBATT_OUT
9 - 10
SUPPLY_
SFH5711
11 - 12
13 - 14
AMBIENT_ AMBIENT_
LIGHT_PIN LIGHT
15 - 16
GND
–
SOURCE, PV+: Harvesting source current sensing pin.
If the power monitoring board is used, then the jumper J5 must be left open;
otherwise pins 1 and 2 of the J5 must be shorted.
–
VBATT+, VBATT_OUT: Battery current sensing pin.
If the power monitoring board is used, then the jumper J6 must be left open;
otherwise pins 1 and 2 of the J6 must be shorted.
–
SUPPLY_SFH5711: Power supply of the ambient light sensor pin (placed on the
top side of the board).
–
AMBIENT_LIGHT, AMBIENT_LIGHT_PIN: Ambient light current sensing pin.
If the power monitoring board is used, then the jumper J7 must be left open.
–
GND: Ground pin.
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4
Jumpers and switches
Jumpers and switches
Table 5. J4 jumper
J4
Function
CLOSE 1 - 2: harvesting board supplied by the on-board PV panel
OPEN 1 - 2: enables an alternative source from the CN1
Table 6. J5 jumper
J5
Function
CLOSE 1 - 2: bypasses power monitoring sense and supply directly the SPV1050
OPEN 1 - 2: power monitoring enabled from the power monitoring board
Table 7. J6 jumper
J6
CLOSE 1 - 2: bypasses power monitoring sense and connects the battery to the BATT
Function pin
OPEN 1 - 2: enables sensing from the monitoring board
Table 8. J7 jumper
J7
Function
CLOSE 1 - 2: not used
OPEN 1 - 2: enables ambient light sensing from the monitoring board
Table 9. J23 jumper
J23
Function
CLOSE 1 - 2: STORE pin supplied by the USB cable
OPEN 1 - 2: STORE pin supplied by the energy harvesting source
Table 10. SW1 and SW2
SW1
Function
SW2
CLOSE 1-3: LDO1 DISABLED
CLOSE 1-3: LDO2 DISABLED
CLOSE 2-3: LDO1 ENABLED
CLOSE 2-3: LDO2 ENABLED
FLOATING: EXTERNAL CONTROL BY J25 FLOATING: EXTERNAL CONTROL BY J25
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Harvesting module and power monitoring board
5
AN4396
Harvesting module and power monitoring board
The harvesting module can be used both: as a standalone device or with the power
monitoring board.
In the standalone mode, leave the CN1 open and connect the jumpers as described below:

Close pins 2 - 3 of the J4 and close pins 1 - 2 of the J5 in order to supply the SPV1050
device by the on-board PV panel.

Close pins 1 - 3 of the J6 in order to connect the on-board battery.
Figure 5. Jumper configuration for harvester module in stand-alone mode
It is possible to monitor the system behavior and efficiency by following the listed steps:

Place a voltmeter between pins 1 - 2 of the CN1 (VIN)

Replace the short on the J5 by an ammeter (IIN)

Place a voltmeter between the TP16 and TP8 (VBATT)

Replace the short on the J6 by an ammeter (IBATT)
The STEVAL-ISV021V1 kit includes the power monitoring board, and the related GUI which
runs on the Windows® XP and Windows 7 OSs.
The power monitoring board and the related GUI allow a quick and intuitive way to monitor
the system performances.
14/19
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Harvesting module and power monitoring board
Before to connect the harvester module to the power monitoring board, set the jumpers as
described below:

Close pins 2 - 3 of the J4 in order to supply the SPV1050 device by the on-board PV
panel

Close pins 2 - 3 of the J5 in order to allow the power monitoring to sense the input
voltage and current.

Close pins 2 - 3 of the J6 in order to allow the power monitoring to sense the battery
voltage and current.

Close pins 2 - 3 of the J7 in order to allow the power monitoring to sense the ambient
light on the PV panel.
Figure 6. Jumper configuration for harvester module connected to power monitoring
board
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Harvesting module and power monitoring board
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Figure 7 shows the connection of the harvesting module and the power monitoring board of
the STEVAL-ISV021V1 kit.
Figure 7. Power monitoring board (left) and energy harvesting module (right)
The power monitoring board allows to measure up to three voltage-current pairs when
connected to a generic DUT. This board can acquire up to 12800 samples per second when
a single channel is active. For multi-channel acquisition the available bandwidth is split
among the three channels. Two channels can acquire currents in the range 1 A - 15 mA,
while the third one works in the range 1 A - 1 mA. This board can be used as a general
purpose measurement board, and in this case is a part of the STEVAL-ISV021V1 kit. The
ambient light irradiation, the input supply operating points (the input voltage and current of
the harvested source) and the output stage operating points (the battery voltage and
current) are sampled.
The sampled parameters can be displayed by the GUI once the monitoring board is
connected to a PC or laptop through the dedicated USB cable.
Note:
Please note, that connecting the harvesting module to the power monitoring board, while
this is not powered through the USB cable, causes current draining from the battery, and
hence potential damages.
The GUI is arranged in four selectable “tabs”:
16/19

Configuration: allowing the setup of the power monitoring board.

Data visualization: not used with the STEVAL-ISV021V1.

Power visualization: displaying the power sink by the load eventually connected to
the “extension” connector J25.

Efficiency: displaying the system performances both in terms of MPPT accuracy and
power efficiency.
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Harvesting module and power monitoring board
Just as an example, Figure 8 the efficiency tab:

The GUI will show the actual PV panel curve according to the current ambient light
conditions.

On the PV panel curve the green dot indicates the real working point, while the blue dot
indicates the maximum power point.

The table on the top right side of the screen shows the main system parameters and
performances.
A detailed description of the GUI is available in the “Software user manual” - UM1752.
Figure 8. STEVAL-ISV021V1 “efficiency” tab
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Revision history
6
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Revision history
Table 11. Document revision history
18/19
Date
Revision
03-Jun-2014
1
Changes
Initial release.
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