AN2946
Application note
Solar-LED streetlight controller with 25 W LED lamp driver
and 85 W battery charger based on the STM32F101Rx
Introduction
The solar-LED streetlight controller described in this application note is designed to achieve
an 85 W solar energy battery charger and a 25 W LED lamp driver. During the daytime the
controller preserves the electricity energy gathered by the solar module (PV module), then
stores it in the battery. In the evening the controller uses the battery energy to power the
LED streetlight. When the battery runs out of power after several rainy days, the controller
enables the external offline power supply (not included in this system) instead of the battery
to power the LED streetlight until the system battery is fully charged again.
Due to the clean nature of solar energy, and the highly efficient energy conversion of the PV
module and very long operating life of the LED lamp, the solar-LED streetlight controller,
compared to conventional streetlights, can save electricity remarkably, thus abating
greenhouse gas (e.g. CO2) emission.
This application note is based on the solution of solar-LED streetlight controller architecture,
including a battery charger and LED lamp driver. The description of the architecture involves
hardware and firmware design with design parameter settings. The solar-LED streetlight
controller demonstration board is shown in Figure 1.
Figure 1.
September 2010
Solar-LED streetlight controller demonstration board
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www.st.com
Contents
AN2946
Contents
1
2
3
Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1
Intended use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3
Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4
Board operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1
Controller features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2
Solar-LED streetlight system architecture . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3
Scope of the solar-LED streetlight controller . . . . . . . . . . . . . . . . . . . . . . . 7
2.4
Main functions of the controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2
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Battery charging management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.4.2
LED lamp driving management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.4.3
System monitoring circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Hardware design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1
4
2.4.1
Circuit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.1
Power supply circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.2
Electricity power collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1.3
LED lamp driving circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1.4
Analog signal acquisition circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2.1
Battery charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2.2
LED driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Firmware design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.1
Main loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.2
Battery charging management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2.1
MPPT principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2.2
Battery charging management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.3
LED lamp driving management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.4
System monitoring management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
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AN2946
5
Contents
Overview of demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5.1
Application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5.2
Application board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.3
Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
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List of figures
AN2946
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Figure 34.
Figure 35.
Figure 36.
Figure 37.
Figure 38.
Figure 39.
Figure 40.
Figure 41.
Figure 42.
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Solar-LED streetlight controller demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Solar-LED streetlight system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
System block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Battery charging pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
LED lamp driving scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
12 V power supply circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 V power supply circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Noise filtering circuit for VDD and VDDA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Solar module control circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Hardware OVP circuit for battery overcharging protection . . . . . . . . . . . . . . . . . . . . . . . . . 12
Battery charger circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
LED lamp driver circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Temperature sensing circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Voltage and current detection circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Charging current versus solar module output voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
MPPT test diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
V-I curve and PSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Battery voltage versus charging current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Charger input current (Isc) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Charger output current (Iba) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Vds on Q2, current on L2, and Vak on D4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
LED lamp current, efficiency vs. battery voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
LED current, efficiency vs. LED voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Driver input current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Driver output current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Vgs, Ids, and Vds on Q4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Main loop flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
80 W solar module I-V and P-V curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
P and O method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
P and O tracing route . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Three-stage charging routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
MPPT flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Ambient light sensing flowchart (day and night judgment) . . . . . . . . . . . . . . . . . . . . . . . . . 26
LED light-off routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
LED light-on routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
System monitoring flowchart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
LED_fault IRQ flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
System self-recovery flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Anti-backflow for battery charging flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Top view of demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Bottom view of demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
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1
Safety instructions
Safety instructions
Warning:
1.1
The demonstration board must be used in a suitable
laboratory by qualified personnel only who are familiar with
the installation, use, and maintenance of electrical systems.
Intended use
The demonstration board is a component designed for demonstration purposes only, and
shall be used neither for domestic installation nor for industrial installation. The technical
data as well as the information concerning the power supply and operating conditions shall
be taken from the documentation included with the demonstration board and strictly
observed.
1.2
Installation
The installation of the demonstration board shall be taken from the present document and
strictly observed. The components must be protected against excessive strain. In particular,
no components are to be bent, or isolating distances altered during the transportation,
handling or usage. The demonstration board contains electrostatically-sensitive
components that are prone to damage through improper use. Electrical components must
not be mechanically damaged or destroyed (to avoid potential risks and health injury).
1.3
Electrical connection
Applicable national accident prevention rules must be followed when working on the mains
power supply. The electrical installation shall be completed in accordance with the
appropriate requirements (e.g. cross-sectional areas of conductors, soldering, and PE
connections).
1.4
Board operation
A system architecture which supplies power to the demonstration board shall be equipped
with additional control and protective devices in accordance with the applicable safety
requirements (e.g. compliance with technical equipment and accident prevention rules).
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General description
AN2946
2
General description
2.1
Controller features
2.2
●
MPPT maximizes solar module efficacy
●
Automatic day and night detection
●
Automatic mains switch enable function when battery low
●
Constant current control for LED lamp
●
Battery charge control
●
Optional LED lighting mode
●
LED indicators for system status monitoring and debugging status
●
Full protection function for OVP, UVP, OCP, and OTP.
Solar-LED streetlight system architecture
The solar-LED streetlight controller not only controls solar energy storage to the battery, but
it also manages the power consumption to the LED streetlight. The system architecture of
the solar-LED streetlight system is illustrated in Figure 2.
Figure 2.
Solar-LED streetlight system
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AN2946
2.3
General description
1.
The sunlight delivers rays of photons (solar energy) which hit the solar panel
(Photovoltaic or PV module). The photons (energy) are absorbed by the PV and
electrons are released.
2.
The electrons flow along the metal contact of the PV and form electricity.
3.
Energy is stored in the battery during daytime and consumed at night.
4.
The LED lamp (LED streetlight) is driven to operate by the LED lamp driver. This
controller monitors the system and manages the light-on and light-off in day and night
time.
5.
When the battery goes low, the controller sends an enable signal to the 'Mains switch'
which enables the AC offline power supply.
6.
The AC offline power supply (not included in this application note) works as a backup
source to power the LED streetlight.
Scope of the solar-LED streetlight controller
The block diagram of the solar-LED streetlight controller is shown in Figure 3. The controller
consists of the following blocks:
●
Auxiliary power supply - supplied from the battery, regulated to 12VDC for driving every
MOSFET and then 3.3 VDC for the MCU and its peripherals.
●
Battery charger - a DC/DC converter using buck topology. It converts solar energy to
electricity and stores the electricity in the battery.
●
LED lamp driver - a DC/DC converter using flyback topology in order to drive the LED
lamp and provide even illumination.
●
Driver - generates gate voltage in order to drive every MOSFET properly in the battery
charger and the LED lamp driver including KCHG.
●
Protection circuits - OVP, UVP, OCP, OTP (through the temperature sense block) and
reverse-connection protection for the battery and the LED lamp.
●
MCU - the microcontroller includes the human machine interfaces (HMI), the DIP
switch for the selection of the operating time schedule and the indicators of the
debugging status. The software routines for OVP, UVP, OCP and OTP are implemented
in the MCU.
Figure 3.
System block diagram
!-V
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General description
AN2946
The MCU implements the sophisticated peripherals as listed in Table 1.
Table 1.
MCU peripheral allocation
Peripheral
Number
Description
ADC
11
USC+, USC-, UBAT, ULED, ISC, IBAT, ILED, TCHG, TBAT, TDRV, TLED
GPIO
12
Inputs
DIP1~4 (up to 16 modes) JTAG
Status indication
Charger_EN for anti-backflow charge
Mains_EN for switching to mains supply
Battery LED1-2 for indicating battery status
Debug LED1-4 for diagnosis (up to 16 messages)
PWM
2
PWMCHG, PWMDRV (100 kHz)
EXT1
1
LED fault
2.4
Main functions of the controller
2.4.1
Battery charging management
During the daytime, the battery is charged by PV electricity according to the typical pattern.
An MPPT (maximum power point tracing) algorithm is applied to enable the PV module to
output as much electricity power as it can. Refer to Section 4.2 for more information
concerning MPPT. The pattern for the 12 V battery system is shown in Figure 4. The pattern
differentiates the entire charging process into 3 stages. During stage 1 and stage 2, the
battery is charged with the solar module maximum power. In stage 3, the battery is charged
in constant voltage algorithm.
Figure 4.
Battery charging pattern
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●
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Stage 1 (trickle charging): UBAT < 11 V. The battery is charged with the maximum
power of the PV module. This stage is designed for a battery which is deeply
Doc ID 15473 Rev 2
AN2946
General description
discharged. In order to prolong battery operating life, the charging current is
constrained at Imax = 0.5 A.
●
Stage 2 (high-current bulk charging): 11 V ≤ UBAT < 14.3 V. In this stage, the battery is
charged with the maximum power of the PV module. The charging current (Imp) may
not be constant.
●
Stage 3 (floating charging): UBAT ≥ 14.3 V. In this stage, battery is charged at constant
voltage (14.3 V).
The voltage values 11 V and 14.3 V define the boundaries of the stages that are based on
the characteristics of a typical 12 V lead acid battery. The voltage needed depends on the
type of battery.
2.4.2
LED lamp driving management
During nighttime, normally the ambient light is weak, the LED lamp lights for N hours. The
determined light-on duration (N hours) can be set by selecting a switch, DIP1~4. The
controller turns on/off the LED lamp to automatically correspond to the ambient light.
Figure 5 illustrates how the controller turns on the LED lamp. The DIP switch also provides a
test mode to test the LED lamp.
Figure 5.
LED lamp driving scheme
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2.4.3
System monitoring circuit
The microcontroller (MCU) provides a real-time system monitoring for the controller,
including:
●
Error detection/protection for solar module output voltage (USC), battery voltage(UBAT),
LED lamp voltage(ULED), battery charging current (IBAT) and LED lamp current(ILED)
●
Temperature detection for the operating temperature of the battery, MOSFET and LED
lamp
●
System self-recovery
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Hardware design
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3
Hardware design
3.1
Circuit description
3.1.1
Power supply circuit
The system auxiliary power supply can be built with a 12 V battery. In order to drive the
power MOSFET and some analog ICs perfectly, a regulated 12 V is required. The 12 V
power supply schematic is shown in Figure 6.
Figure 6.
12 V power supply circuit
The MCU requires a 3.3 V source which is obtained from the output of the linear regulator
(U11), see Figure 7 .
Figure 7.
3.3 V power supply circuit
Since the 3.3 V supply is mainly for the MCU, a proper filter, which avoids high-frequency
switching noise interference between the digital power supply (VDD) and analog power
supply (VDDA), is strongly recommended. The filter circuit is shown in Figure 8.
10/38
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AN2946
Hardware design
Figure 8.
Noise filtering circuit for VDD and VDDA
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3.1.2
Electricity power collection
In Figure 9, C1, and C4//C5//C6 are used to reject the high switching frequency interference
from the charger so that only the "clean" current flows through the solar cells (P1). When
photons hit the solar cells, P1 releases electrons which flow along the metal contacts and
stores electricity to C1 and C4/C5/C6 through R1//R2//R3//R4 and Q1. R1~R4 are current
sense resistors which are used to sense the solar module current. An operational amplifier
U1 (LM258D) is used to amplify and smooth the sense signal, then feedback to the MCU.
When solar cells charge the battery with high current, Q1 is turned on in order to minimize
the power losses. Q1 is turned off if solar cells voltage falls below the battery voltage. Q1
also works as a polarity protection diode, preventing that the solar module is reversely
connected. The gate driving signal (PWM_Input) of Q1 is given by the MCU through U4. In
order to properly drive Q1, the 3.3 V PWM signal from the MCU must be sent to U4
(comparator TS391). Q11 and Q13 are configured as the push-pull totem to turn on/off Q1
perfectly.
Figure 9.
Solar module control circuit
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A hardware solution to protect the battery from being overcharged is important. When
battery voltage exceeds 15 V (example of 12 V battery in system), D3 in Figure 10 is
triggered and SCR (Q10) is turned on. The battery provides latch-current to Q10 and the
fuse (F1 in Figure 11) is blown. Then battery is protected.
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Hardware design
AN2946
Figure 10. Hardware OVP circuit for battery overcharging protection
The schematic of the battery charger is shown in Figure 11 which is based on buck topology.
Q2, D4 are the buck MOSFET and diode, respectively. L2 is the inductor and C13 is the
output capacitor. The charger operates in a continuous current mode so that small output
current ripple is achieved and a small output capacitor can be used. C10 and C11 are used
as a snubber to suppress high voltage spikes.
Since Q2 is floating and high-side transformer T2 is used to drive the MOSFET, the gate
driving circuit is similar to the one shown in Figure 9.
Resistors R9, R17 ~ R20 and R55 are used to sense the charge current to the battery. U3
(TSC101) is the high-side current sensor which amplifies the signal and gives feedback to
the MCU.
P2 is the connector to the battery. One fuse (F1) is in series with the battery to prevent
catastrophic failure. To prevent reverse connection of the battery, one Schottky diode D14 is
added. F1 blows out with D14 if the battery is reversely connected. This helps to protect the
rest of the circuits.
Figure 11. Battery charger circuit
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3.1.3
Hardware design
LED lamp driving circuit
The LED lamp driver is designed with flyback topology. No isolation is required in this
application. Flyback is suitable for a wide ratio range of output voltage to input voltage. The
battery voltage is 11 V ~ 14.3 V while for the LED lamp, which is connected in a 3*7 matrix
(3 LED lamps in series and 7 strings in parallel), the maximum LED voltage is defined as
12 V. The flyback converter keeps the LED current constant in the above-mentioned battery
voltage range. In Figure 12, T1 is the flyback transformer and Q4 is the power MOSFET. D5
and D9 clamp the maximum voltage across Q4 in the off-state. D10 acts as the output
rectifier and C30 and C33 are the output capacitors. R46, R47 and U9 are used to sense the
LED lamp current and feedback to the MCU for constant current regulation. The PWM signal
from the MCU is converted from TTL level to CMOS level via U2 and amplified by Q7 and
Q8 to drive Q4. When OCP and/or OVP activate, Q3 and Q9 are used to guarantee a single
turn-on within each switching cycle. The MOSFET current is sensed by resistors R30, R33
and R54 and amplified by U5B. The output of U5B is used to achieve OCP. There are two
levels of OCP implemented in the LED lamp driver. The MOSFET current is sensed and
transferred to comparators U7A and U7B. U7B sets the first current limit which is activated
cycle by cycle. R37 and R36 form a voltage divider and set the threshold at the negative
input of U7B. Overcurrent in the primary circuit of T1 results in high logic output of U7B, thus
pulling down the voltage of the 'LED_Protection' node at the Q5 collector. Consequently,
comparator U2 outputs low voltage and forces Q4 to shut down. In case a heavy overload or
short-circuit occurs, such as a physical short-circuit of T1 or D10 which might exist for some
time, a second level OCP is needed to protect the driver. R41 and R43 form another voltage
divider and set a higher threshold. A high current spike from Q4 triggers the threshold and
U7A generates 'LED_Fault' interrupt to the MCU. After receiving continuous interrupts, the
MCU stops outputting the 'PWM_Driver' signal and waits for a certain time for the next try
(refer to Section 4.4). Such burst mode operation definitely lowers the voltage stress and
current stress on power components. The OVP of the LED lamp is achieved by D12. The
principal is similar to that of the first level of OCP.
Doc ID 15473 Rev 2
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Hardware design
AN2946
Figure 12. LED lamp driver circuit
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3.1.4
Analog signal acquisition circuit
The operating voltage, current and temperature of the battery and LED lamp are monitored
by the MCU. The temperature sensing circuits are illustrated in Figure 13. The voltage and
current sensing circuits are shown in Figure 14. For the battery charger and LED lamp
driver, NTC(s) is soldered on the heat sink of MOSFET (or rectifier). The operating
temperature of the MOSFET (or rectifier) is sensed via NTC(s) and sent to the MCU. These
key power components are protected against overtemperature. For the battery and LED
lamp, the sensing NTC(s) is applied on the battery case and the heat sink of the LED lamp
with wires connected to P4 and P5. For each temperature sensing circuit, a simple RC filter
is added before the signal feeds to the MCU. The temperature sensing is not only for
protection but also applicable for charge pattern optimization online. The battery life is
prolonged.
14/38
Doc ID 15473 Rev 2
AN2946
Hardware design
Figure 13. Temperature sensing circuits
For the LED lamp, if the sensed temperature rises to a certain level, the LED lamp current is
reduced to correspond to entering LP (low power) mode. The LED lamp is dimmed then
without further increasing temperature, the LED lamp is shut down only when the sensed
temperature rises to an even higher level. For all the voltage and current sensing, an RC
filter and clamp circuit are added before the signal feeds to the MCU. Track routing of these
sensing circuits should be done very carefully to avoid picking up noise, otherwise the noise
influences the MCU and results in an unpredictable result.
Figure 14. Voltage and current detection circuit
3.2
Test results
3.2.1
Battery charger
As discussed in Section 2.4.1, the battery charger operation is divided into 3 stages. This
section shows us the test results for each stage.
●
Stage 1:
In this stage, when VBATTERY < 11 V, the controller executes the MPPT algorithm with
current constraint IBATTERY < 0.5 A. The charging current is shown in Figure 15.
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Hardware design
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Figure 15. Charging current versus solar module output voltage
!-V
The charging current is measured against different output voltages of the solar module. A
DC source is used to simulate the solar module output and when its voltage changes from
13.1 V to 19.1 V, the charging current is limited to around 0.5 A. This demonstrates the
proper operation of the first stage.
●
Stage 2:
In stage 2, when 11 V < VBATTERY < 14.3 V, MPPT is implemented. To simulate the V-I curve
of the solar module, the test method is proposed as shown in Figure 16 with two important
equations below.
Equation 1
Usc = Udc – R ⋅ Isc
Equation 2
Psc = Usc ⋅ Isc = ( Udc – R ⋅ Isc ) ⋅ Isc
Figure 16. MPPT test diagram
!-V
The V-I curves of this test system and charger power are shown in Figure 17.
16/38
Doc ID 15473 Rev 2
AN2946
Hardware design
Figure 17. V-I curve and PSC
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According to Equation 1 and Equation 2, the maximum power point (MPP) occurs at
Usc = 0.5 × Udc. A different R value results in different output power at the MPP delivered to
the charger. From Table 2 as long as Udc is 36 V, Usc is kept at18 V no matter what the R
value is. Table 3 shows the result with fixed R and variable Udc. Usc is always half of Udc
during steady state. Thus the test diagram shows the way to find the MPP during the test.
Table 2.
Test results for different values of R (Vdc = 36 V)
R[Ω]
Usc [V]
Isc [A]
Uba [V]
Iba [A]
Charger
efficiency [%]
4.6
18.0
3.90
13.08
5.03
93.7
5.2
18.0
3.45
13.08
4.41
94.0
6.0
18.0
3.00
13.03
3.88
93.6
7.1
18.0
2.53
12.81
3.31
93.1
8.8
18.0
2.05
12.54
2.76
93.8
11.6
18.0
1.55
12.34
2.10
92.9
17.3
18.0
1.04
12.07
1.43
92.2
34.0
18.0
0.53
11.96
0.69
86.5
Doc ID 15473 Rev 2
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Hardware design
AN2946
Table 3.
●
Test results for different values of Vdc (R = 4.6 Ω)
Udc [V]
Usc [V]
Isc [A]
Uba [V]
Iba [A]
Charger
efficiency [%]
36
18.0
3.90
13.08
5.03
93.7
35
17.5
3.80
12.99
4.79
93.6
34
17.0
3.65
12.90
4.57
95.0
33
16.5
3.50
12.82
4.33
96.1
32
16.0
3.48
12.73
4.12
94.2
31
15.5
3.38
12.65
3.90
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15.0
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Stage 3:
In stage 3 when VBATTERY ≥ 14.3 V, the controller enters into floating charging, and Uba is
limited to 14.3 V. Figure 18 shows the battery voltage (Uba) and charging current (Iba) in
this stage.
Figure 18. Battery voltage versus charging current
The result shows that with different charging currents, the battery voltage is kept at around
13.8 V and remains constant. Figure 19 and 20 show the typical current output from the
solar module and the current charged to the battery. Both currents are smooth and no large
current ripple is observed. In Figure 21 the inductor current waveform shows that the buck
converter works at continuous current mode. Peak-to-peak current (IL) ripple is around 0.7
A. Such a small current ripple requires a small output capacitor. The turn-off switching
voltage spike of the MOSFET (Vds) and diode (Vak) are very small in actuality.
18/38
Doc ID 15473 Rev 2
AN2946
Hardware design
Figure 19. Charger input current (Isc)
Figure 20. Charger output current (Iba)
!-V
!-V
Figure 21. Vds on Q2, current on L2, and Vak on D4
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!-V
LED driver
The LED driver provides the LED lamp with constant current for different battery and lamp
voltages. The LED currents are shown in Figure 22 and 23.
Figure 22. LED lamp current, efficiency vs. battery voltage
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Doc ID 15473 Rev 2
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Hardware design
AN2946
Figure 23. LED current, efficiency vs. LED voltage
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LED current is constantly regulated with different lamp and battery voltages. The measured
efficiency is around 82%. The efficiency is not high when compared to a buck converter, but
it can keep LED current constant for a large input voltage range. Figure 24 and 25 show
some typical waveforms for LED drivers.
Figure 24. Driver input current
Figure 25. Driver output current
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!-V
Figure 26. Vgs, Ids, and Vds on Q4
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20/38
Doc ID 15473 Rev 2
AN2946
4
Firmware design
Firmware design
In accordance with the main functions of the controller described in Section 2.4, solar-LED
lamp controller firmware also consists of the following 3 main modules:
●
Battery charging management
●
LED lamp driving management
●
System monitoring circuit
The main loop in Section 4.1 coordinates the above 3 function modules. All the reference
parameters are listed in Table 4.
Table 4.
Firmware reference parameters
Parameter
Value
Description
USC-th1
7.0 V
Lower threshold of solar cell cathode voltage
USC-th2
15.0 V
Upper threshold of solar cell cathode voltage
USCth
5.0 V
Solar cell voltage threshold for detecting day and night
UBATth1
10.0 V
Lower limit voltage for battery
UBATth2
11.0 V
Empty charge voltage for battery
UBATth3
13.8 V
Full charge voltage for battery
UBATth4
14.5 V
Upper limit voltage for battery
ULEDth
13.0 V
Upper limit voltage for LED
ISCth
0.5 A
Current threshold for switching on/off KCHG
IBATth1
0.5 A
Charging current for battery (deep discharge)
IBATth2
8.0 A
Upper limit of charging current for battery
ILEDth1
2.0 A
Current for LED (LP mode)
ILEDth2
2.45 A
Nominal current for LED
ILEDth3
2.8 A
Upper limit current for LED
TCHGth1
60 ºC
Recovery temperature for battery charger
TCHGth2
90 ºC
Upper limit temperature for battery charger
TBATth1
30 ºC
Recovery temperature for battery
TBATth2
45 ºC
Upper limit temperature for battery
TDRVth1
60 ºC
Recovery temperature for LED driver
TDRVth2
90 ºC
Upper limit temperature for LED driver
TLEDth1
80 ºC
Threshold temperature to enter LP mode for LED
TLEDth2
100 ºC
Upper limit temperature for LED
Timth1
1 sec
Cool down period for recovery
Timth2
1 min
Continuous sensing time for day & night judgment
Timth3
1 ms
Response time of PWM output
Timth4
10 min
MPPT self-calibration time interval
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Firmware design
AN2946
Table 4.
4.1
Firmware reference parameters (continued)
Parameter
Value
Description
EXTIth
3
Number of times that LED_Fault EXTI has been triggered
Δ
1 system clock
cycle (~28 ns)
Step of duty cycle adjustment (may not be constant)
Main loop
In the main loop in Figure 27, the parameter 'Timth3' restricts the execution time of every
loop within around 1 ms to make sure system is in steady state after changing the duty cycle
of the battery charger or LED lamp driving. A loop speed that is too fast might cause an
inaccurate value to be processed by the ADC.
Figure 27. Main loop flowchart
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22/38
Doc ID 15473 Rev 2
AN2946
Firmware design
Once the battery is deeply discharged, and the voltage falls below 'UBATth2', the MCU stops
driving the LED lamp immediately. For battery life cycle considerations, the battery cannot
be discharged until it is fully charged. DD_Flag is set when UBAT < UBATth2 and is reset
when UBAT ≥ UBATth3.
4.2
Battery charging management
4.2.1
MPPT principle
The objective of the MPPT algorithm is to get the maximum battery charging power. Taking
into account the charger efficiency, this is the most efficient way to utilize solar energy. In
Figure 28 there exists a maximum power point for each curve.
Figure 28. 80 W solar module I-V and P-V curve
!-V
In actual conditions, the I-V curve and P-V curve of the solar module change with different
irradiance and temperature which means the charging current cannot remain constant even
when the charging voltage is fixed. This kind of state causes the MPPT algorithm to be
adaptive and dynamic. The solar-LED streetlight controller adopts one of the MPPTs, i.e.
P&O (perturbation and observation) method.
Figure 29. P and O method
!-V
1.
Step 1: Suppose the charger is working at point A, the duty cycle is DC(A). At the next
step, the MCU increases the duty cycle to DC(B). The charger then moves to point B at
Doc ID 15473 Rev 2
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Firmware design
AN2946
steady state. Since the resulted power at point B is higher than the power at point A,
the MCU continues to increase the duty cycle.
2.
Step 2: The MCU increases the duty cycle from DC(B) to DC(C). During steady state
the charger operates at point C. Because the power at point C is still higher than the
power at point B, the MCU keeps the same trend and increases the duty cycle.
3.
Step 3: The charger now moves to point D after the MCU increases the duty cycle from
DC(C) to DC(D). Since the power at point D is lower than the power at point C, the
MCU reverses the direction. At the next step, it decreases the duty cycle and moves to
C.
4.
Step 4: The MCU keeps decreasing duty cycle from DC(C) to DC(B). After detecting
that the power at B point is lower than that at C point, MCU reverses direction again.
Then system comes back to step 2.
The P&O tracing route can be described as shown in Figure 30. This tracing route explains
that the MPPT algorithm is dynamic. The charger does not operate at a fixed point, and it
works within a certain range that the maximum power point locates.
Figure 30. P and O tracing route
!-V
The P&O method is based on the fact that the P-V curve remains almost unchanged during
a very short time period. Generally, the MCU executes each P&O step in several
milliseconds, while the P-V curve drift caused by environmental change usually takes a few
seconds or even several minutes, which is much longer. The P&O method is a feasible
method to achieve MPP tracking.
24/38
Doc ID 15473 Rev 2
AN2946
4.2.2
Firmware design
Battery charging management
Figure 31. Three-stage charging routine
!-V
The battery charging flowchart is illustrated in Figure 31. The MPPT algorithm is involved in
stage 1 and stage 2 charging. The stage 1 is a current constraint. In stage 3, the charger
keeps changing the charging current to maintain a constant charging voltage.
The MPPT algorithm illustrated in Figure 32, simplifies the conventional P&O method. Since
battery voltage cannot drastically change in a short period, the maximum power point must
lie on the maximum current point. This allows the MCU to compare current instead of a
power comparison which is more complex for an embedded system.
Figure 32. MPPT flowchart
!-V
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Firmware design
4.3
AN2946
LED lamp driving management
The controller judges whether there is sufficient ambient light (daytime) or weak ambient
light (nighttime) by detecting the solar module voltage. When the ambient light becomes
weak, the solar module voltage might fall below a certain level. If the voltage does not
exceed this level for a period, the controller considers that it is nighttime. The parameter
'Timth2' is used to avoid misjudgment caused by very cloudy weather or a solar eclipse. The
day and night judgment routine is illustrated in Figure 33.
Figure 33. Ambient light sensing flowchart (day and night judgment)
!-V
Once the controller detects that it is night and starts to turn on the LED, the light-on routine
increases the duty cycle of the LED driver by 'Δ' for every loop. LED driving is implemented
by constant current control. Generally, it takes 200 ms ~ 300 ms to reach the nominal
current. For streetlight applications, this startup time is acceptable. Figure 34 shows light-off
routines for LED lamp driving. The LED lamp does not turn on if PWM driving is zero.
Figure 34. LED light-off routine
!-V
To turn on the LED lamp perfectly, the MCU also detects the LED lamp temperature. In
Figure 35 when the LED temperature exceeds 'TLEDth1', the controller reduces the target
current to enter LP mode (low power). The LP mode has been introduced in Section 3.1.4.
This action is to prevent loss of efficiency at a high temperature for the LED and to extend
the LED life cycle as well.
26/38
Doc ID 15473 Rev 2
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Firmware design
Figure 35. LED light-on routine
!-V
4.4
System monitoring management
The system monitoring routine is executed at the beginning of every loop. It checks if
voltage, current or temperature is abnormal or not. A corresponding protective action is
implemented and 'ErrorFlag' is set if any error occurs. The controller maintains the
protective action until 'ErrorFlag' is cleared by the system recovery routine. The flowchart is
shown in Figure 36.
Figure 36. System monitoring flowchart
!-V
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Firmware design
AN2946
In system monitoring management, LED_Fault IRQ is the only interrupt to trigger the MCU
EXTI peripheral which is implemented by the hardware and firmware. In some abnormal
situations, the primary current of LED driving might rise radically, and then the pulse-shaped
LED_Fault signal is generated by a comparator. Several rising edges of this interrupt in EXTI
tell the controller to stop driving the LED and wait for system recovery. The flowchart is
shown in Figure 37.
Figure 37. LED_fault IRQ flowchart
!-V
A complete monitoring system should include a self-recovery function. Every second, which
is defined by 'Timth1', the controller tries to recover system errors by clearing 'ErrorFlag'.
This enables all the error functions paused at the last system monitoring routine to run
again. The system self-recovery flowchart is shown in Figure 38.
Figure 38. System self-recovery flowchart
!-V
To prevent battery power backflow through the charger, KCHG should be turned off when
charging current is very low. In normal conditions, KCHG is turned on to reduce power loss in
its body diode. The flowchart of anti-backflow for the battery charger is shown in Figure 39.
28/38
Doc ID 15473 Rev 2
AN2946
Firmware design
Figure 39. Anti-backflow for battery charging flowchart
!-V
Doc ID 15473 Rev 2
29/38
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Doc ID 15473 Rev 2
17&
Application schematic
5.1
Overview of demonstration board
5
30/38
9
Overview of demonstration board
AN2946
Figure 40. Schematic
!-V
AN2946
5.2
Overview of demonstration board
Application board
Figure 41. Top view of demonstration board
Figure 42. Bottom view of demonstration board
Doc ID 15473 Rev 2
31/38
Overview of demonstration board
5.3
Bill of material
Table 5.
BOM
AN2946
Name
Value
Rated
Type
B1
One way 6x6 mm
(SMD), 4.3 mm(H), tactile switch
OMRON
C1, C6
1 µF
(1210), 100 V, ceramic capacitor
C2, C3, C12, C14, C24,
C36, C39, C41, C42, C43,
C46, C48, C49, C50, C51,
C52, C56, C57, C58, C60,
C62, C65, C66, C67,
C68, C77, C79
100 nF
(0603), 50 V, ceramic capacitor
C4, C5, C13
470 µF
63 V, Al-cap electrolytic capacitor
C7, C8, C35, C38, C45,
C53, C73, C74
1 µF
(0805), 25 V, ceramic capacitor
C9, C22, C34, C44, C75,
C76, C80
22 µF
50 V, Al-cap electrolytic capacitor
C10, C11, C25, C26
220 pF
(0805), 50 V, ceramic capacitor
C15, C20
1 µF
(1206), 50 V, ceramic capacitor
C17
560 pF
(0603), 50 V, ceramic capacitor
C18, C19, C30, C33
220 µF
50 V, Al-cap electrolytic capacitor
C23, C59, C61, C63, C69,
C70, C71, C72,
330 nF
(0805), 50 V, ceramic capacitor
C27, C29, C32, C64, C83
100 pF
(0603), 50 V, ceramic capacitor
C28
220 pF
(0603), 250 V, ceramic capacitor
C47
10 µF
(3528-21), 16 V, tantalum
C54, C55
20 pF
(0603), 50 V, ceramic capacitor
CN1
20-way box header
(Right angle mounting), JTAG connector
Tyco electronics
D1, D11, D13, D17, D18,
D19, D20, D21, D22, D23,
D24, D25, D26, D27, D28,
D29, D30, D31, D32, D33,
D34, D35, D36, D37
BAT46JFILM
(SOD323), small signal Schottky diode
STMicroelectronics
D2, D3, D12
15 V
(SOD 80C), Zener diode
D4, D10
STPS20H100CFP
(TO-220FPAB), power Schottky rectifier
STMicroelectronics
D5, D9
SMAJ24A-TR
(SMA or DO-214AC), 24V 400W
TransilTM (TVS)
STMicroelectronics
D7
3.9 V
(SOD 80C), Zener diode
D8
STPS1H100A
(SMA or DO-214AC), power Schottky
rectifier
STMicroelectronics
D14
STPS2045CFP
(TO-220FPAB), power Schottky rectifier
STMicroelectronics
32/38
Doc ID 15473 Rev 2
Rubycon
Rubycon
Rubycon
VISHAY
AN2946
Table 5.
Overview of demonstration board
BOM (continued)
Name
Value
Rated
Type
D16
STPS1L60A
(SMA or DO-214AC), power Schottky
rectifier
STMicroelectronics
F1
10 A
(2.54 x 7.2 mm, axial lead), 251 series
fuse
Littelfuse®
JP1 (see Table 6)
0.64x0.64 mm, 2 way
2.54 mm pitch, Pin strip header
3M
L2 (see Table 6)
39 µH
Inductor
BOBITRANS
L5, L6
600 Ω @ 100 MHz
(0603), Chip ferrite bead, 25%, 200mA
max.
MuRata
LD1, LD2, LD3, LD4
80 mcd, yellow
(0603), LED
VISHAY
LD5
45 mcd, red
(3.0, diffused, radio lead), LED
VISHAY
LD6
10 mcd, green
(3.0, undiffused, radio lead), LED
VISHAY
P1, P2, P3
Terminal block
2 Terminal, pitch 7.5 mm
DEGSON®
P4, P5, P6
Header, 2 pin
HDR1x2, pitch 2.54 mm
Q1
STP40NF10
(TO-220), N-channel MOSFET
STMicroelectronics
Q2, Q4
STP75NF75FP
(TO-220FP), N-channel MOSFET
STMicroelectronics
Q3, Q5, Q6, Q7, Q11,
Q12
MMBTA42
(SOT-23), NPN bipolar transistor
STMicroelectronics
Q8, Q9, Q13, Q14
BC807
(SOT-23), PNP bipolar transistor
Q10
TYN616RG
(TO-220AB), Triac
R1, R2, R3, R4, R9, R17,
R18, R19, R20, R46, R47,
R55
0.1 Ω
(1206), 1%, resistor
R5, R7, R10, R12, R15,
R16, R22, R23, R24, R26,
R28, R31, R40, R53,
R101
10 Ω
(0805), 1%, resistor
R6, R13, R29
10 kΩ
(0805), 5%, resistor
R8
0.2 Ω
(Axial lead), cement, 2 W, resistor
R11, R45, R48, R49, R59,
R60, R61, R62, R63, R64,
R65, R67, R69, R95,
R97, R104, R105, R110,
R111, R112, R113, R114,
R117, R118, R119, R120,
R121, R122, R123, R124,
R125
10 kΩ
(0603), 5%, resistor
R14, R27, R50
1.2 kΩ
(0805), 5%, resistor
R21, R70, R71, R72, R73,
R74, R106
330 Ω
(0603), 5%, resistor
R25
1.8 kΩ
(0603), 5%, resistor
R30, R33, R54
33 mΩ
(1210), 1%, resistor
Doc ID 15473 Rev 2
STMicroelectronics
TOKEN®
33/38
Overview of demonstration board
Table 5.
AN2946
BOM (continued)
Name
Value
Rated
R32, R88
NTC, 10 kΩ
(0805), NTC resistor
R34, R107, R108, R116
1 kΩ
(0603), 1%, resistor
R35
24 Ω
(1206), 5%, resistor
R36, R41
10 kΩ
(0603), 1%, resistor
R37
12 kΩ
(0603), 1%, resistor
R38, R39
4.7 kΩ
(0603), 5%, resistor
R102
560 Ω
(1206), 5%, resistor
R43
9.1 kΩ
(0603), 1%, resistor
R44, R89, R91, R93
3.3 kΩ
(0603), 1%, resistor
R51
330 kΩ
(0603), 5%, resistor
R52
120 Ω
(0603), 5%, resistor
R56, R58, R96
47 kΩ
(0603), 5%, resistor
R57
3.3 kΩ
(0603), 5%, resistor
R66
1 MΩ
(0603), 1%, resistor
R68
1.8 kΩ
(0603), 1%, resistor
R75
150 kΩ
(0805), 1%, resistor
R76, R78, R81, R84
10 kΩ
(0805), 1%, resistor
R77, R80
82 kΩ
(0805), 1%, resistor
R79, R82, R85, R86, R87,
R90, R92, R94
10 Ω
(0603), 5%, resistor
R83
39 kΩ
(0805), 1%, resistor
R98, R99, R100, R103
1 kΩ
(0603), 5%, resistor
R109, R115
20 kΩ
(0603), 1%, resistor
S1
DIP Switch
4 Position DIP Switch
T1 (see Table 6)
33 µH
EER25.5, transformer
BOBITRANS
T2 (see Table 6)
1 mH
Driver transformer
BOBITRANS
U1, U5
LM258D
U2, U4, U8
TS391ILT
(SO), single voltage comparator
STMicroelectronics
U3, U9
TSC101AILT
(SO), current sense IC
STMicroelectronics
U6
L78L12ABD-TR
(SO8 narrow), positive voltage regulator
STMicroelectronics
U7
LM193D
(SO8), dual voltage comparator
STMicroelectronics
U10
STM32F101RXT6
(LQFP64), 32-bit microprocessor
STMicroelectronics
U11
L4931ABD33-TR
(SO8 narrow), linear regulator
STMicroelectronics
X1
8 MHz
(φ3x8) crystal oscillator
Yuechung
International Corp.
34/38
Type
(SO8 narrow), dual operational amplifiers STMicroelectronics
Doc ID 15473 Rev 2
AN2946
Overview of demonstration board
Note:
STM32F101R4, STM32F101R6, STM32F101R8, STM32F101RB, STM32F101RC
STM32F101RD, STM32F101RE are all equivalent for this purpose.
Table 6.
Pin strip header
Figure
Accessory for JP1
Description
M20 series jumper socket
L2
– 1:
– 2:
– 3:
– 4:
– 5:
– 6:
39 µH +/- 4% (W1//W2 and twisted)
Winding 1: pin 1 to pin 5 (18 turns CCW)
Winding 2: pin 2 to pin 4 (18 turns CCW)
Wire gage: AWG31*20
Core: EER28-Z-PC40
Bobbin: BEER28-1110CPFR
T1
– 1:
– 2:
– 2:
– 3:
– 4:
– 4:
– 5:
– 6:
33 µH +/- 4% (W1+W3 @ 50 kHz, 1VRMS)
Leakage < 0.1 µH (W2 short-circuit)
Winding 1: pin 1 to pin 5 (5 turns CCW)
Winding 2: pin 8 to pin 10 (10 turns CCW)
Winding 3: pin 5 to pin 3 (5 turns CCW)
Wire gage: AWG31*20
Core: EER28-Z-PC40
Bobbin: BEER28-1110CPFR
T2
– 1:
– 2:
– 3:
– 2:
– 3:
– 4:
– 4:
– 5:
– 6:
1 mH (W1+W3 @ 50 kHz, 1VRMS)
Leakage < 10 µH (W2 short-circuit)
No air-gap is required
Winding 1: pin 1 to pin 2 (17 turns CCW)
Winding 2: pin 8 to pin 6 (34 turns CCW)
Winding 3: pin 2 to pin 3 (17 turns CCW)
Wire gage: AWG31
Core: EE10/11-Z-PC40
Bobbin: BE10-118CPSFR
Doc ID 15473 Rev 2
35/38
References
6
AN2946
References
1.
"BAT46JFILM, Small signal Schottky diode" (datasheet)
2.
"STPS20H100CFP, Power Schottky rectifier" (datasheet)
3.
"STPS1L60A, power Schottky rectifier" (datasheet)
4.
"STPS2045CFP, power Schottky rectifier" (datasheet)
5.
"SMAJ24A-TR, 24 V 400 W TransilTM" (datasheet)
6.
"STPS1H100A, power Schottky rectifier" (datasheet)
7.
"MMBTA42, NPN bipolar transistor" (datasheet)
8.
"STP40NF10, N-channel power MOSFET" (datasheet)
9.
"STP60NF06FP, N-channel power MOSFET" (datasheet)
10. "STP75NF75FP, N-channel power MOSFET" (datasheet)
11. "TYN616RG, Triac" (datasheet)
12. "LM258D, Low power dual operational amplifiers" (datasheet)
13. "TS391ILT, Single voltage comparator" (datasheet)
14. "TSC101AILT, current sense IC" (datasheet)
15. "L78L12ABD, positive voltage regulator" (datasheet)
16. "STM32F101RXT6, 32-bit microcontroller" (datasheet)
36/38
Doc ID 15473 Rev 2
AN2946
7
Revision history
Revision history
Table 7.
Document revision history
Date
Revision
16-Oct-2009
1
Initial release.
2
– For easy mount and better operating life of demo-board, below
type of connectors are changed.
1: P1: Solar panel connector
2: P2: Battery connector
3: P3: LED lamp connector
– MCU reset switch is renamed as B1.
– Battery use only 12VDC. Below figures are renew according to the
modification.
– Figure 1, 6, 7, 9, 10, 11, 12, 13, 14, 18, 40, 41, 42 changed
– Table 5 updated
28-Sep-2010
Changes
Doc ID 15473 Rev 2
37/38
AN2946
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