Test Report - PMP7647_RevC
December 12
th
, 2013 1 TII - Reference Designs
TEST REPORT OF MPPT & LED DRIVER
PMP 7647
Test Report - PMP7647_RevC
December 12
th
, 2013 2 TII - Reference Designs
CONTENTS
Contents
I. INTRODUCTION .................................................................................................................................................................... 3
II. DESCRIPTION ........................................................................................................................................................................ 3
III. BLOCK DIAGRAM ............................................................................................................................................................ 4
IV. SPECIFICATIONS .............................................................................................................................................................. 5
V. BOARD LAYOUT .................................................................................................................................................................. 5
VI. TEST SETUP ....................................................................................................................................................................... 6
VII. TEST DATA ........................................................................................................................................................................ 7
a. MPPT PERFORMANCE ......................................................................................................................................................... 7
b. LED DRIVER PERFORMANCE ............................................................................................................................................ 7
c. MPPT EFFICIENCY PLOT .................................................................................................................................................... 7
VIII. WAVEFORMS .................................................................................................................................................................... 8
a. Switching Node Waveforms ................................................................................................................................................ 8
b. Gate waveforms ................................................................................................................................................................... 9
IX. POWER GAIN WITH MPP .............................................................................................................................................. 10
a. Test Set-up ......................................................................................................................................................................... 10
b. Test Results ........................................................................................................................................................................ 10
X. SCHEMATIC ......................................................................................................................................................................... 11
a. Power Stage ....................................................................................................................................................................... 11
b. Controller and Bias Supply ................................................................................................................................................ 12
XI. BILL OF MATERIALS ..................................................................................................................................................... 13
XII. CONCLUSION .................................................................................................................................................................. 13
XIII. APPENDIX ........................................................................................................................................................................ 14
Test Report - PMP7647_RevC
December 12
th
, 2013 3 TII - Reference Designs
I. INTRODUCTION
The following document is a compilation of test results of the PMP7647 reference design, a 12A
MPPT solar charge controller & 700mA LED driver. The test results are taken with simulated solar
panel input corresponding to 12V panel.
II. DESCRIPTION
The PMP7647 is developed around the MSP430F5132 controller IC. The design is targeted for low
power solar charger and LED driver solutions such as solar street lights. This design is capable of
charging 12V batteries with up to 10A output current from 12V panels. However, it can be easily
adapted to 24V systems by just changing the MOSFETs to 60V rated parts. Also, the design can
drive up to 15 LEDs in series with 700mA of current. It is possible to adapt the design for LED
currents up to 1.1A with minimum change in hardware.
The MPPT section has a typical electrical efficiency of 97% at full load. This efficiency
figure includes the losses in battery reverse protection and panel reverse flow protection MOSFETs,
which are part of the design. The high efficiency is the result of the low gate charge MOSFETs from
TI used in the design, and also the optimum layout. Another feature is the relatively small sized
components used, possible due to the high operating frequency (settable from 100 - 200 KHz). The
design has built-in battery charge profile for 12V Lead acid batteries. The design presently uses
‘perturb and observe’ algorithm for MPP tracking. This gives fast acquisition of MPP operation.
The LED driver section is a boost converter. The electrical efficiency of boost section is
about 93% while driving 12 LEDs at 700mA, and is around 91% while driving 6 LEDs at 350mA.
The section is protected with load and converter cut-off during overload, short circuit and load open
fault situations. There is also provision to dim the output after specified time intervals. Though in a
typical application the time intervals are in hours, the board is programmed for one minute intervals
of 700mA and 350mA current drive for easy demonstration of the feature. The design is also
capable of detection of ambient light based on the panel voltage, and taking appropriate decisions
to turn on LEDs, charge battery in MPPT mode or go to standby accordingly. Low battery voltage
protection by dimming the LEDs to 10% brightness and subsequently going to low power mode with
further reduction in voltage is also implemented. The voltage levels at which these actions are taken
can be set by software.
The various parameters of the circuit like battery charge current, load current, load timing
pattern, battery under voltage set points etc can be set using a GUI made for the design. This
makes customization a lot easier.
The circuit takes only under 4mA of standby current while operating from battery. This is
further reduced to under 1mA while the circuit is in battery under voltage cut-off. Software
programmable indications are provided in hardware, but are left non-configured.
Surge protection and EMI filtering components are not present on this design, and has to
be added depending upon required specification levels.
Test Report - PMP7647_RevC
December 12
th
, 2013 4 TII - Reference Designs
III. BLOCK DIAGRAM
Test Report - PMP7647_RevC
December 12
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, 2013 5 TII - Reference Designs
IV. SPECIFICATIONS
Input Voltage Range: 15VDC - 22VDC
Storage: 12V battery
Charging Current: 10A, with current limit set at 12A
Output: 12 LEDs at 700mA
Board Form Factor: 100 mm x 45 mm x 32 mm
Expected efficiency: >95% for MPPT charger, and >90% for LED driver
V. BOARD LAYOUT
