Buck
Boost
SM72445 Evaluation module Design Specification
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3
SM72445 Evaluation module
Design Specification
Symbol
Parameter
Min
Typ
Max
V
MPP
PV Module MPP Voltage
15 Vdc
40Vdc
P
MPP
PV Module Power
10 W
350 W
V
OC
PV Module Open Circuit Voltage
50 Vdc
I
SC
PV Module Short-Circuit Current
11A
V
OUT
Output Voltage
0 Vdc
43 Vdc
I
OUT
Output Current
12.5A
OVP
Overvoltage Protection Threshold
45V
OTP
Overtemperature Protection Threshold
125
o
C
MPP
EFF
MPP Efficiency
98.5%
PM
EFF
Panel-Mode Efficiency
99.5%
CONFIGURATION MODES
The SM72445 is configured through I2C communication or through resistor settings on pin A0, A2, A4 and
A6. The default configuration setting on the board is:
Pin name
Pin Voltage
Description
A0
3.0V
“Soft” output voltage limit of 40V (AVOUT=3V)
A2
0V
220kHz operation, uses dedicated FET switch for higher efficiency
A4
5.0V
Internal current protection not used
A6
1.56V
Long slew rate limit, 60s in a 1:1 conversion ratio at start-up before enabling
optimization
Modifications to the configuration can be performed by changing the resistor settings. The change in
configuration will only happen at start-up and during reset of the IC.
“PANEL MODE” OPERATION
The board is configured to use “Panel Mode” FETs to reach the highest possible efficiency at a 1:1
conversion ratio. The SM72445 will disconnect the DC/DC converter and turn on this switch whenever it
detects that the panel is matched to the load. The detail of this operation can be found in the SM72445
datasheet. Alternatively, the SM72445 can be configured to run the DC/DC converter in a Panel-Mode
behavior instead, driving the high-side FETs of the converter in a mostly ONstate (
Figure 2
) and achieving
the same function as the dedicated Panel-Mode FETs. This option optimizes the component count and the
cost of the solution but slightly reduces the efficiency of the system in the band close to a 1:1 conversion
ratio. To configure the board in this mode, the resistor couple R29 and R39 can be changed to modify the
voltage at pin A2. In addition, T1 should be removed. Check the SM72445 datasheet for additional details
on the different configuration settings.
Figure 2. Panel Mode Operation Using Converter's FET (“Boost” waveform is taken at drain of Q3,
“Buck” waveform was taken at drain of Q4.)
6
AN-2241 SM72445 Evaluation Board
SNVA649 – May 2012
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