MAX20800_V01 [MAXIM]
MPP Tracking DC-DC Converter;型号: | MAX20800_V01 |
厂家: | MAXIM INTEGRATED PRODUCTS |
描述: | MPP Tracking DC-DC Converter |
文件: | 总9页 (文件大小:1010K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
MAX20800
MPP Tracking DC-DC Converter
General Description
Benefits and Features
The MAX20800 family of Cell-String Optimizers enables
cell-string Maximum Power Point Tracking (MPPT),
providing superior photovoltaic (PV) module energy harvest
and reliability as compared to both standard panels and
those incorporating module level MPPT technologies.
● Performs MPPT on 20-24 Series Connected PV Cells
● Fast MPPT Reacts Quickly to Changing Conditions
● Integrated Voltage-Limiting Clamps Output Voltage
● Integrated Current-Limiting Clamps Output Current
Photovoltaic cells can only deliver maximum power under
specific electrical conditions that vary significantly with
exposed irradiance and temperature. Series connections
of PV cells creates a significant sensitivity to cell
mismatch, resulting in less than optimal power and energy
production under real-world conditions. The MAX20800
Cell-String Optimizer enables a string of PV cells to
deliver their collective maximum power into a wide range
of load conditions. This enhanced electrical flexibility
eliminates power loss from mismatch in PV strings
and arrays, ultimately improving energy production and
system design flexibility.
● Active Bypass function eliminates diodes and hot-
spots
● Supports Panel Flash and Electroluminescence (EL)
Testing
● Peak 99.1%, CEC 98.7% and Euro 98.3% Efficiency
Additional unique advantages provided by the Cell-String
Optimizers:
• Reduction in performance degradation over the PV
module operating lifetime
• Elimination of high losses associated with bypass
diode conduction
Ordering Information appears at end of data sheet.
• Limit the operating voltage of the PV module
MAX20800 Cell-String Optimizer Embedded in 60-Cell PV Panel
PV+
C
BST
PV+
MAX20800
PV-
V
BST
V
CC
L
OUT
C
OUT
IN
C
VCC
U
1
C
OUT
PV-
19-8575; Rev 4; 2/18
MAX20800
MPP Tracking DC-DC Converter
Absolute Maximum Ratings
Input Voltage (PV+)..................................................-0.3V ~ 21V
Output Voltage (DC).................................................-0.3V ~ 21V
Output Voltage (25ns) .................................................-6V ~ 25V
Peak Current (OUT) ............................................................±25A
Junction Temperature (T )...............................................+150°C
J
IC Junction Temperature (2hrs) (Note 1) ........................+200°C
Storage Temperature Range............................ -65°C to +150°C
Peak Reflow Temperature...............................................+260°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Operating Ratings
Input Voltage (V
) ................................................1.5V to 18V
PV+
Output Current (I
) ................................................ -4A to 12A
OUT
Junction Temperature (T )...................................-40ºC to 150ºC
J
Package Information
PACKAGE CODE: 10FCQFN
Package Code
P105A3F+1
21-100119
90-100039
Outline Number
Land Pattern Number
THERMAL RESISTANCE, FOUR-LAYER BOARD
Junction to Case (θ MAX)
1°C/W
JC
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board.
For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Note 1: IC Junction Temperature can reach 200°C for a limited duration of two hours as in accordance with IEC61730 and UL1703
testing requirements.
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MAX20800
MPP Tracking DC-DC Converter
Electrical Characteristics
Typical values are at TA = +25°C. V
connected to 20 series-connected PV cells, unless otherwise noted. (Note 2)
PV+
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage Range for MPPT
V
6.5
15.5
V
PV_+
Open circuit
75
7
Input Quiescent Current
I
mA
PV_+
Active bypass
MAX20800T / MAX20800TA,
max sourcing current for MPPT mode
10.6
11.2
11.3
I
OUT(MAX)_MPP
MAX20800TB,
max sourcing current for MPPT mode
Output-Current Limiting
A
MAX20800T / MAX20800TA,
max sourcing current
12.0
12.6
I
OUT(MAX)
MAX20800TB, max sourcing current
Max sourcing current with OUT+ < 1V
MAX20800T, 10A output
11.9
4.0
I
OUT(MAX)_SC
10.7
12.6
11.1
11.7
13.6
11.3
120
130
150
V
MAX20800TA, 10A output
MP(MAX)
OC(MAX)
MAX20800TB, 10A output
MAX20800T, open circuit
Output-Voltage Limiting
V
V
MAX20800TA, open circuit
MAX20800TB, open circuit
Bypass-Voltage Drop (Note 3)
Overtemperature Threshold
V
PV_+ = 1.5V, I
MPPT enable
MPPT disable
= 12A
mV
°C
BYPASS
OUT
T
SHUTDOWN
D
Duty-Cycle Range
0
100
%
ms
%
MPPT Loop Response Time
MPPT Efficiency
t
0.4
MPPT
ŋ
I
= 8A
99.9
MPPT
OUT
Note 2: Limits are 100% tested at T = 32°C. Limits over the operating temperature range and relevant supply voltage range are
A
guaranteed by design and characterization.
Note 3: Using the standard Maxim Evaluation Kit.
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MAX20800
MPP Tracking DC-DC Converter
Typical Operating Characteristics
POWER vs. VOLTAGE BY IRRADIANCE
CURRENT vs. VOLTAGE BY IRRADIANCE
toc01
toc02
14
300
MAX20800,1000W/m2
MAX20800, 1000 W/m²
STANDARD PV, 1000W/m2
STANDARD PV, 500W/m2
STANDARD PV, 250W/m2
2
MAX20800,500W/m
MAX20800, 500 W/m²
MAX20800, 250W/m2
12
250
200
150
100
50
MAX20800, 250 W/m²
STANDARD PV, 1000 W/m²
10
STANDARD PV, 500 W/m²
STANDARD PV, 250 W/m²
8
6
4
2
0
0
0
5
10
15
20
0
5
10
VOLTAGE (V)
15
20
VOLTAGE (V)
POWER vs. VOLTAGE BY TEMPERATURE
CURRENT vs. VOLTAGE BY TEMPERATURE
toc03
toc04
300
250
200
150
100
50
14
12
10
8
MAX20800, 25°C
STANDARD PV, 25°C
STANDARD PV, 75°C
MAX20800, 25°C
MAX20800, 75°C
MAX20800, 75°C
STANDARD PV, 25°C
STANDARD PV, 75°C
6
4
2
0
0
0
5
10
VOLTAGE (V)
15
20
0
5
10
15
20
VOLTAGE (V)
CONVERSION EFFICIENCY vs. IMP
MPPT EFFICIENCY vs. ISC
toc05
toc06
100
99
98
97
96
95
94
93
92
91
90
100
99.9
99.8
99.7
99.6
99.5
99.4
99.3
99.2
99.1
99
24 CELLS
20 CELLS
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
IMP (A)
IIMP(A)
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MAX20800
MPP Tracking DC-DC Converter
Pin Configuration
PV+ 4
5 OUT
PV- 3
PV- 2
6 V
BST
7 PV-
V
1
CC
9
PV-
8
10
PV-
PV-
(BOTTOM VIEW)
Pin Description
PIN
NAME
FUNCTION
1
V
Internal Power Supply
CC
2–3, 7–10
PV-
PV+
OUT
PV Negative Power Input and Control Ground
PV Positive Power Input
MPPT Output
4
5
6
V
Internal Power Supply
BST
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MAX20800
MPP Tracking DC-DC Converter
The output voltage of the PV module is electronically
limited and independent of irradiance and temperature,
guaranteeing a single output voltage that is safe for PV
system maximum voltage calculations under all operating
conditions. Refer to the Electrical Characteristics table for
detailed voltage-limiting specifications.
Detailed Description
Maximum Power Point Tracking (MPPT)
In the Maximum Power Point Tracking (MPPT) mode
of operation, the Cell-String Optimizer devices replace
bypass diodes while performing the MPPT function on an
isolated group of series connected PV cells (cell-string).
Each cell-string operates at its own unique maximum
power point regardless of the operating point of other
cell-strings in the same PV module or series string of
modules.
Electronic Current Limiting
The MAX20800 devices are designed to work with all
mainstream PV cell technologies. In order to ensure
proper MPPT operation, the PV cell maximum power
current should remain below the maximum value indi-
cated in the Electrical Characteristics table. If this range is
exceeded, the device no longer extracts maximum power,
resulting in performance loss during these conditions.
“Voltage vs. Current by Irradiance” (TOC01) depicts the
electrical characteristics of a cell-string when operating
both with and without the MAX20800 device, under three
different irradiance conditions. Conventional cell-strings
are limited by their ability to deliver maximum power at a
single current and voltage (IMP and VMP, respectively)
that are directly related to irradiance and temperature.
Cell-strings optimized with the MAX20800 can arbitrarily
scale their output current higher with a proportional
reduction in output voltage. The additional degree of
freedom afforded by this functionality enables maximum
power delivery regardless of the string current set by
the inverter. This concept is clearly depicted in “Voltage
vs. Power by Irradiance,” (TOC02) where it can be seen
that optimized cell-strings deliver constant power for any
current equal or larger than the IMP of the cell-string.
The output current sourced by the PV module is electroni-
cally limited and independent of irradiance and tempera-
ture, guaranteeing a single output current that is safe for
PV system maximum current calculations under all operat-
ing conditions. Refer to the Electrical Characteristics table
for detailed current limiting specifications.
Active Bypass
Under extremely low irradiance and other atypical conditions,
MPPT operation is not possible and the device reverts to
Active Bypass mode of operation. In Active Bypass, the
low-side power FET remains enabled so that external
current can pass through a low resistance connection
from the PV- to OUT pins of the device. Additionally,
the high-side power FET remains disabled so that the
cell-string operates in the open-circuit condition instead
of in reverse breakdown (as is typical with conventional
bypass schemes). The MAX20800’s active bypass mode
delivers a lower-loss bypass methodology that also
actively prevents PV cell hot-spots, eliminating thermal
stress and possible subsequent wear-out or degradation.
The MAX20800 performs this isolating DC-DC converter
function with monolithic Power FETs, in a synchronous
buck converter topology, that are fully integrated alongside
precision control circuitry. MPPT is performed with a
“perturb and observe” algorithm that is both extremely fast
and accurate. The maximum power point is tracked with a
typical effectiveness of 99.9% and a fast sampling speed,
allowing maximal energy recovery when exposed to fast
moving clouds or obstruction shading.
Conditions under which the device reverts to Active
Bypass mode:
Electronic Voltage Limiting
The MAX20800 isolates PV cells from the PV module
output terminals with a synchronous DC-DC converter in
a buck topology. As such, the maximum output voltage of
the PV module can be independently limited in voltage
while the PV cells themselves continue to operate at their
natural maximum power voltage.
●
●
●
Undervoltage detection on PV+ input.
String current exceeding the electronic current limit.
IC temperature exceeding the internal temperature
protection limit.
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MAX20800
MPP Tracking DC-DC Converter
If these two conditions are met, the MAX20800 enabled
panels can undergo industry standard flash testing. In
particular, the first condition is a function of the panel
manufacturer’s flash testing setup. The second condition
is typically supported by the flash test hardware manufacturer
by means of software programmable options.
Reverse Current
When the OUT pin is exposed to reverse currents, the
MAX20800 device enters the Reverse Current mode of
operation. While in this operating mode, the MPPT function
is disabled and the DC-DC converter operates at a
maximum duty cycle to pass the reverse current directly
back into the PV cells. Therefore, most of the power
delivered by the reverse current power source is absorbed
by the series-connected PV cells, as is the case with
conventional PV modules.
Contact a Maxim representative for further details.
PV System Design Considerations
PV modules incorporating the MAX20800 family of MPPT
devices operate much like conventional modules, albeit
with electronically limited output currents and voltages,
improved energy harvest and enhanced reliability
characteristics. Photovoltaic system design is very similar
to that of conventional systems.
The Reverse Current mode of operation is seamlessly
entered and exited as external conditions demand.
Consequently, electroluminescence and other reverse
current tests are supported without any changes to
standard testing procedures. As the output current reverts
to a positive direction, MPPT operation automatically
resumes.
●
Maximum modules per string can be easily calculated
by dividing the maximum system voltage or maximum
MPPT window voltage of the inverter by the electronically
limited maximum output voltage of the PV module.
The electronic-voltage limiting is not impacted by
irradiance or temperature, so no derating factors are
needed or recommended.
Flash Test Mode
The current-voltage curve of an MPPT-enabled PV module
differs significantly from that of a conventional module.
Additionally, typical flash test sweeps are performed at
a rate faster than the MAX20800 MPPT response time.
For both of these reasons, the full MPPT enabled output
characteristics of a MAX20800 enabled PV module would
not be observable by most flash test equipment.
●
●
Maximum source current per module is electronically
limited, so all DC conductors, fuses, and inverter
inputs can be rated with a single derating factor of 1.25
x I
. The selection of I
is carefully
OUT_MAX
OUT_MAX
chosen to enable a 15A series fuse ratings for the PV
module (see Electrical Characteristics table).
In order to support production QA flash testing, the
MAX20800 devices have a special flash test mode of
operation. While in this mode, the DC-DC converter does
not perform MPPT but rather operates at the maximum
duty cycle resulting in flash test curve measurements
similar to those of the conventional PV modules.
MAX20800 enabled PV modules are compatible with
standard commercial grid-tie inverters. Some inverters
offer a “Global Sweep” function that periodically
takes the system off-MPP to sweep across the entire
acceptable voltage range and ensure the inverter
is not operating at a local (false) MPP point. It is
possible to disable the Global Sweep function,
maximizing operating time at MPP and, therefore,
increasing the energy harvest.
In order to successfully flash test MAX20800 enabled
panels, two important conditions must be met.
1) All ambient light must be eliminated before the flash
test begins.
2) The flash tester must sweep the panel voltage in the
direction of open circuit to short circuit.
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MAX20800
MPP Tracking DC-DC Converter
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
10 FCQFN
10 FCQFN
10 FCQFN
10 FCQFN
10 FCQFN
10 FCQFN
MAX20800TPB+
MAX20800TPB+T
MAX20800TPBA+
MAX20800TPBA+T
MAX20800TPBB+
MAX20800TPBB+T
-40°C to +150°C
-40°C to +150°C
-40°C to +150°C
-40°C to +150°C
-40°C to +150°C
-40°C to +150°C
+Denotes a lead(Pb)-free/RoHS-compliant package.
T= Tape and reel.
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MAX20800
MPP Tracking DC-DC Converter
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
0
6/16
Initial release
—
Updated Benefits and Features and Absolute Maximum Ratings sections;
Electrical Characteristics table and Typical Operating Characteristics 1-5;
MAX20800 Cell-String Optimizer Embedded in 60-Cell PV Panel figure, Pin
Configuration, Pin Description table, Electronic Current Limiting section, and
Ordering Information.
1
4/17
1–6, 8
Updated Absolute Maximum Ratings sections, Electrical Characteristics table,
and Ordering Information.
2–3,
5, 8
2
11/17
3
4
12/17
2/18
Updated the Ordering Information table.
8
3
Updated the Electrical Characteristics table.
For information on other Maxim Integrated products, visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2018 Maxim Integrated Products, Inc.
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