SM72441MT [TI]

Programmable Maximum Power Point Tracking Controller for Photovoltaic Solar Panels; 可编程最大功率点跟踪控制器，用于光伏太阳能电池板


型号：	SM72441MT
厂家：	TEXAS INSTRUMENTS
描述：	Programmable Maximum Power Point Tracking Controller for Photovoltaic Solar Panels 可编程最大功率点跟踪控制器，用于光伏太阳能电池板电池控制器
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SM72441

SM72441 Programmable Maximum Power Point Tracking Controller for

Photovoltaic Solar Panels

Literature Number: SNOSB64F

November 20, 2011

SM72441

Programmable Maximum Power Point Tracking Controller

for Photovoltaic Solar Panels

General Description

Features

The SM72441 is a programmable MPPT controller capable of

controlling four PWM gate drive signals for a 4-switch buck-

boost converter. Along with SM72295 (Photovoltaic Full

Bridge Driver) it creates a solution for an MPPT configured

DC-DC converter with efficiencies up to 98.5%. Integrated in-

to the chip is an 8-channel, 12 bit A/D converter used to sense

input and output voltage and current, as well as board con-

figuration. Externally programmable values include maximum

output voltage and current as well as different settings on slew

rate, and soft-start.

Renewable Energy Grade

■

Programmable maximum power point tracking

Photovoltaic solar panel voltage and current diagnostic

Single inductor four switch buck-boost converter control

VOUT Overvoltage protection

Over-current protection

Package

TSSOP-28

■

Block Diagram

30134202

FIGURE 1. Block Diagram

301342

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Connection Diagram

30134203

Top View

TSSOP-28

Ordering Information

Order Number

Description

NSC Package Drawing

Supplied As

Package Top Mark

SM72441MTX

TSSOP-28

MTC28

2500 Units in Tape and

Reel

S72441

SM72441MTE

SM72441MT

MTC28

250 Units in Tape and

Reel

S72441

48 Units in rail

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Pin Descriptions

Name Description

RST Active low signal. External reset input signal to the digital circuit.

NC1 No Connect. This pin should be grounded.

VDDD Digital supply voltage. This pin should be connected to a 5V supply, and bypassed to VSSD with a 0.1uF monolithic

ceramic capacitor.

VSSD Digital ground. The ground return for the digital supply and signals.

NC2 No Connect. This pin should be pulled up to the 5V supply using 10k resistor.

NC3 No Connect. This pin should be grounded using a 10k resistor.

NC4 No Connect. This pin should be grounded using a 10k resistor.

NC5 No Connect. This pin should be pulled up to 5V supply using 10k resistor.

NC6 No Connect. This pin should be pulled up to 5V supply using 10k resistor.

NC7 No Connect. This pin should be grounded.

LED LED pin outputs a pulse during normal operation.

VDDA Analog supply voltage. This voltage is also used as the reference voltage. This pin should be connected to a 5V supply,

and bypassed to VSSA with a 1uF and 0.1uF monolithic ceramic capacitor.

VSSA Analog ground. The ground return for the analog supply and signals.

A/D Input Channel 0. Connect a resistor divider to 5V supply to set the maximum output voltage. Please refer to

application section for more information on setting the resistor value.

AVIN A/D Input to sense input voltage.

A/D Input Channel 2. Connect a resistor divider to 5V supply to set MPPT update rate. Please refer to application

section for more information on setting the resistor value.

AVOUT A/D Input to sense the output voltage.

A/D Input Channel 4. Connect a resistor divider to 5V supply to set the maximum output current. Please refer to

application section for more information on setting the resistor value.

AIIN A/D Input to sense input current.

A/D Input Channel 6. Connect a resistor divider to 5V supply to set the maximum output voltage slew rate. Please

refer to application section for more information on setting the resistor value.

AIOUT A/D Input to sense the output current.

NC8 No Connect. This pin should be grounded using a 10k resistor.

NC9 No Connect. This pin should be connected with 150k pull-up resistor to 5V supply.

LIB

HIB

HIA

LIA

Low side boost PWM output.

High side boost PWM output.

High side buck PWM output.

Low side buck PWM output.

OVP Overvoltage Protection Pin. Active Low. SM72441 will reset once voltage on this pin drops below its threshold voltage.

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the Texas Instruments Sales Office/

Distributors for availability and specifications.

Recommended Operating

Conditions

Operating Temperature

-40°C to 105°C

V_ASupply Voltage

V_DSupply Voltage

Digital Input Voltage

Analog Input Voltage

Junction Temperature

+4.75V to +5.25V

+4.75V to V_A

0 to V_A

Analog Supply Voltage V_A

(VDDA -VSSA)

Analog Supply Voltage V_D

(VDDD -VSSD)

-0.3 to 6.0V

-0.3 to V_A+0.3V

max 6.0V

-0.3 to V_A+0.3V

0 to V_A

Voltage on Any Pin to GND

-40°C to 125°C

Input Current at Any Pin (Note 3)

Package Input Current (Note 3)

Storage Temperature Range

ESD Rating (Note 2)

±10 mA

±20 mA

-65°C to +150°C

Human Body Model

2 kV

Specifications in standard typeface are for T_J= 25°C, and those in boldface type apply over the full operating junction temperature

range.(Note 3)

Symbol

Parameter

Conditions

Min

Typ

Max

Units

ANALOG INPUT CHARACTERISTICS

AVin, AIin

0 to V_A

Input Range

AVout, AIout

I_DCL

DC Leakage Current

±1

µA

Track Mode

Hold Mode

C_INA

Input Capacitance(Note 4)

DC Voltage Measurement

Accuracy

V_ERR

0.1

DIGITAL INPUT CHARACTERISTICS

V_IL

V_IH

Input Low Voltage

Input High Voltage

0.8

2.8

Digital Input Capacitance(Note

C_IND

µA

I_IN

Input Current

±0.01

±1

DIGITAL OUTPUT CHARACTERISTICS

V_OH

V_OL

I_SOURCE= 200 µA V_A= V_D= 5V

V_D-0.5

Output High Voltage

Output Low Voltage

I_SINK= 200 µA to 1.0 mA V_A= V_D= 5V

0.4

Hi-Impedance Output Leakage

Current

I_OZH, I_OZL

C_OUT

V_A= V_D= 5V

±1

µA

Hi-Impedance Output

Capacitance (Note 4)

POWER SUPPLY CHARACTERISTICS (C_L= 10 pF)

Analog and Digital Supply

V_A,V_D

4.75

5.25

V_A≥ V_D

Voltages

I_A+ I_D

P_C

V_A= V_D= 4.75V to 5.25V

Total Supply Current

Power Consumption

PWM OUTPUT CHARACTERISTICS

f_PWM

PWM switching frequency

Dead time

210

kHz

t_DEAD

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation

of the device is guaranteed. Operating Ratings indicate conditions for which the device is intended to be functional, but does not guarantee specific performance

limits. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics tables.

Note 2: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.

Note 3: Min and Max limits are 100% production tested at 25°C. Limits over the operating temperature range are guaranteed through correlation using Statistical

Quality Control (SQC) methods. Limits are used to calculate National’s Average Outgoing Quality Level (AOQL).

Note 4: Not tested. Guaranteed by design.

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photovoltaic module. MPPT performance is very fast. Con-

vergence to the maximum power point of the module typically

occurs within 0.01s. This enables the controller to maintain

optimum performance under fast-changing irradiance condi-

tions.

Operation Description

OVERVIEW

The SM72441 is a programmable MPPT controller capable of

outputting four PWM gate drive signals for a 4-switch buck-

boost converter. The typical application circuit is shown in

Figure 2.

Transitions between buck, boost, and buck-boost modes are

smoothed, and advanced digital PWM dithering techniques

are employed to increase effective PWM resolution. Output

voltage and current limiting functionality are integrated into

the digital control logic. The controller is capable of handling

both shorted and no-load conditions and will recover smoothly

from both.

The SM72441 uses an advanced digital controller to generate

its PWM signals. A maximum power point tracking (MPPT)

algorithm monitors the input current and voltage and controls

the PWM duty cycle to maximize energy harvested from the

30134204

FIGURE 3. High Level State Diagram for Startup

STARTUP

SM72441 has a soft start feature that will ramp its output volt-

age for a fixed time of 250ms. MPPT mode will be entered

during soft start if the load current exceeded the minimum

current threshold. Otherwise, buck-boost operation is entered

after soft-start is finished where the ratio between input and

output voltage is 1:1. Refer to Figure 3 for a high level state

diagram of startup. The current threshold to transition be-

tween MPPT to standby (buck-boost) mode and vice versa

can be set by feeding the output of current sensing amplifier

(Figure 2) to the AIIN and AIOUT pin. For an appropriate volt-

age level, refer to AIIN and AIOUT section of this datasheet.

30134205

FIGURE 4. Start-Up Waveforms of Controlled Output

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MAXIMUM OUTPUT VOLTAGE

Current limit is triggered when AIOUT (pin 21) voltage is equal

to A4 (pin 18).

Maximum output voltage on the SM72441 is set by resistor

divider ratio on pin A0. (Please refer to Figure 2 Typical Ap-

plication Circuit).

AVIN PIN

AVIN pin is an A/D input to sense the input voltage of

SM72441. A resistor divider can be used to scale the max

voltage to about 4V, which is 80% of the full scale of the A/D

input.

CONFIGURABLE SETTINGS

Where RT1 and RB1 are the resistor divider on the ADC pin

A0 and RFB1 and RFB2 are the output voltage feedback re-

sistors. A typical value for RFB2 is about 2 kΩ.

The voltage on A0 sets the max output voltage; whereas the

voltage on A2 enables MPPT update rate and limits the max

boost ratio when output current is below the standby thresh-

old. Output current limit is set by the voltage on A4 and output

voltage slew rate limit is set on A6. In order to set a slew rate

limit of 125V/sec, the ratio of the two resistors in A6 should

be 9:1.

CURRENT LIMIT SETTING

Maximum output current can be set by changing the resistor

divider on A4 (pin 18). (Refer to Figure 2 ). Overcurrent at the

output is detected when the voltage on AIOUT (pin 21) equals

to the voltage on A4 (pin 18). The voltage on A4 can be set

by a resistor divider connected to 5V whereas a current sense

amplifier output can be used to set the voltage on AIOUT.

The low current condition is detected if the voltage on AIIN is

less than 0.488V (rising) and 0.293 (falling) + ΔI or if the volt-

age on AIOUT is less than 0.488 V (rising) and 0.293 (falling)

+ ΔI. If low current is detected, the converter operates in

standby mode and limit the maximum duty cycle to either a 1

(buck-boost), 1.15 (boost) or 1.25 (boost) conversion ratio

(programmable). In this case no MPPT will be performed.

AIIN AND AIOUT PIN

These two pins are used to set current threshold from standby

(buck-boost mode) to MPPT mode and from MPPT mode into

standby mode.

The actual value of current will depend on the gain of the cur-

rent sensing amplifier circuitry that feeds the AIIN and AIOUT

pins.

In order to transition from standby to MPPT mode, the follow-

ing conditions have to be satisfied:

1) AIIN and AIOUT voltage > 0.488V

2) Iout < Iout_max

For more complete information on the various settings based

on the voltage level of A2, please refer to Table 1 below. Vfs

denotes the full scale voltage of the ADC which is equal to

VDDA where VDDA is a reference voltage to analog ground.

On the other hand, in order to transition from MPPT to standby

mode, the following condition have to be satisfied:

A typical value for top configuration resistors (RT1 to RT4)

should be 20 kΩ.

1) AIIN and AIOUT voltage < 0.293V

2) Iout < Iout_max

TABLE 1. List of configurable modes on ADC Channel 2

ADC Channel 2

MPPT Update Time

Slew Rate

Detection

Low Current

Detection

Initial Boost Ratio

Delta I

0 < VADC2 < Vfs/16

1.2 ms

38 ms

77 ms

38 ms

77 ms

Disabled

Enabled

Disabled

Enabled

N/A

1Vfs/16 < VADC2 <2Vfs/16

2Vfs/16 < VADC2 <3Vfs/16

3Vfs/16 < VADC2 <4Vfs/16

4Vfs/16 < VADC2 <5Vfs/16

5Vfs/16 < VADC2 <6Vfs/16

6Vfs/16 < VADC2 <7Vfs/16

7Vfs/16 < VADC2 <8Vfs/16

8Vfs/16 < VADC2 <9Vfs/16

9Vfs/16 < VADC2 <10Vfs/16

10Vfs/16 < VADC2 <11Vfs/16

11Vfs/16 < VADC2 <12Vfs/16

12Vfs/16 < VADC2 <13Vfs/16

13Vfs/16 < VADC2 <14Vfs/16

14Vfs/16 < VADC2 <15Vfs/16

15Vfs/16 < VADC2 <16Vfs/16

N/A

1.15

1.25

1.15

1.25

60 (0.3 A)

90 (0.45 A)

120(0.6 A)

120

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RESET PIN

puts is 0V to V_A. Going beyond this range will cause the ESD

diodes to conduct and result in erratic operation.

When the reset pin is pulled low, the chip will cease its normal

operation and turn-off all of its PWM outputs. Below is an os-

cilloscope capture of a forced reset condition.

The capacitor C1 in Figure 6 has a typical value of 3 pF and

is mainly the package pin capacitance. Resistor R1 is the on

resistance of the multiplexer and track / hold switch; it is typ-

ically 500Ω. Capacitor C2 is the ADC sampling capacitor; itis

typically 30 pF. The ADC will deliver best performance when

driven by a low-impedance source (less than 100Ω). This is

especially important when sampling dynamic signals. Also

important when sampling dynamic signals is a band-pass or

low-pass filter which reduces harmonic and noise in the input.

These filters are often referred to as anti-aliasing filters.

30134208

FIGURE 5. Reset Operational Behavior

30134209

As seen in Figure 5, the initial value for output voltage and

load current are 28V and 1A respectively. After the reset pin

is grounded, both the output voltage and load current de-

creases immediately. MOSFET switching on the buck-boost

converter also stops immediately. V_LOBindicates the low side

boost output from the SM72295.

FIGURE 6. Equivalent Input Circuit

DIGITAL INPUTS and OUTPUTS

The digital input signals have an operating range of 0V to

V_A, where V_A= VDDA - VSSA. They are not prone to latch-

up and may be asserted before the digital supply V_D, where

V_D= VDDD - VSSD, without any risk. The digital output sig-

nals operating range is controlled by V_D. The output high

voltage is V_D– 0.5V (min) while the output low voltage is 0.4V

(max).

ANALOG INPUT

An equivalent circuit for one of the ADC input channels is

shown in Figure 6. Diode D1 and D2 provide ESD protection

for the analog inputs. The operating range for the analog in-

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Physical Dimensions inches (millimeters) unless otherwise noted

NS Package Drawing MTC28

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SM72441MT [TI]

相关型号：

SM72441MT/NOPB

SM72441MTE

SM72441MTE/NOPB

SM72441MTX

SM72441MTX/NOPB

SM72441_15

SM72442

SM72442

SM72442MT

SM72442MT/NOPB

SM72442MTE

SM72442MTE/NOPB