SM3320-BATT-EV-NOPB Datasheet, PDF (1/21 Pages) Texas Instruments – AN-2121 SolarMagic™ SM3320-BATT-EV Charge Controller Reference Design

Application Report
SNOSB76C – December 2010 – Revised May 2013
AN-2121 SolarMagic™ SM3320-BATT-EV Charge
Controller Reference Design
.....................................................................................................................................................
ABSTRACT
The SM72442 MPPT digital controller and SM72295 photovoltaic full bridge drivers are designed to control
high-efficiency DC/DC conversion used in photovoltaic applications. This application report details the
usage of those devices in a battery charging application. The reference design is meant to provide support
for a wide variety of implementations, however, unless otherwise noted, this reference design system is
shown charging a 12V commercial automotive lead acid battery.
Contents
1 Charging Profile ............................................................................................................. 3
2 Features ...................................................................................................................... 3
3 Quick Setup Procedure .................................................................................................... 4
4 10V Power Supply .......................................................................................................... 4
5 DC/DC Converter ........................................................................................................... 5
6 Programmable Modes/Gain Settings ..................................................................................... 6
7 Current Sense Gains and Offset .......................................................................................... 6
8 Start-Up Circuitry ............................................................................................................ 7
9 Output FET Disabling ....................................................................................................... 8
10 Output Current Regulation ................................................................................................. 9
11 Voltage Regulation .......................................................................................................... 9
12 MPPT ....................................................................................................................... 10
13 Microcontroller Functions ................................................................................................. 11
13.1 Normal Operation ................................................................................................. 11
13.2 Start-Up Operation ............................................................................................... 11
13.3 Safety Feature .................................................................................................... 11
14 Microcontroller Program Code ........................................................................................... 13
14.1 Function: check_lead_acid() .................................................................................... 14
14.2 Function: Main() .................................................................................................. 14
14.3 Function: get_i2c_data ........................................................................................... 14
14.4 Function: send_i2c_command(char number) ................................................................. 15
14.5 Function: Set_Voutmax() ........................................................................................ 15
14.6 Function: Check_low_current() ................................................................................. 15
15 Charging a Li-ion Battery ................................................................................................. 15
16 Bill of Materials ............................................................................................................. 17
17 Charge Controller System Schematic .................................................................................. 19
List of Figures
1 Lead-Acid Charging Profile ................................................................................................ 3
2 System Connection ......................................................................................................... 4
3 10V Power Supply .......................................................................................................... 4
4 DC/DC Converter Stage ................................................................................................... 5
5 Buck Gate Drive Signals From SM72442................................................................................ 5
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SNOSB76C – December 2010 – Revised May 2013
AN-2121 SolarMagic™ SM3320-BATT-EV Charge Controller Reference
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