SM72441MTE/NOPB

SM72441 www.ti.com SNOSB64G – OCTOBER 2010 – REVISED APRIL 2013 SM72441 Programmable Maximum Power Point Tracking Controller for Photovoltaic Solar Panels Check for Samples: SM72441 FEATURES DESCRIPTION • • • 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 into the chip is an 8-channel, 12 bit A/D converter used to sense input and output voltage and current, as well as board configuration. Externally programmable values include maximum output voltage and current as well as different settings on slew rate, and soft-start. 1 2 • • • 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 VDDA AVin AIN0 AIin AIN1 AVout AIN2 VDDD D0 D1 D2 CS_N SCLK AIout AIN3 DIN ADC DOUT A0 AIN4 A2 AIN5 A4 AIN6 A6 AIN7 D3 D4 D5 D6 D7 Vin Iin Vout Iout MPPT CONTROLLER HIA LIA ADC CONTROLLER ADC_C VSSA HIB LIB CLK GEN VSSD Figure 1. Block Diagram 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2010–2013, Texas Instruments Incorporated SM72441 SNOSB64G – OCTOBER 2010 – REVISED APRIL 2013 PV(+) www.ti.com Vo Rsen_in Gate 2 Current Sensing Amplifier Gate 4 Vo R PV(-) 5V 0.01 PF R 0.01 PF Rsen_out 0.01 PF Gate 3 Gate 1 49.9: 2.2 PF 2.2 PF 5V VDDD VDDA AVIN AIIN Current Sensing Amplifier AIOUT Current Sensing Amplifier Current sensing Amplifier RT1 RT2 RT3 NC7 RT4 NC1 .1 PF 0.1 PF 0.1 PF A0 A2 A4 A6 0.1 PF RB2 RB3 10k RB4 10k 10k CONFIGURATION RESISTOR 10k 10k 10k NC2 PWM1 SM72441 Gate 1 150k NC6 RST 10k NC3 10k OVP RFB1 AVOUT LED VSSA Gate 2 H-Bridge Driver 5V NC9 NC8 Gate 3 PWM2 HIA NC5 NC4 Gate 4 PWM3 LIB LIA 5V RB1 PWM4 HIB RFB2 VSSD Figure 2. Typical Application Circuit 2 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Product Folder Links: SM72441 SM72441 www.ti.com SNOSB64G – OCTOBER 2010 – REVISED APRIL 2013 Connection Diagram Top View 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 RST OVP NC1 LIA VDDD HIA 26 VSSD HIB 25 NC2 LIB 24 NC3 NC9 23 NC8 22 NC5 AIOUT 21 NC6 A6 20 NC7 AIIN 19 LED A4 18 VDDA AVOUT 17 VSSA A2 16 AVIN 15 NC4 SM72441 A0 27 Figure 3. TSSOP-28 Package See Package Drawing PW0028A Pin Descriptions Pin Name 1 RST Active low signal. External reset input signal to the digital circuit. 2 NC1 No Connect. This pin should be grounded. 3 VDDD Digital supply voltage. This pin should be connected to a 5V supply, and bypassed to VSSD with a 0.1uF monolithic ceramic capacitor. 4 VSSD Digital ground. The ground return for the digital supply and signals. 5 NC2 No Connect. This pin should be pulled up to the 5V supply using 10k resistor. 6 NC3 No Connect. This pin should be grounded using a 10k resistor. 7 NC4 No Connect. This pin should be grounded using a 10k resistor. 8 NC5 No Connect. This pin should be pulled up to 5V supply using 10k resistor. 9 NC6 No Connect. This pin should be pulled up to 5V supply using 10k resistor. 10 NC7 No Connect. This pin should be grounded. 11 LED LED pin outputs a pulse during normal operation. 12 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. 13 VSSA Analog ground. The ground return for the analog supply and signals. 14 A0 15 AVIN 16 A2 17 Description 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. 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. 18 A4 19 AIIN 20 A6 21 AIOUT 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. 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. A/D Input to sense the output current. Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Product Folder Links: SM72441 3 SM72441 SNOSB64G – OCTOBER 2010 – REVISED APRIL 2013 www.ti.com Pin Descriptions (continued) Pin Name 22 NC8 No Connect. This pin should be grounded using a 10k resistor. Description 23 NC9 No Connect. This pin should be connected with 150k pull-up resistor to 5V supply. 24 LIB Low side boost PWM output. 25 HIB High side boost PWM output. 26 HIA High side buck PWM output. 27 LIA Low side buck PWM output. 28 OVP Overvoltage Protection Pin. Active Low. SM72441 will reset once voltage on this pin drops below its threshold voltage. These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) (2) Analog Supply Voltage VA (VDDA -VSSA) -0.3 to 6.0V Analog Supply Voltage VD (VDDD -VSSD) -0.3 to VA +0.3V, max 6.0V Voltage on Any Pin to GND -0.3 to VA +0.3V Input Current at Any Pin (Note 3) ±10 mA Package Input Current (Note 3) ±20 mA Storage Temperature Range ESD Rating (3) (1) (2) (3) -65°C to +150°C Human Body Model 2 kV Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation of the device is ensured. Operating Ratings indicate conditions for which the device is intended to be functional, but does not ensure specific performance limits. For specified performance limits and associated test conditions, see the Electrical Characteristics tables. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. Recommended Operating Conditions Operating Temperature -40°C to 105°C VA Supply Voltage +4.75V to +5.25V VD Supply Voltage +4.75V to VA Digital Input Voltage 0 to VA Analog Input Voltage 0 to VA Junction Temperature 4 -40°C to 125°C Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Product Folder Links: SM72441 SM72441 www.ti.com SNOSB64G – OCTOBER 2010 – REVISED APRIL 2013 Electrical Characteristics Specifications in standard typeface are for TJ = 25°C, and those in boldface type apply over the full operating junction temperature range. (1) Symbol Parameter Conditions Min Typ Max Units - 0 to VA - V ANALOG INPUT CHARACTERISTICS AVin, AIin AVout, AIout Input Range IDCL DC Leakage Current CINA Input Capacitance (2) VERR DC Voltage Measurement Accuracy - - ±1 µA Track Mode - 33 - pF Hold Mode - 3 - pF 0.1 % DIGITAL INPUT CHARACTERISTICS VIL Input Low Voltage - - 0.8 VIH Input High Voltage 2.8 - - V V CIND Digital Input Capacitance (2) - 2 4 pF IIN Input Current - ±0.01 ±1 µA VD-0.5 - - V - - 0.4 V ±1 µA 2 4 pF 4.75 5 5.25 V 7 10 15 mA 50 78 mW DIGITAL OUTPUT CHARACTERISTICS VOH Output High Voltage ISOURCE = 200 µA VA = VD = 5V VOL Output Low Voltage ISINK = 200 µA to 1.0 mA VA = VD = 5V IOZH , IOZL Hi-Impedance Output Leakage Current VA = VD = 5V COUT Hi-Impedance Output Capacitance (2) POWER SUPPLY CHARACTERISTICS (CL = 10 pF) VA ,VD Analog and Digital Supply Voltages VA ≥ VD IA + ID Total Supply Current VA = VD = 4.75V to 5.25V PC Power Consumption VA = VD = 4.75V to 5.25V PWM OUTPUT CHARACTERISTICS fPWM PWM switching frequency 210 kHz tDEAD Dead time 38 ns (1) (2) Min and Max limits are 100% production tested at 25°C. Limits over the operating temperature range are specified through correlation using Statistical Quality Control (SQC) methods. Limits are used to calculate Texas Instrument’s Average Outgoing Quality Level (AOQL). Not tested. Specified by design. Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Product Folder Links: SM72441 5 SM72441 SNOSB64G – OCTOBER 2010 – REVISED APRIL 2013 www.ti.com OPERATION DESCRIPTION OVERVIEW The SM72441 is a programmable MPPT controller capable of outputting four PWM gate drive signals for a 4switch buck-boost converter. Refer to the Typical Application Circuit diagram (Figure 2). 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 photovoltaic module. MPPT performance is very fast. Convergence 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 conditions. 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. RESET SOFT-START RST Pin is low or Iout < Iout_th OVP Pin is low Buck Boost Iout >= Iout_th Iout >= Iout_th Iout < Iout_th MPPT Figure 4. High Level State Diagram for Startup STARTUP SM72441 has a soft start feature that will ramp its output voltage 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 4 for a high level state diagram of startup. The current threshold to transition between 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 voltage level, refer to the AIIN AND AIOUT PIN section of this datasheet. 6 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Product Folder Links: SM72441 SM72441 www.ti.com SNOSB64G – OCTOBER 2010 – REVISED APRIL 2013 Figure 5. Start-Up Waveforms of Controlled Output MAXIMUM OUTPUT VOLTAGE Maximum output voltage on the SM72441 is set by resistor divider ratio on pin A0. (Please refer to Figure 2 Typical Application Circuit). VOUT_MAX = 5 x (RFB1 + RFB2) RB1 x RFB2 RT1 + RB1 (1) Where RT1 and RB1 are the resistor divider on the ADC pin A0 and RFB1 and RFB2 are the output voltage feedback resistors. A typical value for RFB2 is about 2 kΩ. 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. 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. In order to transition from standby to MPPT mode, the following conditions have to be satisfied: 1) AIIN and AIOUT voltage > 0.488V 2) Iout < Iout_max On the other hand, in order to transition from MPPT to standby mode, the following condition have to be satisfied: 1) AIIN and AIOUT voltage < 0.293V 2) Iout < Iout_max Current limit is triggered when AIOUT (pin 21) voltage is equal to A4 (pin 18). 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. Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Product Folder Links: SM72441 7 SM72441 SNOSB64G – OCTOBER 2010 – REVISED APRIL 2013 www.ti.com CONFIGURABLE SETTINGS 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 threshold. 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. 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 voltage 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. The actual value of current will depend on the gain of the current sensing amplifier circuitry that feeds the AIIN and AIOUT pins. 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. A typical value for top configuration resistors (RT1 to RT4) should be 20 kΩ. Table 1. List of Configurable Modes on ADC Channel 2 8 ADC Channel 2 MPPT Update Time Slew Rate Detection Low Current Detection Initial Boost Ratio Delta I 0 < VADC2 < Vfs/16 1.2 ms Disabled Disabled N/A N/A 1Vfs/16 < VADC2