SPV1040 High efficiency solar battery charger with embedded MPPT Features ■ 0.3 V to 5.5 V operating input voltage ■ 140 mΩ internal synchronous rectifier ■ 120 mΩ internal power active switch ■ 100 kHz fixed PWM frequency ■ Duty cycle controlled by MPPT algorithm ■ Output voltage regulation, overcurrent and overtemperature protection ■ Input source reverse polarity protection ■ Built-in soft-start ■ Up to 95% efficiency ■ 3 mm x 4.4 mm TSSOP8 package Smart phones and GPS systems ■ Wireless headsets ■ Small appliances, sensors ■ Portable media players ■ Digital still cameras ■ Toys and portable healthcare a resistor divider. The maximum output current is set with a current sense resistor according to charging current requirements. The SPV1040 protects itself and other application devices by stopping the PWM switching if either the maximum current threshold (up to 1.8 A) is reached or the maximum temperature limit (up to 155 °C) is exceeded. Applications ■ TSSOP8 An additional built-in feature of the SPV1040 is the input source reverse polarity protection, which prevents damage in case of reverse connection of the solar panel at the input. Table 1. Device summary Order codes Package SPV1040T Packaging Tube TSSOP8 Description SPV1040TTR Tape and reel The SPV1040 device is a low power, low voltage, monolithic step-up converter with an input voltage range from 0.3 V to 5.5 V, and is capable of maximizing the energy generated by even a single solar cell (or fuel cell), where low input voltage handling capability is extremely important. Thanks to the embedded MPPT algorithm, even under varying environmental conditions (such as irradiation, dirt, temperature) the SPV1040 offers maximum efficiency in terms of power harvested from the cells and transferred to the output. The device employs an input voltage regulation loop, which fixes the charging battery voltage via October 2011 Doc ID 18080 Rev 3 1/15 www.st.com 15 Contents SPV1040 Contents 1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.1 Soft-start mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.2 Startup mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.3 MPPT mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.4 Constant voltage regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.5 Constant current regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.6 Overcurrent protection (OVC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.7 Overtemperature protection (OVT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.8 Shutdown mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.9 Undervoltage lockout (UVLO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.10 Reverse polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.11 Burst mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.12 Sleep-IN mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2/15 Doc ID 18080 Rev 3 SPV1040 1 Block diagram Block diagram Figure 1. Block diagram 9287 /[ 67$576,*1$/ =(52&5266,1* '(7(&725 9EJ $1$/2*%/2&. ,&75/B3/86 90335() 5(9(56(32/$5,7< &21752/ '5,9(56 29(57(03(5$785( &/2&. 033%/2&. 0336(7 29(5&855(17 &/2&. %XUVW5HI ;6+87 ,&75/B0,186 3:0 %856702'( ',*,7$/ &25( '$&&2'( ,RXW 5HJ 9LQ5HJ 9RXW 5HJ *1' 0336(7 Figure 2. 90335() 9&75/ 9EJ Simplified application circuit L Lx XSHUT VPV GND CIN MPP-SET RS VOUT ICTRL_PLUS ICTRL_MINUS VBATT RF1 CF RF2 R1 COUT VCTRL R2 AM02612v1 For setting up the application and simulating the related test results please go to www.st.com/edesignstudio Doc ID 18080 Rev 3 3/15 Pin description 2 SPV1040 Pin description Table 2. Pin description Pin Name Type 1 MPP-SET I 2 GND Description Non-inverting input to sense the PV cell voltage. It cannot be left floating. Ground Power ground reference. 8 XSHUT I Shutdown input pin: XSHUT = LOW: device in Power Off mode XSHUT = HIGH: device enabled for Operating mode This pin cannot be left floating. 3 LX I Booster inductor connection. 7 ICTRL_PLUS I Non-inverting input of constant current control loop. It cannot be left floating. 6 ICTRL_MINUS I Inverting input of constant current control loop. It cannot be left floating. 5 VCTRL I Non-inverting input of constant voltage control loop. It cannot be left floating. 4 VOUT O Booster output voltage. Figure 3. Pin connection (top view) 1 MPP-SET XSHUT 8 2 GND ICTRL_PLUS 7 3 LX ICTRL_MINUS 6 4 VOUT VCTRL 5 AM02613v1 4/15 Doc ID 18080 Rev 3 SPV1040 Maximum ratings 3 Maximum ratings 3.1 Absolute maximum ratings Table 3. Absolute maximum ratings Symbol MPP-SET GND 3.2 Analog input Ground Range [min, max] Unit [-5.5, VOUT] V 0 V XSHUT Analog input [-5.5, VOUT] V LX Analog input [-5.5, VOUT] V ICTRL_PLUS Analog input [-0.3, VOUT] V ICTRL_MINUS Analog input [-0.3, VOUT] V [-0.3, VOUT] V [-0.3, 5.5] V Value Unit 135 °C/W VCTRL Analog input VOUT Analog output Thermal data Table 4. Symbol Rth j-amb Note: Parameter TSSOP8 thermal data Parameter Thermal resistance, junction-to-ambient Tjop Junction operating temperature -40 to 125 °C Tstg Storage temperature -40 to 150 °C RthJA was measured on a 2-layer PCB: FR4, 35 µm Cu thickness, 2.8 cm2 Doc ID 18080 Rev 3 5/15 Electrical characteristics 4 SPV1040 Electrical characteristics VMPP-SET = 0.5 V, VCTRL = Ictrl+ = Ictrl- = GND, XSHUT = 0.5 V, TJ = -40 °C to 125 °C, unless otherwise specified. Table 5. Electrical characteristics Symbol Parameter Test condition Min Typ Max Unit Input source section VMPP-SET Low boost voltage threshold VOUT = 3.3V Iq Quiescent current ILOAD=0mA, VCTRL=2V, VOUT=3.3V, 60 80 μA ISD Shutdown current VOUT = 3.3V, VCTRL=2V, ILOAD = 0mA, XSHUT = GND 0.7 5 μA Irev Reverse input source current VMPP-SET=-4V, VOUT = 1.5V 1 5 μA Undervoltage lockout threshold for turn ON @VOUT = 3.3V VMPP-SET increasing VUVLO Undervoltage lockout threshold for turn OFF VMPP-SET decreasing @VOUT = 3.3V 0.4 0.45 0.50 0.27 0.34 0.14 0.24 V V V Power section RDS_ON-N N-channel power switch ON resistance RDS_ON-P P-channel synchronous rectifier ON resistance VCTRL=2V 120 mΩ 140 mΩ 2 V 5.2(1) V 3 W Control section VMPPT-THR VOUT POUT (2) MPPT-mode threshold Vout increasing, VMPP-SET = 1.5V Output voltage range VMPP-SET ≥ 1.5V Maximum output power VMPP-SET ≥ 1.5V 1.7 1.8 2 Maximum inductor current peak 1.5 1.65 1.8 A FPWM PWM signal frequency 70 100 130 kHz VREF Internal VCTRL reference voltage VOUT ≥ 1.8V, VCTRL increasing 1.2 1.25 1.3 V VIctrl Sensing current offset ICTRL+ - ICTRL- decreasing 40 50 60 mV XSHUT logic LOW XSHUT increasing XSHUT logic HIGH XSHUT decreasing ILx 0.27 0.34 V XSHUT 6/15 Doc ID 18080 Rev 3 0.14 0.24 V SPV1040 Electrical characteristics Table 5. Symbol Electrical characteristics (continued) Parameter Test condition Min Typ Max Unit Thermal shutdown Tshutdown Overtemperature Temperature increasing threshold for turn OFF 155 °C Overtemperature threshold for turn ON 130 °C Temperature decreasing 1. In order to increase the Vout as much as possible up to 5.2 V a Schottky diode must be placed between the Lx and Vout pins, as shown in Figure 2. 2. Given Tj = Ta + RthJA x PD, and assuming RthJA = 135°C/W, and that in order to avoid device destruction Tjmax must be ≤ 125 °C, and that in the worst conditions TA = 85 °C, the power dissipated inside the device is given by: Tj – Ta P D ≤ ----------------- = 295mW R thJA Therefore, if in the worst case the efficiency is assumed to be 90%, then PIN-MAX = 3.3 W and POUT-MAX = 3 W. Doc ID 18080 Rev 3 7/15 Typical characteristics SPV1040 5 Typical characteristics Figure 4. Efficiency vs output voltage 5 PV Figure 5. Cells - VOC = 2.5 V, VMPP = 2.1 V, LX = 10 µH WŽƵƚͬWŝŶ WŽƵƚͬWŝŶ ϵϯй ϵϮй ϵϭй /ŵƉƉсϮϬϬ ŵ Efficiency vs output voltage 5 PV Cells - VOC = 2.5 V, VMPP = 2.1 V, LX = 22 µH ϵϱй ϵϯй /ŵƉƉсϮϬϬ ŵ ϵϭй /ŵƉƉсϰϬϬ ŵ /ŵƉƉсϰϬϬ ŵ ϵϬй /ŵƉƉсϲϬϬ ŵ ϴϵй /ŵƉƉсϲϬϬ ŵ /ŵƉƉсϴϬϬ ŵ /ŵƉƉсϴϬϬ ŵ ϴϵй /ŵƉƉсϭϬϬ Ϭŵ ϴϳй /ŵƉƉсϭϬϬ Ϭŵ /ŵƉƉсϭϮϬ Ϭŵ /ŵƉƉсϭϮϬ Ϭŵ ϴϴй ϴϱй ϴϳй ϯ͘ϬϬ Figure 6. ϰ͘ϬϬ ϱ͘ϬϬ ϴϯй sŽƵƚs ϯ͘ϬϬ Efficiency vs output voltage 2 PV Cells - VOC = 1 V, LX = 10 µH Figure 7. WŽͬWŝŶ WŽͬWŝŶ ϵϮй ϵϭй ϵϬй /ŵƉƉсϭϰϬ Ϭŵ ϰ͘ϬϬ ϱ͘ϬϬ Efficiency vs output voltage 2 PV Cells - VOC = 1 V, LX = 22 µH ϵϯй ϵϮй ϵϭй /ŵƉƉсϮϱŵ /ŵƉƉсϮϱŵ /ŵƉƉсϱϬŵ ϴϵй /ŵƉƉсϱϬŵ ϵϬй /ŵƉƉсϳϱŵ /ŵƉƉсϳϱŵ /ŵƉƉсϭϬϬ ŵ ϴϴй sŽƵƚs /ŵƉƉсϭϬϬ ŵ ϴϵй /ŵƉƉсϭϱϬ ŵ /ŵƉƉсϮϬϬ ŵ /ŵƉƉсϭϱϬ ŵ /ŵƉƉсϮϬϬ ŵ ϴϴй ϴϳй ϴϳй ϴϲй ϯ Figure 8. ϰ ϱ sŽƵƚs Efficiency vs output voltage 3 PV Cells - VOC = 1.6 V, LX = 10 µH Figure 9. WŽͬWŝŶ WŽͬWŝŶ ϵϯй ϯ ϵϮй ϰ ϱ sŽƵƚs Efficiency vs output voltage 3 PV Cells - VOC = 1.6 V, LX = 22 µH ϵϯй ϵϮй ϵϭй ϵϭй /ŵƉƉсϮϱŵ /ŵƉƉсϱϬŵ ϵϬй ϴϵй ϴϵй /ŵƉƉсϳϱŵ /ŵƉƉсϭϬϬ ŵ ϴϴй /ŵƉƉсϭϬϬ ŵ /ŵƉƉсϮϬϬ ŵ /ŵƉƉсϭϱϬ ŵ ϴϳй /ŵƉƉсϮϬϬ ŵ ϴϲй ϴϳй ϴϱй ϯ 8/15 /ŵƉƉсϱϬŵ /ŵƉƉсϳϱŵ /ŵƉƉсϭϱϬ ŵ ϴϴй /ŵƉƉсϮϱŵ ϵϬй ϰ ϱ sŽƵƚs ϯ Doc ID 18080 Rev 3 ϰ ϱ sŽƵƚs SPV1040 Typical characteristics Figure 10. Efficiency vs output voltage 4 PV Cells - VOC = 2.2 V, LX = 10 µH WŽͬWŝŶ WŽͬWŝŶ ϵϲй Figure 11. Efficiency vs output voltage 4 PV Cells - VOC = 2.2 V, LX = 22 µH ϵϱй /ŵƉƉсϮϱŵ /ŵƉƉсϱϬŵ ϵϰй ϵϯй ϵϮй /ŵƉƉсϮϱŵ ϵϭй /ŵƉƉсϱϬŵ /ŵƉƉсϳϱŵ /ŵƉƉсϳϱŵ /ŵƉƉсϭϬϬ ŵ ϵϬй /ŵƉƉсϭϬϬ ŵ /ŵƉƉсϭϱϬ ŵ /ŵƉƉсϭϱϬ ŵ ϵϯй /ŵƉƉсϮϬϬ ŵ /ŵƉƉсϮϬϬ ŵ ϴϵй ϴϴй ϵϮй ϯ ϰ ϱ sŽƵƚs Figure 12. VLX and ILX waveforms - D = 39% ϯ͘ϬϬ ϰ͘ϬϬ ϱ͘ϬϬ sŽƵƚs Figure 13. VLX and ILX waveforms - D = 68% 9287 9 9287 9 9/; ,/; ,/; 9/; For setting up the application and simulating the related test results please go to www.st.com/edesignstudio Doc ID 18080 Rev 3 9/15 Detailed description 6 SPV1040 Detailed description The SPV1040 is a monolithic, high efficiency, low voltage, self-powered DC-DC converter that operates over a 0.3 V to 5.5 V DC input voltage range and provides a single output voltage. The device provides regulated output voltage and current by sensing the VCTRL feedback of the external resistor divider and the voltage drop on the external sense resistor Rs, respectively. High efficiency is ensured by low power consumption in any working mode and by the embedded Perturb & Observe MPPT algorithm. The SPV1040 guarantees its own safety and application safety by stopping the N-channel power switch in case of overcurrent or overtemperature conditions. 6.1 Soft-start mode In order to guarantee powerup even when VOUT is very low (battery completely discharged), a proper startup strategy has been implemented. Taking into account that the device is powered by the VOUT voltage, If VOUT is lower than 0.8 V, the device moves from power off to soft-start mode and the current flows from the input to output through the intrinsic body diode of the synchronous rectifier. In this condition VOUT follows the LX voltage. The IC exits Startup mode when VOUT reaches 0.8 V. 6.2 Startup mode When VOUT goes above 0.8 V but it is still lower than 2 V, a proper biasing of both MOSFETs is not yet guaranteed. In such conditions, the N-channel power switch is forced ON with a fixed duty cycle and the energy is transferred to the load via the intrinsic body diode of the Pchannel synchronous switch. If the shutdown overcurrent limit is exceeded, the power switch is immediately turned OFF. The SPV1040 leaves Startup mode as soon as VOUT goes above 2 V. 6.3 MPPT mode Once the device has exited Startup mode, the SPV1040 enters MPPT mode to search for the maximum power point. The Perturb & Observe algorithm is based on monitoring either the voltage or the current supplied by the DC power source unit so that the PWM signal duty cycle is increased or decreased step by step according to the input power trend. Refer to Figure 14, which illustrates the MPPT working principle. 6.4 Constant voltage regulation The constant voltage control loop consists of an internal voltage reference, an op amp and an external resistor divider that senses the battery voltage and fixes the voltage regulation set-point at the value specified by the user. 10/15 Doc ID 18080 Rev 3 SPV1040 6.5 Detailed description Constant current regulation The constant current control loop consists of an op amp and an external sense resistor that feeds the current sensing circuit with a voltage proportional to the DC output current. This resistor determines the current regulation set-point and must be adequately rated in terms of power dissipation. It provides the capability to fix the maximum output current to protect the battery. 6.6 Overcurrent protection (OVC) When the current that flows through the inductor reaches 1.8 A (overcurrent shutdown limit), the N-channel power switch is immediately forced OFF and the P-channel synchronous rectifier is switched ON. Once the overcurrent condition has expired (the inductor current goes below 1.8 A) the N-channel power switch is turned back ON. 6.7 Overtemperature protection (OVT) When the temperature sensed at silicon level reaches 155 °C (overtemperature shutdown limit), the N-channel power switch is immediately forced OFF and the P-channel synchronous rectifier is switched ON. The device becomes operative again as soon as the silicon temperature goes below 130 °C. 6.8 Shutdown mode The XSHUT pin low shuts OFF all internal circuitry, achieving the lowest power consumption mode. 6.9 Undervoltage lockout (UVLO) In order to prevent batteries from over-discharging, the device turns OFF in case of MPPSET voltage lower than 0.24 V (no irradiation). A hysteresis has been implemented to avoid unpredictable ON-OFF switching. 6.10 Reverse polarity In order to avoid damage to the device and battery discharge when the solar panel connection is reverse-inserted, a dedicated protection circuit has been implemented. In such condition, the SPV1040 stays OFF until the panel is inserted correctly. Doc ID 18080 Rev 3 11/15 Detailed description SPV1040 Figure 14. MPPT working principle 6.11 Burst mode When the output voltage reaches the battery charge voltage, the MPP-SET voltage drops below 450 mV, or the output current reaches the output maximum current limit, the duty cycle D drops down to 10% and the device evolves from Operating mode to Burst mode. The converter no longer works at constant frequency, but at frequencies gradually lower (1 TON over 1 PWM cycle, 1 TON over 2 PWM cycles, …,1 TON over 16 PWM cycles) prior to entering Sleep-IN mode. 6.12 Sleep-IN mode Once Sleep-IN mode has been entered, no current is provided to the load. The device exits this mode once the cause which forced it into this state is no longer present. 12/15 Doc ID 18080 Rev 3 SPV1040 7 Package mechanical data Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark. Table 6. TSSOP8 package mechanical data millimeters Symbol Min. Typ. A Max. 1.200 A1 0.050 0.150 A2 0.800 b 0.190 0.300 c 0.090 0.200 1.000 CP 1.050 0.100 D 2.900 3.000 3.100 e – 0.650 – E 6.200 6.400 6.600 E1 4.300 4.400 4.500 L 0.450 0.600 0.750 L1 1.000 0 8 Figure 15. TSSOP8 package mechanical drawing Doc ID 18080 Rev 3 13/15 Revision history 8 SPV1040 Revision history Table 7. 14/15 Document revision history Date Revision Changes 08-Oct-2010 1 Initial release 06-Apr-2011 2 Updated coverpage, DFN8 information deleted, Chapter 3, Chapter 4 and Chapter 6 04-Oct-2011 3 – Updated Figure 1, Figure 2, Table 2 and Table 5 – Minor text changes Doc ID 18080 Rev 3 SPV1040 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners. © 2011 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com Doc ID 18080 Rev 3 15/15