MP2611GL-Z

MP2611 2A, 1-Cell Li-Ion Battery Switching Charger For USB and Adapter Power The Future of Analog IC Technology DESCRIPTION FEATURES The MP2611 is a monolithic switching charger with built-in power MOSFETs for a single-cell Li-Ion battery pack. It achieves up to a 2Acharge current that can be programmed through an accurate sense resistor over the whole input range. It can operate from separate inputs for USB or AC adapter: For USB input, the input current limit can be programmed to 500mA and 900mA through the USBM pin to cover both USB2.0 and USB3.0 standards. • • • • • • • The MP2611 regulates the charge current and battery voltage using two control loops to realize highly accurate constant-current charge and constant-voltage charge. A 100% duty cycle can be achieved when battery voltage is close to the input voltage due to the high-side P-Channel MOSFET. • • • • • Battery charge temperature and charging status are always monitored for each condition. Two status-monitor output pins indicate the battery charging status and input status. The MP2611 also features internal reverse-blocking protection. • • • • 4.5V-to-6V Operating Input Voltage Up to 100% Duty Operation. Up to 2A Programmable Charge Current ±0.5% Battery Voltage Accuracy Separate Inputs for USB and AC Adapter Fully-Integrated Power Switches Programmable Input Current Limit for the USB Port No External Reverse Blocking Diode Required Charging Operation Indicators Programmable Safety Timer Thermal Shutdown Cycle-by-Cycle Over Current Protection Battery Temperature Monitor and Protection APPLICATIONS Smartphones Portable Hand-Held Solutions Portable Media Players All MPS parts are lead-free and adhere to the RoHS directive. For MPS green status, please visit MPS website under Products, Quality Assurance page. “MPS” and “The Future of Analog IC Technology” are registered trademarks of Monolithic Power Systems, Inc. The MP2611 is available in a 3mm x 4mm QFN14 package. TYPICAL APPLICATION AC Adapter Input C1 1 22uF 4 USB Port C2 ACIN 22uF R1 1.5k MP2611 11 R2 1.5k 12 6 R3 MP2611 Rev. 1.12 12/7/2012 13 CSP BATT STAT1 PGND STAT2 VREF33 EN USBM C3 1uF RNTC SW USBIN NTC AGND 5 TMR 3 L 2.2uH RS1 50m 9 8 C4 22uF 2 10 7 1-cell battery ON OFF 14 CTMR RILIM 0.1uF www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 1 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER ORDERING INFORMATION Part Number* MP2611GL Package QFN14 (3x4mm) Top Marking 2611 * For Tape & Reel, add suffix –Z (eg. MP2611GL–Z); PACKAGE REFERENCE TOP VIEW 1 14 2 13 3 12 4 11 5 10 6 9 7 8 EXPOSED PAD ON BACKSIDE ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance ACIN ........................................................... 7.5V USBIN ......................................................... 7.5V SW ..................................... -0.3V to (VIN + 0.3V) CSP, BATT .......................................-0.3V to 6V All the Other Pins ..............................-0.3V to 6V (2) Continuous Power Dissipation (TA=25°C) ............................................................. 2.6W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature................. -65°C to 150°C QFN14 (3mm x 4mm) ............. 48 ...... 10... °C/W Recommended Operating Conditions (3) ACIN ..................................................4.5V to 6V USBIN ................................................4.5V to 6V Operating Junction Temp. (TJ)..-40°C to +125°C MP2611 Rev. 1.12 12/7/2012 (4) θJA θJC Notes: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX)-TA)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device is not guaranteed to function outside of its operating conditions. 4) Measured on JESD51-7, 4-layer PCB. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 2 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER ELECTRICAL CHARACTERISTICS VIN(5) = 5V, TA= 25°C, Unless Otherwise Noted. Parameters Symbol Condition AC Input ACIN Operating Range ACIN Under Voltage Lockout (UVLO) Rising Threshold ACIN Under Voltage Lockout (UVLO) Threshold Hysteresis Switching Frequency Constant Charger Current High-side PFET On Resistance Low-side NMOS On Resistance High-side PFET Peak Current Limit Dead Time Supply Current Min Typ Max Units VACIN 4.5 5 6 V VUVLO 3.55 3.75 3.95 V fS ICC RS1=50mΩ RH_DS(ON) RL_DS(ON) 2.0 mA EN =4V 20 μA 2 130 200 3.5 10 VUSBIN 4.5 5 6 V VUVLO 3.55 3.75 3.95 V 200 IUSB_LIM RILIM =82.5kΩ, VUSBIN = 5V, VBATT=4V RILIM =45.3kΩ, VUSBIN = 5V, VBATT=4V mV 450 500 mA 810 900 mA 110 mΩ EN =0V, No load 2.0 mA EN =4V, No load 30 μA 4.221 4.42 V V V mV V mV %ICC %ICC Battery Charger Terminal Battery Voltage VBATT_FULL VIN=5V Battery Over-Voltage Threshold VBOVP VIN=5V Recharge Threshold at VBATT VRECHG Recharge Hysteresis Trickle-Charge Threshold VTC Trickle-Charger Hysteresis Trickle-Charge Current ITC Termination Charge Current IBF Maximum Current-Sense Voltage (CSP to BATT) STAT1/STAT2 Open-Drain Sink Current VDRAIN =0.3V MP2611 Rev. 1.12 12/7/2012 MHz EN =0V, No load High-side PFET On Resistance USB Supply Current 1.5 A mΩ mΩ A ns USBIN Under Voltage Lockout (UVLO) Threshold Hysteresis USB Input Current limit mV 2.2 3 IIN USB Input USBIN Operating Range USBIN Under Voltage Lockout (UVLO) Rising Threshold 1.8 200 4.179 4.26 5 4.2 4.34 4.0 100 3 300 10 10 15 15 100 mV 9 mA www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 3 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER ELECTRICAL CHARACTERISTICS (continued) VIN(5) = 5V, TA= 25°C, Unless Otherwise Noted. Parameters Symbol VIN Min Head-room (Reverse Blocking) CSP, BATT Current Condition Min VIN-VBATT ICSP,IBATT Typ Max 200 Charging Disabled Units mV 1 µA Protection Trickle-Charge Time Total Charge Time NTC High Temp. Rising Threshold NTC Low Temp. Falling Threshold Thermal Shutdown(6) EN Logic VTH_High VTH_Low TSHTDWN CTMR=0.1µF 30 min CTMR=0.1µF RNTC=NCP18XH103,50°C RNTC=NCP18XH103, 0°C 180 32 74 150 34 76 min %VREF33 %VREF33 °C 0.8 V 30 72 EN Input Low Voltage 1.2 EN Input High Voltage EN Input Current VREF33 Output Voltage VREF33 Load Regulation VVREF33 ∆VVREF33 V EN =4V 4 EN =0V 0.2 3.23 ILOAD=0 to 20mA 3.3 0.2 μA 3.37 V V Notes: 5) VIN represents VACIN or VUSBIN which depends on the input mode. The following is the same. 6) Guaranteed by design.. MP2611 Rev. 1.12 12/7/2012 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 4 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER TYPICAL CHARACTERISTICS VIN=5V, C1=C2=22µF, C4=22µF, CTMR=0.1µF, L=1.5µH, RS1=50mΩ, RILIM=40.2kΩ, Battery Simulator, Unless Otherwise Noted. BATT Voltage Accuracy Charge Current Accuracy USB Current Limit Accuracy vs. Temperature vs. Temperature vs. Temperature AC/USB Mode 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 -1.4 -1.6 -40-25 -10 5 20 35 50 65 80 95110125 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -40-25 -10 5 20 35 50 65 80 95110 125 VREF Accuracy vs. Temperature MP2611 Rev. 1.12 12/7/2012 USB Mode, IUSB_LIM=500mA 1.50 1.25 1.00 0.75 0.50 0.25 0.00 -0.25 -0.50 -0.75 -1.00 -1.25 -1.50 -40-25-10 5 20 35 50 65 80 95110125 Quiescent Current vs. Temperature 2.0 QUIESCENT CURRENT (mA) AC/USB Mode 1.20 1.00 0.80 0.60 0.40 0.20 0.00 -0.20 -0.40 -0.60 -0.80 -1.00 -1.20 -40-25-10 5 20 35 50 65 80 95110125 AC/USB Mode VEN=0V, AC/USB Mode 1.8 Shutdown Current vs. Temperature VEN=4V (Disabled), AC/USB Mode 10 9 1.6 1.4 1.2 1.0 8 7 6 0.8 0.6 0.4 -40-25-10 5 20 35 50 65 80 95110 125 5 4 -40-25-10 5 20 35 50 65 80 95110125 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 5 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER TYPICAL PERFORMANCE CHARACTERISTICS VIN=5V, C1=C2=22µF, C4=22µF, CTMR=0.1µF, L=1.5µH, RS1=50mΩ, RILIM=40.2kΩ, Battery Simulator, Unless Otherwise Noted. Breakdown Voltage Battery Reverse Current Shutdown Current AC/USB Mode AC/USB Mode, VIN=PGND/Float VEN=4V (Disabled), AC/USB Mode 4000 2.0 3500 1.8 1.4 2500 1.2 2000 1.0 1500 0.8 15 10 0.6 1000 0.4 500 0 20 1.6 3000 0 25 5 0.2 1 2 3 4 5 6 7 INPUT VOLTAGE(V) 8 0 9 1.5 Charge Full Voltage Accuracy vs. VIN 2 2.5 3 3.5 4 BATTERY VOTLAGE (V) 4.5 Charge Current Accuracy vs. VIN AC/USB Mode 0.100 0.30 0.075 AC Mode USBM Input Current Limit Accuracy 25 0.20 20 0.10 0.025 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 INPUT VOLTAGE (V) USB Mode 30 0.050 15 0.00 0.000 10 -0.025 -0.10 5 -0.050 -0.20 -0.075 -0.100 4.5 0 4.9 5.3 5.7 6.1 INPUT VOLTAGE(V) -0.30 4.5 6.5 VREF33 Regulation Accuracy MP2611 Rev. 1.12 12/7/2012 VBATT=3.7V 5.0 5.5 6.0 INPUT VOLTAGE(V) 6.5 USB INPUT CURRENT LIMIT (mA) Battery Float 4.9 5.3 5.7 6.1 INPUT VOLTAGE(V) 6.5 USBM Input Current Limit vs. 1000/RILIM RS1=50m, AC Mode 0.20 0.15 0.10 0.05 0.00 -0.05 -0.10 -0.15 -0.20 -0.25 -0.30 -0.35 -0.40 -0.45 -0.50 4.5 0 1000 USB Mode -5 0 200 400 600 800 1000 IUSB_LIM SET POINT (mA) Case Temperature vs. Battery Voltage 100RS1=50m, AC Mode 900 80 800 700 60 600 500 40 400 300 20 200 100 0 0 5 10 15 20 25 0 3.0 3.2 3.4 3.6 3.8 4.0 BATTERY VOLTAGE (V) www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 4.2 6 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN=5V, C1=C2=22µF, C4=22µF, CTMR=0.1µF, L=1.5µH, RS1=50mΩ, RILIM=40.2kΩ, Battery Simulator, Unless Otherwise Noted. 1.6 1.2 1 0.4 0.2 1000 800 VACIN=5V VACIN=4.5V 0 1 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 BATTERY VOLTAGE(V) 1800 100 VACIN=4.5V VACIN=5V VACIN=6V 95 VACIN=4.5V 80 1000 75 800 600 70 VUSBIN=4.5V VACIN=5V VACIN=6V 65 400 60 200 55 0 1 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 BATTERY VOLTAGE (V) 50 1.0 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 BATTERY VOLTAGE (V) USB Mode Efficiency VREF Startup Waveform VBATT=3.7V, En On 100 95 80 75 70 70 65 65 60 60 55 55 800 1200 1600 2000 CHARGE CURRENT (mA) 100 1200 85 MP2611 Rev. 1.12 12/7/2012 0 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4.0 4.3 BATTERY VOLTAGE(V) 85 85 50 400 IUSB_LIM=1A 0.5 I USB_LIM=0.5A 90 90 75 1 1400 90 80 1.5 IUSB_LIM=1.5A AC Mode Efficiency in TC/CC Charge VUSBIN>5V 1600 AC Mode Efficiency in CV Charge 95 IUSB_LIM=2A 2 Frequency vs. Battery Voltage FREQUENCY (kHz) FREQUENCY (kHz) 1200 200 VUSBIN=4.5V 0.6 0 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4.0 4.3 BATTERY VOLTAGE (V) VACIN=6V 1400 400 VUSBIN=5V 0.8 2.5 USB Mode 1600 600 3 VUSBIN=5.5V 1.4 Frequency vs. Battery Voltage AC Mode 1800 USB Mode Charge Curve CHARGE CURRENT (A) 2.2 2.0 1.8 VACIN=4.5V 1.6 1.4 1.2 VACIN=5V 1.0 0.8 0.6 0.4 0.2 0 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4.0 4.3 BATTERY VOLTAGE(V) USB Mode Charge Curve CHARGE CURRENT (A) CHARGE CURRENT(A) AC Mode Charge Curve VUSBIN=4.5V VEN 200mV/div. VUSBIN=5.5V VUSBIN=5V 50 1.0 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 BATTERY VOLTAGE (V) VREF33 2V/div. STAT2 2V/div. STAT1 2V/div. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 7 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN=5V, C1=C2=22µF, C4=22µF, CTMR=0.1µF, L=1.5µH, RS1=50mΩ, RILIM=40.2kΩ, Battery Simulator, Unless Otherwise Noted. BATT Float Waveform Low Input Voltage Low Input Voltage USB/AC Mode Charge State Charge State AC Mode, VACIN=4.5V, VBATT=3.8V VIN 2V/div. VBATT 1V/div. VSW 2V/div. AC Mode, VACIN=4.5V, VBATT=4V VACIN 1V/div. VACIN 1V/div. VBATT 1V/div. VBATT 1V/div. VSW 2V/div. VSW 2V/div. IL 1A/div. IL 1A/div. IL 500mA/div. Low Input Voltage Charge State Low Input Voltage Charge State TC Charge Steady State AC Mode, VACIN=4.5V, VBATT=4.02V AC Mode, VACIN=4.5V, VBATT=4.18V AC/USB Mode, VBATT=1.5V VACIN 1V/div. VACIN 1V/div. VIN 2V/div. VBATT 1V/div. VBATT 1V/div. VBATT 500mV/div. VSW 2V/div. VSW 2V/div. VSW 2V/div. IL 1A/div. IL 1A/div. IL 500mA/div. CC Charge Steady State CC Charge Steady State CV Charge Steady State AC Mode, VACIN=5V, VBATT=3.8V USB Mode, VUSBIN=5V, VBATT=3.8V AC / USB Mode, VBATT=4.2V VACIN 2V/div. VBATT 1V/div. VSW 2V/div. IL 500mA/div. MP2611 Rev. 1.12 12/7/2012 VACIN 1V/div. VBATT 1V/div. VIN 2V/div. VBATT 1V/div. VSW 2V/div. VSW 2V/div. IL 500mA/div. IL 200mA/div. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 8 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN=5V, C1=C2=22µF, C4=22µF, CTMR=0.1µF, L=1.5µH, RS1=50mΩ, RILIM=40.2kΩ, Battery Simulator, Unless Otherwise Noted. Power On Power Off En On AC Mode, VBATT=3.8V AC Mode, VBATT=3.8V AC Mode, VBATT=3.8V VACIN 2V/div. VBATT 2V/div. VEN 2V/div. VBATT 1V/div. VACIN 2V/div. VBATT 1V/div. VSW 2V/div. VSW 5V/div. VSW 5V/div. ICHG 1A/div. ICHG 1A/div. ICHG 1A/div. En Off AC Adapter Insertion AC Adapter Removal AC Mode, VBATT=3.8V VACIN=6V, VUSBIN=4.5V, VBATT=4.1V VACIN=6V, VUSBIN=4.5V, VBATT=4.1V VACIN 1V/div. VUSBIN 1V/div. VBATT 1V/div. VUSBIN 1V/div. VEN 2V/div. VBATT 1V/div. VBATT 1V/div. VSW 5V/div. VACIN 1V/div. ICHG 1A/div. ICHG 1A/div. ICHG 1A/div. NTC Control Timer Out VBATT=3.7V CTMR=150pF, VBATT=3.7V VTMR 1V/div. VNTC 2V/div. VBATT 1V/div. VSW 5V/div. ICHG 1A/div. MP2611 Rev. 1.12 12/7/2012 Short-Circuit Protection VIN 2V/div. VBATT 2V/div. STAT2 2V/div. STAT1 2V/div. ICHG 1A/div. VSW 5V/div. IL 1A/div. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 9 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER PIN FUNCTIONS Package Pin # 1 2 3 4 5 6 7 8 9 Name Description AC Adapter Power Input. Bypass ACIN to PGND with at least a 4.7μF ceramic capacitor when the pin is not applied for powering. Power Ground. Voltage reference for the regulated output voltage: Take extra care with its layout. Place this node should be placed outside of the switching diode (SW-pin) to the PGND input ground path to prevent switching current spikes from inducing voltage noise into the part. SW Switch Output. Connect to the switched side of the external inductor. USB Power Input. Bypass USBIN to PGND with at least a 4.7μF ceramic capacitor when USBIN the pin is not applied for powering. AGND Analog Ground. VREF33 Internal Linear Regulator Reference Output. Powered from ACIN or USBIN. USB Input Current-Limit Set. Connect a resistor from this pin to AGND to program the USBM USB mode input current limit. BATT Positive Battery Terminal. Battery Current Sense Positive Input. Connect resistor RS1 between CSP and BATT to CSP sense the charge current. ACIN 10 EN 11 STAT1 12 STAT2 13 NTC 14 TMR MP2611 Rev. 1.12 12/7/2012 On/Off Control Input. Charging Status Indicator: 1. Charging; 2. End of charge; 3. Charging Suspended; 4. Fault; 5. Invalid Input Supply. Thermistor Input. Connect a resistor from this pin to the VREF33 and the thermistor from this pin to AGND. Internal Safety Timer Control. Connect a capacitor from this node to AGND to set the timer. And the timer can be disabled by connecting this pin to AGND. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 10 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER BLOCK DIAGRAM Figure 1: Functional Block Diagram MP2611 Rev. 1.12 12/7/2012 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 11 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER OPERATION The MP2611 is a monolithic switching charger with built-in power MOSFETs for a single-cell LiIon battery pack. It achieves up to a 2A charge current that can be programmed through an accurate sense resistor over the whole input range. It can operate with separate inputs for USB and AC adapter: For USB mode, the input current limit can be programmed to 500mA and 900mA via the USBM-pin for both USB2.0 and USB3.0. Charge Cycle (Trickle ChargeÆ CC ChargeÆ CV Charge) The MP2611 regulates the charge current (ICHG) and battery voltage (VBATT) using two control loops to realize highly-accurate constant current (CC) charge and constant voltage (CV) charge. The device uses the resistor RS1 to sense the battery charge current and amplifies the signal using the internal amplifier A3 (Figure 1). The charge starts in trickle-charge mode (TC, 10% of the constant current ICC) until the battery voltage reaches 3V. If the charger stays in the tricklecharge mode until it triggers a time-out condition, the charging terminates. Otherwise, the charger operates in constant-current charging mode. The COMPI voltage, regulated by the amplifier GMI, determines the duty cycle. When the battery voltage rises to the constantvoltage mode threshold, the amplifier GMV regulates the COMP-pin and the duty cycle. Consequently, the charger operates in constantvoltage mode. Figure 2: Li-Ion Battery Charge Profile MP2611 Rev. 1.12 12/7/2012 ACIN and USBIN Detection There are two separate battery charger inputs; ACIN for the AC adapter, and USBIN for the USB port. ACIN is used as the battery-charger primary power supply. As soon as the ACIN voltage exceeds ACIN UVLO (3.75V), Q1 turns on and Q2 turns off. The adapter charges the battery with up to 2A constant charge current through the step-down DC/DC converter implemented by Q1 and Q3. The charge current can be set by RS1. If the ACIN input is absent or less than 3.75V, the USBIN can act as the power supply for the battery charger: Q1 turns off and Q2 turns on. USB supply mode uses the input current limit loop so that the threshold can be programmed by connecting a resistor RILIM from the USBM-pin to AGND. When ACIN and USBIN are both absent, Q1 and Q2 are completely off and the reverse blocking function blocks the battery reverse-leakage current to the input port. Note that if ACIN and USBIN are both present, the device selects the AC adapter as the power supply of the charger. However, avoid this practice. DC/DC Converter The MP2611 integrates both the high-side switch and the synchronous low-side switch, which provides high efficiency and eliminates the external Schottky diode. During normal operation, the high-side switch turns on for a period of time to ramp-up the inductor current at each rising edge of the internal oscillator, and switches off when the peak inductor current rises above the COMP voltage. Once the high-side switch turns off, the synchronous switch turns on immediately and stays on until the next cycle starts (see Figure 1). The device allows the high-side switch to remain on for more than one switching cycle and increases the duty cycle while the input voltage drops close to the output voltage. When the duty cycle reaches 100%, the high-side switch is held on continuously to deliver current to the output. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 12 MP2611 – 2A, 1-CELL SWITCHING CHARGER FOR USB AND ADAPTER POWER Charge-Full Termination and Auto-Recharge When the charge current drops below the termination threshold (IBF) during the CV charge phase, the charger ceases charging and the STAT1 -pin becomes an open drain. The timer will also be reset and turned off. If the battery voltage falls below 4.0V, auto-recharge begins and the timer restarts a new charge cycle. The charger can exit the timer-out fault state and initiates a new charge cycle when one of the following conditions occurs: Charger Status Indication Negative Thermal Coefficient (NTC) Thermistor The MP2611 has a built-in NTC window comparator that allows it to sense the battery temperature via the thermistor packed internally in the battery. It ensures a safe battery operating environment. Connect an appropriately-valued resistor from VREF33 to the NTC-pin and connect the thermistor from the NTC-pin to AGND. The resistor divider with a dividing ratio depends on the battery temperature determins the voltage on the NTC-pin. Once the voltage at the NTC-pin is out of the NTC window, the MP2611 stops charging. The charger restarts if the voltage re-enters the NTC window range. STAT1 and STAT2 are two open-drain NMOS outputs that must connect to the VREF33 output or some other bias power supply through pull-up resistors. Their output logic level combinations indicate three status of the charger: Table 1: Charging Status Indicator Low STAT1 Low Low High High High STAT2 Charger Status Charging End of Charge; Faults (Thermal Shutdown; Time-Out; NTC Fault) Input Power Absent; VIN-VBATT