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2A,24V Input, 600kHz 2/3-Cell Switching Li-ion Battery Charger MP26123 Rev. 1.01 www.MonolithicPower.com 1 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. The Future of Analog IC Technology
DESCRIPTION
The MP26123 is a monolithic DC-DC step- down switching charger for 2- or 3-cell Li-ion battery packs. It has an integrated high-side power MOSFET can output up to a 2A charge current. It also has peak-current–mode control for fast loop response and easy compensation. The MP26123 uses a sense resistor to control a programmable charge current, and accurately regulates the charge current and charge voltage using two control loops. The MP26123 has multiple fault condition protections that include cycle-by-cycle current limiting and thermal shutdown. Other safety features include battery temperature monitoring and protection, charge status indication and programmable timer to cease the charging cycle when timer out. The MP26123 requires a minimal number of readily-available external components. The MP26123 is available in a 4mm x 4mm 16- pin QFN package.
FEATURES
Charges 2- or 3-Cell Li-Ion Battery Packs Wide Operating Input Range Programmable Charging Current of up to 2A ±0.75% V BATT Accuracy 0.2 Ω Integrated Power MOSFET Up to 90% Efficiency Fixed 600kHz Frequency Preconditioning for Fully Depleted Batteries Charging Status Indicator Input Supply Fault Indicator Thermal Shutdown Cycle-by-Cycle Over-Current Protection Battery Temperature Monitor and Protection
APPLICATIONS
Mobile Internet Device Portable Media Player Netbook Charger for 2- or 3-Cell Li-Ion Batteries Distributed Power Systems For MPS green status, please visit MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 2 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved.
ORDERING INFORMATION
Part Number* Package Top Marking Free Air Temperature (TA) MP26123DR QFN16 (4x4mm) M26123 -40°C to +85°C *For Tape & Reel, add suffix –Z (e.g. MP26123DR–Z) For RoHS compliant packaging, add suffix –LF (e.g. MP MP26123DR–LF–Z) PACKAGE REFERENCE TOP VIEW EXPOSED PAD ON BACKSIDE PIN 1 ID VCC NTC ACOK CHGOK GND CSP BATT COMPI 13141516 8765 COMPVCELLSENVREF33 TMRBSTSWVIN ABSOLUTE MAXIMUM RATINGS (1) Continuous Power Dissipation (TA = 25°C) (2) Recommended Operating Conditions (3) Thermal Resistance (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 T J(MAX), the junction-to- ambient 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 circui try 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 board.
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 3 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved.
ELECTRICAL CHARACTERISTICS
VIN = 19V, TA = 25°C, CELLS=0V, unless otherwise noted. Parameters Symbol Condition Min Typ Max Units CELLS=0V 8.337 8.4 8.463Terminal battery voltage V BATT CELLS=Float 12.505 12.6 12.695 V CSP，BATT current ICSP,IBATT Charging disabled 1 µA Switch on resistance R DS(ON) 0.2 Ω Switch leakage EN= 4V, VSW = 0V 0 1 μA CC(5) 4.1 A Peak current limit TRICKLE 2 A CC current I CC RS1=100m Ω 1.8 2.0 2.2 A Trickle charge current I TRICKLE 10% I CC Trickle charge voltage threshold V TC 3 V/cell Trickle charge hysteresis 350 mV Termination current threshold I BF 5% 10% 15% I CC Oscillator frequency f SW CELLS=0V, VBATT =7V 600 kHz Fold-back frequency V BATT =0V 190 kHz Maximum duty cycle 90 % Maximum current sense voltage (CSP to BATT) VSENSE 170 200 230 mV Minimum on time (5) t ON 100 ns Under-voltage lockout threshold rising 3 3.2 3.4 V Under-voltage lockout threshold hysteresis 200 1000 mV Open-drain sink current V DRAIN =0.3V 5 mA Dead battery indicator In trickle mode CTMR=0.1μF 30 min Recharge threshold at VBATT V RECHG 4.0 V/cell Recharge hysteresis 100 mV NTC low-temp rising threshold R NTC=NCP18X103, 0°C 70.5 73.5 76.5 %of VREF33 NTC high-temp falling threshold RNTC=NCP18X103, 50°C 27.5 29.5 31.5 %of VREF33 VIN min head-room (reverse blocking) VIN −V BATT 180 mV
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 4 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. ELECTRICAL CHARACTERISTICS (continued) VIN = 19V, TA = 25°C, CELLS=0V, unless otherwise noted. Parameters Symbol Condition Min Typ Max Units EN input low voltage 0.4 V EN input high voltage 1.8 V EN=4V 4 EN input current EN=0V 0.2 μA EN =4V 0.5 mA Supply current (shutdown) EN =4V, Consider VREF33 pin output current, R 3=10k,RNTC=10k 0.665 mA Supply current (quiescent) EN =0V, CELLS=0V 2.0 mA Thermal shutdown (5) 150 °C VREF33 output voltage 3.3 V VREF33 load regulation I LOAD =0 to 10mA 30 mV Notes: 5) Guaranteed by design.
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 5 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. PIN FUNCTIONS Pin # Name Description 1 VCC IC supply voltage. 2 NTC Thermistor Input. Connect a resistor from this pin to VREF33, and the thermistor from this pin to ground. 3 ACOK Valid Input Supply Indicator. Open drain out put. Add pull-up resistor. Logic LOW indicates the presence of a valid input supply.
4 CHGOK
Charging Status Indicator. Open drain output. Add pull-up resistor. Logic LOW indicates normal charging. Logic HIGH indicates either a completed charge process or suspended process because of some fault. 5 VREF33 Internal Linear Regulator, 3.3V Reference Output. Bypass to GND with a 1 μF ceramic capacitor. 6 EN On/Off Control Input. 7 CELLS Command Input for the Number of Li-ion Cells. Connect to VREF33 or float for 3-cell operation. Ground for 2-cell operation. 8 COMPV V-LOOP Compensation. Decouple this pin with a capacitor and a resistor. 9 COMPI I-LOOP Compensation. Decouple this pin with a capacitor and a resistor. 10 BATT Positive Battery Terminal.
11 CSP
Battery-Charge Current-Sense–Positive Input. Connect a resistor RS1 between CSP and BATT. The full charge current is: mΩRS1 200mVAICHG .
12 GND
Ground. This pin is the voltage reference for the regulated output voltage. This node should be placed outside of the switching diode (D2) to the input ground path to prevent switching current spikes from inducing voltage noise into the part. 13 TMR Set Safe Timer Period. 0.1µA current charge s and discharges the external capacitor decoupled to GND. The capacitor value programs the timer period.
14 BST
Bootstrap. Requires a charged capacitor to driv e the power switch’s gate above the supply voltage. Connect a capacitor between SW and BST pins to form a floating supply across the power switch driver. 15 SW Switch Output.
16 VIN
Regulator Input Voltage. The MP26123 regulates a 9V-to-24V input to a voltage suitable for charging either a 2- or 3-cell Li-ion battery. Requires capacitors to prevent large voltage spikes from appearing at the input.
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 6 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS VIN=19V, C1=4.7 μF, C2=22 μF, L=4.7 μH, RS1=100m Ω, Real/Simulation Battery Load, T A=25°C, unless otherwise noted.
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 7 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN=19V, C1=4.7 μF, C2=22 μF, L=4.7 μH, RS1=100m Ω, Real/Simulation Battery Load, T A=25°C, unless otherwise noted.
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 8 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN=19V, C1=4.7 μF, C2=22 μF, L=4.7 μH, RS1=100m Ω, Real/Simulation Battery Load, T A=25°C, unless otherwise noted.
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 9 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. FUNCTIONAL BLOCK DIAGRAM Figure 1—Functional Block Diagram
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 11 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. Automatic Recharge After the battery has completely recharged, the charger disables all blocks except the battery voltage monitor to limit leakage current. If the battery voltage falls below 4.0V/Cell, the chip will begin recharging using soft-start. The timer will then reset to avoid timer-related charging disruptions. Charger Status Indication MP26123 has two open-drain status outputs: ACOK and CHGOK . The ACOK pin goes low when the IC supply voltage VCC exceeds the under-voltage lockout threshold and the regulated voltage VIN is 300mV higher than V BATT to make sure the regulator can operate normally. CHGOK indicates charge status. Table 1 describes ACOK and CHGOK outputs under different charge conditions. Table 1―Charging Status Indication ACOK CHGOK Charger Status low low In charging low high End of charge, NTC fault, timer out, thermal shutdown, EN disable high high VIN –VBATT<0.3V. VCC<UVLO, Timer Operation MP26123 uses the internal timer to limit the charge period during trickle charge and total charge cycle. Once the charge time exceeds the time limit the MP26123 terminates charging. A good battery should fully recharge within the allotted time period; otherwise the battery has a fault. An external capacitor at the TMR pin programs the time period. The trickle mode charge time is: TMR TRICKLE _ TMR CT3 0 m i n s 0.1 F The total charge time is: TMR TOTAL _ TMR CT 3hours 0.1 F When time-out occurs, charger is suspended. And only refresh the input power or EN signal or auto-recharge (The event that V BATT falls through 4V/cell) can restart the charge cycle. Negative Thermal Coefficient (NTC) Thermistor The MP26123 has a built-in NTC-resistance window comparator that allows the MP26123 to sense the battery temperature through the thermistor included in the battery pack. Connect a resistor with an appropriate value from VREF33 to the NTC pin, and connect the thermistor from the NTC pin to GND. A resistor divider determines the voltage on the NTC pin as a function of the battery temperature. Charging halts when the NTC voltage falls below the lower NTC window threshold. Charging resumes when the voltage is within the NTC window range. Power Path Management MP26123 is a stand-alone switching charger. Typically, the regulated input voltage VIN receives power from the adapter input, V IN, through a diode that blocks the battery voltage to VCC. For power path application, however, V IN powers the system and charges the battery simultaneously so the user can start-up a device with a drained battery when it is connected to an adapter. Replace the diode from the stand-alone switching charger circuit with a MOSFET to improve system efficiency and reduce voltage drop of the block device. An additional MOSFET between VIN and the battery allows the battery to charge even in the absence of an adapter or connection to an invalid adapter. Figure 3 shows a typical application circuit with power-path management. When the adapter input is invalid or absent, the block diode is replaced by a MOSFET controlled by ACOK signal.
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 12 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 10k Figure 3—MP26123 with Power-Path Management
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 13 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. OPERATION FLOW CHART Figure 4— Normal Charging Operation Flow Chart
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 14 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. OPERATION FLOW CHART (continued) Figure 5—Fault Protection Flow Chart
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER MP26123 Rev. 1.01 www.MonolithicPower.com 15 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved.
APPLICATION INFORMATION
Setting the Charge Current The charge current of MP26123 is set by the sense resistor RS1 (See Typical Application), and determined with the following equation: mΩRS1 200mVAICHG (1) Selecting the Inductor Use a 1µH to 10µH inductor for most applications. The inductance value can be derived from the following equation. OUT IN OUT IN L OSC V( V V )L VI f Where ΔIL is the inductor ripple current. Choose ΔIL to be approximately 30% of the maximum charge current, 2A. VOUT is the 2- or 3-cell battery voltage. The maximum inductor peak current is: L L(MAX) CHG III 2 (3) Under light load conditions below 100mA, use a larger inductor value to improve efficiency. Select an inductor with a DC resistance of less than 200mΩ to optimize efficiency. NTC Function As Figure 6 shows, the low temperature threshold and high-temperature threshold are preset internally to 73.5%·VREF33 and 29.5%·VREF33 using a resistive divider. For a given NTC thermistor, we can select appropriate R3 and R6 resistors to set the NTC window. For the thermistor (NCP18XH103) noted in above electrical characteristic, At 0°C, R NTC_Cold = 27.445k; At 50°C, RNTC_Hot = 4.1601k. Assuming that the NTC window is between 0°C and 50°C, we can derive the following equations: NTC _ Cold TH _ Low NTC _ Cold R6 //R V 73.5%R3 R6 //R VREF33 (4) TH_ HighNTC _ Hot NTC _ Hot VR6 //R 29.5%R3 R6 //R VREF33 (5) According to equation (4) and equation (5), we determine R3 = 9.63k and R6 = 505k. For simplification, select R3=10k and R6 no connect to approximate the specification. NTC VREF33 Low Temp Threshold High Temp Threshold RNTC VTH_Low VTH_High Figure 6— NTC function block Selecting the Input Capacitor The input capacitor reduces the surge current drawn from the input and also the switching noise from the device. Chose an input capacitor with an impedance at the switching frequency less than the input source impedance to prevent high- frequency–switching current. Use ceramic capacitors with X5R or X7R dielectrics with low ESR and small temperature coefficients. A 4.7µF capacitor is sufficient for most applications. Selecting the Output Capacitor The output capacitor limits output voltage ripple and ensures regulation loop stability. The output capacitor impedance should be low at the switching frequency. Use ceramic capacitors with X5R or X7R dielectrics. PC Board Layout Connect the high frequency and high current paths (GND, IN and SW) to the device with short, wide, and direct traces. Place the input capacitor as close as possible to the IN and GND pins. Place the external feedback resistors next to the FB pin. Keep the switching node SW short and away from the feedback network.
MP26123 – 2A, 24V INPUT, 600kHz 2-3 CELL SWITCHING LI-ION BATTERY CHARGER NOTICE: The information in this document is subject to change wi thout notice. Please contact M PS for current specifications. Users should warrant and guaran tee that third party Intellectual Property right s are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MP26123 Rev. 1.01 www.MonolithicPower.com 16 10/28/2011 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved.
PACKAGE INFORMATION
QFN16 (4 x 4mm) SIDE VIEW TOP VIEW 1613 BOTTOM VIEW 3.90 4.10 2.15 2.45 3.90 4.10 2.15 2.45 0.65 BSC 0.25 0.35 0.80 1.00 0.00 0.05
0.20 REF
2.30 0.65 0.35 RECOMMENDED LAND PATTERN
3.80 NOTE:
1) ALL DIMENSIONS ARE IN MILLIMETERS. 2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH. 3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX. 4) JEDEC REFERENCE IS MO-220, VARIATION VGGC. 5) DRAWING IS NOT TO SCALE. PIN 1 ID SEE DETAIL A PIN 1 ID OPTION A 0.45x45º TYP. PIN 1 ID OPTION B R0.25 TYP. DETAIL A PIN 1 ID INDEX AREA 1.00 0.50 0.70