RT9526 Linear Single Cell Li-Ion Battery Charger with Input Over Voltage Protection General Description Features The RT9526 is a fully integrated low cost single cell Li-ion battery charger ideal for portable applications. The RT9526 is capable of being powered up from AC adapter and USB (Universal Serial Bus) port inputs. The RT9526 enters sleep mode when supplies are removed. The RT9526 optimizes the charging task by using a control algorithm including preconditioning mode, fast charge mode, and constant voltage mode. The charging task will remain in constant voltage mode to hold the battery in a full charge condition. The charge current can be programmed with an external resistor. The internal thermal feedback circuitry regulates the die temperature to optimize the charge rate under all ambient temperatures. The RT9526 features 28V maximum rating voltage for VIN. The other features are under voltage protection and over voltage protection for the AC adapter supply. z and SOT-23-6 packages to achieve best solution for PCB space and total BOM cost saving considerations. Ordering Information z z z z z z z z Applications z z z z Cellular Phones Digital Cameras PDAs and Smart Phones Portable Instruments Pin Configurations (TOP VIEW) IMIN ISET BATT RT9526 6 Package Type E : SOT-23-6 QW : WDFN-8L 2x2 (W-Type) QWA : WDFN-8L 2x3 (W-Type) Lead Plating System G : Green (Halogen Free and Pb Free) Note : Richtek products are : 2 3 CHG_SB GND VIN SOT-23-6 VIN PGB CHG_SB ENB 1 2 3 4 9 8 7 6 5 BATT ISET IMIN GND RoHS compliant and compatible with the current requireWDFN-8L 2x2 ments of IPC/JEDEC J-STD-020. ` 4 Suitable for use in SnPb or Pb-free soldering processes. VIN PGB CHG_SB ENB 1 2 3 4 GND ` 5 GND The RT9526 is available in WDFN-8L 2x2, WDFN-8L 2x3 z 28V Maximum Rating for AC Adapter Internal Integrated Power FETs AC Adapter Power Good Status Indicator Programmed Charging Current Charge Status Indicator Programmed End of Charge Current Under Voltage Protection Over Voltage Protection Thermal Feedback Optimizing Charge Rate RoHS Compliant and Halogen Free 9 8 7 6 5 BATT ISET IMIN GND WDFN-8L 2x3 DS9526-01 April 2011 www.richtek.com 1 RT9526 Marking Information RT9526GE RT9526GQW EN= : Product Code EX=DNN RT9526GQWA JJ : Product Code DNN : Date Code 04 : Product Code W : Date Code JJW 04W W : Date Code Typical Application Circuit Adapter or USB VIN CIN RISET RIMIN BATT COUT RT9526 ISET PGB IMIN GND CHG_SB R1 VBATT R2 VBATT ENB Function Pin Description SOT-26-6 3 Pin No. WDFN-8L 2x2 / WDFN-8L 2x3 1 Pin Name VIN Pin Function 6 5 5, 9 (Exposed Pad) 6 7 IMIN ISET Supply Voltage Input. VIN can withstand up to 28V input. Power Good Indicator. This pin connects to VIN with 10SL N-MOSFET as power good condition. Charge Status Indicator Output (Open drain). Indicate low when battery is charging; indicate high when battery charging finished or any fault happened. Charge Enable (Active Low). Connect this pin with 200kΩ pull low resistor. Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. EOC Current Setting Pin. Charge Current Set Point. 4 8 BATT Battery Charge Current Output. -- 2 PGB 1 3 CHG_SB -- 4 ENB 2 www.richtek.com 2 GND DS9526-01 April 2011 RT9526 Function Block Diagram Switch Well BATT VIN BASE VREF IBIAS Sleep Mode ISET Current Set Block CC/CV/TR Multi Loop Controller EOC Set Block IMIN CHG_SB OVP UVLO ENB 200k DS9526-01 April 2011 Logic PGB GND www.richtek.com 3 RT9526 Flow Chart Standby State P-MOSFET = OFF VIN - VBATT > VOS YES NO YES BATT > 2.8V NO Soft-Start NO Sleep State P-MOSFET = OFF VIN < UVLO & VIN < OVP & ENB = L YES ICHG_FAST, HG_SB = L CV State VBATT = 4.2V ICHG = 0A CHG_SB =H Power Off State P-MOSFET = OFF Fast-Charge ICHG_FAST = 150mA RSET = 29.4k CHG_SB = L Pre_Charge ICHG_PRE = (1/6) x YES VBATT ≥ 8 4.2V NO Any State or VIN > OVP or VIN > UVLO or ENB = H Figure 1. Operation State Diagram for Charger function VIN > UVLO & VIN < OVP & VIN-VBATT > VOS YES NO PGB = L PGB = H Figure 2. PGB State ENB = L NO CHG _SB = H NO YES ICHG < IIMIN & VBATT > 2.8V YES NO CHG_SB = H CHG_SB = L ICHG < ICHG_FAST & VBATT < 2.8V YES Figure 3. CHG_SB State www.richtek.com 4 DS9526-01 April 2011 RT9526 Absolute Maximum Ratings z z z z z z z z (Note 1) Supply Voltage, VIN -----------------------------------------------------------------------------------------------------CHG_SB, PGB Pins -----------------------------------------------------------------------------------------------------Others -----------------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SOT-23-6 -------------------------------------------------------------------------------------------------------------------WDFN-8L 2x2 -------------------------------------------------------------------------------------------------------------WDFN-8L 2x3 -------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SOT-23-6, θJA --------------------------------------------------------------------------------------------------------------WDFN-8L 2x2, θJA --------------------------------------------------------------------------------------------------------WDFN-8L 2x2, θJC --------------------------------------------------------------------------------------------------------WDFN-8L 2x3, θJA --------------------------------------------------------------------------------------------------------WDFN-8L 2x3, θJC --------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------- Recommended Operating Conditions z z −0.3V to 28V −0.3V to 7V −0.3V to 6V 0.4W 0.606W 0.833W 250°C/W 165°C/W 8.2°C/W 120°C/W 8.2°C/W 260°C 150°C −65°C to 150°C (Note 3) Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 4.5V, TA = 25°C unless otherwise specified) Parameter Min Typ Max Unit VPOR_H 3.4 3.8 4.2 V VPOR_H 3.1 3.5 3.9 V VIN − V BATT VOS Rising VOS_H -- 90 150 mV VIN − V BATT VOS Falling VPOR_L 10 50 -- mV -- 300 500 μA VIN POR Rising Threshold Voltage VIN POR Falling Threshold Voltage Symbol VIN Standby Current Test Conditions VBATT = 4.5V BATT Sleep Leakage Current ISLEEP -- 1 5 μA Battery Regulation Voltage VREG 4.158 4.2 4.242 V VIN Power FET On-Resistance ISET Set Voltage (Fast Charge Phase) Charge Current Accuracy RDS(ON) -- 0.6 -- Ω -- 1.21 -- V 135 150 165 mA BATT Pre-Charge Threshold V CHG_PRE 2.7 2.8 2.9 V BATT Pre-Charge Threshold Hysteresis ΔVCHG_PRE 40 100 150 mV Pre-Charge Current ICHG_PRE 12 16.7 21.3 % ENB Input Threshold Voltage IBATT = 0.5A VISET RISET = 29.4kΩ Logic-High VIH Logic-Low VIL VIN = 4.2V to 24V 1.5 -- -- -- -- 0.4 V To be continued DS9526-01 April 2011 www.richtek.com 5 RT9526 Parameter Thermal Regulation VIN Over Voltage Protection Threshold VIN OVP Hysteresis Symbol Test Conditions Min Typ Max Unit TREG -- 115 -- °C VOVP 10 11 13 V ΔVOVP -- 0.4 -- V PGB Pull Down Voltage 5mA -- 200 -- mV CHG_SB Pull Down Voltage 5mA -- 200 -- mV RIMIN = 137kΩ 20 30 40 mA RIREF = 29.4kΩ 90 110 130 mA EOC Current Setting IIMIN EOC Rising Threshold Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. θJA is measured in natural convection at TA = 25°C on a low-effective thermal conductivity single-layer test board of JEDEC 51-3 thermal measurement standard. The measurement case position of θJC is on the exposed pad of the packages. Note 3. The device is not guaranteed to function outside its operating conditions. www.richtek.com 6 DS9526-01 April 2011 RT9526 Typical Operating Characteristics Battery Current vs. Charging Time Battery Current vs. Charging Time 0.20 4.5 VIN = 5V, RISET = 29.4kΩ, RIMIN = 137kΩ 0.18 4.0 Battery Voltage (V) Battery Current (A) 0.16 0.14 0.12 0.10 0.08 0.06 3.5 3.0 2.5 2.0 1.5 0.04 1.0 0.02 0.5 VIN = 5V, RISET = 29.4kΩ, RIMIN = 137kΩ 0.0 0.00 0 5000 0 10000 15000 20000 25000 30000 35000 5000 10000 15000 20000 25000 30000 35000 Charging Time (s) Charging Time (s) Charging Current vs. Input Voltage 4.30 155 4.28 150 Charging Current (mA)1 Battery Regulation Voltage (V)1 Battery Regulation Voltage vs. Charge Current 4.26 4.24 4.22 4.20 4.18 4.16 4.14 4.12 100 200 300 400 140 135 130 125 120 115 110 105 VIN = 5V RISET = 24.9Ω 100 4.10 0 VBATT = 3V VBATT = 3.7V 145 3.0 500 4.5 6.0 Charge Current vs. Battery Voltage Charge Current (mA) 450 9.0 10.5 Battery Regulation Voltage vs. Input Voltage 4.4 VIN = 5V Battery Regulation Voltage (V)1 500 7.5 Input Voltage (V) Change Current (mA) 400 350 300 RISET = 9.1k RISET = 29.4k RISET = 9.1k 250 200 150 100 50 0 4.2 4.0 3.8 3.6 3.4 IBATT = 20mA 3.2 0.5 1.3 2.1 2.9 Battery Voltage (V) DS9526-01 April 2011 3.7 4.5 4 5 6 7 8 9 10 11 Input Voltage (V) www.richtek.com 7 RT9526 Charge Current vs. RISET Charge Current vs. Temperature 1200 180 1100 Charging Current (mA)1 Charge Current (mA) 160 140 120 100 80 60 40 20 VIN = 5V, VBATT = 3.7V, RISET = 29.4kΩ 1000 900 800 700 600 500 400 300 200 VIN = 5V, VBATT = 3.7V 100 0 0 -50 -25 0 25 50 75 100 125 Temperature (°C) 3 13 23 33 43 53 63 RISET (kkΩ Ω) EOC Current vs. RISET 90 EOC Current (mA) 80 70 60 50 40 30 20 10 VIN = 5V, VBATT = 3.7V 0 50 130 210 290 370 450 ( kΩ ) RIMIN (kΩ) www.richtek.com 8 DS9526-01 April 2011 RT9526 Application Information The RT9526 is a fully integrated low cost single cell Li-ion battery charger operable in Constant Current (CC) mode or Constant Voltage (CV) mode. The CC mode current is set with the external resistor, RISET, and the CV mode voltage is fixed at 4.2V. If the battery voltage is below a typical 2.8V pre-charge threshold, the RT9526 charges the battery with a trickle current until the battery voltage rises above the pre-charge threshold. The RT9526 is capable of being powered up from AC adapter and USB (Universal Serial Bus) port inputs. Trickle CC CV 4.2V Charge Voltage ICHG_FAST 75 % ICHG_FAST Charge Current 2.8V IIMIN 16.7 % ICHG_FAST CHG_SB CHG Indication Figure 1. Typical Charge Profile Time VIN Over Voltage Protection a. Battery Pre-Charge Current The input voltage is monitored by the internal comparator. The OVP threshold is set at 11V (typ.). When the input voltage exceeds the threshold, the controller outputs a logic signal to turn off the power P-MOSFET to prevent high input voltage from damaging the electronics in the handheld system. Nevertheless, an AC input voltage over 28V will still damage the RT9526. When the input over voltage condition is removed, the controller will enable the output again by running through soft-start. During a charge cycle, if the battery voltage is below the pre-charge threshold, the RT9526 applies a pre-charge mode to the battery. This feature revives deeply discharged cells and protects battery life. The internally determined pre-charge rate of the RT9526 is 16.7% of the constant charge current. Charger Enable Input ENB is an active-low logic input to enable the charger. Drive the ENB pin low or leave it floating to enable the charger. This pin has a 200kΩ internal pull down resistor. So when left floating, the input is equivalent to logic-low. Drive this pin high to disable the charger. b. Battery Fast-Charge Current (CC Mode) The RT9526 offers ISET pin to determine the fast-charge current via an external resistor, RISET, connected between ISET and GND. The fast-charge current can be calculated by the following equation : V ICHG_FAST = KISET x ISET (mA) RISET KSET = 3640; VSET = 1.21 (typ.) c. Battery Voltage Regulation (CV Mode) Battery Charge Profile The RT9526 charges a Li-ion battery under Constant Current (CC) mode or Constant Voltage (CV) mode. The constant current of ISET is set via the external resistor, RISET, and the constant voltage is fixed at 4.2V. If the battery voltage is below a typical 2.8V pre-charge threshold, the RT9526 charges the battery with a trickle current until the battery voltage rises above the pre-charge threshold. When the battery voltage reaches 4.2V, the charger enters CV mode and regulates the battery voltage at 4.2V to fully charge the battery without the risk of over charge. The battery voltage regulation feedback is through the BATT pin. The RT9526 monitors the battery voltage between the BATT and GND pins. When battery voltage is close to battery regulation voltage threshold, the voltage regulation phase begins and the charging current begins to taper down. When battery voltage is over battery regulation voltage threshold and charge mode stops, the RT9526 still monitors the battery voltage. Charge current is resumed when the battery voltage falls under battery regulation voltage threshold. Sleep Mode The RT9526 enters sleep mode if both AC and USB are removed from the input. This feature prevents draining the battery during the absence of input supply. DS9526-01 April 2011 www.richtek.com 9 RT9526 Power Good This open-drain output pin is used to indicate the input voltage status. The PGB output asserts low when 1. VIN > VPOR temperature falls below thermal regulation threshold (115°C) by the hysteresis level. This feature prevents the maximum power dissipation from exceeding typical design conditions. 2. VIN − VBATT > VOS Selecting the Input and Output Capacitors 3. VIN < VOVP In most applications, a 1μF high frequency decoupling capacitor placed in close proximity to the input is sufficient. However, depending on the power supply characteristics and cable length, it may be necessary to add an additional 10μF ceramic capacitor to the input. For the RT9526, a small output capacitor is required for loop stability. A 1μF ceramic capacitor placed between the BATT pin and GND is typically sufficient. It can be used to drive an LED or communicate to the host processor. Note that ON indicates the open-drain transistor is turned on and LED is bright. CHG_SB Indication The CHG_SB pin is an open-drain output capable to at least 10mA current when the charger starts to charge and turns off when the EOC current is reached. The CHG_SB signal is interfaced either with a micro processor GPIO or an LED for indication. End-Of-Charge Current (EOC) Connect a resistor between the IMIN pin and GND to set the EOC current. The EOC current level, I IMIN, is programmable via the external resistor, RIMIN, as shown in the following equation : IIMIN = 4148 RIMIN (mA) Upon reaching the End-Of-Charge (EOC) current, the charger indicates charge completion via the CHG_SB pin, but the charger continues to output 4.2V voltage. Figure 1 shows the typical charge profile and the EOC/reset event. The CHG_SB signal asserts low when the trickle charge starts and changes to high at EOC. After EOC is reached, the charge current has to rise above 75% of ICHG_FAST before the CHG_SB signal is allowed to turn on Thermal Considerations For recommended operating condition specifications of the RT9526, the maximum junction temperature is 125°C and TA is the ambient temperature. The junction to ambient thermal resistance, θ JA , is layout dependent. For SOT-23-6 packages, the thermal resistance, θJA, is 250°C/W on a standard JEDEC 51-3 single-layer thermal test board. For WDFN-8L 2x2 packages, the thermal resistance, θJA, is 165°C/W on a standard JEDEC 51-3 single-layer thermal test board. For WDFN-8L 2x3 packages, the thermal resistance, θJA, is 120°C/W on a standard JEDEC 51-3 single-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by the following formula : PD(MAX) = (125°C − 25°C) / (250°C/W) = 0.400W for SOT-23-6 package PD(MAX) = (125°C − 25°C) / (165°C/W) = 0.606W for WDFN-8L 2x2 package again. A current surge after EOC may occur due to a load connected to the battery. PD(MAX) = (125°C − 25°C) / (120°C/W) = 0.833W for WDFN-8L 2x3 package Temperature Regulation and Thermal Protection The maximum power dissipation depends on the operating ambient temperature for fixed T J (MAX) and thermal resistance, θJA. For the RT9526 packages, the derating curves in Figure 2 allow the designer to see the effect of rising ambient temperature on the maximum power dissipation. In order to maximize charge rate, the RT9526 features a junction temperature regulation loop. If the power dissipation of the IC results in junction temperature greater than the thermal regulation threshold (115°C), the RT9526 will cut back on the charge current and disconnect the battery in order to maintain thermal regulation at around 115°C. This operation continues until the junction www.richtek.com 10 DS9526-01 April 2011 Maximum Power Dissipation (W)1 RT9526 0.9 Layout Consideration Single-Layer PCB The RT9526 is a fully integrated low cost single-cell Liion battery charger ideal for portable applications. Careful PCB layout is necessary. For best performance, place all peripheral components as close to the IC as possible. A short connection is highly recommended. The following guidelines should be strictly followed when designing a PCB layout for the RT9526. 0.8 0.7 0.6 0.5 0.4 WDFN-8L 2x3 WDFN-8L 2x2 SOT-23-6 0.3 0.2 ` Input capacitor should be placed close to the IC and connected to the ground plane. The trace of input on the PCB should be placed far away from the sensitive devices and shielded by the ground. ` The GND and exposed pad should be connected to a strong ground plane for heat sinking and noise protection. ` The connection of RISET should be isolated from other noisy traces. ` Output capacitor should be placed close to the IC and connected to the ground plane to reduce noise coupling. 0.1 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 2. Derating Curve for RT9526 Package CIN should be placed near the IC to improve performance. VIN BATT R1 BATT BATT R2 VIN PGB CHG_SB ENB 1 2 3 4 GND CIN COUT 9 8 7 6 5 The copper area connecting the resistors of ISET and IMIN should be minimized and kept far away from noise sources. BATT RISET ISET IMIN GND RIMIN GND The GND plane should be connected to a strong ground plane for heat sinking and noise protection. Figure 3. PCB Layout Guide DS9526-01 April 2011 www.richtek.com 11 RT9526 Outline Dimension H D L C B b A A1 e Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 0.889 1.295 0.031 0.051 A1 0.000 0.152 0.000 0.006 B 1.397 1.803 0.055 0.071 b 0.250 0.560 0.010 0.022 C 2.591 2.997 0.102 0.118 D 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 H 0.080 0.254 0.003 0.010 L 0.300 0.610 0.012 0.024 SOT-23-6 Surface Mount Package www.richtek.com 12 DS9526-01 April 2011 RT9526 D2 D L E E2 1 e SEE DETAIL A b 2 1 2 1 A A1 A3 DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.200 0.300 0.008 0.012 D 1.950 2.050 0.077 0.081 D2 1.000 1.250 0.039 0.049 E 1.950 2.050 0.077 0.081 E2 0.400 0.650 0.016 0.026 e L 0.500 0.300 0.020 0.400 0.012 0.016 W-Type 8L DFN 2x2 Package DS9526-01 April 2011 www.richtek.com 13 RT9526 D D2 L E E2 SEE DETAIL A 1 e b 2 A A1 1 2 1 A3 DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.200 0.300 0.008 0.012 D 1.900 2.100 0.075 0.083 D2 1.550 1.650 0.061 0.065 E 2.900 3.100 0.114 0.122 E2 1.650 1.750 0.065 0.069 e L 0.500 0.350 0.020 0.450 0.014 0.018 W-Type 8L DFN 2x3 Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: [email protected] Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. www.richtek.com 14 DS9526-01 April 2011