SGM41524YTDC8G/TR

SGM41524 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging GENERAL DESCRIPTION FEATURES The SGM41524 is a compact and efficient Lithium ion ● Constant Current, Constant Voltage (CCCV) (Li+) or Lithium ion polymer (Li+/polymer) battery Charging with Floating Time-Out Timer charger. It can provide power and charge the single cell ● Constant Current Pre-charge battery of a system typically found in compact portable ● Maximum 2.3A Charging for 4.2V to 4.5V Battery device. An internal switching buck converter regulates ● 1.34MHz Switching Frequency the supply input for charging the battery and powering ● Programmable Charge Voltage and Current the system even if the battery is absent. The converter ● 4.15V Input Voltage Regulation can also operate as a simple pass-through switch with ● Output Voltage Fold-Back Charge Retaining no switching if the load and input voltages are close. ● Thermal Regulation Options A typical application circuit is shown in Figure 2. The SGM41524 features resistor programmable constant current and constant voltage charging capability plus a charge limiting timer and operates in compliance with the BAJ/JEITA safety guide. An NTC (β = 3950K) can  SGM41524: +115℃  SGM41524C: +55℃ ● Typical Peak Efficiency of 92% at 1.5A, VIN = 5V ● -40℃ to +85℃ Operating Temperature Range ● Available in a Green TDFN-2×3-8BL Package be used for battery temperature sensing on top of the internal junction temperature monitoring. The IND status output pin can be connected to LEDs to indicate the operating conditions, such as power input ok (POK), in charging (CHG), VIN over-voltage (POK and CHG APPLICATIONS Powering and Charge Control of Systems with 500mAh to 6000mAh Li+/Polymer Batteries alternate blinking) and no power/disabled (OFF). Voltage fold-back on the output is provided to power the system from the input while retaining battery charge and preventing overcharge. Input under-voltage regulation is implemented by reducing the load current such that VIN stays above a minimum when the source is weak. Similarly, the die temperature can be regulated and limited by reducing output power to avoid device or the circuit board being overheated. These features simplify the system design and ensure safe and reliable operation as well as improved user experience. The SGM41524 is delivered in a Green TDFN-2×3-8BL package. The device operates in -40℃ to +85℃ with two thermal regulation options for +55℃ or for +115℃. SG Micro Corp www.sg-micro.com NOVEMBER 2020 – REV. A. 1 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 PACKAGE/ORDERING INFORMATION MODEL PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE ORDERING NUMBER PACKAGE MARKING PACKING OPTION TDFN-2×3-8BL -40℃ to +85℃ SGM41524YTDC8G/TR CBA XXXX Tape and Reel, 3000 TDFN-2×3-8BL -40℃ to +85℃ SGM41524CYTDC8G/TR CG1 XXXX Tape and Reel, 3000 SGM41524 MARKING INFORMATION NOTE: XXXX = Date Code and Trace Code. YYY X XXX Serial Number Trace Code Date Code - Year Green (RoHS & HSF): SG Micro Corp defines "Green" to mean Pb-Free (RoHS compatible) and free of halogen substances. If you have additional comments or questions, please contact your SGMICRO representative directly. ABSOLUTE MAXIMUM RATINGS Voltage Range (with Respect to GND) VIN (VVBAT = 4V)................................................................ 6V VBAT (VIN Open) ................................................................ 6V CC, CV, IND, NTC, SW...................................... -0.3V to 6V Package Thermal Resistance TDFN-2×3-8BL, θJA .................................................. 90℃/W Junction Temperature .................................................+150℃ Storage Temperature Range ....................... -65℃ to +150℃ Lead Temperature (Soldering, 10s) ............................+260℃ ESD Susceptibility HBM, Any Pin to Ground and Power ........................... 4000V CDM ............................................................................ 1000V Surge Test (1) Input Surge Discharge ................................................. 11V Input Over-Voltage Clamp ...................8V or 50mA, 24 hours NOTE: 1. Peak current in IEC61000-4-5 1.2μs/50μs 2Ω waveform. RECOMMENDED OPERATING CONDITIONS Supply Voltage Range ........................................3.5V to 5.5V CC, CV, IND, NTC ............................................ -0.3V to 5.5V Charge Current Setting Range ...........................0.3A to 2.3A Operating Junction Temperature Range ...... -40℃ to +125℃ Environmental Temperature Range ............... -40℃ to +85℃ SG Micro Corp www.sg-micro.com OVERSTRESS CAUTION Stresses beyond those listed in Absolute Maximum Ratings may cause permanent damage to the device. Exposure to absolute maximum rating conditions for extended periods may affect reliability. Functional operation of the device at any conditions beyond those indicated in the Recommended Operating Conditions section is not implied. ESD SENSITIVITY CAUTION This integrated circuit can be damaged if ESD protections are not considered carefully. SGMICRO recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because even small parametric changes could cause the device not to meet the published specifications. DISCLAIMER SG Micro Corp reserves the right to make any change in circuit design, or specifications without prior notice. NOVEMBER 2020 2 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 PIN CONFIGURATION (TOP VIEW) SW 1 IND 2 CV 3 CC 4 EP 8 GND 7 VIN 6 NTC 5 VBAT TDFN-2×3-8BL PIN DESCRIPTION PIN NAME TYPE FUNCTION 1 SW O Buck Converter Switching Node. Connect to the output inductor. 2 IND O Status Indication Output. It can source or sink constant current when powered (charging or not charging). It can only sink current if no power is applied. 3 CV I Charge Voltage Programming Input Pin. Connect a resistor between this pin and ground to select one of the seven charging voltages. 4 CC I Charge Current Programming/Charge-Inhibit Input Pin. Connect a resistor between this pin and GND to program the constant charge current ICC, (RCCSET = K/ICC). Pull up this pin to a voltage higher than VINH to inhibit and stop charging. 5 VBAT I Battery Voltage Sense Input. 6 NTC I NTC Temperature Sensing Input. Connect to an NTC thermistor (β = 3950K) with other end grounded and biased to VIN by a 1.5 × RNTC25℃ resistor. Ground this pin if NTC is not used. 7 VIN P Power Input Pin. 8 GND G Ground Reference Pin. Exposed Pad EP IC Exposed Pad. Thermal pad is internally grounded and must be connected to the PCB GND plane. NOTE: I: Input, O: Output, IO: Input or Output, G: Ground, P: Power for the Circuit, IC: Internal Connection, NC: Not Connected. SG Micro Corp www.sg-micro.com NOVEMBER 2020 3 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 ELECTRICAL CHARACTERISTICS (VVIN = 5V, VVBAT = 3.8V, Full = -40℃ to +85℃, typical values are at TJ = +25℃, unless otherwise noted.) PARAMETERS SYMBOL CONDITIONS Over-Voltage Protection Threshold VOVP VBAT open, VVIN = 5V to 6V Minimum Input Operation Voltage VCHGm VBAT open, VVIN = 5V to 4V VIN Supply Current IQ ILKGFLD Leakage Current into the VBAT (1) TEMP MIN TYP MAX +25℃ 5.51 5.67 5.84 Full 5.49 5.67 5.85 +25℃ 3.90 4.04 4.17 Full 3.85 4.04 4.20 IND open, fold-back mode, RCV = 1kΩ, set VVBAT = 4.17V, no switching +25℃ 15 20 Full 15 21 Fold-back mode, RCV = 1kΩ, set VVBAT = 4.17V, no switching +25℃ 0.1 1.4 Full 0.1 1.5 +25℃ 0.1 1.4 Full 0.1 1.5 ILKG VIN open, VVBAT = 3V to 4.5V Charge Output Regulation Voltage VCHG CV pin connected to GND Charge Voltage Step VSTEP UNITS V V μA μA μA Charge Loop The Minimum Voltage Drop between VIN and VBAT Required for Switch Charging +25℃ 4.175 4.20 4.225 Full 4.145 4.20 4.255 Full 50 V mV VDROPm LDO charge mode, input voltage is greater than VCHGm Full 2 20 40 mV VDROPM Switch charge mode, input voltage is greater than VCHGm Full 120 170 230 mV Full Charge Voltage Fold-Back when NTC Temperature is out of 10℃ to 45℃ Range VDEG Compare with VCHG in 10℃ to 45℃ NTC temperature range Charge Current Decrease at NTC Temperature Regulation (1) IDEG As percentage of ICC in 10℃ to 45℃ NTC temperature range 5℃ Threshold (1) DT1 As percentage of VVIN 10℃ Threshold (1) DT2 As percentage of VVIN 45℃ Threshold (1) DT3 As percentage of VVIN 55℃ Threshold (1) DT4 As percentage of VVIN Floating Charge Timer Start Threshold VFLT As percentage of VCHG Fold-Back Retaining Output Voltage FR As percentage of VCHG Recharge Threshold VRR As percentage of VCHG Battery Precondition Charge Current IPRE VVIN = 5V, VVBAT < 60% × VCHG Battery Precondition Threshold Voltage VPRE As percentage of VCHG 50 mV +25℃ 28 30 32 Full 27 30 33 +25℃ 62 63 65 Full 61 63 66 +25℃ 56 58 59 Full 55 58 60 +25℃ 21 23 24 Full 20 23 25 +25℃ 16 17 18 Full 15 17 19 +25℃ 96.5 98.0 99.4 Full 96.4 98.0 99.5 +25℃ 96.8 97.1 97.5 Full 96.7 97.1 97.7 +25℃ 94.0 95.5 97.0 Full 93.9 95.5 97.1 +25℃ 67 97 128 Full 65 97 130 +25℃ 57 60 63 Full 56 60 65 % % % % % % % % mA % NOTE: 1. Parameters guaranteed by product characterization. SG Micro Corp www.sg-micro.com NOVEMBER 2020 4 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 ELECTRICAL CHARACTERISTICS (continued) (VVIN = 5V, VVBAT = 3.8V, Full = -40℃ to +85℃, typical values are at TJ = +25℃, unless otherwise noted.) PARAMETERS Load Pre-charge Current Load Pre-charge Period Charge Current Setting Ratio SYMBOL CONDITIONS ILOADPRECHG When power-up at VVBAT < 60% × VCHG tLOADPRECHG K RCC = 10kΩ, K = ICC × RCCSET Charge Inhibition Voltage Threshold VINH Voltage forcing on the CC pin to inhibit charging Fast Charge Current ICC RCC = 10kΩ, VVBAT = 3.8V, VVIN = 5V Charge Termination Current Threshold IRES Floating Charge Termination Time tFCOT Input Voltage Regulation Threshold VINREG Thermal Regulation Threshold (1) Thermal Shutdown Temperature Thermal Shutdown Hysteresis BAT Voltage Monitoring Period before Turning into Fold-Back Switch Operation TYP +25℃ 4.23 5.00 5.77 Full 4.05 5.00 5.83 +25℃ 9450 10000 10500 Full 9150 10000 10800 Full MAX 300 UNITS mA 1.5 ms V V +25℃ 0.945 1 1.050 Full 0.915 1 1.080 +25℃ 95 140 175 Full 85 140 190 +25℃ 77 92 107 Full 74 92 108 +25℃ 4.00 4.15 4.30 Full 3.98 4.15 4.32 A mA min V SGM41524C 55 ℃ TOTR SGM41524 115 ℃ TSHUT Temperature increasing 155 ℃ 20 ℃ TSHUT_HYST tMON RDS(ON)-H Low-side Switch MOSFET On-Resistance between SW and GND RDS(ON)-L PWM Switching Frequency MIN TOTR High-side Switch MOSFET On-Resistance between VIN and SW Peak Current Limit VVBAT = 3.8V, VIN for making charge current to 0 TEMP IPEAK fS +25℃ 162 192 222 Full 155 192 224 +25℃ 140 170 Full 140 200 +25℃ 120 150 Full 120 180 Full 3.2 ms mΩ mΩ A +25℃ 1.13 1.34 1.55 Full 1.08 1.34 1.56 MHz Indication Driving IND Sink Current (1) IINDSNK VVIN = 5V IND Source Current (1) IINDSRC VVIN = 5V IND Blink Period tBLINK Input OVP state +25℃ 0.7 1.3 1.9 Full 0.4 1.3 2.5 +25℃ 0.6 1.3 2.0 Full 0.4 1.3 2.5 +25℃ 162 192 222 Full 155 192 224 mA mA ms NOTE: 1. Parameters guaranteed by product characterization. SG Micro Corp www.sg-micro.com NOVEMBER 2020 5 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 TYPICAL PERFORMANCE CHARACTERISTICS VVIN = 5V, VVBAT = 3.8V, TJ = +25℃, unless otherwise noted. DCM Mode Switch Waveform CCM Mode Switch Waveform 5V/div 5V/div VSW VSW 500mA/div IL 500mA/div IL Time (500ns/div) Time (500ns/div) Start-up Charge by VIN, with 3.7V Battery at BAT Start-up Charge by VIN, with10Ω Resistor at BAT IL 5V/div 5V/div VIN VSW 1A/div IL VBAT 5V/div VSW 2V/div 2V/div 5V/div 1A/div VBAT VIN Time (5ms/div) Time (1ms/div) Forcing CC = 2V to Disable Charge Recovery Charge by Release CC VSW Time (50μs/div) SG Micro Corp www.sg-micro.com VSW IL VCC 2V/div 2V/div VCC VBAT 1A/div IL 2V/div 5V/div 2V/div 5V/div 1A/div VBAT Time (20μs/div) NOVEMBER 2020 6 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 TYPICAL PERFORMANCE CHARACTERISTICS (continued) VVIN = 5V, VVBAT = 3.8V, TJ = +25℃, unless otherwise noted. Efficiency vs. Charge Current 98 Charge Current (mA) 96 Efficiency (%) 94 92 90 88 86 84 2000 1500 1000 500 VBAT = 3.8V 0 500 1000 1500 2000 2500 Charge Current vs. RCC 2500 0 3000 VBAT = 3.8V 0 0.05 Charge Current (mA) 0.1 0.15 0.2 0.25 1/RCC (kΩ) Battery Precondition Charging Load Pre-charge Fast Charging with Constant Current Charging for Constant Voltage VCHG 98% × VCHG Fast Charge Current Current Voltage 60% × VCHG Voltage FoldBack Retaining Floating Charging Timer Starts Current Falls below the Termination Level or Floating Time-Out CHG Indication Stops Load Current Curve with Less Load Current Load Pre-charge (~300mA) Curve with More Load Current IRES (Termination Current) IPRE (Precondition Charge Current) Figure 1. Charging Voltage/Current Profile SG Micro Corp www.sg-micro.com NOVEMBER 2020 7 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 POK CHG TYPICAL APPLICATION RCHG L1 2.2μH System Load COUT BAT SW 1 8 GND IND 2 7 VIN CV 3 6 NTC SGM41524 CC 4 RCV RPOK CIN 5.5V RB 15kΩ 5 VBAT RNTC 10kΩ (β = 3950K) RCC Figure 2. Typical Application Circuit FUNCTIONAL BLOCK DIAGRAM NTC RCHG RPOK ~5.5V Operation VIN CIN RNTC 10kΩ (β = 3950K) GND D 2 RB 15kΩ POK CHG IND 6 BAJ/ JEITA L 2.2μH SGM41524 1 TOTR State Machine SW System Load GIS:1 CS 5 GM VBAT COUT CCCV Modulator QR 7 QH 3 Reverse Block QL ICCI 4 CV BAT RCV CC RCC 8 Figure 3. Block Diagram ESSENTIAL SEQUENCE VVIN normal VVIN over-voltage VCHGhys VCHGm Charge starts tON_D tNOR Charge stops Load pre-charge before normal charge tret IND stops Charge resumes Stop blinking Switching stops for over-voltage Start to blink VINDM VCHGm Figure 4. Essential On/Off Timing SG Micro Corp www.sg-micro.com NOVEMBER 2020 8 SGM41524 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging FUNCTION DESCRIPTION AND APPLICATION Power-Up with Low/No Battery If the battery is not attached or its voltage is less than 60% of VCHG (VVBAT < 0.6VCHG), the device feeds the VBAT with a current limited to less than 300mA for about 5ms to pre-charge the battery and system load before it goes into battery precondition charging state. This pre-charge period can increase the voltage of a 500μF capacitor (between VBAT and GND) for up to 3V before the device starts to deliver the lower preconditioning current (almost 97mA). If the load is started before fast charge phase, the supply capacity will be limited to the precondition charge current for a relatively long time. The initial 5ms pre-charge period can quickly bring the device to the fast charge or even fold-back phase when there is no battery attached and provide enough power for the system operation in a short time. SG Micro Corp www.sg-micro.com The charging profile is shown in Figure 1. When the battery voltage is less than 0.6VCHG, the output current is regulated to a low and safe preconditioning level (IPRE). On the other hand when the input supply is present and charge is complete, the output goes to the safe voltage fold-back mode for powering the load. In this mode, the output current is limited to less than peak switch current limit (IPEAK) and not to the programmed charge current limit. Figure 5 shows the load transient response of the evaluation board circuit whose charge current is programmed for less than the load current. VBAT 1A/div This device does not have a separate battery switch to connect or disconnect the battery from the system (load). However, it uses voltage fold-back retaining for battery safety and lifetime extension when the battery is fully charged and input power is present. With this method, battery energy loss is lower because there is no switch in the discharge path. The only disadvantage is that if the battery voltage is excessively low, then start the system instantly is not possible because charge path cannot be separated and it may take a few minutes to charge the battery and reach to an adequate voltage level to start the load system. Charging Profile and Fold-Back Retaining 1V/div The SGM41524 is a general purpose stand-alone switch mode charger device designed for powering systems using Li+/poly rechargeable batteries. Several features are provided including charge voltage and current programming and status indication. Input voltage and die temperature are constantly monitored to prevent output power failure. If the input supply voltage drops too low, the device reduces the output power to reduce loading on the input and prevent further drop and power failure. Similarly, if the junction is overheated by heavy load, the output power is reduced to prevent thermal shutdown and system power failure. It is also capable for various charging modes like constant-current, constant-voltage, constant-current pre-charging, and trickle charging (when input source is weak). IBAT Time (500μs/div) Figure 5. Load Transient Response in Fold-Back Supply The input voltage is monitored during charging. If the source is weak and cannot maintain its voltage under heavy load, the charging current is reduced to avoid system power collapse due to input voltage drop. The charge is considered full if the battery voltage exceeds the floating voltage VFLT and the charge current drops below the end of charge current (IRES) or if the floating charge timer runs out of time (tFCOT). When the full charge status is detected, the output will drop to the fold-back voltage specified by fold-back retaining output voltage ratio (FR ratio is typically 97.1% of VCHG as specified in the EC table) and converter continues to work but indicator shows "not charging". If the battery voltage is higher than fold-back level, the switching will stop. VBAT is monitored periodically and if it drops below that level the buck converter starts to operate and regulate the output to the fold-back level. The full charge state is continued until the input power is recycled or if the battery voltage drops below the recharge voltage level (VRR). NOVEMBER 2020 9 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 FUNCTION DESCRIPTION AND APPLICATION (continued) If the voltage drop between the input and output (VDROP) is small and less than VDROPm, the device goes into forward diode state and stops switching. Switching is resumed if the VDROP exceeds VDROPM level. The CHG indication will turn off if the time of VDROP < VDROPm is longer than the retaining time (tRET). Charge Current Programming and Turn Off Charge current is programmed by RCCSET resistance by RCCSET = K/ICC where the K is charge current setting ratio which is typically 10000V as specified in the EC table. Pulling the CC pin to a voltage level higher than VINH turns the device off (disabled). When this pin is released the device resumes the status before being inhibited. Charge Voltage Programming Charging voltage can be programmed in one of the 7 preset values by setting a voltage on CV pin. A 50μA current source is internally connected to CV pin. Programming can be done by directly applying a voltage to the CV pin, or by connecting a resistor to GND that results in the same voltage as shown in Table 1. Table 1. Conditions for Selecting a Charging Voltage Charging Voltage (V) 4.2 4.25 4.3 4.35 4.4 4.45 4.5 Forcing Voltage (V) GND 0.6 1.0 1.4 1.8 2.6 Open Separation Thresholds (V) < 0.4 0.4 to 0.8 0.8 to 1.2 1.2 to 1.6 1.6 to 2.0 2.0 to 2.4 > 2.4 Grounding Resistance (kΩ) short 12 20 28 36 52 Open NOTE: Sourcing current out of the CV is 50μA typically. BAJ/JEITA Charging Extending and Safety This device implements the battery temperature related charging control in compliance with the BAJ/JEITA guide on safe use of secondary Lithium ion batteries. An NTC (β = 3950K) can be used as shown in Figure 2 (or Figure 3) for battery temperature sensing. As specified in Table 2, the charging voltage and current are reduced when the sensed battery temperature is out of the preferred charging range (10℃ to 45℃). When the temperature is too high (above SG Micro Corp www.sg-micro.com 55℃), the device stops charging and when it is too low (less than 5℃), only the small precondition current is charged. Table 2. Temperature Related Charging Control Temperature Range Charging Voltage Charging Current Low range, < 5℃. VCHG - 50mV IRES Low charging range, 5℃ to 10℃ Recommended charging range, 10℃ to 45℃ VCHG - 50mV 70% ICC VCHG ICC High charging range, 45℃ to 55℃ VCHG - 50mV 70% ICC — 0 High range, > 55℃ NOTE: The VCHG and the ICC (charging voltage and current) are selected in accordance with the battery's specification. If NTC feature is not used, connect the NTC pin to ground. The device checks for grounded NTC pin once during the startup when the input voltage is exceeding 2.7V. Indication and Status Reading The IND output can have 4 states to show different conditions: (1) Low (sink current) to indicate the input power is available (or not charging); (2) High (source current) to indicate the device is in charging; (3) Hi-Z (open) for indicating no power is available (when VIN < VCHGm) or when it is turned off by pulling the CC pin voltage up; and (4) blinking or alternatingly Low and High (sinking and sourcing current) if an input over-voltage occurs. IND voltage can be used as a signal for the host or other circuit for status detection. Note that in the high impedance state (Hi-Z), the POK LED and CHG LED are forward biased by the input voltage (all in series) and they can turn on depending on the drive current determined by the LED forward voltages and series resistances. Input Voltage Regulation and Thermal Regulation To prevent power shutdown, the output current is gradually reduced if VIN drops close to the minimum (VCHGm). Output current eventually reaches to zero when VIN falls to VCHGm level. Similarly, if the junction temperature increases close to its maximum (TOTR), the output current is progressively reduced and will reach to zero when the temperature reaches to TOTR. NOVEMBER 2020 10 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 FUNCTION DESCRIPTION AND APPLICATION (continued) Component Selection and Layout Inductor Selection Small inductors and capacitors can be chosen thanks to the high operating switching frequency of the 1.34MHz. Select an inductor with a saturation current a little bit higher than the charging current (ICHG) plus half the ripple current peak to peak magnitude (IRIPPLE): ISAT ≥ ICHG + (1/2) IRIPPLE (1) The inductor ripple current depends on the input voltage (VVBUS), the duty cycle (D = VVBAT/VVBUS), the switching frequency (fS) and the inductance (L). In CCM (e.g. full load): IRIPPLE = VVBUS × D × (1 − D ) fS × L (2) The maximum inductor ripple current occurs when the duty cycle (D) is 0.5 or near. Typically, the inductor ripple is designed in the range between 20% and 40% of the maximum charging current as a trade-off between inductor size and efficiency. Smaller inductor results in higher ripple (AC) current flowing into the capacitor and switches and can reduce efficiency. Input Capacitor Choose the input capacitance with enough RMS current rating to decouple input switching AC currents away from input. Low ESR ceramic capacitor such as X5R or X7R is preferred for input decoupling. Typically, 10μF capacitance is suitable for 1A to 2A charging current. Keep the capacitor(s) close to VIN and GND pins to minimize the parasitic inductance in the input ripple current circulation path. In the worst-case, the RMS of the ripple current is half of the DC charging current (ICHG) when duty cycle is D = 50%. If the converter does not operate at 50% duty cycle, then the worst-case occurs when duty cycle is closest to 50%. The input RMS current (ICIN) can be estimated by Equation 3. ICIN= ICHG × D × (1 − D ) (3) Output Capacitor A few factors must be considered to design the output capacitance. First, the SGM41524 has the internal loop compensation for the buck converter that is optimized for ceramic output capacitance larger than 10μF. The output capacitor (COUT) circulates the output ripple current and prevents it from going into the battery. Having AC current in the battery results in extra heating and lower lifetime. SG Micro Corp www.sg-micro.com Equation 4 gives the output capacitor RMS current ICOUT when no battery is attached. ICOUT= I RIPPLE 2× 3 ≈ 0.29 × IRIPPLE (4) The RMS ripple voltage in worst case is calculated as: IRIPPLE (5) VRIPPLE = 2 × π × fS × COUT The capacitance should be selected large enough for meeting the system requirement for acceptable VRPPLE. In the system design, operation with no battery must be considered carefully. Typically, the presence of the battery helps in filtering of the sags and ripples and provides peak energy demands when load surges occur. When the battery is absent, a relatively large capacitor is needed to have proper performance. Beside the VRIPPLE requirement, the load starting inrush current is another factor to consider for output capacitor selection. If at the beginning the device turns into fold-back, the converter does not start switching as the output capacitor holds the voltage higher than the fold-back retaining voltage. VBAT voltage is monitored periodically and as long as it is above fold-back voltage, it is only the output capacitor that powers the system in the absence of the battery. The capacitance should be large enough to maintain the VBAT voltage and prevent dropping below minimum system requirement before the switching fold-back mode supply operation starts. The capacitance for fulfilling this requirement is highly dependent on how the load starts, including its timing, start current and acceptable voltage drop. Verification with a prototype is recommended if operation without a battery is considered. Layout Guide 1. Place VIN capacitor close to the VIN pin and GND pin. 2. Place the inductor terminal close to the SW pin and minimize the copper area of switching node trace. Do not use multiple layers for this connection. 3. Minimize the return loop area and ripple current path length through the inductor and the output capacitor(s) to the device GND pin. 4．Use copper plane for power GND and place multiple via between top and bottom GND plane for better heat dissipation and noise immunity. NOVEMBER 2020 11 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 FUNCTION DESCRIPTION AND APPLICATION (continued) PCB Layout Example Top Layer Bottom Layer Top Solder Via L BAT CBAT LED LED SW 1 8 GND IND 2 7 VIN CV 3 6 NTC CC 4 5 VBAT RCV CIN VIN R = 15kΩ RNTC RCC R = 3.3kΩ R = 3.3kΩ TOP VIEW GND Figure 6. Typical PCB Layout SG Micro Corp www.sg-micro.com NOVEMBER 2020 12 Compact Switch Li+/Poly Battery Charger Safe and Reliable Charging SGM41524 System Load L1 2.2μH BAT C1 10μF SW 1 8 GND IND 2 7 VIN CV 3 SGM41524 CC 4 R1 0Ω LED2 LED1 FUNCTION DESCRIPTION AND APPLICATION (continued) R3 3.3kΩ C2 10μF R4 3.3kΩ VIN 5.5V 6 NTC R5 15kΩ 5 VBAT R6 10kΩ (β = 3950K) R2 6.8kΩ Figure 7. Typical Application Circuit, Programmed for Charge Current of ICC = 1.47A, and Voltage of VCHG = 4.20V Table 3. Bill of Materials for Typical Application Circuit Designator Quantity Description Size Maker U1 1 Switch Li+/Poly Battery Charger TDFN-2×3-8BL SGMICRO L1 1 Ind, 2.2μH, Irms = 4.3A, Isat = 6.1A, DCR = 40mΩ 4.0*4.0*2.0mm Sunlord C1, C2 2 Cap, Cerm, 10μF, 10V, X5R 0603 SAMSUNG R1 1 Res, 0Ω, 1% 0603 UniOhm R2 1 Res, 6.8kΩ, 1% 0603 UniOhm R3, R4 2 Res, 3.3kΩ, 5% 0603 UniOhm R5 1 Res, 15kΩ, 1% 0603 UniOhm R6 1 NTC, 10kΩ, 1%, β = 3950K 0603 Sunlord LED1, LED2 2 Chip Light Emitting Diode, Blue 0603 Nationstar Part Number SGM41524/SGM41524C WPN4020H2R2MT SDNT1608X103F3950FTF FC-DA1608BK-470H10 REVISION HISTORY NOTE: Page numbers for previous revisions may differ from page numbers in the current version. NOVEMBER 2020 ‒ REV.A to REV.A.1 Page Updated Absolute Maximum Ratings and Recommended Operating Conditions sections ................................................................................... 2 Changes from Original (DECEMBER 2019) to REV.A Page Changed from product preview to production data ............................................................................................................................................. All SG Micro Corp www.sg-micro.com NOVEMBER 2020 13 PACKAGE INFORMATION PACKAGE OUTLINE DIMENSIONS TDFN-2×3-8BL D N5 e N8 L k E1 E D1 N4 b N1 BOTTOM VIEW TOP VIEW 1.63 0.65 1.75 A 2.95 A1 A2 SIDE VIEW 0.25 0.50 RECOMMENDED LAND PATTERN (Unit: mm) Symbol Dimensions In Millimeters MIN MAX A 0.700 A1 0.000 A2 Dimensions In Inches MIN MAX 0.800 0.028 0.050 0.000 0.203 REF 0.031 0.002 0.008 REF D 1.950 2.050 0.077 0.081 D1 1.530 1.730 0.060 0.068 E 2.950 3.050 0.116 0.120 E1 1.650 1.850 0.065 0.073 b 0.200 0.300 0.008 0.500 BSC 0.020 BSC k 0.250 REF 0.010 REF L SG Micro Corp www.sg-micro.com 0.012 e 0.300 0.450 0.012 0.018 TX00141.001 PACKAGE INFORMATION TAPE AND REEL INFORMATION REEL DIMENSIONS TAPE DIMENSIONS P2 W P0 Q1 Q2 Q1 Q2 Q1 Q2 Q3 Q4 Q3 Q4 Q3 Q4 B0 Reel Diameter A0 P1 K0 Reel Width (W1) DIRECTION OF FEED NOTE: The picture is only for reference. Please make the object as the standard. KEY PARAMETER LIST OF TAPE AND REEL Reel Diameter Reel Width W1 (mm) A0 (mm) B0 (mm) K0 (mm) P0 (mm) P1 (mm) P2 (mm) W (mm) Pin1 Quadrant TDFN-2×3-8BL 7″ 9.5 2.30 3.30 1.10 4.0 4.0 2.0 8.0 Q2 SG Micro Corp www.sg-micro.com TX10000.000 DD0001 Package Type PACKAGE INFORMATION CARTON BOX DIMENSIONS NOTE: The picture is only for reference. Please make the object as the standard. KEY PARAMETER LIST OF CARTON BOX Length (mm) Width (mm) Height (mm) Pizza/Carton 7″ (Option) 368 227 224 8 7″ 442 410 224 18 SG Micro Corp www.sg-micro.com DD0002 Reel Type TX20000.000