BM0203A

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www..bookly..com FFeeaattuurreess  Input Supply Range: 9V ～ 14V  End-Charge-Current Detection Output  Constant Switching Frequency for Minimum Noise  Automatic Battery Recharge  Automatic Shutdown When Input Supply is Removed  Automatic Trickle Charging of Low Voltage Batteries  Battery Temperature Sensing  Stable with Ceramic Output Capacitor  SOP-8L Package DDeessccrriippttiioonn The BM0203A is a complete battery charger controller for two (8.4V) cells lithium-ion batteries. The BM0203A provides a small, simple and efficient solution to fast charge Li-ion battery. An external sense resistor sets the charge current with high accuracy. An internal r esistor divider and precision reference set the final float voltage to 8.4V. When the input supply is removed, the BM0203A automatically enters a low current sleep mode. The BM0203A is available in the SOP-8L package. BM0203A SSttaannddaalloonnee LLii--IIoonn SSwwiittcchh MMooddee BBaatttteerryy CChhaarrggeerr AApppplliiccaattiioonn  Charging Docks  Handheld Instruments  Portable Computers 1.5A PWM开关式两节锂电池8.4V充电管理芯片

www.bookly.com TTyyppiiccaall AApppplliiccaattiioonn CCiirrccuuiitt VIN PROG CHRG SW TS FBGND L1 4.7µH DC+ 10k 22µF 10µF R1 2k VOUT Dual-cell Batteries VREF 1D1 SS34 330µF Electrolytic Capacitor SS24 4.7µF D3 SS14 10k R4 10k 9V ~ 14V BM0203A *The charge current can be set by IOUT = 0.11V/R3. PPiinn AAssssiiggnnmmeenntt AAbbssoolluuttee MMaaxxiimmuumm RRaattiinnggss (Note 1) Note 1: Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2: The BM0203A is guaranteed to meet performanc e specifications from 0°C to 85°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. 8 7 6 5 1 2 3 4 TOP VIEW SOP-8L PIN NAME FUNCTION

1 VREF Voltage Reference to Drive LED

2 VIN Input

3 SW Switch Output

4 GND Ground

5 CHRG Open-Drain Charge Status for Output

6 FB Feedback

7 PROG Charge Current Program

8 TS Temperature Sense

www.bookly.com EElleeccttrriiccaall CChhaarraacctteerriissttiiccss Operating Conditions: TA=25℃, unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Input Voltage Range 9 14 V ISLEEP VIN Sleep Current V IN=7V, VOUT=7.22V 40 μA IIN Input Supply Current Current Mode 260 μA FOSC Oscillator Frequency for Output VIN=9V, VOUT=7V, R3=0.1Ω 0.78 MHz EFFI Efficiency for Output VIN=9V, VOUT=8V 95 % VIN=12V, VOUT=8V 93 % Battery Voltage Regulation Constant-current Charge VO(REG) Output Voltage 8.3 8.44 8.54 V VPROG– VFB Voltage Regulation Threshold 110 mV Precharge Comparator V(MIN) Precharge Threshold V IN=9V 5.5 V Precharge Current Regulation I(PRECHG) Precharge Current Regulation R3=0.1Ω, V IN=9V 100 mA VRCH comparator（Battery Recharge Threshold） V(RCH) Recharge Threshold V IN=12V VO(REG) -150mV V VREF Pin VREF Constant-Current Charge V IN=9V, VOUT=7.8V 3.3 V Charge Termination V IN=9V, VOUT=8.5V 3.3 V CHRG Pin VOL(CHRG) Output(low) Voltage <0.15 V TS Pin VTS-COLD TS Pin Threshold Voltage(Cold) VTS from Low to High 2.422 V VTS- HOT TS Pin Threshold Voltage(Hot) VTS from High to Low 0.479 V ITS TS Pin Output Current 99.5 μA

www.bookly..com TTyyppiiccaall PPeerrffoorrmmaannccee CChhaarraacctteerriissttiiccss Operating Conditions: TA=25℃, unless otherwise specified. Recharge Voltage Offs et from Full Charged Voltage vs. Input Voltage 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 9 1 01 11 21 31 41 51 6 Input Voltage (V) Vrecharge(V) Oscillator Frequency vs.Supply Voltage (Vout=8V) 650 660 670 680 690 700 710 720 730 740 750 9 1 01 11 21 31 41 51 6 Supply Voltage (V) Oscillator Frequency (kHz) Supply Current vs. Supply Voltage 0.25 0.255 0.26 0.265 0.27 0.275 0.28 0.285 0.29 0.295 0.3 9 1 01 11 21 31 41 51 6 Supply Voltage (V) Supply Current(mA) Efficiency vs. Input Voltage 100 9 1 01 11 21 31 41 51 6 Input Voltage (V) Efficiency (%) VBAT= 8V VBAT= 7V

www.bookly .com PPiinn AAssssiiggnnmmeenntt VREF (Pin 1): Voltage reference to drive LED. VIN (Pin 2): Positive Input Supply Voltage. It provides power to the charger. VIN can range from 9V to 16V and should be bypassed with at least a 22μF capacitor. SW (Pin 3): Switch Node Connection to inductor. This pin connects to the drain of the internal main power MOSFET switches. GND (Pin 4): Ground. CHRG (Pin 5): Open-Drain Charge Status Output. When the battery is charging, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge cycle is completed or reverse battery lockout / No AC is detected, CHRG is forced high impedance. FB (Pin 6): Feedback Pin. Receive the feedback voltage from the output. PROG (Pin 7): Charge Current Program. The output current is set by an external resistor according to the following formula: IOUT = 0.11V/R3. TS (Pin 8): Temperature Sense.

www.bookly.com AApppplliiccaattiioonn IInnffoorrmmaattiioonn Functional Description The BM0203A is an advanced s witch mode charger for two-cell Li-Ion applications. Refer to Operation Flow Chart (Figure 1) in this section. Figure1: Operation Flow Chart

www.bookly.com Qualification and Precharge When power is applied, the BM0203A starts a charge-cycle if a battery is already present or when a battery is inserted. Charge qualification is based on battery temperature and voltage. The BM0203A suspends charge if the battery temperature is outside the V TS1 to V TS2 range and suspends charge until the battery temperature is within the allowed range. The BM0203A also checks the battery voltage. If the battery voltage is below the precharge threshold V (MIN) , the BM0203A uses precharge to condition the battery. The conditioning charge rate I (PRECHG) is set at approximately 10% of the regulation current. The conditioning current also minimizes heat dissipation in the external pass-element during the initial stage of charge. See Figure 2 for a typical charge- profile. Figure 2: Typical Charge Profile Current Regulation Phase The BM0203A regulates current while the battery-pack voltage is less than the regulation voltage, VO(REG). The BM0203A monitors charge current by the voltage drop across a sense-resistor, R3, in series with the battery pack, and the resistor, R3, connected to the PROG pin. In order to set the current, first choose R3 based on the regulation threshold VIREG = VPROG – VFB across this resistor. The following formula calculates the value of the Sense resistor: Battery Voltage Regulation The voltage regulation feedback occurs through the FB pin. This input is tied to the positive side of the battery pack. The BM0203A monitors the battery-pack voltage between the FB and GND pins. The BM0203A is offered in a fixed two-cell voltage version (8.4 V).

www.bookly.com Charge Termination Recharge The BM0203A monitors the charging current during the voltage-regulation phase. The BM0203A declares a done condition and terminates charge when the current drops to the charge termination threshold, ITERM. A new charge cycle begins when the battery voltage falls below the VRCH threshold. Battery Temperature Monitoring A negative temperature coefficient (NTC) thermistor located close to the battery pack can be used to monitor battery temperature and will not allow char ging unless the battery temperature is within an acceptable range. Connect a 10kΩ thermistor from the TS pin to ground. With the 99.5µA pull-up current source, the hot temperature voltage threshold is 479mV. For Cold te mperature, the voltage t hreshold is set at 2.422V with 99.5µA of pull-up current. The charge cycle begins or resumes once the temperature is within the acceptable range. Charge Status Indication The BM0203A reports the status of the charge on the CHRG pin. The following table summarized the operation of the CHRG pin. Condition CHRG pin Battery conditioning and charging Low Charge complete (done) Hi-Z Temperature fault or sleep mode Hi-Z The CHRG pin can be used to drive a chip LED. Low-Power Sleep Mode When the input supply is disconnected, the charger automatically enters power-saving sleep mode. This feature prevents draining the battery pack during the absence of VIN. Input and Output Capacitors Since the input capacitor is assumed to absorb all input switching ripple current in the converter, it must have an adequate ripple current rating. Worst-case RMS ripple current is appr oximately one-half of output charge current. Actual capac itance value is not critical. Solid tantalum capacitors have a high ripple current rating in a relatively small surface mount package, but c aution must be used when tantalum capacitors are used fo r input bypass. High input sur ge currents can be created when the adapter is hot-plugged to the charger and solid tant alum capacitors have a known failure mechanism when subjected to very high turn-on surge currents. Selecting the highest possible voltage rating on the capacitor will minimize problems. Consult with the manufacturer before use. The selection of output capacitor C OUT is primarily determined by ESR required to improve ripple voltage and load transient. The output ripple ΔVOUT is approximately bounded by:

www.bookly..com Since ΔIL increases with input voltage, the output ripple is highest at maximum input voltage. Typically, once the ESR require ment is satisfied, the capacitance is adequate for filtering and has the necessary RMS current rating. Switching ripple current splits between the battery and the out put capacitor depending on the ESR of the output capacitor and the battery impedance. EMI considerations usually make it desirable to minimize ripple current in the battery leads. Ferri te beads or an inductor may be added to increase battery impedance at the 500kHz switching frequency. If the ESR of the output capacitor is 0.2Ω and the battery impedance is raised to 4 Ω with a bead or inductor, only 5% of the current ripple will flow in the battery. Board Layout Suggestions When laying out the printed circuit board, the following considerations should be taken to ensure proper operation of the BM0203A.To minimize radiation, pass transistor and the input bypass capacitor traces should be kept as short as possible. The PROG and SW pins should be connected directly to the sense resistor for best charge current accuracy. The ground pin also works as a heat sink, therefore use a generous amount of copper around the ground pin. This is especially important for high VIN and/or high gate c apacitance applications.

www.bookly.com PPaacckkaaggiinngg IInnffoorrmmaattiioonn Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 1.350 1.750 0.053 0.069 A1 0.100 0.250 0.004 0.010 A2 1.350 1.550 0.053 0.061 b 0.330 0.510 0.013 0.020 c 0.170 0.250 0.006 0.010 D 4.700 5.100 0.185 0.200 E 3.800 4.000 0.150 0.157 E1 5.800 6.200 0.228 0.244 e 1.270(BSC) 0.050(BSC) L 0.400 1.270 0.016 0.050 θ 0° 8° 0° 8°