MIC79110 Micrel MIC79110 Simple 1.2A Linear Li-Ion Battery Charger General Description Features The Micrel MIC79110 is a simple and accurate lithium ion battery charger. Featuring a built-in pass transistor, precision programmable current limiting (±5%), and precision voltage termination (±1.5% over temperature) all in a very small package, the MIC79110 packs full functionality into a small space. Other features of the MIC79110 include two independent end-of-charge indications, including a digital indication that is programmable with a resistor-to-ground and an analog current output that is proportional to the output current, allowing for monitoring of the actual charging current. Additional features include very low dropout (500mV over the temperature range), thermal shutdown, and reverse polarity protection. In the event the input voltage to the charger is disconnected, the MIC79110 also provides minimal reverse-current and reversed-battery protection. Available in both fixed 4.2V and adjustable outputs, the MIC79110 is offered in the leadless 3mm x 3mm MLF-10 with an operating junction temperature range of –40˚C to +125˚C. • Input voltage range: 2.5V to 16V • High output voltage accuracy of ±0.75% over –5°C to +60˚C and ±1.5% over temperature • Current Limit ±5% accurate from –5°C ≤ Tj ≤ + 125°C • Programmable End-of-Charge Flag • Analog output proportional to output current • Adjustable and Fixed 4.2V Output • Low dropout voltage of 500mV at 700mA load, over temperature • 1.2A output current • Excellent line and load regulation specifications • Reverse current and reverse battery protection • Thermal shutdown and current limit protection • Tiny 3mm × 3mm MLF™-10 package • Junction Temperature Range: –40°C to +125°C Applications • • • • • • • • • • Cellular phones PDAs Digital cameras Camcorders MP3 players Notebook PCs Portable Meters Cradle chargers Car chargers Battery packs Typical Application 10kΩ MIC79110 VIN VIN SHUTDOWN SD ENABLE DEOC RSET 167Ω 4.2V Li-Ion Cell SNS REOC 4kΩ 4.2VBAT BAT ACHG GND 1kΩ MLF and MicroLeadFrame is a trademark of Amkor Technology. Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com July 2004 1 M9999-072004 MIC79110 Micrel Ordering Information Part Number Voltage Marking Junction Temp. Range MIC79110-4.2BML 4.2V L942 –40°C to +125°C 10-lead 3mm × 3mm MLF™ Package MIC79110BML ADJ L9AA –40°C to +125°C 10-lead 3mm × 3mm MLF™ Pin Configuration SD 1 10 GND SD 1 10 GND RSET 2 9 REOC RSET 2 9 REOC SNS 3 8 DEOC ADJ 3 8 DEOC BAT 4 7 ACHG BAT 4 7 ACHG VIN 5 6 VIN VIN 5 6 VIN 3mm x 3mm Fixed Output 3mm x 3mm Adjustable Output Pin Description Pin Number Pin Name 1 SD 2 RSET Current limit: Sets constant current limit threshold via an external resistor to ground. IRSET = (0.2V/RSET) × 1000 3 SNS (Fixed voltage only): Sense output, connect directly to battery 3 ADJ (Adjustable voltage only): Feedback input. 4 BAT Battery Terminal. Connect to single-cell lithium-ion battery. 5, 6 VIN Input supply pin. 7 ACHG Analog Charge Indicator Output: Current source output equal to 1/1000th of the output current. 8 DEOC Digital End-of-Charge Output: N-Ch open drain output. Low indicates charging, a current that is higher than the programmed current set by REOC is charging the battery. When the current drops to less than the current set by REOC, the output goes high impedance, indicating end-of-charge. 9 REOC End-of-Charge Set: Sets end-of-charge current threshold via an external resistor to ground. IEOC = (0.2V/REOC) × 1000 10 GND Ground MICxxxx/xxxx Pin Function Shutdown Input. Logic High = Off; Logic Low = On X-2 DRAFT Rev m/03-A Month 2003 MIC79110 Micrel Absolute Maximum Ratings (1) Operating Ratings (2) Input Supply Voltage (VIN) .................................. 0V to 18V Shutdown Input Voltage (V) ................................ 0V to 18V Output Voltage (ADJ) .................................................... 10V Power Dissipation .................................... Internally Limited Junction Temperature .............................. –40°C to +125°C Input Supply Voltage ........................................ 2.5V to 16V Shutdown Input Voltage (V) .................................. 0V to 7V Output Voltage (ADJ) ................................................... 9.6V Junction Temperature Range (TJ) ........... –40°C to +125°C θJA (MLF™-10) ........................................................ 60°C θJC (MLF™-10) ......................................................... 2°C Electrical Characteristics TA = 25°C with VIN = VOUT + 1V; ILOAD = 100µA ; CBATT = 10µF; SD = 0V; RSET=1kΩ. Bold values indicate –40ºC < TJ < +125°C; unless otherwise specified. Parameter Condition Min Output Voltage Accuracy Variation from VOUT = 4.2V; TJ = –5°C to +60°C; ILoad = 50mA ADJ Pin Voltage Accuracy Max Unit –0.75 +0.75 % –1.5 +1.5 % 0.6045 V +0.1 %/V 0.5955 Typ 0.6 Line Regulation VIN = Vout + 1V to 16V @ ILOAD = 50mA Load Regulation ILOAD = 0.1mA to 1A 0.3 ILOAD = 100mA, Rset = 167Ω 160 250 mV ILOAD = 700mA, Rset = 167Ω 375 550 mV ILOAD = 10mA, Rset = 167Ω 2 3 mA ILOAD = 700mA, Rset = 167Ω 24 35 mA VIN Pin Current SD = VIN 120 300 µA Shutdown Pin Current SD = 5.2V, VBAT = 0 0.1 5 µA Shutdown Input Threshold Logic High, regulator off Dropout Voltage(3) Ground Current –0.1 1.1 V Logic Low, regulator on 0.9 Shutdown Hysteresis Current Limit Accuracy(4, 5) % 60 VOUT = 0.9 × VNOM; IOUT = 1.2A, RSET = 167Ω, TJ = –40°C to +85°C VOUT = 0.9 × VNOM; IOUT = 0.1A, RSET = 2kΩ Current Limit Setpoint Range(5) Maximum Current Limit RSET shorted to ground, VBAT = 0.9 × VNOM VBAT Reverse Current VIN = High impedance or ground V mV –5 +5 % –20 +20 % 0.1 1.2 A 1.65 2.5 A 4.2 20 µA 1.25 Digital End–of–Charge (DEOC) Output IEOC (6, 7) REOC = 4kW Current Falling 35 30 50 65 70 mA mA IEOC (6, 7) REOC = 4kW Current Rising 50 40 70 95 100 mA mA DEOC Logic–Low Voltage IDEOC = 5mA, IBAT = 700mA 0.74 0.95 V DEOC Leakage Current Logic High = VIN = 16V 0.1 DEOC On Resistance VIN = +5V 150 190 Ω REOC Maximum Current Limit REOC shorted to ground 0.5 1.0 2.0 mA IBAT = 50mA 45 46 55 µA IBAT = 1.2A, TJ = –40°C to +85°C 800 950 1150 µA µA Analog Charge Indicator (ACHG) Output ISOURCE(8) Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. July 2004 3 M9999-072004 MIC79110 Micrel 3. Dropout Voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V differential. For outputs below 2.5V, dropout voltage is the input-to-output voltage differential with the minimum input voltage 2.5V. Minimum input operating voltage is 2.5V. 4. Vnom denotes the nominal output voltage. 5. IRSET = (0.2V/RSET) * 1000 6. Output Current IEOC when Digital End-of-Charge output goes high impedance. Currents greater than IEOC, the DEOC output is low, currents lower than IEOC, DEOC is high impedance. 7. IEOC = (0.2V/REOC) * 1000 8. ISOURCE is the current output from ACHG pin. A resistor to ground from the ACHG pin will program a voltage that is proportional to the output current. Block Diagram VIN BAT Current Limit Sense SNS + DEOC SD RSET Thermal Shutdown VREF End of Charge Detect Current Limit Set ACHG REOC GND MIC79110 Block Diagram M9999-072004 4 July 2004 MIC79110 Micrel 4.5 250mA -40 500mA -30 -20 V -10 1 10 100 FREQUENCY (kHz) 70 65 60 55 50 45 ISET = 1.2A 40 -40 -20 0 20 40 60 80 100 TEMPERATURE (ºC) Ground Current vs. Supply Voltage 3.5 2.5 2.0 1.5 1.0 0.5 35 30 0 1 2 3 4 SUPPLY VOLTAGE (V) Dropout Voltage vs. Temperature 1.5 1.0 0.5 20 15 10 5 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 1 2 3 4 SUPPLY VOLTAGE (V) 4.3 4.1 3.9 3.7 I = 0A BAT 3.5 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) 50 40 30 20 10 10 Battery Voltage vs. Temperature 0.5 0.4 0.3 0.2 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) Dropout Voltage 1.05 1.00 0.95 0.90 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) VOUT=4.2V 700 600 500 400 300 200 100 0 5 1.10 200 400 600 800 1000 1200 BATTERY CURRENT (mA) VOUT = 4.2V 0.7 I =0A BAT 0.6 Shutdown Threshold vs. Temperature 5 20 800 IBAT=1.2A 1 2 3 4 SUPPLY VOLTAGE (V) 30 0.1 Ground Current vs. Supply Voltage 0 40 0.8 5.1 4.9 4.7 4.5 Battery Current vs. Ground Current 50 0 0 5 Ground Current vs. Temperature 5.5 5.3 1.15 IBAT=0A IBAT = 1.2A 2.0 0 5 25 July 2004 2.5 60 IBAT=0A 3.0 0 GROUND CURRENT (mA) 75 IBAT = 0A 3.0 0 0 1000 GROUND CURRENT (mA) GROUND CURRENT (mA) = VOUT+1V Ground Current vs. Temperature 80 GROUND CURRENT (mA) IN VOUT = 4.2V 0 0.1 DROPOUT VOLTAGE (mV) 50mA 3.5 DROPOUT VOLTAGE (mV) 0mA -50 4.0 0 4.5 BATTERY VOLTAGE (V) -60 SHUTDOWN (V) PSRR (dB) -70 60 GROUND CURRENT (mA) BATTERY VOLTAGE (V) -80 Dropout Characteristics ACCURACY (%) PSRR -90 0.2 0.4 0.6 0.8 1 1.2 BATTERY CURRENT (A) Battery Current vs. Battery Voltage 4.0 3.5 3.0 2.5 2.0 1.5 1.0 R SET = 165kΩ 0.5 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 BATTERY CURRENT (A) M9999-072004 MIC79110 Micrel 2.5 2.0 1.5 1.0 0.5 0 0 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 100 200 300 400 500 600 BATTERY CURRENT (mA) VIN=0V VRSET=0V 10 8 6 4 2 50 45 40 35 30 25 20 M9999-072004 600 500 400 300 200 100 04 3.5 3 2.5 2 1.5 1 0.5 0 REOC (kΩ) Battery Current 505 15 10 5 0 -20 0 20 40 60 80 100 120 -40 TEMPERATURE (°C) REVERSE BATTERY CURRENT (µA) 00 1 2 3 4 5 6 7 8 9 10 BATTERY VOLTAGE (V) DEOC Threshold vs. REOC DEOC Hysteresis HYSTERESIS (mV) REVERSE CURRENT (µA) 12 1000 900 800 700 RSET (kΩ) Reverse Current vs. Battery Voltage 14 DEOC THRESHOLD (mA) 3.0 VIN = VOUT+1V VOUT = 4.2V 1.6 BATTERY CURRENT (A) 3.5 1.8 0.50 = 2kΩ VIN = VOUT+1V VOUT = 4.2V SET 0 0.05 0.10 R 4.0 BATTERY CURRENT (A) BATTERY VOLTAGE (V) 4.5 Battery Current vs. RSET 0.15 0.20 0.25 0.30 0.35 0.40 0.45 Battery Current vs. Battery Voltage 504 503 502 501 500 RSET = 40Ω 499-5 5 15 25 35 45 TEMPERATURE (°C) 55 Reverse Battery Current vs. Temperature 9 8 7 6 5 4 3 2 1 0 -20 0 20 40 60 80 100 120 -40 TEMPERATURE (°C) 6 July 2004 MIC79110 Micrel Line Transient Load Transient Load Current (500mA/div) 16V VIN=3.6V 5V VIN=3.6V 100µA Output Voltage (200mV/div) TIME (20µs/div.) TIME (100µs/div.) Shutdown Transient Shutdown (2V/div) Battery Switch (1V/div) VBAT (1V/div) IBAT (500mA/div) Battery Current Enable Transient TIME (100µs/div.) July 2004 VIN = 3.6V 1.2A Output Voltage (500mV/div) Input Voltage (5V/div) VIN = 3.6V TIME (200µs/div.) 7 M9999-072004 MIC79110 Micrel Constant Output Voltage/Current Charging The MIC79110 features constant voltage and constant current output to correctly charge lithium-ion batteries. The constant voltage is either 4.2V or adjustable. The constant current is set by the Rset pin and is constant down to around 300mV. Since Rset can be set below 500mA, the minimum output current is set at 500mA for output voltages below 100mV. This minimum voltage starts the charging process in lithium-ion batteries. If the output current is too low, the battery will not begin charge. Application Information M9999-072004 MIC79110 V-I Curve Detailed Description The MIC79110 forms a complete charger for 1-cell Lithiumion batteries. It includes precision voltage control (0.75% over temperature) to optimize both cell performance and cycle life. All are compatible with common 4.2V Lithium-ion chemistries. Voltages other than 4.2V can be obtained with the adjustable version. Other features include current limit, end-of-charge flag and end-of-charge current limit using an external resistor. The shutdown pin enables low quiescent current when not charging. Current Limit Mode MIC79110 features an internal current limit that is set by the Rset pin with a resistor-to-ground. The maximum current is calculated by the following equation: IRset = (0.2/Rset) × 1000 Using a 167Ω Rset resistor will achieve the maximum current limit for the MIC79110 at 1.2 amperes. End of Charge REOC pin is connected to a resistor-to-ground. This resistor is used to set the end of charge current for the lithium ion battery as follows: IREOC = (0.2/REOC) × 1000 Using a 4kΩ REOC resistor will set the end-of-charge current at 50mA. IReoc should be set at 10% of the battery’s rated current. Digital End-of Charge Output This pin is the output of an open drain. When tied high to the supply using a resistor, the output will toggle high or low depending on the output current of Ibat. - Low state indicates that the Ibat current is higher than the programmed current set by REOC. - High state indicates that the Ibat current is lower than the programmed current set by REOC. The output goes high impedance indicating end-ofcharge. Analog-End-Of-Charge Output The ACHG pin provides a small current that is proportional to the charge current. The ratio is set at 1/1000th of the output current. Shutdown The SD pin serves as a logic input (active low) to enable the charger. Built-in hysteresis for the shutdown pin is 50mV over temperature. Reverse Polarity Protection In the event that VBAT > VIN and the shutdown pin is active low, there is reverse battery current protection built in. The current is limited to less than 10µA over temperature. I Current Standard V-I Curve Standard V-I Curve IMAX = (0.2/RSET)×1000 0.7V I Current 500mA MIC79110 V-I Curve Lithium Ion Batteries Lithium-ion batteries are charged in two stages to reach full capacity. The first stage charges the battery with maximum charge current until 90% of the battery cell’s voltage limit is reached. The second stage tops off the charge with constant voltage charge as the charge current slowly decreases. End of charge is reached when the current is less than 3% of the rated current. A third stage will occasionally top off with charge with constant voltage charge if the battery voltage drops below a certain threshold. Voltage/Cell Charge Current Stage 1 Max. charge current is applied until the cell voltage limit is reached Stage 2 Max. cell voltage is reached Charge current starts to drop as full charge is approached Stage 3 Occasional topping charge about 1 per 500h CURRENT VOLTAGE (A/V) 1.25/5 .... 1.00/4 0.75/3 0.50/2 Terminate charge when current < 3% of rated current 0.25/1 .... 1 2 3 TIME (hrs) All lithium-ion batteries take approximately 3 hours to charge with the second stage taking twice as long as the first stage. Some chargers claim to be fast chargers by skipping the second stage and just charges the battery until the cell voltage is reached. This only charges the battery to 70% 8 July 2004 MIC79110 Micrel capacity. An increase in the charge current during stage 1 does not shorten the total charge time. It will only shorten the time for stage 1 to complete and lengthen the time in stage 2. The lithium-ion loses charge due to aging whether it is used or not. Do not store the batteries at full charge and high heat because it will accelerate the aging process. Try and store with 40% charge and in a cool environment. Lithium-Ion Safety Precautions Every lithium ion battery pack should have a safety board which monitors the charge and discharge of the pack and prevents dangerous occurrences. The specifications of these safety boards are dictated by the cell manufacturer and may include the following: • Reverse polarity protection • Charge temperature must not be charged when temperature is lower than 0°C or above 45°C. • Charge current must not be too high, typically below 0.7C • Discharge current protection to prevent damage due to short circuits. • Protection circuitry for over voltage applied to the battery terminals. • Overcharge protection circuitry to stop charge when the voltage per cell rises above 4.3V. • Over discharge protection circuitry to stop discharge when the battery voltage falls below 2.3V (varies with manufacturer). • Thermal shutdown protection for the battery if the ambient temperature is above 100°C. Start Charging Lithium-Ion Battery Standby Mode Do not charge 1 Shutdown Pin 0 Charging Monitor Ibat Deoc Flag is High Stop Charge Stop Charge Current Limit Irset Deoc Flag is Low Continue Charge Ibat Ieoc<Ibat<Irset <4.3V Stop Charge End of Charge Battery Charging <Ieoc Battery Voltage >4.3V <125C Die Temperature >125C July 2004 9 M9999-072004 MIC79110 Micrel Simple Charger - External Trigger to Reset Charge Cycle reset External Trigger to Reset Charge Cycle Reset 1 - VIN steps up to a voltage greater than VBAT. 2 - SD held low by CSD until active high DEOC pulls shutdown low. 3 - Deoc releases SD, resistor pull-up from SD pin'vo VIN pulls VSD to VIN. 4 - An external signal applied to the gate of the external NCH pulls SD pin-to-ground. 5 - Ibattery is near zero (2 to 4µA) because VIN is below VBAT and the reverse shutoff circuit is turning the charge to the battery off. 6 - IBAT is decreased as VBAT approaches VBAT set voltage. IBAT decreases below the DEOC threshold and DEOC is released high allowing VSD to go high 7 - External NCH turns part on, after a small delay IBAT turns on. 8 - Active high DEOC pin goes high because of reverse shutoff. DEOC remains high until IBAT exceeds DEOC threshold, then goes low. 9 - IBAT decreases below (see #5) DEOC threshold. 10 - Active low DEOC is high because VIN is below VBAT and reverse shutoff holds DEOC comparator off. As VIN increases above VBAT, the reverse voltage shutoff turns off, DEOC comparator becomes active. While IBAT is below DEOC threshold DEOC active low goes low, when IBAT exceeds DEOC threshold IBAT goes high. 11 - Legitimate Activation of active low DEOC until SD shuts down part and DEOC AL (active low) goes high. Reset charge cycle. SD GND RSET REOC 200Ω 2kΩ VSENSE DEOC VBAT ACHG VIN CDELAY 0.1µF VIN 1MΩ The VIN voltage steps up to a voltage greater than VBAT. When Vin is below Vbat, the Ibat current is near zero and the reverse shutoff circuit is turning the charge to the battery off. The IBAT slowly increases as VIN rises above VBAT. DEOC is pulled low when the Ibat current is above the Ieoc current set by REOC. When the DEOC is low, the shutdown pin is also forced low and helps discharge CSD. When the VBAT reaches the set voltage, the Ibat begins to slowly drop. When the Ibat is less than the IEOC threshold, the DEOC output goes high impedance, indicating end-of-charge. When an external signal is applied to the gate, the external NCH pulls the SD and DEOC pins to ground. This restarts the charging process. Vin VSD Vbat set voltage Vbat SD threshold 1 2 2 3 Vgate 6 5 4 7 Ibattery 8 Active high DEOC pin 9 9 10 M9999-072004 Active low DEOC pin 10 July 2004 MIC79110 Micrel Auto Top Off Charger - Application Circuit SD RSET Top-Off-Charger with Internal Reset - Application Circuit SD GND RSET REOC 200 ohms 200 ohms 2kΩ 2kΩ VSENSE DEOC VSENSE DEOC VBAT R1 3M R2 1M VIN GND REOC VBAT ACHG VIN R1 3meg R2 1meg ACHG VIN VIN VIN LI-ion Battery LI-ion Battery VIN This circuit is similar to the auto top off charger circuit mentioned above except that the DEOC pin is externally triggered to restart the charging cycle. It still uses the same resistor divider to set the minimum battery voltage before the lithium-ion needs to be recharged. Auto-Shutdown Using Shutdown Pin Lithium-Ion batteries will begin to lose their charge over time. The MIC79110 can be configured to automatically recharge the battery if the voltage drops below a certain voltage. This minimum voltage is set by a resistor divider at the battery and connected to the SD pin. When the battery voltage falls below the minimum voltage, the SD pin is pulled low to start the normal charging process. Battery charging VIN Self discharge VOUT VIN VBAT R1 SD CIN GND R2 4.2 V COUT VBattery VBat min Deoc trip IBattery The shutdown pin on the MIC79110 can be used to automatically shutdown the battery charger when the input voltage rises above a safe operating voltage. To keep the part from heating up and entering thermal shutdown, we can connect the shutdown pin to VIN using a resistor divider. Use the following equation to setup the maximum VIN. Vs R1 VBat min=0.975V( R2 +1) R2=1meg VIN (MAX) VBat min 1 R1=( 0.975 -1) R 2 VSD = R1 R2 +1 Vbat set (4.2V) The MIC79110 can be connected to a wall wart with a rectified DC voltage and protected from over voltages at the input. Vbat 4 Vbat low set by divider. 2 3 1 SD Voltage 1 - SD not held low by active high DEOC because DEOC Comparator’s inputs do not common-mode to ground. Divider holds SD low so part can start. 2 - SD held low by divider 3 - SD held low by active high DEOC 4 - Divider voltage above SD threshold and DEOC open 5 - Divider voltage drops below SD threshold and charging begins again. July 2004 11 M9999-072004 MIC79110 Micrel Package Information 0.85 +0.15 —0.05 1.60 +0.15 —0.15 3.00 BSC. 0.80 +0.15 —0.15 1.50 BSC. 0.01 +0.04 —0.01 0.48 typ. PIN 1 ID 0.23 +0.07 —0.05 1 1 1.50 BSC. +0.15 2 1.15 —0.15 2 5.0 3.00 BSC. 3 2.30 +0.15 —0.15 3 0.20 dia 0.50 BSC. 0.40 +0.15 —0.05 TOP SEATING PLANE BOTTOM TERMINAL TIP 0.23 +0.07 —0.05 0.50 BSC. 0.01 +0.04 —0.01 0.50 BSC. TERMINAL TIP ODD TERMINAL SIDE EVEN TERMINAL SIDE MICREL, INC. 1849 FORTUNE DRIVE TEL + 1 (408) 944-0800 FAX SAN JOSE, CA 95131 + 1 (408) 474-1000 WEB USA http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2004 Micrel, Incorporated. M9999-072004 12 July 2004