SC1410A Constant Voltage/Constant Current Battery Charger POWER MANAGEMENT Description Features The SC1410A is designed to provide a simple, fast charging solution for rechargeable batteries that require constant-current and/or constant voltage charging, including nickel-cadmium (NiCd), nickel-metal-hydride (NiMH) and lithium-ion (Li-Ion). With a voltage reference accuracy of 0.5% the SC1410A satisfies the tight constant-voltage charging requirements of lithium cells. Charges NiCd, NiMH and Lithium-lon batteries High efficiency current mode with 1.5A internal The SC1410A simplifies battery charger design by integrating a high efficiency PWM with an internal 1.5A switch and 0.1ohm current sense resistor, while the 500kHz switching frequency allows a very small inductor to be used. Only one external resistor is required to program the full 1.5A charging current to within 5% accuracy. switch and sense resistor 3% Typical charging current accuracy Precision 0.5% voltage reference for voltage mode charging or over voltage protection Current sensing can be either terminal of battery Low reverse battery drain current: 3A Charging current soft start Shutdown control 500kHz switching uses small inductor Applications Chargers for NiCd*, NiMH* and Lithium batteries Step down switching regulator with precision Charging circuits for batteries ranging from 2V to 18V are easily implemented using the SC1410A. No ground sensing of current is required, allowing the battery's negative terminal to be connected directly to ground. No blocking diode is required between the IC and the battery since the SC1410A enters sleep mode and consumes only 3A when the AC adapter is unplugged. Other features include soft start, overvoltage protection, and a shutdown pin. The SC1410A is available in a 16 pin QSOP package. adjustable current limit *NiCd and NiMh batteries require external charge termination circuitry not contained in the SC1410A Typical Application Circuits Figure 2: Charging Lithium batteries Figure 1: 500kHz Li-lon cell phone charger 1N5819 SW Cin 0.22uF 1N4148 6.19k OVP SENSE 1N4148 BAT Cout 1k 300 6.19k 1uF BAT Cout SC1410A 22uF 4.2V 10uF VC OVP SENSE + 1k 300 + 22uF 4.2V NDS355N 70.6k 0.25% 100k 0.25% + NDS355N 4.2V 240k 0.25% 100k 0.25% 1410 SCH41 Revision: September 14, 2005 1N5819 0.1uF BOOST GND 1uF SC1410A Cin PROG 33uH VC 11 to 18V VCC 0.22uF 0.1uF BOOST GND SW 1N5819 10uF PROG 10uH 1N5819 8.2 to 18V VCC 1410 SCH42 1 www.semtech.com SC1410A POWER MANAGEMENT Absolute Maximum Ratings Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. Parameter Symbol Maximum Units Supply Voltage VVCC(MAX) 20 V -3 V +24/-5 V 8 V 1.5 A Switch Voltage with respect to GND Boost Pin Voltage with respect to GND VC, PROG, OVP Pin Voltage IBAT (Average) Thermal Resistance, Junction to Case JC 30 C/W Thermal Resistance, Junction to Ambient JA 75 C/W Operating Temperature Range TA 0 to 70 C Storage Temperature Range TSTG -65 to +150 C Lead Temperature (Soldering) 10 Sec. TLEAD 300 C Electrical Characteristics Unless specified: VVCC = 16V, VBAT = 8V, IBAT=0 Parameter Conditions Min Typ Max Units 4.5 6.5 mA Supply Current VPROG = 2.7V, VVCC 20V DC Battery Current, IBAT 8V < VVCC < 18V, 0V < VBAT 16V RPROG = 4.93k RPROG = 3.28k RPROG = 49.3k 0.93 1.35 75 1.0 1.5 100 1.07 1.65 125 A A mA Minimum Input Operating Voltage Undervoltage lockout 6.2 7 7.8 V Reverse Current from Battery VBAT 12V, 0C TJ 70C 3 20 A Boost Pin Current VVCC - VBOOST 18V 2V VBOOST - VVCC 16V (Switch ON) 0.25 6 30 14 A mA VVCC = 10V ISW = 1.5A. VBOOST - VSW 2V ISW =1A,VBOOST - VSW < 2V 0.5 0.65 2.0 IBOOST/ISW During Switch ON VBOOST = 24V, ISW 1A 20 35 mA/A Switch OFF Leakage Current VSW = 0V, VVCC 18V 4 200 A VVCC-2 V 20 A Switch Switch ON Resistance Maximum VBAT with Switch ON Minimum IPROG for Switch ON Minimum IPROG for Switch OFF 2005 Semtech Corp. 4 VPROG 1V 0.5 2 2.4 mA www.semtech.com SC1410A POWER MANAGEMENT Electrical Characteristics (Cont.) Unless specified: VVCC = 16V, VBAT = 8V, IBAT=0 Parameter Conditions Min Typ Max Units Sense Resistance (RS1) 0.08 0.12 Total Resistance from SENSE to BAT 0.2 0.25 -200 700 -375 1300 A Current Sense Amlifier Inputs (SENSE, BAT ) BAT Bias Current VVC < 0.3V VVC > 0.6V Input Common Mode Limit (Low) -0.25 V Input Common Mode Limit (High) VVCC-2 V Reference Reference Voltage RPROG = 3.28k, Measured at OVP with VA supplying IPROG and Switch OFF 2.448 2.465 2.482 V Reference Voltage Tolerance 8V VVCC 18V, 0C TJ 70C 8V VVCC 18V, 0C TJ 125C 2.446 2.441 2.465 2.480 2.489 V Switching Frequency 440 500 550 kHz Maximum Duty Cycle 77 Oscillator % Current Amplifier (CA2) Transconductance VVC = 1V, IVC = 1A 150 250 Maximum VVC for Switch OFF IVC Current (Out of Pin) VVC 0.6V 550 mho 0.6 V 100 A 2.5 mho Voltage Amplifier (VA) Transconductance Output Source Current,VVCC = 10V OVP Input Bias Current 2005 Semtech Corp. Output current from 100A to 500A 0.5 VPROG = VOVP = VREF +30mV 1.3 At 0.75mA VA Output Current 3 1.2 mA 50 150 nA www.semtech.com SC1410A POWER MANAGEMENT Pin Configuration Ordering Information Device TOP VIEW P ackag e (1) SC1410ACQS.TR GND 1 16 GND SW 2 15 VCC2 BOOST 3 14 VCC1 GND 4 13 PROG OVP 5 12 VC NC 6 11 NC SENSE 7 10 BAT GND 8 9 GND SC1410ACQSTRT (2) QSOP-16 Notes: (1) Only available in tape and reel packaging. A reel contains 2500 devices. (2) Lead free product. This product is fully WEEE and RoHS compliant. (16 Pin QSOP) Pin Descriptions Pin Number Pin Name 1,8,9,16 GND These Ground Pins are fused to the die attach paddle for optimum thermal performance connect these pins to large PCB copper area. 2 SW Switch output. 3 BOOST 4 GND Ground pin. 5 OVP Feedback node for constant voltage output, ground if not required. 6,11 NC 7 SENSE 10 BAT Current amplifier CA1 input. 12 VC Control signal of the inter loop of the current mode PWM. Switching starts at 0.7V and higher VC corresponds to higher charging current in normal operation. A capacitor of at least 1uf to GND filters out noise and controls the rate of soft start. To shut down switching, pull this pin low. Typical output current is 30uA. 13 PROG This pin is for programming the charging current and for system loop compensation. 14 VCC1 Supply for the chip. 15 VCC2 Supply for the chip. 2005 Semtech Corp. Pin Function This pin is used to bootstrap and drive the switch power NPN transistor to a low on-voltage for low power dissipation. No connection, do not connect to these pins. Current amplifier CA1 input. Sensing can be at either terminal of the battery. 4 www.semtech.com SC1410A POWER MANAGEMENT Block Diagram + VCC SHUTDOWN 500kHz OSCILLATOR VCC - 0.7V BOOST S Q + R VSW QSW VBAT SLOPE COMP. - SW + + CA1 - + VC 1k IPROG = 500uA/A IBAT + VA - 60k CA2 SENSE RS1 BAT OVP VREF 2.465V + PROG 1410 SCH22 C PROG R PROG I PROG Theory of Operation As the voltage at the OVP pin rises, reaching VREF, the voltage amplifier VA sources current into RPROG, reducing IBAT. IBAT will go from full programmed current to zero with only a few mV increase at the OVP pin. The SR latch is set by the 500kHz oscillator, turning on the output transistor (QSW). The outer control loop of CA2, the 60k resistor and external components on the VC pin sets a DC level against which the inner loop DC and AC current information generated by RS1, CA1 and the buffer and divider is compared. When the voltage at the + pin of the comparator exceeds the DC level at the - pin, the latch is reset and QSW turned off. The SC1410A is a current mode, buck converter which operates in constant current (CC) and constant voltage (CV) modes. There are two feedback mechanisms, a fraction of the output voltage is sensed at OVP and the output current is sensed by RS1. When either or both of these feedback mechanisms are implemented, the loops act to maintain a nearly constant voltage of VREF at the PROG pin. In CC mode, the current amplifier CA1 and the sense resistor RS1 combine to generate a program current (IPROG) to output current ratio of 500A/A. The programmed output current is therefore given by :IBAT = 2000 IPROG = 2 2.465 RPROG or R PROG = 4.93 IBAT where IBAT is in Amps, RPROG in k 2005 Semtech Corp. 5 www.semtech.com SC1410A POWER MANAGEMENT Component Selection Soft Start - A capacitor on the VC Pin implements the soft start function for the SC1410A. Soft start controls the rate at which output voltage rises so that high current surges can be avoided or minimized. In order for soft start to be effective, the soft start time must be much longer than the ramp up time of the input supply. The ratio of the soft start cap to the PROG pin cap must also be chosen to ensure that the PROG pin does not lag the soft start. Recommended values for the soft start capacitor and the PROG pin capacitor are 1uF and 0.1uF respectively. The input supply must also be specified with some care. It is possible for a current limited or power limited input supply to "latch-up" and operate at a lower output voltage than it is designed for, be sure that the supply can provide adequate power at the UVLO point. For example, charging a battery at 800mA with a 3.6V terminal voltage (typical for a partially discharged single cell Li-Ion) requires 3.6*0.8=2.88W, allowing for efficiency one might choose a 3.6W Input supply or 300mA at 12V. However if the 300mA is a hard current limit, as the supply ramps up through the SC1410A UVLO at 7V, the available output power is only 7*0.3 or 2.1W. If soft start is too fast or the input supply ramp up is too slow, the input supply will become "stuck" at this low level and will oscillate around the 1410A UVLO point. To prevent this from happening, choose a higher power input supply or ensure soft start timings are adequate or use an external UVLO, holding down the VC pin until the input supply has ramped to a voltage where it can sustain the required output power. Inductor - A suitable value of inductor for most applications is 10uH, this value is a compromise between ripple current and size. A 10uH inductor will result in less than 1A pk. pk. ripple at maximum input voltage and 50% duty cycle, which is the worst case. Higher inductance values will result in lower ripple but for similar current ratings, will be physically larger and more costly. The inductor should be sized so that it will not saturate at peak current. Peak inductor current is:IPK = IO + (V - VO ) VO IN VIN L f 2 Input and Output capacitors - There are no special requirements for input and output capacitors beyond the capability to handle the ripple current. For the input capacitor(s) the RMS ripple current rating required is approximately 50% of IBAT and for the output capacitor(s) the worst case RMS ripple rating required can be determine from:IRMS = (V - VO ) VO IN VIN L f 2 3 Note that this ripple rating is not a function of IBAT. Worst case ripple current rating requirement occurs at VO=VIN/2. Good choices for input and output capacitors are high value ceramics, special polymer capacitors such as those from Panasonic or, if space permits, low ESR aluminum electrolytics. Tantalum capacitors are not recommended, particularly for input capacitors unless they are specially tested for surge current and heavily derated for voltage. RPROG - The current programming resistor determines the charging current according to the following equations:IBAT = 2000 IPROG = 2 2.465 RPROG or R PROG = 4.93 IBAT where IBAT is in Amps, RPROG in k 2005 Semtech Corp. 6 www.semtech.com SC1410A POWER MANAGEMENT Typical Characteristics Efficiency at 4.2V output 100% Vout=4.2V Input diode losses included Efficiency (%) 90% 8V 80% 12V Vin=18V 70% 60% 0.0 0.2 0.4 0.6 0.8 1.0 0.8 1.0 Io (A) Efficiency at 8.4V output 100% Vout=8.4V Input diode losses included Efficiency (%) 90% 12V Vin=15V 80% 70% 60% 0.0 0.2 0.4 0.6 Io (A) VC Pin characteristics -200 IVC (A) -150 -100 -50 0 0.0 0.5 1.0 1.5 2.0 VVC (V) 2005 Semtech Corp. 7 www.semtech.com SC1410A POWER MANAGEMENT Outline Drawing - QSOP-16 DIMENSIONS MILLIMETERS INCHES DIM MIN NOM MAX MIN NOM MAX A D e N 2X E/2 E1 ccc C 2X N/2 TIPS .069 .053 .010 .004 .065 .049 .008 .012 .010 .006 .189 .193 .197 .150 .154 .158 .236 BSC .025 BSC .010 .020 .016 .033 .041 (.041) 16 0 8 .004 .007 .008 A A1 A2 b c D E1 E e h L L1 N 01 aaa bbb ccc E 1 2 3 e/2 B D aaa C SEATING PLANE h A2 A C h A1 bxN bbb 1.35 1.75 0.25 0.10 1.65 1.25 0.20 0.31 0.25 0.15 4.80 4.90 5.00 3.80 3.90 4.00 6.00 BSC 0.635 BSC 0.25 0.50 0.40 0.84 1.04 (1.04) 16 0 8 0.10 0.18 0.20 H C A-B D c GAGE PLANE 0.010 SIDE VIEW SEE DETAIL A L (L1) DETAIL 01 A NOTES: 1. CONTROLLING DIMENSIONS ARE IN INCHES (ANGLES IN DEGREES). 2. DATUMS -A- AND -B- TO BE DETERMINED AT DATUM PLANE -H3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 4. REFERENCE JEDEC STD MO-137, VARIATION AB. 2005 Semtech Corp. 8 www.semtech.com SC1410A POWER MANAGEMENT Land Pattern - QSOP-16 X DIM (C) G C G P X Y Z Z Y DIMENSIONS INCHES MILLIMETERS (.195) .123 .025 .016 .072 .268 (4.96) 3.12 0.635 0.40 1.84 6.80 P NOTES: 1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 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