L6902 1A CONSTANT CURRENT BATTERY CHARGER PRODUCT PREVIEW UP TO 1A BATTERY CHARGER OPERATING INPUT VOLTAGE FROM 8V TO 36V PRECISE 3.3V (±2%) REFERENCE VOLTAGE 5% CHARGING CURRENT ACCURACY OUTPUT VOLTAGE ADJUSTABLE FROM 1.235V TO 34V 250KHz INTERNALLY FIXED FREQUENCY VOLTAGE FEEDFORWARD ZERO LOAD CURRENT OPERATION INTERNAL CURRENT LIMITING PROTECTION AGAINST FEEDBACK DISCONNECTION THERMAL SHUTDOWN SO8 MINIDIP ORDERING NUMBERS: L6902D L6902N DISTRIBUTED POWER SUPPLY MOBILE PC & SUBNOTEBOOK APPLICATION CHARGES FOR NiCd, NiMH AND LITHIUM BATTERIES SIMPLE, SMALLER & EFFICIENT STEPDOWN CONVERTERS BATTERY EQUIPPED SYSTEMS DESCRIPTION The L6902 is a complete and simplest IC for batteries charging application. Based a voltage mode structure it is a step down switching converter integrating a current error am- TEST AND APPLICATION CIRCUIT Vi = 8 V t o 3 6 V 5 8 L6902 Vo ( A d j ) 6 1 V r ef C1 4 ( 3 . 3 V) 10 0 7 3 L1 2 56 R s en se 0.1 D1 R1 C3 47 5K C2 22 n Ocober 2000 This is preliminary information on a new product now in development. Details are subject to change without notice. 1/7 L6902 DESCRIPTION (continued) plifier to have a constant voltage and constant current control for a most efficient charging solution of the modern rechargeable batteries including lithium-ion, NiMH and NiCd. By means of 0.1ohm onboard current sense resistor and the availability of the current sense pins (both compatible to Vcc and for Cs- compatible with GND too) a charging current programming is very simple and accurate (+/-5%). The device can charge batteries in a wide range of outputs voltage (from 1.26 to 34V) from a single cell till to multiple cells or battery packs. The internal robust P-Chanel DMOS transistor with a typical of 250mohm assures high efficiency and a minimum dropout even at high output current level. The internal limiting current (latched function) of typical value of 3A protects the device from accidental output short circuit avoiding dangerous batteries damage. Other protections as on chip overvoltage protection, thermal shutdown togheter the internal frequency modulation complete the device for a safe and reliable application. The internal fixed switching frequency of 250KHz, and the possibility to have the device in SO-8 pin allows to built an ultra compact battery charger with a minimum board space. PIN CONNECTION OUT 1 8 VCC CS+ 2 7 G ND CS- 3 6 VR E F COMP 4 5 FB PIN FUNCTION N. Name Description 1 OUT 2 CS+ Current Error Amplifier input (current sense at higher voltage) 3 CS- Current Error Amplifier input (current sense at lower voltage) 4 COMP 5 FB 6 VREF 3.3V VREF. No cap is need for stability. 7 GND Ground 8 VCC Unregulated DC input voltage. Regular Output E/A output to be used for frequency compensation Stepdown feedback input. Connecting directly to this pin results in an output voltage of 1.23V. An external resistive divider is required for higher output voltages. THERMAL DATA Symbol R th j-amb 2/7 Parameter Thermal Resistance Junction to Ambient Max. Minidip SO8 Unit 90 120 °C/W L6902 ABSOLUTE MAXIMUM RATINGS Symbol Parameter V8 Input Voltage V1 Output DC voltage Output peak voltage at t = 0.1µs I1 Maximum output current 4 V , V5 Analog pins V2, V3 Analog pins Ptot Tj Tstg Value Unit 40 V -1 to 40 -5 to 40 V V Internally limited 4 V -0.3V to VCC V 1 0.75 W W Operating junction temperature range -40 to 150 °C Storage temperature range -55 to 150 °C Power dissipation at Tamb ≤ 60 °C Minidip SO8 ELECTRICAL CHARACTERISTICS (Refer to the test circuit, unless otherwise specified.) Symbol Parameter Test Condition Min. Operating input voltage range VO = 1.235V; IO = 1A • Vd Dropout voltage VCC = 8V; IO = 1A • IO Operating charging current with Rsense = 0.1Ω Il Maximum limiting current VCC = 8V to 36V Vba tt (max) Maximum Vbatt with switch ON V CC fs Switching frequency δ Duty cycle Typ. Max. Unit 36 V 0.25 0.5 V 8 • 0.95 0.92 1 1 1.05 1.08 A A • 1.96 2.8 3.64 A VCC-2 V 287 275 kHz kHz 100 % 1.259 1.272 V V • 212 225 250 250 0 DYNAMIC CHARACTERISTICS V5 Voltage feedback 8V , VCC , 36V, 20mA < IO < 1A η Efficiency VO = 5V, VCC = 12V • 1.21 1.198 1.235 1.235 90 % DC CHARACTERISTICS Iqop Iq Iqst-by Total operating quiescent current Quiescent current Duty cycle = 0; VFB = 1.5V Total stand-by quiescent current Vinh > 2.2V VCC = 36V; Vinh > 2.2V • 3 5 mA 2.7 mA • • 50 80 100 150 µA µA VOLTAGE ERROR AMPLIFIER V OH High level output voltage VOL Low level output voltage VFB = 1.5 Source output current Vcomp = 1.9V; VFB = 0.9V Io sink Sink output current Vcomp = 1.9V; VFB = 1.5V Ib Source bias current Io source VFB = 0.9 3.650 V 0.4 V 250 300 µA 1 1.5 mA 2.5 4 µA 3/7 L6902 ELECTRICAL CHARACTERISTICS (continued) Symbol gm Parameter Test Condition DC open loop gain RL = 0 Transconductance Icomp = -0.1 to 0.1mA Vcomp = 1.9V Min. Typ. Max. Unit 54 62 dB 2.3 ms CURRENT ERROR AMPLIFIER Voffs Input offset voltage VCS- = 1.8V; VCS+ = Vcomp IP Pin output current IO = 1A; Vout < VCC-2V 95 100 105 mV 1.5 3 µA 3.234 3.300 3.366 V 3.200 3.300 3.400 V REFERENCE SECTION Reference Voltage IREF = 0 to 5mA VCC = 8V to 36V Line Regulation IREF = 0mA VCC = 8V to 36V 5 10 mV Load Regulation IREF = 0 to 5mA 8 15 mV 8 96 mA Short Circuit Current 4/7 • 64 L6902 mm DIM. MIN. TYP. A a1 inch MAX. MIN. TYP. 1.75 0.1 0.25 a2 MAX. 0.069 0.004 0.010 0.065 1.65 a3 0.65 0.85 0.026 0.033 b 0.35 0.48 0.014 0.019 b1 0.19 0.25 0.007 0.010 C 0.25 0.5 0.010 0.020 c1 45° (typ.) D (1) 4.8 5.0 0.189 0.197 E 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 3.81 0.150 F (1) 3.8 4.0 0.15 0.157 L 0.4 1.27 0.016 0.050 M S OUTLINE AND MECHANICAL DATA 0.6 0.024 SO8 8 ° (max.) (1) D and F do not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm (.006inch). 5/7 L6902 mm inch DIM. MIN. A TYP. MAX. MIN. 3.32 TYP. MAX. 0.131 a1 0.51 B 1.15 1.65 0.045 0.065 b 0.356 0.55 0.014 0.022 b1 0.204 0.304 0.008 0.012 0.020 D E 10.92 7.95 9.75 0.430 0.313 0.384 e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 F 6.6 0.260 I 5.08 0.200 L Z 6/7 3.18 OUTLINE AND MECHANICAL DATA 3.81 1.52 0.125 0.150 0.060 Minidip L6902 Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. 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