LTC4121/LTC4121-4.2 40V 400mA Synchronous Step-Down Battery Charger FEATURES DESCRIPTION n Wide Input Voltage Range: 4.4V to 40V The LTC 4121 is a 400mA constant-current/constant- n Temperature Compensated Input Voltage voltage (CC/CV) synchronous step-down battery charger. Regulation for Maximum Power Point Tracking In addition to CC/CV operation, the LTC4121 regulates its (MPPT) input voltage to a programmable percentage of the input n Adjustable Float Voltage 3.5V to 18V (LTC4121) open-circuit voltage. This technique maintains maximum n Fixed 4.2V Float Voltage Option (LTC4121-4.2) power transfer with high impedance input sources such n High Efficiency: Up to 95% as solar panels. n 50mA to 400mA Programmable Charge Current An external resistor programs the charge current up to n 1% Feedback Voltage Accuracy 400mA. The LTC4121-4.2 is suitable for charging Li-Ion/ n Programmable 5% Accurate Charge Current Polymer batteries, while the programmable float voltage n Thermally Enhanced, Low Profile (0.75mm) of the LTC4121 is suitable for several battery chemistries. 16-Lead (3mm 3mm) QFN Package The LTC4121 and LTC4121-4.2 include an accurate RUN pin threshold, low voltage battery preconditioning and bad APPLICATIONS battery fault detection, timer termination, auto-recharge, and NTC temperature qualified charging. The FAULT pin n Handheld Instruments provides an indication of bad battery or temperature faults. n Solar Powered Devices n Industrial/Military Sensors and Devices Once charging is terminated, the LTC4121 signals end-of- charge via the CHRG pin, and enters a low current SLEEP L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective mode. An auto-restart feature starts a new charging cycle owners. if the battery voltage drops by 2.2%. TYPICAL APPLICATION High Efficiency, Wide Input Voltage Range Charging with LTC4121 LTC4121 Efficiency vs V at V = 8.4V IN FLOAT 97 IN INTV CC 200mA, R = 6.04k PROG RUN BOOST 2.2F 400mA, R = 3.01k PROG 10F 10k 22nF 95 MPPT SLF6025T-470MR48 LTC4121 SW 93 CHGSNS V IN + V + 200mV BAT BAT TO 40V 1.96M 91 22F PROG FB 787k 89 + FREQ GND FBG Li-Ion R PROG V = 8.3V BAT 87 5 10 15 20 25 30 35 40 4121 TA01a V (V) IN 4121 TA01b 4121fc 1 For more information www.linear.com/LTC4121 EFFICIENCY (%)LTC4121/LTC4121-4.2 ABSOLUTE MAXIMUM RATINGS (Note 1) IN, RUN, CHRG, FAULT, MPPT ................... 0.3V to 43V I , I , ........................................................5mA CHRG FAULT BOOST ................................... V 0.3V to (V + 6V) I , I (LTC4121) .................................................5mA SW SW FB FBG SW (DC) ........................................ 0.3V to (V + 0.3V) I (LTC4121-4.2) ...........................................5mA IN BATSNS SW (Pulsed <100ns) ......................1.5V to (V + 1.5V) I .................................................................. 5mA IN INTVCC CHGSNS, BAT, FB/BATSNS, FBG ................ 0.3V to 18V Operating Junction Temperature Range FREQ, NTC, PROG, INTV .......................... 0.3V to 6V (Note 2) .................................................. 40C to 125C CC I , I ..................................................... 600mA Storage Temperature Range .................... 65C to 150 CHGSNS BAT PIN CONFIGURATION LTC4121 LTC4121-4.2 TOP VIEW TOP VIEW 16 15 14 13 16 15 14 13 INTV 1 12 NTC INTV 1 12 NTC CC CC BOOST 2 11 FBG BOOST 2 11 NC GND GND IN FB IN BATSNS 3 10 3 10 SW 4 9 BAT SW 4 9 BAT 5 6 7 8 5 6 7 8 UD PACKAGE UD PACKAGE 16-LEAD (3mm 3mm) PLASTIC QFN 16-LEAD (3mm 3mm) PLASTIC QFN T = 125C, = 54C/W T = 125C, = 54C/W JMAX JA JMAX JA EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB TO OBTAIN EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB TO OBTAIN JA JA ORDER INFORMATION (