LT1769 Constant-Current/ Constant-Voltage 2A Battery Charger with Input Current Limiting FEATURES DESCRIPTIO n The LT 1769 current mode PWM battery charger is a Simple Solution to Charge NiCd, NiMH and Lithium simple, efficient solution to fast charge modern recharge- Rechargeable BatteriesCharging Current able batteries including lithium-ion (Li-Ion), nickel-metal- Programmed by Resistors or DAC n hydride (NiMH) and nickel-cadmium (NiCd) that require Adapter Current Limit Allows Maximum Possible constant-current and/or constant-voltage charging. The Charging Current During System Use* n internal switch is capable of delivering 2A** DC current Precision 0.5% Accuracy for Voltage Mode Charging n (3A peak current). Charge current can be programmed by Available in 20-Lead Exposed Pad TSSOP and resistors or a DAC to within 5%. With 0.5% reference voltage 28-Lead Narrow SSOP Packages n accuracy, the LT1769 meets the critical constant-voltage High Efficiency Current Mode PWM with 3A Internal charging requirement for Li-Ion cells. Switch n 5% Charge Current Accuracy A third control loop is provided to regulate the current n Adjustable Undervoltage Lockout drawn from the input AC adapter. This allows simulta- n Automatic Shutdown When AC Adapter is Removed neous operation of the equipment and battery charging n Low Reverse Battery Drain Current: 3m A without overloading the adapter. Charge current is reduced n Current Sensing Can Be at Either Terminal of the Battery to keep the adapter current below specified levels. n Charging Current Soft Start The LT1769 can charge batteries ranging from 1V to 20V. n Shutdown Control Ground sensing of current is not required and the batterys U negative terminal can be tied directly to ground. A saturat- APPLICATIO S ing switch running at 200kHz gives high charging effi- n Chargers for NiCd, NiMH, Lead-Acid, Lithium ciency and small inductor size. A blocking diode is not Rechargeable Batteries required between the chip and the battery because the n Switching Regulators with Precision Current Limit chip goes into sleep mode and drains only 3m A when the , LTC and LT are registered trademarks of Linear Technology Corporation. wall adapter is unplugged. *US patent number 5,723,970 **See LT1510 for 1.5A charger see LT1511 for 3A charger D3 R7 SS24 500 TYPICAL APPLICATIO V (ADAPTER INPUT) IN GND CLP 11V TO 28V R S4 C1 ADAPTER 1F CURRENT SENSE SW CLN C2 TO MAIN V D1 CC 0.47F SYSTEM LOAD C * SS24 IN R5 BOOST 15F L1** UNDERVOLTAGE LT1769 LOCKOUT 22H COMP1 UV D2 1N4148 R6 2nF PROG 5k V SPIN C 300 10k R PROG C 4.93k PROG OVP SENSE BAT 0.33F 1F 1% R R S2 S3 NOTE: COMPLETE LITHIUM-ION CHARGER, 200 200 NO TERMINATION REQUIRED. R , R7 S4 1% 1% AND C1 ARE OPTIONAL FOR I LIMITING IN V BAT *TOKIN OR UNITED CHEMI-CON/MARCON R3 R S1 + C OUT 8.4V 390k CERAMIC SURFACE MOUNT 0.05 22F Li-Ion 0.25% **22H SUMIDA CDRH125 BATTERY CURRENT TANT BATTERY SEE APPLICATIONS INFORMATION FOR SENSE 1511 F01 VOLTAGE SENSE INPUT CURRENT LIMIT AND UNDERVOLTAGE LOCKOUT GENERAL SEMICONDUCTOR. FOR T LESS THEN 100C J R4 MBRS130LT3 CAN BE USED 162k 0.25% Figure 1. 2A Lithium-Ion Battery Charger 1769fa 1 U ULT1769 ABSOLUTE MAXIMUM RATINGS (Note 1) Supply Voltage Operating Ambient Temperature (V , CLP and CLN Pin Voltage) ......................... 30V Commercial ............................................ 0 C to 70 C CC BOOST Pin Voltage with Respect to V ................. 25V Industrial ........................................... 40 C to 85 C CC I (Average)........................................................... 2A Storage Temperature Range ................. 65 C to 150 C BAT Operating Junction Temperature Range Lead Temperature (Soldering, 10 sec).................. 300 C Commercial ........................................... 0 C to 125 C Industrial ......................................... 40 C to 125 C PACKAGE/ORDER INFORMATION ORDER PART ORDER PART TOP VIEW TOP VIEW NUMBER NUMBER GND** 1 28 GND** SW 1 20 GND GND** 2 27 GND** LT1769CGN LT1769CFE BOOST 2 19 V CC1 GND** 3 26 GND** LT1769IGN LT1769IFE UV 3 18 V CC2 SW 4 25 V * CC1 GND 4 17 V CC3 BOOST 5 24 V * CC2 GND 5 16 PROG UV 6 23 V * CC3 OVP 6 15 V C GND** 7 22 GND** *ALL V PINS SHOULD CC CLN 7 14 GND GND** 8 21 PROG BE CONNECTED TOGETHER CLOSE TO CLP 8 13 UV OUT OVP 9 20 V C THE PINS COMP1 9 12 BAT ** ALL GND PINS ARE CLP 10 19 UV OUT FUSED TO INTERNAL DIE SENSE 10 11 SPIN CLN 11 18 COMP2 ATTACH PADDLE FOR HEAT SINKING. CONNECT COMP1 12 17 BAT FE PACKAGE THESE PINS TO THE BOTTOM METAL 20-LEAD PLASTIC TSSOP EXPANDED PC LANDS PLATE OF THIS PACKAGE SENSE 13 16 SPIN FOR PROPER HEAT T = 125 C, q = 35 C/ W IS FUSED TO INTERNAL JMAX JA GND** 14 15 GND** SINKING. 35 C/W GROUND AND IS FOR EXPOSED PAD IS GROUND THERMAL RESISTANCE HEAT SINKING. SOLDER (MUST BE SOLDERED TO PCB) GN PACKAGE ASSUMES AN INTERNAL THE BOTTOM METAL 3.0 4.1 28-LEAD PLASTIC SSOP GROUND PLANE PLATE ONTO PCB EXPOSED PAD SIZE: (.188) (.162) DOUBLING AS A HEAT GROUND PLANE FOR T = 125 C, q = 35 C/ W** JMAX JA SPREADER HEAT SINKING. Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. V = 16V, V = 8V, R = R = 200W (see Block Diagram), A CC BAT S2 S3 V = V . No load on any outputs unless otherwise noted. CLN CC PARAMETER CONDITIONS MIN TYP MAX UNITS Overall Supply Current V = 2.7V, V 20V l 4.5 6.8 mA PROG CC V = 2.7V, 20V < V 25V l 4.6 7.0 mA PROG CC Sense Amplifier CA1 Gain and Input Offset Voltage 8V V 25V , 0V V 20V CC BAT (With R = 200W , R = 200W)R = 4.93k l 93 100 107 mV S2 S3 PROG (Measured across R )(Note 2) R = 49.3k l 810 12 mV S1 PROG T < 0 C713mV A V = 28V, V = 20V CC BAT R = 4.93k l 90 110 mV PROG R = 49.3k l713 mV PROG T < 0 C614mV A 1769fa 2 U W U W U WW