LT1620/LT1621 Rail-to-Rail Current Sense Amplifier DESCRIPTIO EATURES F n The LT 1620 simplifies the design of high performance, Accurate Output Current Programming n controlled current battery charging circuits when used in Usable in Charging Applications Up to 32V Output n conjunction with a current mode PWM controller IC. Programmable Load Current Monitor for End-of- Charging-Cycle Notification (16-Pin Version) The LT1620 regulates average output current independent n Dual Function IC (LT1621) Allows Convenient of input and output voltage variations. Output current can Integration of Load and Input Current Sensing be easily adjusted via a programming voltage applied to n Level-Shifted Current Sense Output for Current Mode the LT1620s PROG pin. PWM Controllers Most current mode PWM controllers have limited output n Can be Used for NiCd, NiMH, Lead-Acid and Lithium- voltage range because of common mode limitations on the Ion Battery Charging current sense inputs. The LT1620 overcomes this restric- n Greater than 96% Efficiency Possible in Charger tion by providing a level-shifted current sense signal, Applications allowing a 0V to 32V output voltage range. n High Output Currents Possible: > 10A Easily Obtained The 16-pin version of the LT1620 contains a program- mable low charging current flag output. This output flag APPLICATI S can be used to signal when a Li-Ion battery charging cycle n is nearing completion. High Current Battery Chargers n High Output Voltage DC/DC Converters The LT1621 incorporates two fully independent current n Constant Current Sources control circuits for dual loop applications. n Overcurrent Fault Protectors , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATI (V + 0.5V) TO 32V BATT V V IN IN + 22F LTC1435 Efficiency 35V SYNCHRONOUS 100 2 BUCK V = 24V IN I TO 4A V = 16V BATT BATT REGULATOR V I SW TH BATT 95 0.025 27H 1.43M SENSE V = 12V BATT 0.1% + INTV FB CC 22F 90 35V V = 6V BATT 0.1F 0.1F 110k 6 0.1% 3k 85 V CC 18 1% SENSE AVG 27 I PROG OUT 80 15.75k LT1620MS8 1% 3 GND 45 + IN IN 75 0 1 2 3 4 5 LT1620/21 F01 BATTERY CHARGE CURRENT (A) SIMPLIFIED SCHEMATIC. SEE FIGURE 2 FOR COMPLETE SCHEMATIC 1620/21 TA02 Figure 1. Low Dropout, High Current Li-Ion Battery Charger 1 EFFICIENCY (%) UO UO ULT1620/LT1621 (Referenced to Ground) (Note 1) ABSOLUTEXAI U RATI GS Sense Amplifier Input Common Mode .......0.3V to 36V Power Supply Voltage: V .......................... 0.3V to 7V CC Operating Ambient Temperature Range Programming Voltage: Commercial ............................................ 0C to 70C PROG, PROG2 ............ 0.3V to V + 0.3V (7V Max) CC Industrial ............................................ 40C to 85C I , SENSE, AVG, AVG2, OUT Storage Temperature Range ................ 65C to 150C MODE Voltage ................ 0.3V to V + 0.3V (7V Max) CC Lead Temperature (Soldering, 10 sec)................. 300C PACKAGE/ORDER I FOR ATIO TOP VIEW TOP VIEW TOP VIEW 16 PROG A 1 V CC A SENSE 1 16 SENSE 1 8 AVG AVG + 15 AVG A 2 IN A NC 2 15 NC I 2 7 PROG OUT 14 SENSE A 3 IN A I 3 14 PROG OUT GND 3 6 V CC 13 I 4 OUT A GND A + NC 4 13 PROG2 IN IN 4 5 12 GND B 5 I GND 5 12 AVG2 OUT B MS8 PACKAGE S8 PACKAGE 11 IN B 6 SENSE B MODE 6 11 V CC 8-LEAD PLASTIC MSOP 8-LEAD PLASTIC SO + 10 7 = 250C/W (MS) IN B AVG B NC 7 10 JA NC = 120C/W (S) JA 9 + 8 V PROG B 8 9 IN IN CC B ORDER PART NUMBER GN PACKAGE GN PACKAGE 16-LEAD PLASTIC SSOP 16-LEAD PLASTIC SSOP LT1620CS8 = 149C/W = 149C/W JA JA LT1620IS8 ORDER PART NUMBER ORDER PART NUMBER LT1620CMS8 LT1620CGN LT1621CGN MS8 PART MARKING LT1620IGN LT1621IGN BC Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS + V = 16.8V, V = 5V, V = 2V, T = 25C unless otherwise noted. IN CC IOUT A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Supply V 5V Supply Voltage l 4.5 5.0 5.5 V CC I DC Active Supply Current SENSE = AVG = PROG = PROG2 = V 2.8 3.8 mA CC CC + LT1620GN 4.5V V 5.5V, IN IN = 100mV l 4.0 mA CC DC Active Supply Current SENSE = AVG = PROG = V 2.3 3.3 mA CC + LT1620S8, LT1620MS8, 1/2 LT1621GN 4.5V V 5.5V, IN IN = 100mV l 3.7 mA CC DC Active Supply Current SENSE = AVG = PROG = V 1.3 1.9 mA CC + LT1620S8, LT1620MS8, 1/2 LT1621GN 4.5V V 5.5V, IN IN = 0mV l 2.1 mA CC Current Sense Amplifier V Input Common Mode Range l032 V CM V Differential Input Voltage Range 0V V 32V l 0 125 mV ID CM + (IN IN ) V Input Offset - Measured at 1 Output V V 32V 5 5 mV OSSENSE CC CM (V)V = 80mV l 6 6 mV SENSE ID 2 U WU U W W W