Datasheet LTC4040 (Analog Devices)

LTC4040 2.5A Battery Backup Power Manager
FeaTures DescripTion
n
Step-Up Backup Supply and Step-Down Battery
The LTC®4040 is a complete 3.5V to 5.5V supply rail bat-
Charger
tery backup system. It contains a high current step-up n
6.5A Switches for 2.5A Backup from 3.2V Battery
DC/DC regulator to back up the supply from a single-cell n
Input Current Limit Prioritizes Load Over Charge
Li-Ion or LiFePO4 battery. When external power is avail-
Current
able, the step-up regulator operates in reverse as a step- n
Input Disconnect Switch Isolates Input During Backup
down battery charger. n
Automatic Seamless Switch-Over to Backup Mode
The LTC4040’s adjustable input current limit function n Input Power Loss Indicator reduces charge current to protect the main supply from n System Power Loss Indicator overload while an external disconnect switch isolates the n Pin Selectable Battery: Li-Ion (3.95V/4.0V/4.05V/4.1V) external supply during backup. When the input supply or LiFePO4 (3.45V/3.5V/3.55V/3.6V) drops below the adjustable PFI threshold, the 2.5A boost n Optional OVP Circuitry Protects Device to >60V regulator delivers power from the battery to the system n Constant Frequency Operation output. n Low Profile (0.75mm) 24-Lead 4mm × 5mm QFN Package An optional input overvoltage protection (OVP) circuit protects the LTC4040 from high voltage damage at the
applicaTions
VIN pin. One logic input selects either the Li-Ion or the n LiFePO4 battery option, and two other logic inputs pro- Fleet and Asset Tracking n gram the battery charge voltage to one of four levels suit- Automotive GPS Data Loggers n able for backup applications. The LTC4040 is available in a Automotive Telematics Systems n low profile (0.75mm) 24-Lead 4mm × 5mm QFN package. Toll Collection Systems n Security Systems L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks and PowerPath is a trademark of Analog Devices, Inc. All other trademarks are the property n USB Powered Devices of their respective owners. Protected by U.S. Patents, including 6522118, 6570372, 6700364, 8139329.
Typical applicaTion 4.5V Backup Application with 4.22V PFI Threshold Normal to Backup Mode Transition W Normal to Backup Mode T aveform ransition (Charge Current Setting: 1A, Input Current Limit Setting: 2A) Waveform (LiFePO4 App.)
5 10 1A VSYS 12mΩ 4.5V 4.5V INPUT SYSTEM 4 8 SUPPLY LOAD 2.2µF V 1500k 100µF BAT = 3.3V ISYS = 1A 3 C 6 CURRENT (A) V SYS = 100µF IN CLN IGATE VSYS 324k V 154k IN RPROG = 2k OVSNS BSTFB 2 4 PFI RSTFB 2.2µH TAGE (V) 60.4k SW VOL I FAULT BAT 10µF 1 BAT 2 LTC4040 V PFO IN RST 0 0 CHRG CLPROG NTC CHGOFF BSTOFF F0 F1 F2 PROG –1 –2 + –0.4 0 0.4 0.8 1.2 NTC LiFePO4 2k 3.6V TIME (ms) 4040 TA01b VSYS 4040 TA01a 4040fb For more information www.linear.com/LTC4040 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Application Package Description Revision History Typical Application Related Parts