LTC4040_15 Datasheet, PDF (1/26 Pages) Linear Technology – 2.5A Battery Backup Power Manager

LTC4040
2.5A Battery Backup
Power Manager
Features
Description
nn _{Step-Up Backup Supply and Step-Down Battery}
Charger
nn _{6.5A Switches for 2.5A Backup from 3.2V Battery}
nn _{Input Current Limit Prioritizes Load Over Charge}
Current
nn _{Input Disconnect Switch Isolates Input During Backup}
nn _{Automatic Seamless Switch-Over to Backup Mode}
nn _{Input Power Loss Indicator}
nn _{System Power Loss Indicator}
nn _{Pin Selectable Battery: Li-Ion (3.95V/4.0V/4.05V/4.1V)}
or LiFePO₄ (3.45V/3.5V/3.55V/3.6V)
nn _{Optional OVP Circuitry Protects Device to >60V}
nn _{Constant Frequency Operation}
nn _{Low Profile (0.75mm) 24-Lead 4mm × 5mm QFN Package}
Applications
nn _{Fleet and Asset Tracking}
nn _{Automotive GPS Data Loggers}
nn _{Automotive Telematics Systems}
nn _{Toll Collection Systems}
nn _{Security Systems}
nn _{USB Powered Devices}
The LTC^®4040 is a complete 3.5V to 5.5V supply rail battery
backup system. It contains a high current step-up DC/DC
regulator to back up the supply from a single-cell Li-Ion
or LiFePO₄ battery. When external power is available,
the step-up regulator operates in reverse as a step-down
battery charger.
The LTC4040’s adjustable input current limit function
reduces charge current to protect the main supply from
overload while an external disconnect switch isolates the
external supply during backup. When the input supply
drops below the adjustable PFI threshold, the 2.5A boost
regulator delivers power from the battery to the system
output.
An optional input overvoltage protection (OVP) circuit
protects the LTC4040 from high voltage damage at the
V_IN pin. One logic input selects either the Li-Ion or the
LiFePO₄ battery option, and two other logic inputs program
the battery charge voltage to one of four levels suitable
for backup applications. The LTC4040 is available in a low
profile (0.75mm) 24-Lead 4mm × 5mm QFN package.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property 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
(Charge Current Setting: 1A, Input Current Limit Setting: 2A)
4.5V INPUT
SUPPLY
2.2µF
12mΩ
4.5V
1500k
1A
SYSTEM
LOAD
100µF
154k
60.4k
V_IN CLN
OVSNS
PFI
IGATE
V_SYS
BSTFB
RSTFB
FAULT
PFO
RST
CHRG
CLPROG
LTC4040
CHGOFF BSTOFF F0 F1 F2
SW
BAT
NTC
PROG
2k
V_SYS
324k
2.2µH
V_IN
10µF
NTC ^{+ LiFePO}4
3.6V
4040 TA01a
Normal to Backup Mode Transition
NormaWlatoveBfoarcmku(pLiMFeoPdeO₄TrAapnps.it)ion Waveform
5
V_SYS
10
4
8
V_BAT = 3.3V
3
V_IN
I_SYS = 1A
C_SYS = 100µF
6
R_PROG = 2k
2
4
1
I_BAT
2
0
0
–1
–0.4
–2
0
0.4
0.8
1.2
TIME (ms)
4040 TA01b
For more information www.linear.com/LTC4040
4040fa
1