CURRENT (A)
LTC4040
2.5A Battery Backup
Power Manager
Fea T Descrip T
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Step-Up Backup Supply and Step-Down Battery The LTC 4040 is a complete 3.5V to 5.5V supply rail battery
Charger backup system. It contains a high current step-up DC/DC
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6.5A Switches for 2.5A Backup from 3.2V Battery regulator to back up the supply from a single-cell Li-Ion
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Input Current Limit Prioritizes Load Over Charge or LiFePO battery. When external power is available,
4
Current the step-up regulator operates in reverse as a step-down
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Input Disconnect Switch Isolates Input During Backup battery charger.
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Automatic Seamless Switch-Over to Backup Mode
The LTC4040s adjustable input current limit function
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Input Power Loss Indicator
reduces charge current to protect the main supply from
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System Power Loss Indicator
overload while an external disconnect switch isolates the
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Pin Selectable Battery: Li-Ion (3.95V/4.0V/4.05V/4.1V)
external supply during backup. When the input supply
or LiFePO (3.45V/3.5V/3.55V/3.6V)
4
drops below the adjustable PFI threshold, the 2.5A boost
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Optional OVP Circuitry Protects Device to >60V
regulator delivers power from the battery to the system
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Constant Frequency Operation
output.
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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
a T
V pin. One logic input selects either the Li-Ion or the
IN
LiFePO battery option, and two other logic inputs program
4
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Fleet and Asset Tracking
the battery charge voltage to one of four levels suitable
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Automotive GPS Data Loggers
for backup applications. The LTC4040 is available in a low
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Automotive Telematics Systems
profile (0.75mm) 24-Lead 4mm 5mm QFN package.
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Toll Collection Systems
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
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Security Systems
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,
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USB Powered Devices
6700364, 8139329.
Typical a T
4.5V Backup Application with 4.22V PFI Threshold
Normal to Backup Mode Transition
(Charge Current Setting: 1A, Input Current Limit Setting: 2A) Normal to Backup Mode Transition Waveform
Waveform (LiFePO App.)
4
5 10
1A
V
SYS
12m
4.5V
SYSTEM
4.5V INPUT
LOAD
SUPPLY
4 8
2.2F
1500k 100F
V = 3.3V
BAT
I = 1A
SYS
3 6
V CLN IGATE V
IN SYS C = 100F
324k SYS
154k
V
IN
OVSNS BSTFB R = 2k
PROG
PFI RSTFB
2 4
2.2H
60.4k SW
FAULT 10F
BAT
I
LTC4040 1 BAT 2
V
PFO IN
RST
CHRG
0 0
CLPROG
NTC
CHGOFF BSTOFF F0 F1 F2 PROG
1 2
+
LiFePO
NTC 4 0.4 0 0.4 0.8 1.2
2k 3.6V
TIME (ms)
4040 TA01b
V
SYS 4040 TA01a
4040fa
1
For more information www.linear.com/LTC4040
VOLTAGE (V)
ion pplica
ions pplica
ion uresLTC4040
a Te Maxi Mu M r a T p in c F T
(Notes 1, 2)
TOP VIEW
V (Transient) t < 1ms, Duty Cycle < 1% .... 0.3V to 7V
IN
V (Steady State), BAT, CLN, V ,
IN SYS
24 23 22 21 20
BSTFB, NTC, OVSNS,
1 19
V PFI
SYS
CHRG, PFO, RST, FAULT ............................... 0.3V to 6V
PROG 2 18 BSTFB
F0, F1, F2, BSTOFF, RSTFB,
CLPROG 3 17 NTC
25
CHGOFF 4 16 OVSNS
PFI, CHGOFF ......0.3V to Max (V , V , V ) + 0.3V
IN BAT SYS
GND
BSTOFF 5 15
IGATE
I .................................................................. 10mA
OVSNS
6 14
V F0
IN
I , I , I , I ..........................................10mA
CHRG PFO RST FAULT
CLN 7 13 F1
I , I ....................................................... 1.1mA
PROG CLPROG 8 9 10 11 12
Operating Junction Temperature Range
(Note 3) ...................................................... 40 to 125C
UFD PACKAGE
Storage Temperature Range ...................... 65 to 125C
24-LEAD (4mm 5mm) PLASTIC QFN
T = 125C, = 43C/W
JMAX JA
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
o r Der i n F Ma T
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC4040EUFD#PBF LTC4040EUFD#TRPBF 4040 24-Lead (4mm 5mm 0.75mm) Plastic QFN 40C to 125C
LTC4040IUFD#PBF LTC4040IUFD#TRPBF 4040 40C to 125C
24-Lead (4mm 5mm 0.75mm) Plastic QFN
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to: