LTC4110
12
4110fb
OVERVIEW
In the typical application, the LTC4110 is placed in series
with main power supply that powers all or part of the
system, which must include the device(s) or system that
needs battery backup.
The LTC4110 has four modes of operation:
• Battery Backup Mode
• Battery Charge Mode
• Battery Calibration Mode
• Shutdown Mode
The LTC4110 provides complete PowerPath control for
the battery backed up load switching automatically from
the main power supply to the battery when battery backup
mode is required. Low loss ideal diode FET switches are
used to connect the main supply or the battery to the
backup load which permit multiple LTC4110’s to work
together in a scalable fashion to permit longer backup
times, redundancy and/or higher load currents. In battery
charge mode, power is drawn from the main supply by a
high effi ciency synchronous fl yback charger. The LTC4110
maintains the state of charge (SOC) of the battery at all
times so the battery is ready at all times. Use of a fl yback
converter permits charging of batteries who’s termination
voltage can be greater than the main supply voltage, while
at the same time providing high DC isolation to minimize
parasitic drain on the battery. Testing, maintenance support
and capacity verifi cation of the battery is supported through
the LTC4110’s calibration mode. In calibration mode, the
same synchronous fl yback used to charge the battery is
OPERATION
also used in reverse to allow safe controlled discharge of
the battery back into the main supply eliminating wasted
heat and energy. The product will not need to provide any
additional thermal management to support this mode.
Shutdown mode disconnects the battery from the load to
preserve capacity and permits shipping the product with
an energized battery installed at the factory, eliminating
battery installation at the site. The LTC4110 supports
optional control and monitoring of all activities by a host
including faults over the industry standard SMBus, which
is a variation of the I
2
C bus. However no host is required
as the LTC4110 is fully functional in a standalone mode.
Combining all these functions into a single IC reduces
circuit area compared to presently available solutions.
The LTC4110 is designed to work with both standard
battery and smart battery confi gurations. Smart batteries
are standard batteries with industry standard gas gauge
electronics built in offering accurate SOC information for
the host. Furthermore, being intimate with all aspects of
the battery, it also has the ability to control the charge
process. Smart batteries use the SMBus as the com-
munication bus for data exchange and charge control.
For more information about smart batteries, see www.
sbs-forum.org for specifi cations or contact Linear Tech-
nology Applications.
It is important to know that the LTC4110 uses the TYPE
pin to learn what type of battery it will be working with.
The TYPE pin setting globally affects all of the operating
modes, options including GPIO and control ranges. Table 1
and Table 2 give you a complete breakdown of all the
battery types supported relative to the TYPE pin settings
Table 1. LTC4110 Battery Pack Charge Mode Capabilities
BATTERY TYPE
CHEMISTRY
MAXIMUM CHARGE TIME (SLA EXCLUDED)
Li-Ion/Polymer
Nickel
SLA/Lead Acid
Standard Battery
Yes
No
Yes
Adj. Up to 12 Hours
Smart Battery
Yes
Yes
Yes
Unlimited
Table 2. LTC4110 Battery Pack Charge Voltage Capabilities
CHEMISTRY
V
CELL
FULL CHARGE
V
CELL
ADJ. RANGE
SERIES CELL COUNT
NOMINAL STACK VOLTAGE (V)
Lead Acid
2.35V
±0.15V
2, 3, 5 and 6
4, 6, 10 and 12
Li-Ion/Polymer
4.2V
±0.3V
1, 2, 3 and 4
3.6, 7.2, 10.8 and 14.4
NiMH/NiCd
N/A
N/A
4, 6, 9 and 10
4.8, 7.2, 10.8 and 12
Super Caps
2.5V, 2.7V or 3V
Yes
2 to 7
5 to 18
