LTC4085-1 Datasheet, PDF (1/24 Pages) Linear Technology – USB Power Manager with Ideal Diode Controller and 4.1V Li-Ion Charger

LTC4085-1
FEATURES
USB Power Manager with
Ideal Diode Controller and
4.1V Li-Ion Charger
DESCRIPTIO
■ _{Seamless Transition Between Input Power Sources:}
Li-Ion Battery, USB and 5V Wall Adapter
■ _{215mΩ Internal Ideal Diode Plus Optional External}
Ideal Diode Controller Provide Low Loss PowerPath^TM
When Wall Adapter/USB Input Not Present
■ _{Load Dependent Charging Guarantees Accurate USB}
Input Current Compliance
■ _{4.1V Float Voltage Improves Battery Life Span and}
High Temperature Safety Margin
■ _{Constant-Current/Constant-Voltage Operation with}
Thermal Feedback to Maximize Charging Rate Without
Risk of Overheating*
■ _{Selectable 100% or 20% Input Current Limit}
(e.g., 500mA/100mA)
■ _{Battery Charge Current Independently Programmable}
Up to 1.2A
■ _{Preset 4.1V Charge Voltage with 0.8% Accuracy}
■ _{C/10 Charge Current Detection Output}
■ _{Tiny (4mm × 3mm × 0.75mm) 14-Lead DFN Package}
U
APPLICATIO S
■ _{Portable USB Devices: Cameras, MP3 Players, PDAs}
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
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, 6700364.
Other patents pending.
The LTC^®4085-1 is a USB power manager and Li-Ion
battery charger designed for portable battery-powered
applications. The part controls the total current used by
the USB peripheral for operation and battery charging.
The total input current can be limited to 20% or 100%
of a programmed value up to 1.5A (typically 100mA or
500mA). Battery charge current is automatically reduced
such that the sum of the load current and charge current
does not exceed the programmed input current limit.
The LTC4085-1 includes a complete constant-current/
constant-voltage linear charger for single cell Li-Ion batter-
ies. This 4.1V version of the standard LTC4085 is intended
for applications which will be operated or stored above
approximately 60°C. Under these conditions, a reduced
float voltage will trade-off initial cell capacity for the benefit
of increased capacity retention over the life of the battery. A
reduced float voltage also minimizes swelling in prismatic
and polymer cells, and avoids open CID (pressure fuse)
in cylindrical cells.
The LTC4085-1 also includes a programmable termina-
tion timer, automatic recharging, an end-of-charge status
output and an NTC thermistor.
The LTC4085-1 is available in a 14-lead low profile 4mm
× 3mm DFN package.
TYPICAL APPLICATIO
5V WALL
ADAPTER
INPUT
5V (NOM)
FROM USB
CABLE V_BUS
I_IN
4.7μF ^{SUSPEND USB POWER}
100mA 500mA SELECT
IN
SUSP
HPWR
WALL
ACPR
OUT
PROG ^LTC4085-1 GATE
CLPROG
BAT
NTC
CHRG
V_NTC
10k
GND TIMER
100k 2k
10k
I_LOAD
TO LDOs,
REGs, ETC
1k
4.7μF
510Ω
*
+
0.1μF
I_BAT
* OPTIONAL - TO LOWER
IDEAL DIODE IMPEDANCE
40851 TA01
Input and Battery Current vs Load Current
R_PROG = 100k, R_CLPROG = 2k
600
I_IN
500
400
I_LOAD
300
200
I_BAT
(CHARGING)
100
0
I_BAT
WALL = 0V
(DISCHARGING)
–100
0 100 200 300 400 500 600
I_LOAD (mA)
40851 TA01b
40851f
1