LTC3558_15 Datasheet, PDF (1/32 Pages) Linear Technology – Linear USB Battery Charger with Buck and Buck-Boost Regulators

FEATURES
Battery Charger
n _{Standalone USB Charger}
n _{Up to 950mA Charge Current Programmable via}
Single Resistor
n _{HPWR Input Selects 20% or 100% of Programmed}
Charge Current
n _{NTC Input for Temperature Qualified Charging}
n _{Internal Timer Termination}
n _{Bad Battery Detection}
Switching Regulators (Buck and Buck-Boost)
n _{Up to 400mA Output Current per Regulator}
n _{2.25MHz Constant-Frequency Operation}
n _{Power Saving Burst Mode}^® _Operation
n _{Low Profile, 20-Lead, 3mm × 3mm QFN Package}
APPLICATIONS
n _{SD/Flash-Based MP3 Players}
n _{Low Power Handheld Applications}
LTC3558
Linear USB Battery Charger
with Buck and
Buck-Boost Regulators
DESCRIPTION
The LTC^®3558 is a USB battery charger with dual high ef-
ficiency switching regulators. The device is ideally suited
to power single-cell Li-Ion/Polymer based handheld ap-
plications needing multiple supply rails.
Battery charge current is programmed via the PROG pin
and the HPWR pin with capability up to 950mA of current
at the BAT pin. The CHRG pin allows battery status to be
monitored continuously during the charging process. An
internal timer controls charger termination.
The part includes monolithic synchronous buck and buck-
boost regulators that can provide up to 400mA of output
current each and operate at efficiencies greater than 90%
over the entire Li-Ion/Polymer battery range. The buck-
boost regulator can regulate its programmed output voltage
at its rated deliverable current over the entire Li-Ion range
without drop out, increasing battery runtime.
The LTC3558 is offered in a low profile (0.75mm), thermally
enhanced, 20-lead (3mm × 3mm) QFN package.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
USB Charger Plus Buck Regulator and Buck-Boost Regulator
USB (4.3V TO 5.5V)
V_CC
1μF
1.74k
PROG
BAT
PV_IN1
PV_IN2
NTC
SW1
LTC3558
CHRG
SUSP
FB1
SWAB2
DIGITAL
CONTROL
HPWR
MODE
SWCD2
V_OUT2
EN1
10μF
4.7μH
2.2μH
324k
EN2
FB2
105k
EXPOSED
GND PAD
V_C2
3558 TA01
+ SINGLE
Li-lon CELL
(2.7V TO 4.2V)
1.2V AT 400mA
324k
10pF
10μF
649k
3.3V AT 400mA
121k
33pF
15k
330pF
22μF
10pF
Demo Board
3558f
1