LTC3559-1_15 Datasheet, PDF (1/24 Pages) Linear Technology – Linear USB Battery Charger with Dual Buck 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}
n _{CHRG Indicates C/10 or Timeout}
Buck Regulators
n _{400mA Output Current}
n _{2.25MHz Constant Frequency Operation}
n _{Zero Current in Shutdown}
n _{Low Noise Pulse Skip Operation or Power Saving}
Burst Mode Operation
n _{Low No-Load Quiescent Current: 35μA}
n _{Available in a Low Profile Thermally Enhanced}
16-Lead 3mm × 3mm QFN Package
APPLICATIONS
n _{SD/Flash-Based MP3 Players}
n _{Low Power Handheld Applications}
LTC3559/LTC3559-1
Linear USB Battery Charger
with Dual Buck Regulators
DESCRIPTION
The LTC^®3559/LTC3559-1 are USB battery chargers with
dual high efficiency buck regulators. The parts are ideally
suited to power single-cell Li-Ion/Polymer based handheld
applications needing multiple supply rails.
Battery charge current is programmed via the PROG pin
and the HPWR pin, with capability up to 950mA at the BAT
pin. The battery charger has an NTC input for temperature
qualified charging. The CHRG pin allows battery status to
be monitored continuously during the charging process.
An internal timer controls charger termination.
Each monolithic synchronous buck regulator provides up
to 400mA of output current while operating at efficiencies
greater than 90% over the entire Li-Ion/Polymer range.
A MODE pin provides the flexibility to place both buck
regulators in a power saving Burst Mode^® operation or a
low noise pulse skip mode.
The LTC3559/LTC3559-1 are offered in a low profile ther-
mally enhanced 16-lead (3mm × 3mm) QFN package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
USB Charger Plus Dual Buck Regulators
USB (4.3V TO 5.5V)
OR AC ADAPTOR
DIGITAL
CONTROL
1μF
1.74k
V_CC
NTC
PROG
LTC3559
CHRG
SUSP
UP TO 500mA
BAT
+
PV_IN
2.2μF
SINGLE
Li-lon CELL
(2.7V TO 4.2V)
4.7μH
SW1
22pF
FB1
655k
309k
2.5V
400mA
10μF
HPWR
EN1
EN2
MODE
GND
SW2
FB2
EXPOSED
PAD
4.7μH
22pF
324k
649k
3559 TA01
1.2V
400mA
10μF
3559fb
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