POWER LOSS (mW)
LTC3552
Standalone Linear Li-Ion
Battery Charger and Dual
Synchronous Buck Converter
FEATURES DESCRIPTIO
Programmable Charge Current Up to 950mA The LTC 3552 is a complete constant-current/constant-
Complete Linear Charger and Dual DC/DC voltage linear charger with a dual DC/DC converter for
Regulator single cell lithium-ion batteries. Its DFN package and low
Buck Converter Output Voltage from 0.6V to 5V external component count make the LTC3552 ideally suited
No MOSFET, Sense Resistor or Blocking Diode for portable applications. Furthermore, the LTC3552 is
Required designed to work within USB power speci cations.
Thermal Regulation Maximizes Charge Rate
No external sense resistor or external blocking diode is
Without Risk of Overheating*
required due to the internal MOSFET architecture. The
Charges Directly from a USB Port
charge voltage is xed at 4.2V and the charge current is
Programmable Charge Current Termination
programmed with a resistor. The charge cycle terminates
Preset 4.2V Charge Voltage with 1% Accuracy
when the charge current drops below the programmed
Charge Current Monitor Output for Gas Gauging*
termination threshold after the nal oat voltage is reached.
Automatic Recharge
When the input supply (wall adapter or USB supply) is
Charge Status Output
removed, the LTC3552 enters a low current state dropping
Power Present Output
the battery drain current to less than 2A. Thermal regula-
2.9V Trickle Charge Threshold
tion maximizes charge rate without risk of overheating.
Soft-Start Limits Inrush Current
The synchronous step-down switching regulators gen-
Low Quiescent Current Buck Converter (40A)
erate adjustable output voltages from 5V down to 0.6V.
Current Mode Operation, Constant Frequency (2.25MHz)
The switching frequency is set at 2.25MHz, allowing the
Low Pro le (5mm 3mm 0.75mm) DFN Package
use of small surface mount inductors and capacitors.
U
APPLICATIO S
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Protected by U.S. patents, including 6522118, 6700364, 5481178, 6580258, 6304066,
Cellular Telephones, PDAs, MP3 Players
6127815, 6498466, 6611131.
Bluetooth Applications
TYPICAL APPLICATIO
Ef ciency Curve/
Power Loss of Regulators
Single Cell Li-Ion Battery Charger with
100 1000
C/5 Termination and Dual DC/DC Converter
95
LTC3552
90 100
EFFICIENCY
V V RUN1
IN IN
4.5V TO
1F 800mA
RUN2 85
6.5V ITERM
4.2V
+
1-CELL
619 BAT
PROG 10F 80 10
Li-Ion
POWER LOSS
1.24k
BATTERY
CHRG V
CC
75
PWR
POR
70 1
EN
MODE/SYNC
4.7H 2.2H
V V
OUT2 OUT1
2.5V/ SW2 SW1 1.8V/
65
400mA 800mA
C C
OUT2 C R4 R2 C OUT1
FF2 FF1 60 0.1
4.7F 10F 1 10 100 1000
68pF 887k 604k 33pF
CER V V CER
FB2 FB1
LOAD CURRENT (mA)
GND
3552 TA01b
R3 R1
V = 3.3V, V = 1.8V
CC OUT
280k 301k
Burst Mode OPERATION
3552 TA01 REGULATOR 1, NO LOAD ON REGULATOR 2
3552f
1
EFFICIENCY (%)
U
ULTC3552
UUW
ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO
(Note 1)
TOP VIEW
Charger Input Supply (V ) ........................ 0.3V to 10V
IN
ITERM 1 16 EN
PROG, ITERM .................................. 0.3V to V + 0.3V
IN
BAT 2 15 PWR
BAT .............................................................. 0.3V to 7V
CHRG 3 14 V
IN
CHRG, PWR, EN ......................................... 0.3V to 10V
MODE/SYNC 4 13 PROG
BAT Short-Circuit Duration ............................Continuous 17
SW2 5 12 SW1
BAT Pin Current ..........................................................1A
POR 6 11 V
CC
PROG Pin Current ....................................................1mA
RUN2 7 10 RUN1
Converter Input Supply (V ) ....................... 0.3V to 6V
CC
V 8 9 V
FB2 FB1
V , V , RUN1, RUN2 ...................0.3V to V +0.3V
FB1 FB2 CC
DHC PACKAGE
MODE/SYNC ....................................0.3V to V + 0.3V
CC 16-LEAD (5mm 3mm) PLASTIC DFN
SW1, SW2 .......................................0.3V to V + 0.3V
T = 125C, = 40C/W (Note 3)
CC
JMAX JA
EXPOSED PAD IS GROUND (PIN 17)
POR ............................................................. 0.3V to 6V
MUST BE SOLDERED TO PCB
Ambient Operating Temperature
ORDER PART NUMBER DHC PART MARKING
Range (Note 2) .................................... 40C to 85C
Maximum Junction Temperature (Note 8) ............ 125C
LTC3552EDHC 3552
Storage Temperature Range ................... 65C to 125C
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: