LINEAR TECHNOLOGY - LTC3555 High Efficiency USB Power Manager + Triple Step-Down DC-DC Manual
Summary
Linear Technology LTC3555 USB power manager with triple DC/DC converter. Integrates PowerPath controller, 1.5A Li-Ion charger, ideal diode, and three step-down regulators (1A/400mA/400mA). Supports USB current limits, I2C control, and voltage scaling in 28-pin QFN. For portable device power management engineers.
Page 1 Text Content
LTC3555/LTC3555-X High Effi ciency USB Power Manager + Triple Step-Down DC/DC
FEATURES DESCRIPTION Power Manager The LTC®3555 family are highly integrated USB com- n High Effi ciency Switching Power Path™ Controller
patible power management and battery charger ICs for
with Bat-Track™ Adaptive Output Control Li-Ion/Polymer battery applications. They include a high n Programmable USB or Wall Current Limit
effi ciency current limited switching Power Path manager
(100m A/500m A/1A) with automatic load prioritization, a battery charger, an ideal n Full Featured Li-Ion/Polymer Battery Charger
diode and three general purpose synchronous step-down
n 1.5A Maximum Charge Current
switching regulators.
n Internal 180mΩ Ideal Diode + External Ideal Diode
The LTC3555 family limits input current to either 100m A
Controller Powers Load in Battery Mode
or 500m A for USB applications or 1A for adapter-powered
n Low No-Load Quiescent Current when Powered from
applications. Unlike linear chargers, the LTC3555 family’s
BAT (<32μA)
switching architecture transmits nearly all of the power avail-
DC/DCs
able from the USB port to the load with minimal loss and
n Triple High Effi ciency Step-Down DC/DCs
heat which eases thermal constraints in small spaces.
(1A/400m A/400m A IOUT)
Two of the three general purpose switching regulators can
n All Regulators Operate at 2.25MHz
provide up to 400m A and the third can deliver 1A. The
n Dynamic Voltage Scaling on Two Outputs
entire product can be controlled via I2C or simple I/O. The
n I2C or Independent Enable, VOUT Controls
LTC3555-1/LTC3555-3 versions offer “instant-on” power
n Low No-Load Quiescent Current: 20μA
FF IC IE delivery to the portable product even with a very low battery
n 28-Pin (4mm × 5mm × 0.75mm) QFN Package
voltage. The LTC3555-3 version also has a reduced charger fl oat voltage of 4.100V for battery safety and longevity.
APPLICATIONS
The LTC3555 family is available in the low profi le 28-pin
n HDD-Based MP3 Players, PDAs, GPS, PMPs
(4mm × 5mm × 0.75mm) QFN surface mount package.
n Portable Medical Products
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Power Path n Handheld Instrumentation and Bat-Track are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6522118 and 6404251.
n Other USB-Based Handheld Products
TYPICAL APPLICATION High Effi ciency Power Path Manager and Triple Step-Down Regulator
Switching Regulator Effi ciency to
USB/WALL TO OTHER
USB COMPLIANT System Load (POUT/PBUS)
4.35V TO 5.5V LOADS
STEP-DOWN REGULATOR
CC/CV
OPTIONAL0V
BATTERY
CURRENT
CHARGER
CONTROL
BAT = 4.2V
CHARGE
Li-Ion
LTC3555/LTC3555-X BAT = 3.3V
3.3V/25m A RTC/LOW
ALWAYS ON LDO
POWER LOGIC
0.8V TO 3.6V/400m A
TRIPLE MEMORY
ENABLE HIGH EFFICIENCY 0.8V TO 3.6V/400m A VBUS = 5V
STEP-DOWN I/O
CONTROLS IBAT = 0m A
SWITCHING 0.8V TO 3.6V/1A 10x MODE
REGULATORS
μPROCESSOR 0.01 0.1 IOUT (A)
I2C PORT I2C
3555 TA01b
3555 TA01
3555fd
Page Summary Contents For LINEAR TECHNOLOGY - LTC3555 High Efficiency USB Power Manager + Triple Step-Down DC-DC Manual
Manual Details
| Brand | Linear |
|---|---|
| Pages | 32 |
| File Size | 309.51 KB |
| Published | June 15, 2026 |
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Frequently Asked Questions
What are the output currents of the three step-down DC/DCs?
Two can deliver 400mA, and the third can deliver 1A.
What is the operating temperature range of the LTC3555?
The operating temperature range is -40°C to 85°C.
What USB input current limits does the LTC3555 support?
It supports 100mA and 500mA for USB, and 1A for adapter-powered applications.
What package does the LTC3555 family use?
It uses a 28-pin 4mm × 5mm × 0.75mm QFN surface mount package.