Linear Technology LTC3455EUF-1 Quick Start Manual

LTC3455EUF-1
DESCRIPTION
Demonstration circuit 1448 is a Dual DC/DC Converter
with USB Power Manager and Li-Ion Battery Charger
featuring the LTC3455EUF-1. Power may be received
from the USB input, a Wall Adapter, or a battery. DC1448
provides the following functions; 700mA CC/CV timer
terminated charger suitable for Li-ion cells, USB power
manager that ensures compliance with the USB power
specification, two 1.5MHz synchronous step down con-
PERFORMANCE SUMMARY
PARAMETER
Wall Adapter Input Voltage Range
USB Input Voltage Range
Battery Charger
Iout
Float Voltage
Trickle Charge Threshold
Recharge Threshold
USB Current
Input Current 500mA Mode
Input Current 100mA Mode
Input Current Suspend Mode
Buck Converters
Switcher 1
Switcher 2
Hot Swap Output
OPERATING PRINCIPLES
Demo Circuit 1448 manages the power supplies that
would be typical for a USB powered device. Power is in-
put from either the USB cable or an adapter to an inter-
mediate voltage bus. This intermediate voltage is then
used to charge a Li-ion battery and to generate two low
Arrow.com.
Downloaded from
Dual DC/DC Converter with USB
Power Manager and Li-Ion Battery
verters and reset and power button status outputs for
interface with a microprocessor.
The LTC3455EUF-1 is available in a 4mm x 4mm 24-
pin exposed-pad QFN package.
Design files for this circuit board are available. Call
the LTC factory.
L
, LTC, and Burst Mode are registered trademarks of Linear Technology Corporation. Hot
Swap is a trademark of Linear Technology Corporation. Other product names may be trade-
marks of the companies that manufacture the products.
Specifications are at T
CONDITIONS
Vin = 5V, VBat = 3.6V
Vin = 5V
Vin = 5V (Battery voltage rising)
V - V
BAT(REGULATED) RECHARGE
Vin = 5V; USB Active 500mA Mode
Vin = 5V; USB Active 100mA Mode
Vin = 5V; USB Suspend
VBat 3.6V
voltage outputs via high efficiency step down converters.
The intermediate voltage bus is preferentially powered
from the Wall Adapter, then from the USB input, and fi-
nally from the battery via an ideal diode. The battery
charger is a CC/CV timer terminated type capable of
DEMO CIRCUIT 1448
QUICK START GUIDE
LTC3455EUF-1
= 25°C
A
MIN
4.75
4.20
585
4.058
440
60
1.72
3.02
3.02
TYP MAX UNITS
5.5 V
5.5 V
690 795 mA
4.142 V
2.85 V
150 mV
500 mA
100 mA
4 20 uA
1.86 V
3.27 V
3.27 V
1