LTC3567 Datasheet, PDF (12/28 Pages) Linear Technology – High Effi ciency USB Power Manager Plus 1A Buck-Boost Converter with I2C Control

LTC3567
TIMING DIAGRAM
00
START
SDA
00
ADDRESS
0100
WR
10
DATA BYTE A
A7 A6 A5 A4 A3 A2 A1 A0
DATA BYTE B
B7 B6 B5 B4 B3 B2 B1 B0
0 1 0 0 1 0 ACK
ACK
ACK
STOP
SCL
123456789123456789123456789
SDA
t_LOW
t_{SU, DAT}
SCL
t_{HD, STA}
START
CONDITION
t_HIGH
t_r
t_f
t_{HD, DAT}
t_{SU, STA}
t_{HD, STA}
t_SP
REPEATED START
CONDITION
t_BUF
t_{SU, STO}
3567 TD
STOP
CONDITION
START
CONDITION
OPERATION
Introduction
The LTC3567 is a highly integrated power management IC
which includes a high efficiency switch mode PowerPath
controller, a battery charger, an ideal diode, an always-on
LDO and a 1A buck-boost switching regulator. The entire
chip is controllable via an I²C serial port.
Designed specifically for USB applications, the PowerPath
controller incorporates a precision average input current
step-down switching regulator to make maximum use of
the allowable USB power. Because power is conserved,
the LTC3567 allows the load current on V_OUT to exceed
the current drawn by the USB port without exceeding the
USB load specifications.
The PowerPath switching regulator and battery charger
communicate to ensure that the input current never vio-
lates the USB specifications.
The ideal diode from BAT to V_OUT guarantees that ample
power is always available to V_OUT even if there is insuffi-
cient or absent power at V_BUS.
An “always-on” LDO provides a regulated 3.3V from avail-
able power at V_OUT. Drawing very little quiescent current,
this LDO will be on at all times and can be used to supply
up to 25mA.
12
The LTC3567 also has a general purpose buck-boost
switching regulator, which can be independently enabled
via direct digital control or the I²C serial port. Along with
constant frequency PWM mode, the buck-boost regulator
has a low power burst-only mode setting for significantly
reduced quiescent current under light load conditions.
High Efficiency Switching PowerPath Controller
Whenever V_BUS is available and the PowerPath switching
regulator is enabled, power is delivered from V_BUS to V_OUT
via SW. V_OUT drives both the external load (including the
buck-boost regulator) and the battery charger.
If the combined load does not exceed the PowerPath
switching regulator’s programmed input current limit, V_OUT
will track 0.3V above the battery (Bat-Track). By keeping
the voltage across the battery charger low, efficiency is
optimized because power lost to the linear battery char-
ger is minimized. Power available to the external load is
therefore optimized.
If the combined load at V_OUT is large enough to cause the
switching power supply to reach the programmed input
current limit, the battery charger will reduce its charge
current by the amount necessary to enable the external
load to be satisfied. Even if the battery charge current is
3567f