LTC3567 Datasheet, PDF (10/28 Pages) Linear Technology – High Effi ciency USB Power Manager Plus 1A Buck-Boost Converter with I2C Control

LTC3567
PIN FUNCTIONS
until it re-enters the valid range. A low drift bias resistor
is required from V_BUS to NTC and a thermistor is required
from NTC to ground. If the NTC function is not desired,
the NTC pin should be grounded.
FB1 (Pin 4): Feedback Input for the (Buck-Boost) Switching
Regulator. When the regulator’s control loop is complete,
this pin servos to 1 of 16 possible set-points based on the
commanded value from the I²C serial port. See Table 4.
V_C1 (Pin 5): Output of the Error Amplifier and Voltage
Compensation Node for the (Buck-Boost) Switching
Regulator. External Type I or Type III compensation (to
FB1) connects to this pin. See Applications Section for
selecting buck-boost loop compensation components.
GND (Pin 6, 12): Power GND Pins for the buck-boost.
SWAB1 (Pin 7): Switch Node for the (Buck-Boost) Switch-
ing Regulator. Connected to internal power switches A
and B. External inductor connects between this node and
SWCD1.
DV_CC (Pin 8): Logic Supply for the I²C Serial Port.
V_IN1 (Pin 9): Power Input for the (Buck-Boost) Switching
Regulator. This pin will generally be connected to V_OUT
(Pin 20). A 1μF (min) MLCC capacitor is recommended
on this pin.
V_OUT1 (Pin 10): Regulated Output Voltage for the (Buck-
Boost) Switching Regulator.
SWCD1 (Pin 11): Switch Node for the (Buck-Boost)
Switching Regulator. Connected to internal power switches
C and D. External inductor connects between this node
and SWAB1.
SCL (Pin 13): Clock Input Pin for the I²C Serial Port. The
I²C logic levels are scaled with respect to DV_CC.
SDA (Pin 14): Data Input Pin for the I²C Serial Port. The
I²C logic levels are scaled with respect to DV_CC.
PROG (Pin 15): Charge Current Program and Charge
Current Monitor Pin. Connecting a resistor from PROG
to ground programs the charge current. If sufficient in-
put power is available in constant-current mode, this pin
servos to 1V. The voltage on this pin always represents
the actual charge current.
CHRG (Pin 16): Open-Drain Charge Status Output. The
CHRG pin indicates the status of the battery charger. Four
possible states are represented by CHRG: charging, not
charging, unresponsive battery and battery temperature
out of range. CHRG is modulated at 35kHz and switches
between a low and high duty cycle for easy recognition
by either humans or microprocessors. See Table 1. CHRG
requires a pull-up resistor and/or LED to provide indica-
tion.
GND (Pin 17): GND pin for USB Power Manager.
GATE (Pin 18): Analog Output. This pin controls the gate
of an optional external P-channel MOSFET transistor used
to supplement the ideal diode between V_OUT and BAT. The
external ideal diode operates in parallel with the internal
ideal diode. The source of the P-channel MOSFET should
be connected to V_OUT and the drain should be connected
to BAT. If the external ideal diode FET is not used, GATE
should be left floating.
BAT (Pin 19): Single Cell Li-Ion Battery Pin. Depending
on available V_BUS power, a Li-Ion battery on BAT will ei-
ther deliver power to V_OUT through the ideal diode or be
charged from V_OUT via the battery charger.
V_OUT (Pin 20): Output Voltage of the Switching Power-
Path Controller and Input Voltage of the Battery Charger.
The majority of the portable product should be powered
from V_OUT. The LTC3567 will partition the available power
between the external load on V_OUT and the internal battery
charger. Priority is given to the external load and any extra
power is used to charge the battery. An ideal diode from
BAT to V_OUT ensures that V_OUT is powered even if the load
exceeds the allotted power from V_BUS or if the V_BUS power
source is removed. V_OUT should be bypassed with a low
impedance ceramic capacitor.
V_BUS (Pin 21): Primary Input Power Pin. This pin delivers
power to V_OUT via the SW pin by drawing controlled current
from a DC source such as a USB port or wall adapter.
SW (Pin 22): Power Transmission Pin for the USB Pow-
erPath. The SW pin delivers power from V_BUS to V_OUT
via the step-down switching regulator. A 3.3μH inductor
should be connected from SW to V_OUT.
3567f
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