LTC3586_15 Datasheet, PDF (12/36 Pages) Linear Technology – High Efficiency USB Power Manager with Boost, Buck-Boost and Dual Bucks

LTC3586/LTC3586-1
Pin Functions
EN2 (Pin 20): Digital Input. This input enables the buck
switching regulator 2.
EN1 (Pin 21): Digital Input. This input enables the buck
switching regulator 1.
V_IN4 (Pin 22): Power Input for Switching Regulator 4
(Boost). This pin will generally be connected to V_OUT.
A 1µF MLCC capacitor is recommended on this pin.
FB2 (Pin 23): Feedback Input for (Buck) Switching Regu-
lator 2. When regulator 2’s control loop is complete, this
pin servos to 0.8V.
V_IN2 (Pin 24): Power Input for (Buck) Switching Regu-
lator 2. This pin will generally be connected to V_OUT.
A 1µF MLCC capacitor is recommended on this pin.
SW2 (Pin 25): Power Transmission Pin for (Buck) Switch-
ing Regulator 2.
SW1 (Pin 26): Power Transmission Pin for (Buck) Switch-
ing Regulator 1.
V_IN1 (Pin 27): Power Input for (Buck) Switching Regula-
tor 1. This pin will generally be connected to V_OUT. A 1µF
MLCC capacitor is recommended on this pin.
FB1 (Pin 28): Feedback Input for (Buck) Switching Regu-
lator 1. When regulator 1’s control loop is complete, this
pin servos to 0.8V.
PROG (Pin 29): 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 30): 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 a high duty cycle for easy recogni-
tion by either humans or microprocessors. See Table 3.
CHRG requires a pull-up resistor and/or LED to provide
indication.
GATE (Pin 31): 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 32): Single Cell Li-Ion Battery Pin. Depending on
available V_BUS power, a Li-Ion battery on BAT will either
deliver power to V_OUT through the ideal diode or be charged
from V_OUT via the battery charger.
EN4 (Pin 33): Digital Input. This input enables the boost
switching regulator 4.
V_OUT (Pin 34): Output Voltage of the Switching
PowerPath Controller and Input Voltage of the Battery
Charger. The majority of the portable product should be
powered from V_OUT. The LTC3586/LTC3586-1 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 (Pins 35, 36): Primary Input Power Pin. These
pins deliver 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 37): Power Transmission Pin for the USB
Power Path. The SW pin delivers power from V_BUS to V_OUT
via the buck switching regulator. A 3.3µH inductor should
be connected from SW to V_OUT.
FAULT (Pin 38): Bi-directional input/output (open-drain)
used to alert or receive information from other power
management ICs regarding an electrical fault.
GND (Exposed Pad Pin 39): Ground. The exposed pad
should be connected to a continuous ground plane on the
second layer of the printed circuit board by several vias
directly under the LTC3586/LTC3586-1.
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