LTC3554 Datasheet, PDF (12/36 Pages) Linear Technology – Micropower USB Power Manager with Li-Ion Charger and Two Step-Down Regulators

LTC3554
PIN FUNCTIONS
LTC3554 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 input current from V_BUS or if the V_BUS power
source is removed. V_OUT should be bypassed with a low
impedance multilayer ceramic capacitor.
SUSP (Pin 19): Suspend Mode Logic Input. If this pin
is driven high the input current limit path is disabled.
In this state the circuit draws negligible power from the
V_BUS pin. Any load at the V_OUT pin is provided by the
battery through the internal ideal diode. When this input
is grounded, the input current limit will be set to desired
value as determined by the state of the HPWR pin. This
pin has a conditional internal pull-down resistor when
power is applied to the V_BUS pin.
V_BUS (Pin 20): USB Input Voltage. V_BUS will usually be
connected to the USB port of a computer or a DC output
wall adapter. V_BUS should be bypassed with a low imped-
ance multilayer ceramic capacitor.
Exposed Pad (Pin 21): Ground. The exposed package pad
is ground and must be soldered to the PC board for proper
functionality and for maximum heat transfer.
3554p
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