LTC4075 LINER [Linear Technology], LTC4075 Datasheet - Page 11

• Manufacturer Part Number: LTC4075
• Description: Dual Input USB/AC Adapter Standalone Li-Ion Battery Chargers
• Manufacturer: LINER [Linear Technology]

OPERATIO
The power supply status output ( ⎯ P ⎯ W ⎯ R ) has two states: pull-
down and high impedance. The pull-down state indicates
that power is present at either DCIN or USBIN. This output
is strong enough to drive an LED. If no power is applied at
either pin, the ⎯ P ⎯ W ⎯ R pin is high impedance, indicating that
the LTC4075 lacks suffi cient power to charge the battery.
The pull-down state is capable of sinking up to 10mA.
The USB power status output (USBPWR) has two states:
pull-down and high impedance. The high impedance
state indicates that the LTC4075 is being powered from
the USBIN input. The pull-down state indicates that the
charger is either powered from DCIN or is in a UVLO
condition (see Table 1). The pull-down state is capable of
sinking up to 1mA.
*LTC4075 ONLY
ENABLE
DRIVEN LOW
BAT < 2.9V
2.9V < BAT
BAT < 4.1V
U
IN VOLTAGE MODE
I
BAT
< I
CHRG STATE: PULLDOWN
CHRG STATE: PULLDOWN
BAT > 2.9V
TERMINATE
1/10th FULL CURRENT
NO CHARGE CURRENT
I
DCIN
CHRG STATE: Hi-Z
CHRG STATE: Hi-Z
TRICKLE CHARGE
FULL CURRENT
SHUTDOWN
DROPS TO 20µA
STANDBY
CHARGE
MODE*
MODE
MODE
MODE
Figure 1. LTC4075 State Diagram of a Charge Cycle
DCIN POWER APPLIED
DCIN POWER
REMOVED
ENABLE
DRIVEN HIGH
DCIN POWER
REMOVED
POWER SELECTION
STARTUP
Thermal Limiting
An internal thermal feedback loop reduces the programmed
charge current if the die temperature attempts to rise above
a preset value of approximately 105°C. This feature protects
the LTC4075 from excessive temperature and allows the
user to push the limits of the power handling capability of
a given circuit board without risk of damaging the device.
The charge current can be set according to typical (not
worst-case) ambient temperature with the assurance that
the charger will automatically reduce the current in worst-
case conditions. DFN power considerations are discussed
further in the Applications Information section.
ENABLE
DRIVEN LOW
USBIN POWER
REMOVED OR
DCIN POWER
APPLIED
USBIN POWER
REMOVED OR
DCIN POWER
ONLY USB POWER APPLIED
APPLIED
LTC4075/LTC4075X
CHRG STATE: PULLDOWN
CHRG STATE: PULLDOWN
I
1/10th FULL CURRENT
NO CHARGE CURRENT
USBIN
CHRG STATE: Hi-Z
TRICKLE CHARGE
CHRG STATE: Hi-Z
FULL CURRENT
SHUTDOWN
DROPS TO 18µA
STANDBY
CHARGE
MODE*
MODE
MODE
MODE
I
IN VOLTAGE MODE
BAT > 2.9V
BAT
< I
TERMINATE
4075 F01
ENABLE
DRIVEN HIGH
BAT < 4.1V
BAT < 2.9V
2.9V < BAT
11
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