ltc4076 Linear Technology Corporation, ltc4076 Datasheet - Page 11

• Manufacturer Part Number: ltc4076
• Description: Dual Input Standalone Battery Charger
• Manufacturer: Linear Technology Corporation

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.
If no power is applied at either pin, the  P  W  R pin is high
impedance, indicating that the LTC4076 lacks sufficient
power to charge the battery. The pull-down state is capable
of sinking up to 10mA.
Thermal Limiting
An internal thermal feedback loop reduces the programmed
charge current if the die temperature attempts to rise above
EN
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
NO CHARGE CURRENT
1/10th FULL 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. LTC4076 State Diagram of a Charge Cycle
DCIN POWER APPLIED
DCIN POWER
REMOVED
EN
DRIVEN HIGH
DCIN POWER
REMOVED
POWER SELECTION
STARTUP
a preset value of approximately 105°C. This feature protects
the LTC4076 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.
EN
DRIVEN HIGH
USBIN POWER
REMOVED OR
DCIN POWER
APPLIED
USBIN POWER
REMOVED OR
DCIN POWER
ONLY USB POWER APPLIED
APPLIED
1/5 FULL CURRENT⇒HPWR = LOW
FULL CURRENT⇒HPWR = HIGH
CHRG STATE: PULLDOWN
CHRG STATE: PULLDOWN
I
1/10th FULL CURRENT
NO CHARGE CURRENT
USBIN
TRICKLE CHARGE
CHRG STATE: Hi-Z
CHRG STATE: Hi-Z
SHUTDOWN
DROPS TO 18µA
STANDBY
CHARGE
MODE
MODE
MODE
MODE
I
IN VOLTAGE MODE
BAT > 2.9V
BAT
< I
TERMINATE
4076 F01
EN
DRIVEN LOW
LTC4076
BAT < 4.1V
BAT < 2.9V
2.9V < BAT
11
4076fa