LTC4065LEDC#TRMPBF Linear Technology, LTC4065LEDC#TRMPBF Datasheet - Page 8

• Manufacturer Part Number: LTC4065LEDC#TRMPBF
• Description: IC CHARGER LI-ION 6-DFN
• Manufacturer: Linear Technology

Specifications of LTC4065LEDC#TRMPBF

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 3.75 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 6-WFDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

OPERATIO
The LTC4065L is a linear battery charger designed prima-
rily for charging single cell lithium-ion batteries. Featuring
an internal P-channel power MOSFET, the charger uses a
constant-current/constant-voltage charge algorithm with
programmable current. Charge current can be programmed
up to 250mA with a final float voltage accuracy of ±0.6%.
The CHRG open-drain status output indicates if C/10 has
been reached. No blocking diode or external sense resistor
is required; thus, the basic charger circuit requires only
two external components. An internal termination timer
and trickle charge low-battery conditioning adhere to
battery manufacturer safety guidelines (Note: The
LTC4065LX does not include this trickle charge feature).
Furthermore, the LTC4065L is capable of operating from
a USB power source.
An internal thermal limit reduces the programmed charge
current if the die temperature attempts to rise above a
preset value of approximately 115°C. This feature protects
the LTC4065L 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 LTC4065L
or external components. Another benefit of the LTC4065L
thermal limit is that charge current can be set according to
typical, not worst-case, ambient temperatures for a given
application with the assurance that the charger will auto-
matically reduce the current in worst-case conditions.
The charge cycle begins when the following conditions are
met: the voltage at the V
mately 80mV above the BAT pin voltage, a program
resistor is present from the PROG pin to ground and the EN
pin is pulled below the shutdown threshold (typically
0.82V).
If the BAT pin voltage is below 2.9V, the charger goes into
trickle charge mode, charging the battery at one-tenth the
programmed charge current to bring the cell voltage up to
a safe level for charging (Note: The LTC4065LX does not
include this trickle charge feature). If the BAT pin voltage
is above 4.1V, the charger will not charge the battery as the
cell is near full capacity. Otherwise, the charger goes into
the fast charge constant-current mode.
LTC4065L/LTC4065LX
8
U
CC
pin exceeds 3.6V and approxi-
When the BAT pin approaches the final float voltage
(4.2V), the LTC4065L enters constant-voltage mode and
the charge current begins to decrease. When the current
drops to 10% of the full-scale charge current, an internal
comparator turns off the N-channel MOSFET on the CHRG
pin and the pin assumes a high impedance state.
An internal timer sets the total charge time, t
cally 4.5 hours). When this time elapses, the charge cycle
terminates and the CHRG pin assumes a high impedance
state. To restart the charge cycle, remove the input voltage
and reapply it or momentarily force the EN pin above V
(typically 0.82V). The charge cycle will automatically re-
start if the BAT pin voltage falls below V
4.1V).
When the input voltage is not present, the battery drain
current is reduced to less than 4µA. The LTC4065L can also
be shut down by pulling the EN pin above the shutdown
threshold voltage. This reduces input quiescent current to
less than 20µA and battery drain current to less than 1µA.
Programming Charge Current
The charge current is programmed using a single resistor
from the PROG pin to ground. The battery charge current
is 205 times the current out of the PROG pin. The program
resistor and the charge current are calculated using the
following equations:
The charge current out of the BAT pin can be determined
at any time by monitoring the PROG pin voltage and using
the following equation:
I
R
BAT
PROG
=
R
=
V
PROG
PROG
205
•
• 205
I
BAT
1
V
,
I
BAT
=
R
205
PROG
V
RECHRG
TIMER
(typically
(typi-
4065lxfa
MS