LTC4063 LINER [Linear Technology], LTC4063 Datasheet - Page 14

• Manufacturer Part Number: LTC4063
• Description: Standalone Linear Li-Ion Charger with Micropower Low Dropout Linear Regulator
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
LTC4063
With User-Selectable Charge Termination, the SmartStart
feature is disabled; when the charger is powered on or
enabled, the LTC4063 automatically begins charging, re-
gardless of the battery voltage. Figure 5 describes charger
operation when User-Selectable Charge Termination is
used.
Programming C/10 Current Detection/Termination
In most cases, an external resistor, R
the charge current detection threshold, I
when setting I
14
R
Figure 6. Two Circuits that Charge at 500mA
Full-Scale Current and Terminate at 50mA
PROG
2k
R
PROG
DETECT
1k
R
DET
V
2k
V
IN
IN
U
to be 1/10th of I
V
V
PROG
IDET
PROG
IDET
POWER ON
CC
CC
U
LTC4063
LTC4063
GND
GND
TIMER
TIMER
Figure 5. State Diagram of a Charger Cycle Using User Termination
BAT
BAT
W
500mA
500mA
BAT < 2.9V
2.9V < BAT
CHG
DET
4063 F06
DETECT
, the IDET pin can
, is needed to set
+
+
CHRG STATE: PULL-DOWN
CHRG STATE:
PULL-DOWN IF I
Hi-Z IF I
TRICKLE CHARGE MODE
U
. However,
1/10 FULL CURRENT
CHARGE MODE
FULL CURRENT
BAT
< I
DETECT
BAT
BAT > 2.9V
> I
DETECT
be connected directly to the PROG pin. This reduces the
component count, as shown in Figure 6.
When PROG and IDET are connected in this way, the full-
scale charge current, I
ent equation:
Stability Considerations
The battery charger constant voltage mode feedback loop
is stable without any compensation provided a battery is
connected. However, a 1µF capacitor with a 1Ω series
resistor to GND is recommended at the BAT pin to keep
ripple voltage low when the battery is disconnected.
When the charger is in constant current mode, the PROG
pin is in the feedback loop, not the battery. The constant
current stability is affected by the impedance at the PROG
pin. With no additional capacitance on the PROG pin, the
charger is stable with program resistor values as high as
10k; however, additional capacitance on this node reduces
the maximum allowed program resistor.
For the LDO regulator, a capacitor (C
nected from OUT to GND to ensure regulator loop stability.
It is recommended that low ESR capacitors be used for
C
C
OUT
OUT
R
4063 F05
PROG
to reduce noise on the output of the linear regulator.
must be ≥ 2µF for best performance.
=
UVLO CONDITION
CHGEN = 5V
CHRG STATE: Hi-Z
500
I
CHG
OR
I
SHUTDOWN MODE
CC
V
DROPS TO 35µA
,
I
CHG
CHG
CHGEN = 0V
OR UVLO
CONDITION
STOPS
=
, is programmed using a differ-
R
500
PROG
V
OUT
) must be con-
4063fb