RT9501A RICHTEK [Richtek Technology Corporation], RT9501A Datasheet - Page 6

• Manufacturer Part Number: RT9501A
• Description: Advanced Lithium-lon Linear Battery Charger
• Manufacturer: RICHTEK [Richtek Technology Corporation]

RT9501A/B
Application Information
Charge Profile
Detection
First, the FB/CE pin must connect to VDD or a voltage
divider to enable the charge function. And then if a battery
is already inserted and the input power source is absent,
the RT9501 will enter sleep mode to prevent draining
power from battery. When input power source and battery
are both existed, another detection is the battery
temperature. The TS pin voltage must be in the allowed
range as shown in Figure 6 and the electrical
characteristics, and then the RT9501 will start the charge
cycle according to the battery voltage conditions.
Precharge Mode
When the battery voltage is lower than the precharge
threshold V
in precharge mode. In this condition, the precharge current
is set at approximately 10% of the constant
current. The purposes of small precharge current are to
minimize the power dissipation on the external switch
during the precharge period and to revive deeply
discharged battery cells.
6
Charge termination current
O(MIN)
Precharge current =
Precharge threshold
Regulation voltage
Regulation current
, the RT9501 begins to charge the battery
Recharge voltage
voltage
Precharge
mode
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Figure 3. Typical charge profile
Constant current
regulation mode
regulation
Preliminary
V
Constant Current Regulation Charge Mode
When the battery voltage is between the precharge
threshold V
RT9501 starts the constant current regulation charge
mode. RT9501 monitors charge current with voltage drop
between two terminals of a sense-resistor, R
connects to pin VDD and CS. The following equation can
calculate the desired charging current.
I
and charge termination mode
IN
O(REG)
Constant voltage regulation
=
V
R
I(SNS)
O(MIN)
CS
R
CS
and the regulation voltage V
Figure 4
FB/CE
CS
VDD
GND
DS9501A/B-03P October 2004
R4
Recharge
mode
BATT
STAT
CC
TS
Q1
O(REG)
CS
, which
Battery
, the