rt9501 Richtek Technology Corporation, rt9501 Datasheet - Page 7

• Manufacturer Part Number: rt9501
• Description: Advanced Lithium-ion Linear Battery Charger
• Manufacturer: Richtek Technology Corporation

Constant Voltage Regulation and Charge
Termination Mode
When the battery voltage reaches the regulation voltage
V
then the charge current begins to decrease as the typical
charge profile shown. As the charge current decreases
to lower than charge terminated current threshold, the
RT9501 will terminate the charge cycle.
Recharge Mode
After the charge termination mode, if the battery voltage
falls to lower than the recharge threshold voltage V
the RT9501 will begin a new charge cycle according to
the battery voltage.
Battery Temperature Detection
The RT9501 continuously detects the battery temperature
by measuring the TS pin voltage. A NTC or PTC
thermistor can parallel with R
voltage. (As shown in Figure 5) The TS pin voltage must
be within normal temperature voltage range that is shown
in Figure 6 and electrical characteristics, and then RT9501
can start working normally.
The R
For NTC Thermistors:
For PTC Thermistors:
Where R
operation temperature and R
highest desired operation temperature. The resistances
of thermistors are specified by the thermistor
manufacturer. If the temperature monitoring function is
not desired, there's an easy method to set R
the same value and disconnect the thermistor to disable
this function.
DS9501A/B-08 October 2008
O(REG)
T1
, the constant voltage feedback control starts, and
and R
TL
is the resistance value in lowest desired
T2
can be derived from following equations.
R =
R
R =
R
T1
T2
T1
T2
=
=
TH
3 (R - R )
5 R
[(2 R ) - (7 R )]
[(2 R ) - (7 R )]
3(R
5 R
T2
is the resistance value in
×
×
×
×
×
to deviate the TS pin
5 R
5 R
TH
TH
×
×
TH
TL
TL
TH
- R )
×
×
TH
TH
R
R
TL
TL
TH
×
×
TL
R
R
×
×
T1
TL
TL
and R
TH
TL
O(RCH)
T2
at
,
GPIO
FB/CE Pin Functions
This pin has two functions, one is to enable/disable the
charge function, and the other is to finely adjust battery
regulation voltage. Connect this pin to VDD to enable
RT9501, and connect to ground to disable it (Figure 7). If
this pin is connected to a voltage divider as shown in
Figure 8, it can be a 2.1V reference voltage to adjust the
output regulation voltage as desired.
V
IN
V
R
R
IN
T1
T2
R
R
CE
CS
Normal Temperature Range
Temperature Fault Range
Temperature Fault Range
Figure 7. For CE pin Function
R
STAT
FB/CE
CS
VDD
CS
R4
Figure 5
Figure 6
STAT
CE
CS
VDD
BATT
GND
CC
TS
Q1
R4
RT9501A/B
BATT
GND
CC
TS
Q1
www.richtek.com
VDD
V
V
GND
C2
TS2
TS1
Thermistor
+
Battery
Battery
Pack
7