LX2206ILD MICROSEMI [Microsemi Corporation], LX2206ILD Datasheet - Page 9

• Manufacturer Part Number: LX2206ILD
• Description: Dual Level Lithium Ion Battery Charger
• Manufacturer: MICROSEMI [Microsemi Corporation]

Copyright © 2005
Rev. 1.2, 2006-12-22
B
ATTERY
temperature during battery charging; this method
assumes the battery pack contains a thermistor
expressly for this purpose. A typical Lithium ion battery
should only be charged from a range of 0°C to 60°C.
For this calculation, a Vishay NTHS0402N01N1003J
Thermistor was used. This thermistor is 327KΩ at 0°C,
100KΩ at 25°C and 24.9KΩ at 60°C. The thermistor
must be biased with a Thevenin voltage source and
series resistance to achieve the proper thresholds. A
fixed value resistor is added in series with the
thermistor to prevent it from becoming too low an
impedance at high temperatures and causing the TMP
input to default to off.
Using a value of R
temperature at 60°C works well; therefore, for this
example, set the value of R
effect of adding 24.9K to the thermistor resistance
values so it becomes 352KΩ at 0°C, 125KΩ at 25°C
and 49.8KΩ at 60°C.
The equations for R
Where R at temperature is the sum of the thermistor
plus R
V
V
R
TH
IN
TH
The LX2206 has an input to monitor the battery
=
TM
=
(
MIN
0.29
0.29
⎛
⎜
⎝
0.74
T
K
.
EMPERATURE
×
×
R
0.74
−
T
1
=
⎞
⎟
⎠
0C
×
×
) (
R
(
−
R
T
TMP
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
TH
T
0.74
=
MIN
=
0C
0C
and V
=
−
×
that is equal to the thermistor
121K
R
M
R
T
T
=
ONITOR
V
=
60C
60C
MIN
TH
TH
)
R
)
R
R
are:
=
NTC
MIN
TH
to 24.9K. This has the
K
=
0.99
A P P L I C A T I O N N O T E
Integrated Products Division
®
Microsemi
Dual Level Lithium Ion Battery Charger
value is so large it is insignificant. In this case, R1 = R
To finish the design it is necessary to create the
Thevenin Voltage and resistance using a voltage
divider from the input pin (IN).
The values of R1 and R2 can be calculated as:
R
In this case, it is not necessary to use R2, because the
R
1
2
=
=
R
K
TH
R
R
1
1
×
−
=
R
P
R
122K
TH
TH
RODUCTION
TMP
=
14,800K
V
IN
D
R
R
ATA
R
NTC
MIN
1
S
HEET
R
2
LX2206
TH.
Page 9