LX2208 データシートの表示（PDF） - Microsemi Corporation
部品番号
コンポーネント説明
メーカー
LX2208 Datasheet PDF : 11 Pages
| |||
LX2208
2 Amp Three Level Lithium Ion Battery Charger
®
TM
PRODUCTION DATA SHEET
APPLICATION NOTE
LAYOUT
In the layout of the Printed Circuit Board (PCB) it is
important to provide a low thermal impedance path from
the thermal pad on the bottom of the LX2208 package to
the ground plane of the circuit board to maximized heat
dissipation. Generally this is accomplished by the use of
multiple thermal vias. This insures the LX2208 stays cool
and can provide the maximum charge current to minimize
the time required to charge the battery.
For latch-up prevention purpose, it is important to place
10µF capacitors (X5R or X7R dielectric) close to the IN
and BAT pins. With long input cables to the adapter or
USB, it is best to use a sheathed cable or twisted wire cable
which is typical of most applications.
The CMP 0.47µF capacitor and 1k resistor should be
placed close to the CMP pin and IN pin; the CMP pin is
located adjacent to the IN pin to facilitate this.
CURRENT PROGRAMMING RESISTORS
The LX2208 has two programming resistors to control
the battery charging current during the constant current
charging mode of the battery charging cycle. When the
H/ L pin is high (selecting the High Current charging
mode), the charge current is determined by the value of the
HCP programming resistor RHCP. The maximum charge
current is determined by the programming current at either
the HCP or LCP programming pins (depending on the state
of H/ L ); the range of each of these channels is identical.
The programming current is the HCP or LCP pin voltage
(typically 1.25V) divided by the value of the programming
resistor. For example, the HCP current with a 7.15k
resistor to GND is:
I HCP
=
1.25
R HCP
=
1.25
7.15k
= 175µA
Charge Current vs IHCP (or ILCP)
2000
1800
1600
1400
1200
1000
800
600
400
200
0
0
50
100
150
200
250
300
350
IHCP (in uA)
Using the table above it can be seen that for a
programming current value of 175µA, the corresponding
maximum charge current is 1A.
The termination current determines the point at which
the charge cycle is terminated and the battery is determined
to be fully charged. The termination current is determined
by the value of the HCP programming current as
determined by the HCP programming resistor RHCP. For a
value of IHCP = 175µA (as was used in the previous
example), the termination current from the chart below can
be seen to be 100mA.
200
180
160
140
120
100
80
60
40
20
0
0
Termination Current vs IHCP
50
100
150 200 250 300
350
IHCP (in uA)
The termination current is always roughly 10% of the
maximum charge current set by the HCP resistor RHCP.
Constant Charge Current (in mA)
RHCP
43.3
169.28k
92
88.67k
460
15.80k
730
9.75k
1000
7.15k
2000
3.56k*
* RHCP minimum value
Termination Current (in mA)
RHCP
4.33
169.28k
9.2
88.67k
46
15.80k
73
9.75k
100
7.15k
200
3.56k*
Copyright © 2007
Rev. 1.0, 2007-04-03
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 8
Share Link: 