LX2202CLQ-TR MICROSEMI [Microsemi Corporation], LX2202CLQ-TR Datasheet - Page 10

• Manufacturer Part Number: LX2202CLQ-TR
• Description: TM 2A Li-Ion Linear Charger and Power Control
• Manufacturer: MICROSEMI [Microsemi Corporation]

Copyright © 2004
Rev. 1.0a, 2006-02-09
R
reduces charge time from USB when the appliance is turned
on while also charging. Because the system power rail can
be a higher voltage than the battery voltage, the system will
require less power from the USB source which leaves more
power available to charge the battery which charges the
battery faster. For example, if the system draws 1W, and
the USB input is 5V, the system draws 1W/5V = 200mA
from the USB source; this leaves 300mA to charge the
battery. In a topology where the load connects directly to
the battery (as is done with conventional linear chargers), if
the average battery voltage is 3.7V, the system will draw
1W/3.7V = 270mA from the USB source, this leaves only
230mA to charge the battery. In this case the LX2202 will
charge the battery 30% faster.
C
circuitry that allows charging from current limited power
sources. The LX2202 increases the impedance of the pass
element under small charge or discharge currents so that
mode change situations can be more readily detected by the
internal circuits. This improved mode discrimination allows
the battery to aid the current limited input power supply
when the system load demands it and to switch back to
charge mode when the system power demand is reduced.
EDUCED
URRENT
The LX2202 has an isolated battery topology which
The LX2202 has special headroom voltage regulation
TM
USB C
L
IMITED
HARGE
P
OWER
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
T
IME
S
UPPLIES
A P P L I C A T I O N N O T E
Integrated Products Division
®
Microsemi
2A Li-Ion Linear Charger and Power Control
USB C
current must be less than 100mA in the low power mode
and less than 500mA in the high power mode. If the
LX2202 is configured as shown in Figure 3, it is possible
for the system to consume more than the maximum
allowed USB current (in which case the battery charging
current will have been fully scaled back). If it is not
possible to regulate the load current when charging from a
USB power source and strict adherence to the USB power
budget is required, in this case the system load can be
applied directly across the battery and the LX2202 will
prevent the combination of the load plus battery from
drawing more power than is allowed for USB compliance.
L
AYOUT
To be compliant with the USB specification, the +5V
•
•
OMPLIANCE
place 10µF ceramic capacitors close to the VDD
and V
path from the thermal pad on the bottom of the
LX2202 package to the ground plane of the circuit
board to maximize the heat dissipation.
It is important when laying out the LX2202 to
It is important to provide a low thermal impedance
G
UIDELINES
P
BAT
RODUCTION
IC terminals to filter switching transients.
D
ATA
S
HEET
LX2202
Page 10