LX2202CLQ 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

LX2202CLQ

2A Li-Ion Linear Charger and Power Control

Microsemi Corporation 

LX2202

TM

® 2A Li-Ion Linear Charger and Power Control

PRODUCTION DATA SHEET

APPLICATION NOTE

REDUCED USB CHARGE TIME

USB COMPLIANCE

The LX2202 has an isolated battery topology which

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.

CURRENT LIMITED POWER SUPPLIES

The LX2202 has special headroom voltage regulation

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.

To be compliant with the USB specification, the +5V

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.

LAYOUT GUIDELINES

• It is important when laying out the LX2202 to

place 10µF ceramic capacitors close to the VDD

and VBAT IC terminals to filter switching transients.

• It is important to provide a low thermal impedance

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.

Copyright © 2004

Rev. 1.0a, 2006-02-09

Microsemi

Integrated Products Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 10

Share Link: