MP26028 – 1A LINEAR LI-ION BATTERY CHARGER WITH TRICKLE CHARGE

MP26028 Rev.1.01

www.MonolithicPower.com

9

10/28/2011

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2011 MPS. All Rights Reserved.

Charge Status Indicator (CHG)

The MP26028 has an integrated charge status

pin that remains low while the battery is

charging. Once the charge current has reduced

the CHG pin will become high impedance.

LEDs ( Figure 1) or to interface with the system.

When interfacing with the system, glitches may

occur on the power supply input (IN) when the

AC-power adapter is plugged in and out. It is

desirable to blank the glitches so that the

system can properly operate with AC power

adaptor. A simple Solution is to add the RC

shown in Figure 5. The size of C5 and C6

depends on the width of the glitch and the rise

time of the interface.

Thermal Protection

The

MP26028

has

proprietary

thermal

protection to prevent the IC from overheating.

When in thermal protection mode, the charge

current becomes a saw-tooth waveform instead

of a DC current. The average current of the

saw-tooth waveform will be lower than the

programmed DC charge current to prevent the

IC from overheating. The frequency and

amplitude of the saw-tooth current waveform

can be altered by changing the capacitance

value connected to the SS pin. Operating in

thermal protection mode will slow down the

charging process. Lowering the input voltage

and enhancing thermal dissipation to the

environment can effectively prevent the IC from

going into thermal protection mode.

Figure 5—Filtered Charge Status & Input Power Good Interface