L6924D datasheet(16/38 Pages) STMICROELECTRONICS

Part #	L6924D

Description	Battery charger system with integrated power switch for Li-ION/Li-POLYMER

PDF	38 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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16 / 38 page

Operation description

L6924D

16/38

Neglecting the voltage drop across the charger (

∆V

MOS) when the device operates in this

condition, its input voltage is equal to the battery one, and so a very low operating input voltage

(down to 2.5V) is required. The power dissipated by the device during this phase is:

When the battery voltage approaches the final value, the charger gets back the control of the

current, reducing it. Due to this, the upstream adapter exits the current limit condition and its

output goes up to the regulated voltage VADP. This is the worst case in power dissipation:

In conclusion, the advantage of the linear charging approach is that the designer has the direct

control of the charge current, and consequently the application can be very simple. The

drawback is the high power dissipation.

The advantage of the Quasi-Pulse charging method is that the power dissipated is dramatically

reduced. The drawback is that a dedicated upstream adapter is required.

)

(

LIM

Eq: 7-4

LIM

BAT

ADP

DIS

−

)

(

Eq: 7-5

L6924D Datasheet(PDF) 16 Page - STMicroelectronics