L6924UTR datasheet(22/37 Pages) STMICROELECTRONICS

Part #	L6924UTR

Description	USB compatible battery charger system with integrated power switch for Li-Ion/Li-Polymer

PDF	37 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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22 / 37 page

Applications information: charging process

L6924U

22/37

Doc ID 14716 Rev 2

Figure 15.

TPRG pin connection

Where,

RPRG = resistor which sets the current (RUSB or RAC)

VREF = 1.8 V,

KT = 279 x 10

VBG = 1.23 V, and

TMAXCH is the charging time given in seconds.

If the battery does not reach the end-of-charge condition before the timer expires, a fault is

issued.

Also during the pre-charge phase there is a safety timer, given by:

Equation 11

If this timer expires and the battery voltage is still lower than VPRETH, a fault signal is

generated, and the charge process finishes.

Note:

When the device is charged in low power USB mode, in order to take into account the

reduced charge current, the maximum charging time is proportionally increased (five times

the maximum charging time calculated with RUSB).

MAXCH

MAXPRECH

L6924UTR Datasheet(PDF) 22 Page - STMicroelectronics