SC810 datasheet(17/19 Pages) SEMTECH

17 / 19 page

SC810

footprint will enable better heat transfer

from the device, especially on PCBs with

internal ground and power planes.

Dynamically Selectable Charge Current

The IPRGM resistance can be altered dynamically under

processor control by switching a second IPRGM pin resis-

tor. When the higher current is required, the switch is

turned on, making the effective programming resistance

equal to the parallel combination of the two resistors. The

external circuit is illustrated in Figure 5.

IPRGM

RIPRGM

RIPRGM_HI

Hi/Lo

Current Select

Figure 5. Dynamic selection of low and high charge

currents.

Note that the IPRGM pin resistor programs the fast-charge,

pre-charge, and termination currents, so all will be modi-

fied by a change in the IPRGM pin resistor.

An open-drain GPIO can be used directly to engage the

parallel resistor R

IPRGM_HI

. Care must be taken to ensure that

the R

DS-ON

of the GPIO is considered in the selection of

IPRGM_HI

. Also important is the part-to-part and tempera-

ture variation of the GPIO R

DS-ON

, and their contribution to

the High Current charge current tolerance. Note also that

IPRGM will be pulled up briefly to as high as 3V during

startup to check for an IPRGM static pinshort to ground. A

small amount of current could, potentially, flow from

IPRGM into the GPIO ESD structure through R

IPRGM_HI

during

this event. While unlikely to do any harm, this effect must

also be considered.

Applications Information (continued)

SC810 Datasheet(PDF) 17 Page - Semtech Corporation

SC810 Datasheet(HTML) 17 Page - Semtech Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Datasheet Download

Link URL