UCS2112 datasheet(31/64 Pages) MICROCHIP

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 2015 Microchip Technology Inc.

DS20005424B-page 31

UCS2112

7.5

Charge Rationing Interactions

When charge rationing is active, regardless of the

specified behavior, the UCS2112 will function normally

until the charge rationing threshold is reached. Note

that charge rationing is only active when the UCS2112

is in the Active state, and it does not automatically

reset when a Removal or Attach Detection event

occurs. This allows charging of sequential portable

devices while charge is being rationed, which means

that the accumulated power given to several portable

devices will still be held to the stated rationing limit.

Changing the charge rationing behavior will have no

effect on the charge rationing data registers. If the

behavior is changed prior to reaching the charge

rationing threshold, this change will occur and be trans-

parent to the user. When the charge rationing threshold

is reached, the UCS2112 will take action as shown in

Table 7-2. If the behavior is changed after the charge

rationing threshold has been reached, the UCS2112

will immediately adopt the newly programmed behav-

ior, clearing the ALERT# pin and restoring switch

operation respectively (see Table 7-4).

TABLE 7-2:

CHARGE RATIONING BEHAVIOR

RATION_BEH

(1 or 2) <1:0>

Behavior

Actions taken

Notes

Report

ALERT# pin asserted.

Report and

Disconnect

(default)

ALERT# pin asserted.

Port power switch dis-

connected.

All bus monitoring is still active.

Toggling the PWR_EN control will cause the

device to change power states as defined by the

registers; however, the port power switch will

remain off until the rationing circuitry is reset. Fur-

thermore, the bypass switch will not be turned on if

enabled via the Attach Detection.

Disconnect

and

Go to Sleep

Port power switch dis-

connected.

Device will enter the

Sleep state.

All VBUS and VS monitoring will be stopped.

Toggling the PWR_EN control will have no effect

on the power state until the rationing circuitry is

reset.

Ignore

Take no further action.

TABLE 7-3:

CHARGE RATIONING RESET BEHAVIOR

Behavior

Reset Actions

Report

Reset the Total Accumulated Charge registers.

Clear the RATION status bit.

Release the ALERT# pin.

Report and Disconnect

Reset the Total Accumulated Charge registers.

Clear the RATION status bit.

Release the ALERT# pin.

Check the PWR_EN controls and enter the indicated power state if the controls

changed.

Disconnect and

Go to Sleep

Reset the Total Accumulated Charge registers.

Clear the RATION status bit.

Check the PWR_EN controls and enter the indicated power state if the controls

changed.

Ignore

Reset the Total Accumulated Charge registers.

Clear the RATION status bit.

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