UCS81003 datasheet(36/108 Pages) MICROCHIP

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UCS81003

DS20005334A-page 36

 2014 Microchip Technology Inc.

7.4.1

CHARGE RATIONING

INTERACTIONS

When charge rationing is active, regardless of the

specified

behavior,

the

UCS81003

will

function

normally until the charge rationing threshold is

reached. Note that charge rationing is only active when

the UCS81003 is in the Active state, and it does not

automatically reset when a Removal or Attach

Detection event occurs. Charger emulation will start

over if a Removal Detection event and Attach Detection

event occur while charge rationing is active and the

charge rationing threshold has not been reached. 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

transparent to the user. When the charge rationing

threshold is reached, the UCS81003 will take action, as

shown in Table 7-1. If the behavior is changed after the

charge rationing threshold has been reached, the

UCS81003

will

immediately

adopt

the

newly

programmed behavior, clearing the ALERT# pin and

restoring switch operation respectively (see Table 7-3).

Disconnect

and Go to Sleep

Reset the Total Accumulated Charge registers.

Clear the RATION status bit.

Check the M1, M2, EM_EN, S0 and PWR_EN controls and enter the indicated power state

if the controls changed (Note 1).

Ignore

Reset the Total Accumulated Charge registers.

Clear the RATION status bit.

TABLE 7-2:

CHARGE RATIONING RESET BEHAVIOR (CONTINUED)

Behavior

Reset Actions

Note 1:

Any time the charge rationing circuitry checks the pin conditions when changing rationing behavior or

resetting charge rationing, if the external pin conditions have changed, then charger emulation will be

restarted (provided emulation is enabled via the pin states). If the pin conditions have not changed, the

UCS81003 returns to the previous power state as if the rationing threshold had not been reached (e.g., it

will not discharge VBUS or restart emulation).

TABLE 7-3:

EFFECTS OF CHANGING RATIONING BEHAVIOR AFTER THRESHOLD REACHED

Behavior

New

Behavior

Actions taken

Ignore

Report

Assert ALERT# pin.

Report

and

Disconnect

Assert ALERT# pin.

Remove charger emulation profile.

Open port power switch. See the Report and Disconnect (default) in Table 7-1.

Disconnect

and

Go to Sleep

Remove charger emulation profile.

Open port power switch.

Enter the Sleep state. See the Disconnect and Go to Sleep entry in Table 7-1.

Note 1:

Any time the charge rationing circuitry checks the pin conditions when changing rationing behavior or

resetting charge rationing, if the external pin conditions have changed, then charger emulation will be

restarted (provided emulation is enabled via the pin states). If the pin conditions have not changed, the

UCS81003 returns to the previous power state as if the rationing threshold had not been reached (e.g., it

will not discharge VBUS or restart emulation).

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