ACT8600 datasheet(43/50 Pages) ACTIVE-SEMI

43 / 50 page

ACT8600

Rev 3, 15-Nov-12

Innovative Power

ActivePMU

TM and ActivePathTM are trademarks of Active-Semi.

2CTM is a trademark of NXP.

- 43 -

www.active-semi.com

General Description

When the system is acting as a USB OTG A-

device, the OTG subsystem can provide power to

VBUS from either 5VIN via Q1 or CHGIN via Q2 as

shown in the figure. If VBUS is connected to a

charger (either a charging port, a USB host or Hub,

or a PC), the battery will be charged via Q3 (see

Single-Cell Li+ ActivePathTM Charger section).

5VIN to VBUS (Q1)

Q1 is a PMOS switch that can provide 5V supply to

VBUS from 5VIN pin which is typically connected to

the output of the Boost regulator (REG4). Q1 is

controlled by ONQ1[ ].

The current for Q1 is limited at 700mA to protect the

Boost regulator or external source connected at

5VIN from overloaded. If the current across Q1 is

over the limitation for more than 256ms, the switch

is turned off automatically. A 0 to 1 transition on

ONQ1[ ] is needed to turned Q1 on again after a

over-current condition.

Q1 may optionally interrupt the processor when there

is a over-current condition. Enable interrupts by

setting the nFLTMSKQ1[ ] bit.

CHGIN to VBUS (Q2)

Q2 is a NMOS switch that can power VBUS from

CHGIN. If Q2 is controlled by ONQ2[ ] and can only

be turned on if Q1 is turned off.

The current for Q2 is limited at 700mA prevent the

external

source

connected

CHGIN

from

overloaded. If the current across Q2 is over the

limitation for more than 256ms, the switch is turned

off automatically. A 0 to 1 transition on ONQ2[ ] is

needed to turned Q2 on again after a over-current

condition.

Q2 also features an over voltage protection

function. When the voltage at CHGIN is above 6V,

Q2 is turned off automatically to avoid an over-

voltage condition at VBUS.

Q2 may optionally interrupt the processor when there

is a over-current condition. Enable interrupts by

setting the nFLTMSKQ2[ ] bit.

Figure 4:

USB OTG subsystem

USB OTG

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