ACT5880 datasheet(83/87 Pages) ACTIVE-SEMI

83 / 87 page

ACT5880

Rev 2, 03-Sep-13

- 83 -

www.active-semi.com

ActivePMU

TM and ActivePathTM are trademarks of Active-Semi.

I2CTM is a trademark of NXP.

Active-Semi Confidential―Do Not Copy or Distribute

Figure 19:

The Charge and Discharge Curves for NiMH

Cell.

Long Cord Power Operation

When a device whose normal operation is with a

power cord connected, the charger may frequently

seesaw charges the battery. Programming the fast

charge current to a smaller volume could have the

end of charge current less than the operation

current and then the end of charge condition does

not happen, forces the charger into floating. The

floating state causes less aging than the frequent

seesaw charge does. For staying in floating, the

total charge time-out function should be disabled

and the battery regulation should be programmed to

100mV lower than the nominal battery charge

termination voltage, which is desired for safe

floating and enlarges the battery life cycles.

USB Charging

The ACT5880 provides the adaptor charge input

detection, the battery installed detection, the

CHGLEV charge current set input and with few

programmable registers for the USB charging. 3

situations in battery powered devices specified in

the "Battery Charging" specification of the USB IF

are supported,

the

no-battery situation,

the

weak/dead battery situation and the battery normal

situation. Specified device behavior in those

situations is required only if the power source is

identified as a host charger or a hub charger.

The ACT5880 deploys the resistive method

recommended by the USB IF for the power source

identification, with its precise threshold ACIN input.

Ref to the Figure 20, a sample circuit uses single

port for both USB connection and charging, in

which the RDUP is 220kΩ, the RISO is 240kΩ and the

RDDW is 220kΩ. The input of an adaptor in

compliance with the "Battery Charging" and the

"YD/T1591" specifications is identified if both the

CHGIN and the ACIN are read valid. Only the

CHGIN read valid is for USB host attached or for

hub attached, while only the ACIN read valid is for

USB OTG A-device attached or for an over-loaded

weak adaptor attached. The resistive detection

provides reliable detection in most cases but the

case of a USB OTG A-device powering the VBUS

with its local 5V, which is a known operation state of

the device. The RDUP and the RISO should be placed

close to the traces connecting the USB receptacle

pins and USB PHY pins, for less branching effect,

which

important

running

high

speed

transmission.

Figure 20:

The Sample Circuit for USB Charging.

When a suitable voltage power applied on the

CHGIN, and while charging function allowed

(SUSCHG=0), if no battery detected, the charger

path turns into the LDO mode, in which it regulates

the VBAT voltage to power the system. The system

defines its way of operation in no-battery situation,

either as a no-battery USB device or turns its self

into device suspend mode with less than 2.5mA

drawn from USB port. In the LDO mode, the output

voltage is set by the VSET[ ], the pass current is

limited to the fast charge current set as a function of

the ISET[ ] and the CHGLEV, and the charge timers

are

cleared.

The

thermal

regulation

keeps

preventing the die from overheating.

When a USB or a hub is attached while the device

is with a weak/dead battery from the device system

point of view, while the charging function is default

enabled

(SUSCHG=0),

the

ACT5880

starts

charging with the fast charge set by the CHGLEV or

precondition charges the battery, dependent on if

the battery voltage is greater or less than the

precondition threshold. The CHGLEV should be

connected to an I/O of the host system with a pull-

down resistor around 1MΩ. Before the processor

1.6V

1.4V

1.2V

1.6V

1.4V

1.2V

1.4V

1.2V

1.0V

0.33C

0.1C

0˚C

20˚C

40˚C

80% 100%120%

1.8C

Charge Curveat 25˚C

Charge Curveat 1C charge

0.2C discharge at 25˚C

ACIN

RISO

ACT5880

Device

USB I/F

RDUP

RDDW

VBUS

CHGIN

Foreign

Adaptor

or USB

VBUS

D+

D-

USB connectors

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