EUP8020X
Battery Voltage Regulation
Note On EUP8020F
The voltage regulation feedback is through the OUT pin.
This input is tied directly to the positive side of the
battery pack. The EUP8020X monitors the battery pack
voltage between the OUT and VSS pins. When the
battery voltage rises to VO(REG) threshold, the voltage
regulation phase begins and the charging current begins
to taper down.
The EUP8020F monitors the charging current during the
voltage regulation phase. Once the taper threshold,
I
(TAPER),is detected the EUP8020F terminates the charge.
There is no taper timer, t(TAPER) for this version.
The resistor connected between the ISET1 and VSS, RSET
,
determines the taper detection level for AC input. For
USB charge, taper level is fixed at 10% of the 100- or
500-mA charge rate.
As a safety backup, the EUP8020X also monitors the
charge time in the charge mode. If charge is not
terminated within this time period, t(CHG), the EUP8020X
turns off the charger and enunciates FAULT on the
STATx pins. Please refer to the Timer Fault Recovery
section for additional details.
Also note that there is I(TERM) detection in EUP8020F.
Sleep Mode
The EUP8020X enters the low-power sleep mode if both
AC and USB are removed from the circuit. This feature
prevents draining the battery during the absence of input
supply.
Charge Taper Detection, Termination and Recharge
The EUP8020X monitors the charging current during the
voltage regulation phase. Once the taper threshold,
I(TAPER),is detected the EUP8020X initiates the taper timer,
Charge Status Outputs
t
(TAPER). Charge is terminated after the timer expires. The
The open-drain STAT1 and STAT2 outputs indicate
various charger operations as shown in the following
table. These status pins can be used to drive LEDs or
communicate to the host processor. Note that OFF
indicates the open-drain transistor is turned off.
resistor connected between the ISET1 and VSS, RSET
determines the taper detection level. The V(TAPER) and
(SET) parameters are specified in the specifications table.
Note that this applies to both AC and USB charging.
,
K
Table 1. Status Pins Summary
V
× K
(SET)
(TAPER)
I
=
------------------ (3)
(TAPER)
R
SET
CHARGE STATE
Precharge in progress
Fast charge in progress
Charge done
STAT1 STAT2
ON
ON
OFF
OFF
OFF
OFF
ON
OFF
ON
OFF
OFF
OFF
The EUP8020X resets the taper timer in the event that
the charge current returns above the taper threshold,
Charge suspend (temperature)
Timer fault
I(TAPER)
.
In addition to the taper current detection, the EUP8020X
terminates charge in the event that the charge current falls
below the I(TERM) threshold. This feature allows for quick
recognition of a battery removal condition or insertion of
a fully charged battery. Note that charge timer and taper
timer are bypassed for this feature. The resistor
connected between the ISET1 and VSS, RSET, determines
the taper detection level. The V(TERM) and K(SET)
parameters are specified in the specifications table. Note
that this applies to both AC and USB charging.
Sleep mode
OFF means the open-drain output transistor on the
STAT1 and STAT2 pins is in an off state.
PG Output
The open-drain PG (Power Good) indicates when the
AC adapter is present. The output turns ON when a valid
voltage is detected. This output is turned off in the sleep
mode. The PG pin can be used to drive an LED or
communicate to the host processor.
V
× K
(SET)
(TERM)
I
=
-------------------- (4)
(TERM)
R
SET
After charge termination, the EUP8020X re-starts the
charge once the voltage on the OUT pin falls below the
V(RCH) threshold. This feature keeps the battery at full
capacity at all times.
DS8020X Ver 1.1 June 2006
10
EUTECH [ EUTECH MICROELECTRONICS INC ]
