MP2608- 28V, 1A DUAL INPUT LINEAR BATTERY CHARGER WITH TIMER
MP2608 Rev. 0.9 www.MonolithicPower.com 10
8/29/2008 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2008 MPS. All Rights Reserved.
Table 1—R
CHG
and I
CHG
Relationship
R
CHG
(k) I
CHG
(mA)
TBD
TBD
Figure 3—Charge Current vs. 1/RPGM
Resistance
V
IN
STATUS
POR Threshold
FAULT
15 Cycles to
1/8 TIMEOUT
V
BATT
V
MIN
V
RECHARGE
I
MIN
t
0
t
1
t
2
t
3
t
4
t
5
t
6
t
7
2.6V
15 Cycles
I
CHARGE
Figure 4—MP2608 Typical Re-Charging
Waveforms
Charge Status and Fault Indication
The open drain pin STATUS is used to indicate
charging status. While battery is being charged,
the
STATUS pin is pulled low, when the battery
full condition is reached or any other condition
prevents the charger from charging, the
STATUS pin will become a floating. STATUS is
then latched till a new charge cycle is started.
Upon a time-out fault event happen, the
FAULT
pin is pulled low. When the V
BATT
is lower than
2.6V for 1/8
th
of timeout period or the charging
can not reach EOC status before the timeout
happens, this fault status is latched, the charging
is suspended, and the
FAULT pin is pulled low.
To clear this fault, either the V
IN
or V
USB
should
be recycled. One time-out period is equivalent to
2
15
oscillator clock cycles. With a 1µF capacitor
on the TMR pin, it takes 3.64 hours.
The Power On and recharge cycle are illustrated
in Figure 4.
