Datasheet

MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
15
Maxim Integrated
As shown in Figure 1, the IC includes a full-featured
charger with thermistor monitor, fault timer, charger
status, and fault outputs. Also included are power-OK
signals for both USB and DC. Flexibility is maintained
with adjustable charge current, input current limit, and
a minimum system voltage (when charging is scaled
back to hold the system voltage up).
The MAX8903_ prevents overheating during high ambi-
ent temperatures by limiting charging current when the
die temperature exceeds +100°C.
DC Input—Fast Hysteretic
Step-Down Regulator
If a valid DC input is present, the USB power path is
turned off and power for SYS and battery charging is
supplied by the high-frequency step-down regulator
from DC. If the battery voltage is above the minimum
system voltage (V
SYSMIN
, Figure 4), the battery charger
connects the system voltage to the battery for lowest
power dissipation. The step-down regulation point is
then controlled by three feedback signals: maximum
step-down output current programmed at IDC, maximum
charger current programmed at ISET, and maximum
PG
PG
DC
DC
BST
LX
LX
CS
CS
SYS
SYS
BAT
BAT
FLT
UOK
DOK
FAULT
OUTPUT
USB PWR-OK
DC PWR-OK
TO VL
R
PU
4 x 100kΩ
18
19
8
24
23
21
20
1
2
3
4
6
27
28
25
26
17 USB
ISET
IDC
R
ISET
R
IDC
DCM
THM
CEN
IUSB
GND
NTC
10kΩ
USUS
5
9
16
12
CHARGE ON
OFF
100mA
500mA
USB SUSPEND
14
7
15
TO SYSTEM
LOAD
CHG
22
CHARGE
INDICATOR
C
DC
4.7µF
L1
1µH
CT
EP
C
CT
0.15µF
C
BST
0.1µF
13
11
10
R
T
10kΩ
1-CELL
LI+
C
BAT
10µF
C
SYS
(SEE TABLE 6 FOR C
SYS
SELECTION)
VL
MAX8903_
VBUS
D-
D+
ID
GND
C
VL
1µF
USB
ADAPTER
DC MODE
499kΩ
(SEE TABLE 5 FOR
INDUCTOR VALUE
SELECTION)
Figure 3. Typical Application Circuit Using a Mini 5 Style Connector or Other DC/USB Common Connector