MAX8903A Maxim Integrated Products, MAX8903A Datasheet - Page 20

• Manufacturer Part Number: MAX8903A
• Description: 2A 1-Cell Li+ DC-DC Charger for USB* and Adapter Power
• Manufacturer: Maxim Integrated Products

www.DataSheet4U.com
2A 1-Cell Li+ DC-DC Charger for USB*
and Adapter Power
raises the cold threshold, while only slightly raising the
hot threshold. Raising R
thresholds, while lowering R
Note that since VL is active whenever valid input power
is connected at DC or USB, thermistor bias current
flows at all times, even when charging is disabled (CEN
= high). When using a 10kΩ thermistor and a 10kΩ
pullup to VL, this results in an additional 250µA load.
This load can be reduced to 25µA by instead using a
100kΩ thermistor and 100kΩ pullup resistor.
Good design minimizes ground bounce and voltage
gradients in the ground plane, which can result in insta-
bility or regulation errors. The GND and PGs should
connect to the power-ground plane at only one point to
minimize the effects of power-ground currents. Battery
ground should connect directly to the power-ground
plane. The ISET and IDC current-setting resistors
should connect directly to GND to avoid current errors.
Connect GND to the exposed pad directly under the IC.
Use multiple tightly spaced vias to the ground plane
under the exposed pad to help cool the IC. Position
input capacitors from DC, SYS, BAT, and USB to the
power-ground plane as close as possible to the IC.
Keep high current traces such as those to DC, SYS,
and BAT as short and wide as possible. Refer to the
MAX8903A Evaluation Kit for a suitable PCB layout
example.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products
Table 4. Package Thermal Characteristics
Continuous
Power
Dissipation
θ
θ
JA
JC
28-PIN 4mm x 4mm THIN QFN
SINGLE-LAYER PCB
1666.7mW
Derate 20.8mW/°C
above +70°C
48°C/W
3°C/W
TB
PCB Layout and Routing
lowers both the hot and cold
TB
raises both thresholds.
Power Dissipation
MULTILAYER PCB
2286mW
Derate 28.6mW/°C
above +70°C
35°C/W
3°C/W
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PROCESS: BiCMOS
PACKAGE TYPE
TOP VIEW
is a registered trademark of Maxim Integrated Products, Inc.
28 TQFN-EP
*EXPOSED PAD
CHG
SYS
SYS
CS
CS
LX
LX
22
23
24
25
26
27
28
+
21
1
PACKAGE CODE
20
2
Package Information
4mm x 4mm
THIN QFN
19
MAX8903A
T2844-1
3
18
4
Pin Configuration
Chip Information
17
5
16
*EP
6
15
7
DOCUMENT NO.
14
13
12
11
10
9
8
21-0139
CEN
ISET
GND
IDC
CT
VL
DOK