MAX8903BETI+ Maxim Integrated Products, MAX8903BETI+ Datasheet - Page 24

• Manufacturer Part Number: MAX8903BETI+
• Description: IC DC/DC CHARGER LI+ 2A 28-TQFN
• Manufacturer: Maxim Integrated Products
• Series: Smart Power Selector™r

Specifications of MAX8903BETI+

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 4.1 V ~ 16 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2A 1-Cell Li+ DC-DC Chargers for USB
and Adapter Power
Example:
From (1):
From (2):
From (3):
From (5):
which is greater than the minimum on-time of 70ns.
From (4):
Choose L
From (7):
Table 6. Recommended Inductor for the MAX8903G
*I
24
V
8.1V to 9.9V, 2A
SAT
SYS(MAX)
V
DC(MIN)
______________________________________________________________________________________
means -30% reduction from nominal inductor value. I
L
IL
OUT MIN T
L
RIPPLE MIN T
OUT MIN T
DC INPUT VOLTAGE RANGE,
OUT
L
_
= 4.2V, R
imum step-down output current)
= 4.5V, V
OUT MAX
CHARGING CURRENT
_
T
= 1μH.
_
ON
_
_
ON
_
=
_
IDC
OFF
5 5
=
DC(MAX)
T
3
OFF
.
OFF
=
V
( .
V
5 5
4 2
= 3kΩ, K = 0.2, I
=
.
=
×
4 2
= 100ns
V
V
4 2
.
4
0 2 2
0 2
−
0 2 2
MHz
.
×
.
.
V
.
3
= 5.5V, V
1
100
V
V
A
×
×
1
×
)
×
100
μ
×
100
H
ns
=
A
A
136
136
ns
=
ns
ns
2 1μ
SYS(MIN)
=
ns
.
=
1 05μ
DC
=
.
420
H
0 85
= 2A (max-
.
mA
H
2.2μH inductor, VLF5014ST-2R2M2R3,
TDK, 4.8mm x 4.6mm x 1.4mm, 59mΩ, 3A I
μ
= 3V,
H
TEMP
means 40°C self-temperature rise.
From (8):
From (6), the saturation current rating for the inductor:
The MAX8903G is a 1MHz switching frequency version of
the MAX8903B (4MHz) to enhance the thermal perfor-
mance with less switching loss. As for the inductor selec-
tion for MAX8903G, this value can be carried out as
explained earlier in this section. Table 6 lists recommend-
ed inductor for the MAX8903G using a 9V input.
Good design minimizes ground bounce and voltage gra-
dients in the ground plane, which can result in instability
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 possi-
ble. Refer to the MAX8903A Evaluation Kit for a suitable
PCB layout example.
IL
RIPPLE MIN T
RECOMMENDED INDUCTOR
_
_
I
ON
SAT
I
=
SAT
>
SAT
PCB Layout and Routing
(
2
5 5
A
.
*, 2.3A I
>
V
+
2 21
.
−
0 420
.
3
1
V
μ
A
2
TEMP
s
)
×
A
136
*
ns
=
341
mA