MAX1909ETIT Maxim Integrated Products, Inc., MAX1909ETIT Datasheet - Page 26

• Manufacturer Part Number: MAX1909ETIT
• Description: Multichemistry Battery Chargers With Automatic System Power Selector
• Manufacturer: Maxim Integrated Products, Inc.

Multichemistry Battery Chargers with Automatic
System Power Selector
Table 2. Recommended Components
Table 2 lists the recommended components and refers
to the circuit of Figure 2. The following sections
describe how to select these components.
MOSFETs P2 and P3 (Figure 1) provide power to the
system load when the AC adapter is inserted. These
devices may have modest switching speeds, but must
be able to deliver the maximum input current as set by
RS1. As always, care should be taken not to exceed
the device’s maximum voltage ratings or the maximum
operating temperature.
The p-channel/n-channel MOSFETs (P1, N1) are the
switching devices for the buck controller. The guidelines
26
REFERENCE QTY
C11, C14,
C12, C13,
C5, C15
C9, C10
C1, C4
______________________________________________________________________________________
C17
C16
D4
D5
L1
2
2
2
3
3
1
1
1
22µF ±20%, 35V E-size low-ESR
tantalum capacitors
AVX TPSE226M035R0300
Kemet T495X226M035AS
1µF ±10%, 25V, X7R ceramic capacitors
(1206)
Murata GRM31MR71E105K
Taiyo Yuden TMK316BJ105KL
TDK C3216X7R1E105K
0.01µF ±10%, 25V, X7R ceramic
capacitors (0402)
Murata GRP155R71E103K
TDK C1005X7R1E103K
0.1µF ±10%, 25V, X7R ceramic
capacitors (0603)
Murata GRM188R71E104K
TDK C1608X7R1E104K
1µF ±10%, 6.3V, X5R ceramic
capacitors (0603)
Murata GRM188R60J105K
Taiyo Yuden JMK107BJ105KA
TDK C1608X5R1A105K
Schottky diode, 0.5A, 30V SOD-123
Diodes Inc. B0530W
General Semiconductor MBR0530
ON Semiconductor MBR0530
25V ±1% zener diode
CMDZ5253B
10µH, 4.4A inductor
Sumida CDRH104R-100NC
TOKO 919AS-100M
Design Procedure
DESCRIPTION
MOSFET Selection
for these devices focus on the challenge of obtaining
high load-current capability when using high-voltage
(>20V) AC adapters. Low-current applications usually
require less attention. The high-side MOSFET (P1) must
be able to dissipate the resistive losses plus the switching
losses at both V
Ideally, the losses at V
to losses at V
the losses at V
losses at V
Conversely, if the losses at V
higher than the losses at V
the size of P1. If DCIN does not vary over a wide range,
the minimum power dissipation occurs where the resistive
losses equal the switching losses.
REFERENCE QTY
R5, R9, R21
P2, P3, P4
R19, R20
N1/P1
R11
R16
RS1
RS2
R4
R6
R7
R8
U1
DCIN(MAX)
DCIN(MAX)
DCIN(MIN)
DCIN(MIN)
1
3
1
2
1
1
1
1
1
2
1
1
1
Dual n- and p-channel MOSFETs, 7A,
30V and -5A, -30V, 8-pin SO, MOSFET
Fairchild FDS8958A or
Single n-channel MOSFETs, +13.5A,
+30V FDS6670S and
Single p-channel MOSFETs, -13.5A,
-30V FDS66709Z
Single, p-channel, -11A, -30V, 8-pin SO
MOSFETs
Fairchild FDS6675
100kΩ, ±5% resistor (0603)
10kΩ ±1% resistors (0603)
590kΩ ±1% resistor (0603)
196kΩ ±1% resistor (0603)
1MΩ ±5% resistor (0603)
1kΩ ±5% resistor (0603)
33Ω ±5% resistor (0603)
10kΩ ±5% resistors (0603)
0.01Ω ±1%, 0.5W sense resistor (2010)
Vishay Dale WSL2010 0.010 1.0%
IRC LRC-LR2010-01-R010-F
0.015Ω ±1%, 0.5W sense resistor (2010)
Vishay Dale WSL2010 0.015 1.0%
IRC LRC-LR2010-01-R015-F
MAX1909ETI/MAX8725ETI (28-pin thin
QFN-EP)
, consider increasing the size of P1.
DCIN(MIN)
, with lower losses in between. If
are significantly higher than the
and V
DCIN(MIN),
DCIN(MAX)
DCIN(MAX)
DESCRIPTION
should be roughly equal
consider reducing
are significantly
.