ADP3026ARU Analog Devices, ADP3026ARU Datasheet - Page 15

• Manufacturer Part Number: ADP3026ARU
• Description: High-Efficiency Notebook Computer Power Supply Controller
• Manufacturer: Analog Devices

From the duty cycle, the required minimum R
each MOSFET can be derived by the following equations:
Upper MOSFET:
Lower MOSFET:
where P
perature dependency of R
efficiency and/or thermal requirements (see Efficiency ). (1
+
normalized R
can be used as an approximation for low voltage MOSFETs.
Maximum MOSFET power dissipation occurs at maxi-
mum output current, and can be calculated as follows:
Upper MOSFET:
Lower MOSFET:
REV. PrB
Maximum Output
Current
Input Capacitors
Output Capacitors
Output Capacitors
R
+3.3 V Output
+5 V Output
DS ON
P Upper
D
T) is generally given for a MOSFET in the form of a
R
(
Lower MOSFET Duty Cycle
(
DS ON
D
)
Upper MOSFET Duty Cycle=
(
is the allowable power dissipation and
(
Lower
)
)
DS(ON)
(
Upper
V
)
V
OUT
IN
vs. temperature curve, but
)
V
IN
TOKIN Multilayer
2 A
Ceramic Caps, 22 µF/25 V
P/N: C55Y5U1E226Z
TAIYO YUDEN INC.
Ceramic Caps, Y5V Series
10 µF/25 V
P/N: TMK432BJ106KM
SANYO POSCAP TPC
Series, 68 µF/10 V
SANYO POSCAP TPC
Series, 68 µF/10 V
V
I
MAX
OUT
DS(ON)
–
V
PRELIMINARY TECHNICAL DATA
OUT
2
. P
I
V
R
V
MAX
IN
DS ON
IN
D
I
will be determined by
(
2
MAX
V
Table VI. Recommended Capacitor Manufacturers
P
P
IN
D
D
)
V
1
2
V
V
OUT
–
IN
(1
IN
V
1
OUT
T
= 0.007/°C
DS(ON)
is the tem-
T
T
)
4 A
TOKIN Multilayer
Ceramic Caps, 2
P/N: C55Y5U1E226Z
TAIYO YUDEN INC.
Ceramic Caps, Y5V Series
2 10 µF/25 V
P/N: TMK432BJ106KM
SANYO POSCAP TPC
Series, 2
SANYO POSCAP TPC
Series, 2
for
(10)
(11)
(12)
(13)
(14)
–15–
The Schottky diode, D1 shown in Figure 2, conducts only
during the dead time between conduction of the two power
MOSFETs. D1’s purpose is to prevent the body-diode of the
lower N-channel MOSFET from turning on and storing
charge during the dead time, which could cost as much as
1% in efficiency. D1 should be selected for forward voltage of
less than 0.5 V when conducting I
tors for upper and lower MOSFET’s are given in Table VII.
Maximum
Output
Vishay/
International
Soft Start
The soft-start time of each of switching regulator can be
programmed by connecting a soft-start capacitor to the corre-
sponding soft-start pin (SS3 or SS5). The time it takes each
regulator to ramp up to its full duty ratio depends propor-
tionally on the values of the soft-start capacitors. The
charging current is 2.5 µA ±20%. The capacitor value to set
a given soft-start time, t
P Lower
68 µF/10 V
68 µF/10 V
D
Siliconix
Rectifier
(
22 µF/25 V
)
Table VII. Recommended MOSFETs
V
IN
C
Si4412DY,
IRF7805,
11 m
2 A
28 m
SS
V
–
IN
V
OUT
2.5
SS
10 A
TOKIN Multilayer
Ceramic Caps, 2
P/N: C55Y5U1E226Z
VISHEY Ceramic Caps,
Z5U Series, 2
SANYO POSCAP TPB
Series, 2
SANYO POSCAP TPB
Series, 2
, is given by:
A
I
MAX
2.6
t
4 A
Si4410DY,
13.5 m
IRF7811,
8.9 m
IRF7805,
11 m
SS
2
MAX
V
(
220 µF/4.0 V
330 µF/6.3 V
R
pF
. Recommended transis-
DS ON
)
(
15 µF/25 V
ADP3026
)
22 µF/25 V
(1
10 A
Si4874DY,
7.5 m
IRFBA3803,
5.5 m
IRF7809,
7.5 m
T
)
(15)
(16)