ADP3026ARU Analog Devices, ADP3026ARU Datasheet - Page 14

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

Coilcraft
Phone: [phone]
Fax: [phone]
Web: www.coilcraft.com
SMT Power Inductors,
Series 1608, 3308, 3316, 5022, 5022HC,
DO3340, Low Cost Solution
SMT Shielded Power Inductors,
Series DS5022, DS3316, DT3316,
Best for Low EMI/RFI
Power Inductors and Chokes,
Series DC1012, PCV-0, PCV-1, PCV-2,
PCH-27, PCH-45, Low Cost
ADP3026
This formula has a maximum at V
= I
current ratings are often based on only 2000 hours of life.
This makes it advisable to further derate the capacitor, or to
choose a capacitor rated at a higher temperature than re-
quired. Several capacitors may also be paralleled to meet
size or height requirements in the design. If electrolytic or
tantalum capacitors are used, an additional 0.1 µF–1 µF ce-
ramic bypass capacitor should be placed in parallel with
C
The selection of C
ries resistance (ESR) and the desired output ripple. A good
rule of thumb is to limit the ripple voltage to 1% of the
nominal output voltage. It is assumed that the total ripple is
caused by two factors: 25% comes from the C
pacitance value, and 75% comes from the capacitor ESR.
The value of C
where I
The maximum acceptable ESR of C
using:
IN
OUT
.
/2. Note that the capacitor manufacturer’s ripple
RIPPLE
I
RMS
= 0.3
OUT
V
OUT
C
OUT
can be determined by:
ESR
OUT
is driven by the required effective se-
I
OUT
V
0.75
2
IN
PRELIMINARY TECHNICAL DATA
and V
–
f V
I
RIPPLE
V
V
OUT
I
RIPPLE
IN
RIPPLE
RIPPLE
RIPPLE
OUT
= 2
Table V. Recommended Inductor Manufacturers
I
can then be found
V
= 0.01
MAX
IN
V
OUT
OUT
Coiltronics
Phone: [phone]
Fax: [phone]
Web: www.coiltronics.com
SMT Power Inductors,
Series UNI-PAC2, UNI-PAC3 and UNI-PAC4,
Low Cost Solution
SMT Power Inductors,
Series, ECONO-PAC, VERSA-PAC,
Best for Low Profile or Flexible Design.
Power Inductors CTX Series,
Low EMI/RFI, Low Cost Toroidal Inductors
but Not Miniature.
, where I
V
bulk ca-
OUT
(8)
(9)
.
(7)
RMS
–14–
Manufacturers such as Vishay, AVX, Elna, WIMA, and
Sanyo provide good high-performance capacitors. Sanyo’s
OSCON semiconductor dielectric capacitors have lower
ESR for a given size, at a somewhat higher price. Choosing
sufficient capacitors to meet the ESR requirement for
C
needed to meet the ripple current requirement.
In surface-mount applications, multiple capacitors may have
to be paralleled to meet the capacitance, ESR, or RMS
current handling requirements. Aluminum electrolytic and
dry tantalum capacitors are available in surface-mount con-
figurations. In the case of tantalum, it is critical that
capacitors are surge tested for use in switching power sup-
plies. Recommendations for output capacitors are shown in
Table VI.
Power MOSFET Selection
N-channel power MOSFETs must be selected for use with
the ADP3026 for both the main and synchronous switch.
The main selection parameters for the power MOSFETs are
the threshold voltage (V
(R
boosted above the input voltage using a bootstrap circuit.
This floating 5 V supply is used for the upper MOSFET gate
drive. Logic-level threshold MOSFETs must be used for
both the main and synchronous switches.
Maximum output current (I
quirement for the two power MOSFETs. When the
ADP3026 is operating in continuous mode, the simplify-
ing assumption can be made that one of the two MOSFETs
is always conducting the load current. The duty cycles for the
MOSFETs are given by:
OUT
DS(ON)
will normally exceed the amount of capacitance
). An internal LDO generates a 5 V supply that is
GS(TH)
MAX
) and ON-resistance
) determines the R
Murata Electronics
North America Inc.
Phone: [phone]
Fax: [phone]
Web: www.murata.com
SMT Power Inductors,
Series LQT2535
Best for Low EMI/RFI
Chip Inductors
LQN6C, LQS66C
DS(ON)
REV. PrB
re-