IR3651STRPBF International Rectifier, IR3651STRPBF Datasheet - Page 14
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IR3651STRPBF
Manufacturer Part Number
IR3651STRPBF
Description
IC CTLR PWM SYNC DC-DC 14SOIC
Manufacturer
International Rectifier
Datasheet
1.IR3651SPBF.pdf
(19 pages)
Specifications of IR3651STRPBF
Pwm Type
Voltage Mode
Number Of Outputs
1
Frequency - Max
460kHz
Duty Cycle
80%
Voltage - Supply
4.5 V ~ 13.2 V
Buck
Yes
Boost
No
Flyback
No
Inverting
No
Doubler
No
Divider
No
Cuk
No
Isolated
No
Operating Temperature
0°C ~ 125°C
Package / Case
14-SOIC (3.9mm Width), 14-SOL
Frequency-max
460kHz
Package
14-Pin SOIC (NB)
Circuit
Sync PWM Controller
Vcc (min)
4.5
Vcc (max)
13.2
Iout (a)
25
Switch Freq (khz)
programmable to 400kHz
Pbf
PbF Option Available
For Use With
IRDC3651 - KIT REF DESIGN SYNCH BUCK REG
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
IR3651STRPBF
Manufacturer:
IR
Quantity:
20 000
Power MOSFET Selection
The IR3651 uses two N-Channel MOSFETs. The
selections criteria to meet power transfer
requirements is based on maximum drain-source
voltage (V
maximum output current, On-resistance R
and thermal management.
The MOSFET must have a maximum operating
voltage (V
voltage (V
The gate drive requirement is almost the same
for both MOSFETs. Logic-level transistor can be
used and caution should be taken with devices at
very low V
complementary MOSFET, which results in shoot-
through current.
The total power dissipation for MOSFETs
includes conduction and switching losses. For
the Buck converter the average inductor current
is equal to the DC load current. The conduction
loss is defined as:
The R
considered for the worst case operation. This is
typically given in the MOSFET data sheet.
Ensure that the conduction losses and switching
losses do not exceed the package ratings or
violate the overall thermal budget.
The switching loss is more difficult to calculate,
even though the switching transition is well
understood. The reason is the effect of the
parasitic components and switching times during
the switching procedures such as turn-on / turn-
off delays and rise and fall times. The control
MOSFET contributes to the majority of the
ϑ
P
P
12/07/2010
cond
cond
=
R
=
=
ds(on)
(upper
(lower
DS(on)
temperatur
in
DSS
gs
DSS
).
switch)
switch)
temperature dependency should be
to prevent undesired turn-on of the
), gate-source drive voltage (V
) exceeding the maximum input
=
e
=
I
I
load
2
load
2
dependency
∗
∗
R
R
ds(on)
ds(on)
∗
∗
(1
D
∗
−
ϑ
D)
∗
ϑ
DS(on)
gs
),
switching losses in synchronous Buck converter.
The synchronous MOSFET turns on under zero
voltage conditions, therefore, the turn on losses
for synchronous MOSFET can be neglected.
With a linear approximation, the total switching
loss can be expressed as:
Where:
V
t
t
T = Switching period
I
The switching time waveforms is shown in
figure10.
r
f
load
= Fall time
= Rise time
ds(off)
90%
10%
= Load current
V
V
GS
Fig. 10: switching time waveforms
DS
P
= Drain to source voltage at the off time
sw
t
d
(ON)
=
V
ds
2
(
off
)
*
t
r
T
+
t
t
r
f
*
I
load
t
IR3651SPBF
d
(OFF)
-
-(10)
t
f
14