ISL6540A Intersil Corporation, ISL6540A Datasheet - Page 19

• Manufacturer Part Number: ISL6540A
• Description: Single-Phase Buck PWM Controller
• Manufacturer: Intersil Corporation

AVX, and the 593D series from Sprague are both surge
current tested.
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notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
FIGURE 12. INPUT-CAPACITOR CURRENT MULTIPLIER FOR
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0
SINGLE-PHASE BUCK CONVERTER
0.1 0.2
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
For information regarding Intersil Corporation and its products, see www.intersil.com
0.3 0.4 0.5 0.6 0.7
DUTY CYCLE (D)
19
0.25Io
0.8 0.9
Δ
I=0Io
0.5Io
ISL6540A
1
MOSFET Selection/Considerations
The ISL6540A requires 2 N-Channel power MOSFETs.
These should be selected based upon r
requirements, and thermal management requirements.
In high-current applications, the MOSFET power dissipation,
package selection and heatsink are the dominant design
factors. The power dissipation includes two loss
components; conduction loss and switching loss. The
conduction losses are the largest component of power
dissipation for both the upper and the lower MOSFETs.
These losses are distributed between the two MOSFETs
according to duty factor (see the equations below). The
upper MOSFET exhibits turn-on and turn-off switching
losses as well as the reverse recover loss, while the
synchronous rectifier exhibits body-diode conduction losses
during the leading and trailing edge dead times.
where D is the duty cycle = V
recover charge; t
dead time, and t
These equations do not include the gate-charge losses that
are proportional to the total gate charge and the switching
frequency and partially dissipated by the internal gate
resistance of the MOSFETs. Ensure that both MOSFETs are
within their maximum junction temperature at high ambient
temperature by calculating the temperature rise according to
package thermal-resistance specifications. A separate
heatsink may be necessary depending upon MOSFET
power, package type, ambient temperature and air flow.
ISL6540A DC/DC Converter Application Circuit
Detailed information on the application circuit, including a
complete Bill-of-Materials and circuit board description, can
be found in application note AN1253. See Intersil’s home
page on the web: http://www.intersil.com.
P
P
P
P
P
LOWER
DEAD
UPPER
SW
Qrr
=
=
=
Q
⎛
⎝
=
=
I
rr
O
⎛
⎝
⎛
⎝
•
⎛
⎝
I
+
I
O
I
O
VIN F
O
----- -
12
I Δ
+
2
2
ON
+
----- -
12
⎞
⎠
+
I Δ
DL
•
I Δ
------- -
•
I Δ
------- -
12
12
⎞
⎠
and t
t
& t
2
OFF
2
•
S
⎞
⎠
⎞
⎠
V
•
OFF
•
DT
r
--------------------------- -
r
-------------------------- -
+
DT
DS ON
DS ON
•
⎛
⎝
I
(
N
are the switching intervals.
(
N
t
O
are leading and trailing edge
DT
U
L
O
–
/VIN; Q
),U
----- -
12
+
),L
I Δ
⎛
⎝
⎞
⎠
I
•
•
O
•
(
D
1 D
–
t
ON
+
----- -
12
–
I Δ
rr
P
DS(ON)
⎞
⎠
is the reverse
SW
)
•
•
+
VIN F
V
P
+
DL
DEAD
P
•
, gate supply
Qrr
•
t
DL
S
March 12, 2007
•
FN6288.2
F
S