ISL6526EVAL2

Manufacturer Part NumberISL6526EVAL2
DescriptionEVALUATION BOARD QFN ISL6526
ManufacturerIntersil
ISL6526EVAL2 datasheet
 


Specifications of ISL6526EVAL2

Main PurposeDC/DC, Step DownOutputs And Type1, Non-Isolated
Voltage - Output2.5VCurrent - Output5A
Voltage - Input3.3 ~ 5VRegulator TopologyBuck
Frequency - Switching300kHzBoard TypeFully Populated
Utilized Ic / PartISL6526Lead Free Status / RoHS StatusContains lead / RoHS non-compliant
Power - Output-  
1
2
3
4
5
6
7
8
9
10
11
Page 11
12
Page 12
13
Page 13
14
Page 14
15
Page 15
Page 13/15

Download datasheet (325Kb)Embed
PrevNext
where Q
is the maximum total gate charge of the upper
GATE
MOSFET, C
is the bootstrap capacitance, V
BOOT
the bootstrap voltage immediately before turn-on, and
V
is the bootstrap voltage immediately after turn-on.
BOOT2
The bootstrap capacitor begins its refresh cycle when the gate
drive begins to turn-off the upper MOSFET. A refresh cycle
ends when the upper MOSFET is turned on again, which
varies depending on the switching frequency and duty cycle.
The minimum bootstrap capacitance can be calculated by
rearranging the previous equation and solving for C
Q
GATE
C
---------------------------------------------------- -
=
BOOT
V
V
BOOT1
BOOT2
Typical gate charge values for MOSFETs considered in
these types of applications range from 20 to 100nC. Since
the voltage drop across Q
is negligible, V
LOWER
simply V
- V
. A Schottky diode is recommended to
CPVOUT
D
minimize the voltage drop across the bootstrap capacitor
during the on-time of the upper MOSFET. Initial calculations
with V
no less than 4V will quickly help narrow the
BOOT2
bootstrap capacitor range.
3.3V
GND
TP
1
4
C
4
0.22µF
5
10
1
9
ENABLE
Component Selection Notes:
C
C
C
- Each 150µF, Panasonic EEF-UE0J151R or Equivalent.
3,
8,
9
D1 - 30mA Schottky Diode, MA732 or Equivalent
L
- 1µH Inductor, Panasonic P/N ETQ-P6F1ROSFA or Equivalent.
1
Q
- Fairchild MOSFET; ITF86110DK8.
1
13
ISL6526, ISL6526A
For example, consider an upper MOSFET is chosen with a
is
maximum gate charge, Q
BOOT1
drop across the bootstrap capacitor to 1V results in a value
of no less than 0.1µF. The tolerance of the ceramic capacitor
should also be considered when selecting the final bootstrap
capacitance value.
A fast recovery diode is recommended when selecting a
bootstrap diode to reduce the impact of reverse recovery
charge loss. Otherwise, the recovery charge, Q
have to be added to the gate charge of the MOSFET and
.
BOOT
taken into consideration when calculating the minimum
bootstrap capacitance.
(EQ. 19)
ISL6526, ISL6526A DC/DC Converter
Application Circuit
Figure 8 shows an application circuit of a DC/DC Converter.
is
BOOT1
Detailed information on the circuit, including a complete Bill
of Materials and circuit board description, can be found in
Application Note AN1021:
http://www.intersil.com/data/an/an1021.pdf.
C
1
0.1µF
11
U
1
VCC
6
OCSET
CT1
ISL6526, ISL6526A
TP
3
3
CPVOUT
D
1
CT2
13
BOOT
CPGND
C
7
14
UGATE
GND
12
PHASE
ENABLE
2
LGATE
COMP
FB
8
7
C
10
33pF
C
R
11
2
2.26kΩ
R
4
6.49kΩ
5600pF
124Ω
R
5
1.07kΩ
FIGURE 8. 3.3V TO 2.5V 5A DC/DC CONVERTER
, of 100nC. Limiting the voltage
g
C
2
1000pF
C
3
R
1
9.76kΩ
C
5
10µF
C
CERAMIC
6
CAP
1µF
0.1µF
L
1
2.5V @ 5A
C
8, 9
Q
1
R
3
C
12
8200pF
, would
RR
GND
FN9055.10
November 24, 2008