ISL6439AIR Intersil, ISL6439AIR Datasheet - Page 13

• Manufacturer Part Number: ISL6439AIR
• Description: IC CTRLR PWM SYNC BUCK 16-QFN
• Manufacturer: Intersil

Specifications of ISL6439AIR

• Pwm Type: Voltage Mode
• Number Of Outputs: 1
• Frequency - Max: 650kHz
• Duty Cycle: 100%
• Voltage - Supply: 3.3 V ~ 5 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 16-VQFN Exposed Pad, 16-HVQFN, 16-SQFN, 16-DHVQFN
• Frequency-max: 650kHz
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

recommended to minimize the voltage drop across the
bootstrap capacitor during the on-time of the upper
MOSFET. Initial calculations with V
will quickly help narrow the bootstrap capacitor range.
For example, consider an upper MOSFET is chosen with a
maximum gate charge, Q
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
Component Selection Notes:
C
D1 - 30mA Schottky Diode, MA732 or Equivalent
L
Q
1
3,8,9
1
- 1μH Inductor, Panasonic P/N ETQ-P6F1ROSFA or Equivalent.
- Fairchild MOSFET; ITF86110DK8.
- Each 150μF, Panasonic EEF-UE0J151R or Equivalent.
3.3V
GND
ENABLE
0.22μF
C
g
4
, of 100nC. Limiting the voltage
13
TP
1
10
4
5
1
9
BOOT2
CT1
CT2
CPGND
GND
ENABLE
COMP
8
FIGURE 8. 3.3V to 2.5V 5A DC/DC CONVERTER
no less than 4V
6.49kΩ
0.1μF
C
R
ISL6439
1
2
33pF
C
VCC
10
ISL6439, ISL6439A
11
5600pF
C
11
FB
CPVOUT
OCSET
UGATE
PHASE
7
LGATE
BOOT
1.07kΩ
U
R
1
5
13
14
12
6
3
2
charge loss. Otherwise, the recovery charge, Q
have to be added to the gate charge of the MOSFET and
taken into consideration when calculating the minimum
bootstrap capacitance.
ISL6439 DC/DC Converter Application
Circuit
Figure 8 shows an application circuit of a DC/DC Converter.
Detailed information on the circuit, including a complete
Bill-of-Materials and circuit board description, can be found
in the ISL6439 Application Note.
TP
D
C
124Ω
1
7
3
R
2.26kΩ
4
R
1000pF
3
0.1μF
9.76kΩ
8200pF
C
R
C
2
1
12
Ceramic
C
10μF
5
Q
1
C
C
1μF
6
3
L
1
C
8,9
2.5V @ 5A
RR
November 5, 2008
GND
, would
FN9057.5