an1219

Using the ISL6440 Evaluation Board
®
Application Note
January 8, 2007
AN1219.1
Using the Evaluation Board
Soft-start and Shutdown
The ISL6440 is a high performance triple-output controller
offering control and protection features for 2 synchronous
buck PWMs.
The soft-start capacitors can be adjusted for sequencing of
the output voltages, PWM startup tracking, and/or to adjust
the startup current required to charge the output capacitors.
The ISL6440 evaluation board highlights the operation of the
IC in an embedded DC/DC converter application. Table 1
shows the available evaluation board.
0.8V
t SS ( PWM1 ) = C 5 ⋅ -----------5μA
TABLE 1. EVALUATION BOARDS
BOARD NAME
ISL6440EVAL1Z
IC
ISL6440IAZ
PACKAGE
24 Ld QSOP
Power and Load Connections
Input Voltage - To connect a +12V power supply to the
evaluation board, connect the positive lead of the power supply
to VIN (P1) post and the ground lead of the supply to the GND
(P2) post.
Output Adjustment
Change the respective output voltage feedback resistors to
modify the output voltage:
R 7⎞
⎛
V OUT2 = 0.8 ⋅ ⎜ 1 + -------⎟
R 8⎠
⎝
(EQ. 1)
1
To independently shutdown the PWMs, the SD1 or SD2 pin
can be pulled to GND using the on board posts, P7 and P8
respectively.
When both PWMs are within ±10% of their set value, the
PGOOD signal will go high. The open drain PGOOD pin is
pulled HIGH to VCC_5V on the board. The PGOOD circuitry
monitors the FBx pin of each regulated output to determine if
the outputs are in regulation. PGOOD can be monitored at
post P9.
A 12V, 5A capable power supply
An electronic load
Four channel oscilloscope with probes
Precision digital multimeters
R 5⎞
⎛
V OUT1 = 0.8 ⋅ ⎜ 1 + -------⎟
R 6⎠
⎝
(EQ. 2)
Power Good
Recommended Test Equipment
•
•
•
•
0.8V
t SS ( PWM2 ) = C 3 ⋅ -----------5μA
Overcurrent Protection
The overcurrent thresholds can be adjusted on the ISL6440
evaluation board. The current sense resistors, ISENSE, are
set at 1.0k. The overcurrent set resistor is 95.3k. The
overcurrent trip point can be adjusted by modifying ROCSET,
R3 and R4:
7 ⋅ R CS
R OCSET = ------------------------------------I OC ⋅ r DS ( ON )
(EQ. 3)
ROCSET is the overcurrent set resistor, RCS is the current
sense resistor, IOC is the desired overcurrent trip point, and
rDS(ON) is the on resistance of the respective PWM’s lower
MOSFET. Refer to the ISL6440 datasheet for more
information on how to select the current sense and
overcurrent select resistors.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2006. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
ISL6440EVAL1Z Schematic
2
Application Note 1219
AN1219.1
January 8, 2007
Application Note 1219
ISL6440EVAL1Z Bill of Materials
ITEM
REFERENCE
QTY
PART NUMBER
1
P1-P9
9
1514-2
Test Point
Turret 0.281 Height
Keystone
2
D1, D2
2
BAT54HT1G
Diode, Schottky
30V, 200mA
On Semi
3
C4
1
H1045-00105-6R3V10- Cap, Ceramic, X5R
T
1µF, 10V, 0603, X5R
Panasonic
4
C9, C10
2
10TPB220M
Cap, POSCAP
220µF, 10V
Sanyo
5
C1, C2
2
C3225X7R1E106
Cap, Ceramic, 1210
10µF, 10%, 25V, 1210, X7R
TDK
6
L1, L2
2
DO3316P-682ML-T
SMT Power Inductor
6.8µH, ±20%, 4.6A, 27mΩ
Coilcraft
7
C3
1
H1045-00105-16V20-T
Capacitor, Ceramic
1µF, 20%, 16V, Y5V, 0603
MURATA
8
Q1, Q2
2
FDS6912A
Dual NFET
6A, 30V, Dual NFET, SO8
Fairchild
9
C5, C6, C7, C8
4
H1045-00104-25V10-T
Cap, Ceramic, 0603
0.1µF, 10%, 6.3V
MURATA/Generic
10
R1, R2, R5, R7
5
Resistor, Film
1kΩ, 0603, 1%, 1/16W
Any
11
R6
1
Resistor, Film
324Ω, 0603, 1%, 1/16W
Any
12
R3, R4
1
Resistor, Film
95.3kΩ, 0603, 1%, 1/16W
Any
13
R9
1
Resistor, Film
5.11kΩ, 0603, 1%, 1/16W
Any
14
R8
1
Resistor, Film
806Ω, 0603, 1%, 1/16W
Any
15
U1
1
ISL6440IAZ
PART TYPE
DESCRIPTION
300kHz, Dual PWM
Controller
VENDOR
Intersil
ISL6440EVAL1Z Layout
TOP SILK
3
LAYER 1
AN1219.1
January 8, 2007
Application Note 1219
ISL6440EVAL1Z Layout (Continued)
LAYER 2
LAYER 3
LAYER 4
BOTTOM SILK
Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to
verify that the Application Note or Technical Brief is current before proceeding.
For information regarding Intersil Corporation and its products, see www.intersil.com
4
AN1219.1
January 8, 2007
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