Intersil ISL6443AEVAL2Z Using Manual

®

Using the Evaluation Board

The ISL6443A is a high performance triple-output controller
offering control and protection features for 2 synchronous
buck PWMs and 1 linear regulator.
The ISL6443A evaluation board highlights the operation of
the IC in an embedded DC/DC converter application. Table 1
shows the available evaluation board.
TABLE 1. EVALUATION BOARDS
BOARD NAME
ISL6443AEVAL2Z ISL6443AIRZ

Recommended Test Equipment

• A 12V, 5A capable power supply
• An electronic load
• Four channel oscilloscope with probes
• Precision digital multimeters

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 the VIN (P1)
post and the ground lead of the supply to the GND (P2) post.
The input voltage to the linear controller is already taken
from the 1.8V output of V
OUT2.

Output Adjustment

Change the respective output voltage feedback resistors to
modify the output voltage using Equation 1:
⎛ ⎞
R
1
⋅
⎜ ⎟
------ -
V = 0.8 1 +
OUT1
⎝ R ⎠
2
⎛ ⎞
R
6
⋅
⎜ ⎟
V 0.8 1 --------- -
= +
OUT3
⎝ R ⎠
11

Soft-Start and Shutdown

The soft-start capacitors can be adjusted for sequencing of
the output voltages, PWM start-up tracking, and/or to adjust
the start-up current required to charge the output capacitors.
0.8V
⋅
t C ------------
=
( )
SS PWM1 2
5μA
To independently shutdown the PWMs, the SD1 or SD2 pin
can be pulled to GND using the on-board posts, P9 and P10
respectively.
Using the ISL6443AEVAL2Z Evaluation Board
Application Note
IC PACKAGE
28 Ld QFN
⎛ ⎞
R
3
⋅
⎜ ⎟
------ -
V = 0.8 1 +
OUT2
⎝ R ⎠
4
(EQ. 1)
0.8V
⋅
t C ------------
=
( )
SS PWM2 3
5μA
(EQ. 2)
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
March 10, 2008

Power Good

When both PWMs are within ±10% of their set value and the
linear regulator output is within 75% of its 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 P8.

Overcurrent Protection

The overcurrent thresholds can be adjusted on the
ISL6443A evaluation board. The current sense resistors,
I , are set at 1.0kΩ. The overcurrent set resistor is
SENSE
95.3kΩ. The overcurrent trip point can be adjusted by
modifying R , R and R
OCSET 5
⋅
7 R
CS
R ------------------------------------ -
=
⋅
OCSET
I r
( )
OC DS ON
R is the overcurrent set resistor, R
OCSET
sense resistor, I is the desired overcurrent trip point, and
OC
r is the ON-resistance of the respective PWM's lower
DS(ON)
MOSFET. Refer to the ISL6443A Data Sheet for more
information on how to select the current sense and
overcurrent select resistors.
|
Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2008. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
AN1391.0
:
10
(EQ. 3)
is the current
CS