an1265

ISL6273EVAL1 Evaluation Board
Application Manual
®
Application Note
August 22, 2006
AN1265.0
Introduction
The ISL6273EVAL1 board provides a convenient platform to
evaluate the performance of the ISL6273 low-quiescent
high-efficiency step-down switching regulator. The ISL6273
is a 1.5MHz, 1.2A adjustable output voltage regulator. The
output voltage is set by a resistor divider consisting of R1
and R2 on the board. The output voltage is set to 1.6V in the
evaluation board but can be modified by changing the R2
value. The evaluation board also allows users to evaluate
the forced PWM or PFM operation mode at light load and the
behavior of the POR signal.
FIGURE 1. PHOTO OF THE ISL6273EVAL1 BOARD
ISL6273EVAL1 Evaluation Board
A photo of the ISL6273EVAL1 board is shown in Figure 1.
The schematic, layout and bill-of-materials (BOM) are given
at the end of this application note. The complete regulator is
located at the center of the board. Various connectors and
jumpers are provided for the convenience of the evaluation.
On the left side of the board are the connectors for the input
power source (Red: VIN; Black: GND). The output
connectors are located on the right side (Red: VO; Black:
GND). The two yellow test points are for the RSI and POR
signals respectively, as labelled on the board. The RSI input
needs either be driven to a low or a high logic input. Do not
leave the RSI input signal floating. The open-drain POR
signal is pulled up to VIN through a 100kΩ resistor (R3), as
shown in the schematics. Jumper H1 allows the user to
enable or disable the IC. Jumper H2 is the mode selection
input. Do not leave the EN or the MODE signal floating.
The settings for the two jumpers are shown in Figure 2. The
evaluation board also offers two oscilloscope probe tip
connectors to minimize the switching noise on the
waveforms. TP1 is the connector for the output voltage and
TP2 is the PHASE signal.
Specifications
Table 1 shows the electrical specification of the regulator in
the evaluation board.
TABLE 1. ELECTRICAL SPECIFICATIONS.
PARAMETER
Input Voltage
Output Voltage (Note)
Output Current
MIN
TYP
MAX
UNIT
2.7
-
5.5
V
-
1.6
-
V
1.2
-
-
A
NOTE: The output voltage can be set to other values by changing the
R2 value.
1
Enable
Disable
PFM
Forced PWM
FIGURE 2. SETTINGS FOR JUMPERS H1 AND H2
Evaluation Board Setup
The following are steps for setting up the evaluation board:
1. Connect Jumper H1 at the position of Enable.
2. Connect Jumper H2 either at the position of PFM or
Forced PWM, but do not leave it floating.
3. Connect the RSI input to either ground or VIN. Do not
leave it floating.
4. Connect a power supply with an output voltage between
2.7V to 5.5V to VIN and GND connectors. Make sure the
power supply has enough current capability (1A
recommended).
5. Connect the output to a load (resistor or electronic load).
6. Turn on the input power supply.
Typical Operating Characteristics
This section shows typical waveforms and performance
captured from the evaluation board.
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
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Application Note 1265
FIGURE 3. STEADY-STATE IN PWM MODE
(VIN = 3.6V; VO = 1.6V; IO = 1A)
FIGURE 5. PFM MODE (VIN = 3V; VO = 1.6V; IO = 50mA)
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FIGURE 4. SOFT-START
FIGURE 6. TRANSIENT LOAD TEST (PFM AND PWM
VIN = 3.6V; VO = 1.6V; IO = 0A~1A)
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Application Note 1265
.
FIGURE 7. SCHEMATIC OF THE ISL6273EVAL1 EVALUATION BOARD
PCB Layout
SILK SCREEN
TOP LAYER
BOTTOM LAYER
FIGURE 8. LAYOUT OF THE ISL6273EVAL1 BOARD
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Application Note 1265
TABLE 2. BILL OF MATERIALS
ITEM
QTY
REF
DESCRIPTION
VENDOR
PART NUMBER
PACKAGE
1
2
C1, C2
Capacitor, SMD, 10µF, 6.3V, 10%, X5R
Any
0805
2
1
C3
Capacitor, SMD, 0.1µF, 6.3V, 10%, X5R
Any
0603
3
1
L1
Inductor, 1.8µH, Coilcraft 1008PS Series
Coicraft
4
3
R1, R2, R3
Resistor, SMD, 100k, 1%
Any
5
6
T1-T6
Circuit Pin Prntd 0.050"D 0.082"L
Mill-Max
3156-2-00-21-00-00-08-0
6
2
TP1, TP2
Conn-Gen, Scope Probe Test PT, Compact
TEKTRONICS
131-5031-00
7
2
H1, H2
Conn-Header, 1x3, Brkawy 1X36, 2.54mm, ST
BERG/FCI
68000-236-1X3
8
1
U1
ISL6273 DFN-10 Package
Intersil
ISL6273
1008PS-182K
0603
3X3 DFN-10
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
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