an1647

Application Note 1647
Author: David Sorlien
ISL9112IRTNEVAL1Z, ISL9112IRT7EVAL1Z Evaluation
Board User Guide
Evaluation Board Features
• ISL9112IRTNZ high efficiency buck-boost regulator with I2C
adjustable output voltage
• Input voltage rating from 1.8V to 5.5V
• I2C programmable output voltage, default 3.3V
• I2C programmable slew rate control
TABLE 2. DESCRIPTION OF CONNECTORS
CONNECTOR
J1
Header for connecting input power
J2
Header for connecting external load
J5
Header for connecting I2C interface
• 1200mA output current at VIN ≥ 3V and VOUT = 3.3V
• 2.5MHz switching frequency
• Jumper selectable EN (enabled/disabled)
• Jumper selectable MODE (auto-PFM/forced-PWM)
• Connectors, test points and jumpers for easy evaluation
Required Equipment
• ISLUSBI2CKIT1Z (includes USB to I2C interface, USB cable
and 4-pin I2C cable)
• Power supply capable of delivering up to 5.5V and 3A
• Electronic load
• Multimeter to measure voltages and currents
• Oscilloscope
Test Points, Connectors and
Jumpers
TABLE 1. DESCRIPTION OF TEST POINTS
TEST POINT(S)
DESCRIPTION
TP1
VOUT Kelvin connection for efficiency
measurements
TP2
LX1 (Input side of power inductor)
TP3
PGND (Power ground)
TP4
LX2 (Output side of power inductor)
TP5
PVIN Kelvin connection for efficiency
measurements
TP6
VIN (supply input for internal reference)
TP7
SCL (I2C clock)
TP8
SDA (I2C data)
TP9
EN (Enable input, drive high to enable device)
TP10
MODE/SYNC (Mode input, drive low for forced
PWM, or apply external clock between 2.75MHz
and 3.25MHz for external sync)
DESCRIPTION
TABLE 3. DESCRIPTION OF JUMPERS
JUMPER
DESCRIPTION
J3
Jumper to select EN input logic state. Set EN = VIN to
enable device, or set EN = GND to disable device.
J4
Jumper to select MODE input logic state. Set
MODE = VIN to enable auto-PFM mode, or set
MODE = GND to select forced PWM mode.
To use external sync feature, remove this jumper and
apply an external clock between 2.75MHz and
3.25MHz on the MODE test point (TP10) or center pin
on the J4 header.
Quick Setup Guide
1. Install jumper on J3, shorting EN to VIN.
2. Install jumper on J4, shorting MODE to VIN.
3. Connect power supply to J1, with voltage setting between
1.8V and 5.5V.
4. Connect electronic load to J2.
5. Place scope probes on VOUT test point, and other test
points of interest.
6. Turn on the power supply.
7. Monitor the output voltage start-up sequence on the scope.
The waveforms will look similar to those shown in Figure 2
and Figure 3.
8. Turn on the electronic load.
9. Measure the output voltage with the voltmeter. The voltage
should regulate within data sheet spec limits (FN7649).
10. To determine efficiency, measure input and output voltages
at the Kelvin testpoints TP5 and TP1, and measure the
input and output currents. Calculate efficiency based on
these measurements.
11. To test external sync, remove the jumper at J4, then apply
an external clock between 2.75MHz and 3.25MHz on the
MODE input (test point TP10, or the center pin of header
J4).
TP11, TP13, TP14 GND (Ground)
TP12
July 10, 2012
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FB (Voltage feedback input, connected to VOUT)
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
Application Note 1647
Evaluation Software
Installation/Use
1. Check your system specs against the system requirements
listed below.
•Windows 98SE, Windows XP, or Windows NT
•CD-ROM drive
•USB port
•At least 20MB free hard disk space
•1024x768 or larger resolution monitor
2. Install the driver for the ISLUSB2I2C interface by double
clicking on the file named “ISLUSBI2C_Driver_Installer.exe”
on the ISL9112 evaluation kit CD-ROM. Follow the
instructions that appear on-screen to install the driver.
3. Install the ISL9112 evaluation software by double clicking on
the file named: “ISL9112_Eval_Installer.exe” on the ISL9112
eval kit CD-ROM. Follow the instructions that appear
on-screen to install the application.
4. Attach the ISLUSBI2C interface to the computer using the
supplied USB cable. The ‘Found New Hardware” dialog will
appear. Select “Install the software automatically” and click
“Next”.
5. Locate the 4-wire I2C cable that is provided with the
ISLUSBI2C kit. Attach one end of this cable to the 4-pin
header on the ISLUSBI2C interface, and connect the other
end of this cable to the corresponding 4-pin header on the
ISL9112 evaluation board.
6. Following the “Quick Setup Guide” on page 1 of this
document, connect the power supply, DC load, and other test
equipment to the ISL9112 evaluation board, then apply
power.
7. Launch the ISL9112 evaluation software. The installer adds a
shortcut in the Start menu: Start → Programs → Intersil →
ISl9112 → ISL9112 Eval. Select this item to launch the
evaluation software.
8. When launched, the ISL9112 evaluation software detects the
ISLUSBI2C interface. At the bottom of the ISL9112
application window is a Log textbox. The message in this
textbox should report: “USB-to-I2C driver initialization
successful” and “USB-to-I2C interface detected.” See Figure 1.
If this message is not displayed, please check connections
and try reinstalling the ISLUSBI2C driver.
9. Try reading the ISL9112 device registers by clicking on the
READ buttons. Observe the activity reported in the Log
textbox. Successful I2C communication will be reported in this
textbox. If there is a communication error, this will also be
reported in the Log textbox.
10. To change the output voltage, use Table 5 to determine the
DCDOUT value that corresponds to the desired output voltage.
Change the value of V Control register accordingly, and also
set the I2CEN bit. Click the Write button to write this value to
the device.
11. To invoke Ultrasonic mode, set the ULTRA bit in the V Control
register, and click the Write button to write this value to the
device.
12. To change the slew rate setting, use Table 5 to determine the
SLEWRATE value that corresponds to the desired slew rate.
Change the value of the Slew Ctrl register accordingly, then
click the Write button to write this data to the device under
test.
13. To observe slew rate control behavior, set the slew rate to a
value other than ‘0b000’, and then change the DCDOUT value
using the evaluation software. Observe VOUT on an
oscilloscope to see the slew rate limited transitions from one
voltage setting to the new voltage setting.
FIGURE 1. ISL9112 EVALUATION SOFTWARE WINDOW
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Application Note 1647
Typical Start-up Waveforms
VIN = 2V
VOUT = 3.3V
LX1 I
= 200mA
2V/DIV OUT
Output Voltage Programming
TABLE 5. ISL9112 OUTPUT VOLTAGE SETTINGS
DCDOUT[4:0]
OUTPUT VOLTAGE
(V)
0b00000
1.9
0b00001
2.0
0b00010
2.1
0b00011
2.2
0b00100
2.3
0b00101
2.4
0b00110
2.5
0b00111
2.6
0b01000
2.7
0b01001
2.8
0b01010
2.9
0b01011
3.0
0b01100
3.1
0b01101
3.2
0b01110
3.3
0b01111
3.4
0b10000
3.5
0b10001
3.6
0b10010
3.7
0b10011
3.8
0b10100
3.9
TABLE 4. ISL9112 SLEW RATE CONTROL SETTINGS
0b10101
4.0
BIT
NAME
TYPE
RESET
0b10110
4.1
2:0
SLEWRATE
R/W
000
0b10111
4.2
0b11000
4.3
0b11001
4.4
0b11010
4.5
0b11011
4.6
0b11100
4.7
0b11101
4.8
0b11110
4.9
0b11111
5.0
LX2
2V/DIV
VOUT
2V/DIV
EN
2V/DIV
400µs/DIV
FIGURE 2. ISL9112 START-UP WITH VIN = 2V AND VOUT = 3.3V
VIN = 4V
VOUT = 3.3V
LX1 I
= 200mA
2V/DIV OUT
LX2
2V/DIV
VOUT
2V/DIV
EN
2V/DIV
400µs/DIV
FIGURE 3. ISL9112 START-UP WITH VIN = 4V AND VOUT = 3.3V
Slew Rate Control
7:3
Reserved
R/W
00000
3
DESCRIPTION
Slew rate control (typ),
expressed as µs per LSB
change in DCDOUT value:
0b000 = 0µs/ΔLSB
0b001 = 1.5µs/ΔLSB
0b010 = 3.1µs/ΔLSB
0b011 = 6.3µs/ΔLSB
0b100 = 12.5µs/ΔLSB
0b101 = 25µs/ΔLSB
0b110 = 50µs/ΔLSB
0b111 = 100µs/ΔLSB
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July 10, 2012
Application Note 1647
Evaluation Board Schematic
J2
VOUT
1
2
3
4
C2
10µF
0805
HDR4
TP12
J4
HDR3
TP10
TP1
TP2
VIN
1.8V TO 5.5V
J1
TP4
1
2
3
4
C1
10µF
0805
U1
ISL9112IRTNZ/IRT7Z
1
12
VOUT
FB
2
L1
2.2µH
3
4
5
6
HDR4
TP5
GND
MODE
LX1
EN
PVIN
SDA
VIN
SCL
11
0
TP6
VIN
MODE
1
2
3
TP11
10
J3
HDR3
TP9
9
EN
8
SDA
7
SCL
TP7
PD
R1
LX2
PGND
VOUT
3.3V (ISL9112IRTNZ)
5.0V (ISL9112IRT7Z)
VIN
1
2
3
TP8
VIN
C3
1µF
J5
TP3
TP13 TP14
1
2
3
4
HDR4B
FIGURE 4. ISL9112 EVALUATION BOARD SCHEMATIC
TABLE 6. ISL9112 EVALUATION BOARD BILL OF MATERIALS
ITEM#
QTY
DESIGNATORS
PART TYPE
FOOTPRINT
DESCRIPTION
VENDORS
1
1
U1
ISL9110IRTNZ
or
ISL9112IRT7Z
L12.3x3C
TQFN
Intersil ISL9112 Buck-Boost Regulator with I2C
Adjustable Output Voltage
INTERSIL
2
1
L1
2.2µH
5x5x1.4
NRS5020T2R2
TAIYO YUDEN
3
2
C1, C2
10µF/10V/X5R
0805
LMK212BJ106KG
TAIYO YUDEN
4
1
C3
1µF/10V/X7R
0603
LMK107BJ105KK
TAIYO YUDEN
6
1
R1
0Ω
0603
Resistor, Generic
ANY
7
2
J1, J2
HDR-4
HDR-4
Vert. Pin Header, 4-Pin, 0.1” Spacing, Generic
ANY
8
2
J3, J4
HDR-3
HDR-3
Vert. Pin Header, 3-Pin, 0.1” Spacing, Generic
ANY
9
1
J5
HDR-4POL
HDR-4POL
Header, 4-pin, Polarized, AMP 3-641213-4
AMP
13
14
TP1, TP2, TP3, TP4,
TP5, TP6, TP7, TP8,
TP9, TP10, TP11,
TP12, TP13, TP14
TEST POINT
TEST POINT
Test Point, Thru-Hole, White,
Mouser 534-5002
KEYSTONE
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Application Note 1647
Evaluation Board Layout
FIGURE 5. ISL9112 EVALUATION BOARD SILKSCREEN TOP
FIGURE 6. ISL9112 EVALUATION BOARD TOP COPPER
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Application Note 1647
Evaluation Board Layout (Continued)
FIGURE 7. ISL9112 EVALUATION BOARD MID LAYER 1 (GND)
FIGURE 8. ISL9112 EVALUATION BOARD MID LAYER 2 (VIN AND VOUT)
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Application Note 1647
Evaluation Board Layout (Continued)
FIGURE 9. ISL9112 EVALUATION BOARD BOTTOM LAYER (GND)
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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