an1922

Application Note 1922
ISL8240MEVAL4Z Dual 20A/Optional 40A Cascadable
Evaluation Board Setup Procedure
The ISL8240MEVAL4Z is a complete, dual step-down switching
mode DC/DC module. The dual outputs can easily be
paralleled for single-output, high current use. It is easy to apply
this high power, current sharing DC/DC power module to
power hungry datacom, telecom and FPGA applications. All
that is needed in order to have a complete, dual 20A design
ready for use are the ISL8240M, a few passive components
and VOUT setting resistors.
Recommended Equipment
The simplicity of the ISL8240M is its off-the-shelf, unassisted
implementation. Patented current sharing in multi phase
operation greatly reduces ripple currents, BOM costs and
complexity. The ISL8240M has a thermally enhanced, compact
17mmx17mmx7.5mm QFN package that operates at full load
and over-temperature. Easy access to all pins, with few external
components, reduces PCB design to a component layer and a
simple ground layer.
Quick Start
This ISL8240MEVAL4Z evaluation board is designed for dual 20A
output applications. Optionally, this board can easily be converted
for 40A single output use. Multiple ISL8240MEVAL4Z boards can
be cascadable through the SYNC and CLKOUT pins to operate
with phase shifting, for paralleling or multiple output use. The
input voltage of this board is 4.5V to 20V and the default outputs
on this board are set at 1.0V and 1.5V.
• 0V to 20V power supply with at least 5A source current
capability
• Electronic load capable of sinking current up to 40A
• Digital Multimeters (DMMs)
• 100MHz quad-trace oscilloscope
For dual output operation, the inputs are BA7 (VIN1), BA8
(GND), BA3 (VIN2) and BA4 (GND). The outputs are BA5
(VOUT1), BA6 (GND), BA1 (VOUT2) and BA2 (GND).
For paralleled single output operation, the inputs are BA7
(VIN1) and BA8 (GND). The outputs are BA5 (VOUT1) and BA6
(GND) with BA5 and BA1 shorted.
Ordering Information
PART NUMBER
ISL8240MEVAL4Z
DESCRIPTION
Evaluation Board
References
• ISL8240M datasheet.
V
VOUT2
+
-
+
LOAD2
(0A~20A)
4.5V TO 20V
LOAD1
(0A~20A)
VIN
+
V
VOUT1
V
+
FIGURE 1. ISL8240MEVAL4Z BOARD IMAGE
September 29, 2015
AN1922.3
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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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 1922
Dual Output Mode
1. Connect a power supply capable of sourcing at least 5A to
inputs BA7 (VIN1), BA8 (GND), BA3 (VIN2) and BA4 (GND) of
the ISL8240MEVAL4Z evaluation board, with a voltage
between 4.5V to 20V. VIN1 and VIN2 can be different with R18
and R19 open.
2. Connect an electronic load or device to be powered to the
outputs BA5 (VOUT1), BA6 (GND), BA1 (VOUT2) and BA2
(GND) of the board. All connections, especially the low
voltage, high current VOUT lines, should be able to carry the
desired load current and should be made as short as possible
3. Make sure that the setup is connected correctly. Turn on the
power supply. If the board is working properly, the green LED
will illuminate; if not, the red LED will illuminate (recheck the
wire/jumper connections in this case). Measure the output
voltages, VOUT1, which should be at 1.0V and VOUT2, which
should be at 1.5V
4. If different output voltages are desired, board resistors can be
exchanged to provide the desired VOUT. Please refer to Table 1
for R2/R4 resistor values, which can be used to produce
different output voltages.
The switching frequency is set to 500kHz by default. The
switching frequency can be adjusted, as recommended in
Table 1. By changing the resistor RFSET, the desired frequency
can be adjusted. If the output voltage is set to ≥1.5V, the output
current will need to be derated at certain conditions to allow for
safe operation. Please refer to the ISL8240M datasheet.
TABLE 1. VALUE OF BOTTOM RESISTOR (TOP RESISTOR R1,
R3 = 1kΩ) AND FREQUENCY SELECTION FOR DIFFERENT
OUTPUT VOLTAGES
VOUT
(V)
R2 /R4
(Ω)
FREQUENCY
(kHz)
RFSET (kΩ)
(VIN = 12V)
1.0
1500
500
237
1.2
1000
550
174
1.5
665
600
140
1.8
499
650
115
2.5
316
700
100
Optional Paralleled Single Output Mode
1. To set up the parallel mode, short JP1 (ENC), JP2 (VMON) and
JP3 (COMP) with a jumper. To set up 180° interleaving phase
between 2 channels, short the MODE pin and GND pin of JP6
with a jumper.
2. Remove R9 and R13. Change R14 to 0Ω. Change R18 and R19
to 0Ω. Short VOUT1 to VOUT2 using short wires or copper
straps. Add C2 for a 470pF capacitor.
4. Connect an electronic load or the device to be powered to the
outputs BA5 (VOUT1) and BA6 (GND) of the board. All
connections, especially the low voltage, high current VOUT
lines, should be able to carry the desired load current and
should be made as short as possible.
5. Make sure the setup is connected correctly prior to applying any
power to the board. Adjust the power supply to 12V and turn on
the input power supply. If the board is working properly, the green
LED will illuminate; if not, the red LED will illuminate (recheck the
wire/jumper connections in this case). Measure the output
voltages, VOUT1, which should be at 1.0V.
6. Apply any load that is less than 40A for normal steady state
operation. Refer to Table 1 to change the output voltage by
changing resistor R2.
TABLE 2. BOARD CONFIGURATION FOR SINGLE OUTPUT 40A
APPLICATION
ENC
VMON
MODE
COMP
R9
R13
R14
Dual
OPEN
OPEN
OPEN
OPEN
0
0
OPEN
Single
ON
ON
ON
ON
OPEN
OPEN
0
For optimized performance of a 2-phase single output
application of the ISL8240M, please refer to application note
AN1923.
Optional Cascadable Mode
Cascadable mode is needed when multiple evaluation boards
are used for paralleling or multiple output use. Follow the steps
shown below:
1. In order to generate CLKOUT at a shifted phase clock signal,
the control loop of VOUT2 needs to be disabled by connecting
VSEN2- to VCC.
2. Program MODE and VSEN2+ pin voltages to set the CLKOUT
signal and the shifted degrees between two phases on the
board (refer to Table 3 on page 4).
3. Use a coaxial cable to connect CLKOUT (J5) to SYNC (J2) of the
next evaluation board, which can be programmed for parallel
or dual output use.
4. If the second board is programmed for parallel use, the
ISHARE pins of the first and second boards need to be tied
together. Using two twisted wires, short two different jumpers
of JP7 (ISHARE/SGND) on two evaluation boards. Add 1nF
capacitors of C14 for different boards to decouple the noise.
5. If the third board is used in cascadable mode, the second
board can only be used in the parallel mode to generate the
CLKOUT signal for the SYNC pin on the third board.
6. Follow the instructions from Steps 1 through 5 for more
cascadable boards.
3. Connect a power supply capable of sourcing at least 5A to the
inputs BA7 (VIN1), BA8 (GND), BA3 (VIN2) and BA4 (GND) of
the ISL8240MEVAL4Z evaluation board, with a voltage
between 4.5V to 20V. VIN1 and VIN2 need to be shorted
together.
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Application Note 1922
Evaluation Board Information
The evaluation board size is 114.3mmx76.2mm. It is a 4-layer
board, containing 2-ounce copper on the top and bottom layers
and 2-ounce copper on all internal layers. The board can be used
as a dual 20A reference design. Refer to “Layout” on page 6. The
board is made of FR4 material and all components, including the
solder attachment, are lead-free.
Thermal Considerations and Current Derating
For high current applications, board layout is very critical in order
to make the module operate safely and deliver maximum
allowable power. To carry large currents, the board layout needs
to be designed carefully to maximize thermal performance. To
achieve this, use sufficient trace width, copper weight and the
proper connectors.
This evaluation board is designed for running dual 20A at room
temperature without additional cooling systems needed.
However, if the output voltage is increased or the board is
operated at elevated temperatures, then the available current is
derated. Refer to the derated current curves in the ISL8240M
datasheet to determine the output current available.
For layout of designs using the ISL8240M, the thermal
performance can be improved by adhering to the following
design tips:
1. Use the top and bottom layers to carry the large current.
VOUT1, VOUT2, Phase 1, Phase 2, PGND, VIN1 and VIN2
should have large, solid planes. Place enough thermal vias to
connect the power planes in different layers under and
around the module.
2. Phase 1 and Phase 2 pads are switching nodes that generate
switching noise. Keep these pads under the module. For
noise-sensitive applications, it is recommended to keep
phase pads only on the top and inner layers of the PCB; do not
place phase pads exposed to the outside on the bottom layer
of the PCB. To improve the thermal performance, the phase
pads can be extended in the inner layer, as shown in Phase 1
and Phase 2 pads on layer 2 (Figure 5) for this dual 20A
evaluation board. Make sure that layer 1 and layer 3 have the
GND layers to cover the extended areas of phase pads at
layer 2 to avoid noise coupling.
3. Place the modules evenly on the board and leave enough
space between modules. If the board space is limited, try to
put the modules with low power loss closely together (i.e. low
VOUT or IOUT) while still separating the module with high power
loss.
4. If the ambient temperature is high or the board space is
limited, airflow is needed to dissipate more heat from the
modules. A heatsink can also be applied to the top side of the
module to further improve the thermal performance
(heatsink recommendation: Aavid Thermalloy, part number
375424B00034G, www.aavid.com).
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Application Note 1922
TABLE 3. ISL8240M OPERATION MODES
1ST MODULE (I = INPUT; O = OUTPUT; I/O = INPUT AND OUTPUT, BI-DIRECTION)
MODE
EN1/FF1 EN2/FF2
(I)
(I)
VSEN2(I)
1
0
0
-
2A
0
1
Active
2B
1
0
-
3A
1
1
3B
1
3C
1
MODES OF OPERATION
OPERATION OPERATION
VMON1
MODE
CLKOUT/REFIN
MODE
OF 2ND 2ND CHANNEL
OUTPUT
OF 2ND
WRT 1ST
OF 3RD
(see Description
MODE VSEN2+
VMON2 MODULE WRT 1ST (O)
for details)
(I)
(I)
(I OR O)
(Note 2) (Note 2)
(Note 1)
MODULE
MODULE
-
-
-
-
-
-
-
Disabled
-
Active
-
VMON1 =
VMON2 to
Keep PGOOD
Valid
-
-
Single Phase
-
-
-
VMON1 =
VMON2 to
Keep PGOOD
Valid
-
-
Single Phase
<VCC -0.7V Active Active
29% to 45%
of VCC (I)
Active
-
0°
-
-
Dual Regulator
1
<VCC -0.7V Active Active
45% to 62%
of VCC (I)
Active
-
90°
-
-
Dual Regulator
1
<VCC -0.7V Active Active >62% of VCC (I)
Active
-
180°
-
-
Dual Regulator
<VCC -0.7V Active Active <29% of VCC (I)
-
Active Active
-
-
4
1
1
5A
1
1
VCC
GND
5B
1
1
VCC
GND
-
5C
1
1
VCC
GND
-
-
Active
-
-60°
-
-
DDR Mode
VMON1
or
Divider
-
180°
-
-
2-Phase
60°
Divider
Divider
180°
5B
5B
6-Phase
60°
VMON1
or
Divider
Active
180°
5C
5C
3 Outputs
60°
6
1
1
VCC
VCC
GND
120°
1kΩ
Active
240°
2B
-
3-Phase
7A
1
1
VCC
VCC
VCC
90°
1kΩ
Divider
180°
7A
-
4-Phase
7B
1
1
VCC
VCC
VCC
90°
1kΩ
Active
180°
7B
-
2 Outputs
(1st module in
Mode 7A)
7C
1
1
VCC
VCC
VCC
90°
1kΩ
Active
180°
3, 4
-
3 Outputs
(1st module in
Mode 7A)
8
Cascaded Module Operation MODEs 5B+5B+7A+5B+5B+5B/7A, No External Clock Required
12-Phase
9
External Clock or External Logic Circuits Required for Equal Phase Interval
5, 7, 8, 9, 10,
11, or
(PHASE >12)
NOTES:
1. “2ND CHANNEL WRT 1ST” means “second channel with respect to first;” in other words, Channel 2 lags Channel 1 by the degrees specified in this
column. For example, 90° means Channel 2 lags Channel 1 by 90°; -60° means Channel 2 leads Channel 1 by 60°.
2. “VMON1” means that the pin is tied to the VMON1 pin of the same module.
“Divider” means that there is a resistor divider from VOUT to SGND; refer to Figure 25 in the ISL8240M datasheet.
“1kΩ” means that there is a 1kΩ resistor connecting the pin to SGND; refer to Figure 23 in the ISL8240M datasheet.
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J1
C9
P1
J4
VOUT2
UNNAMED_1_SMCAP_I67_B
E
C8
C12
C11
1000PF
P5
UNNAMED_1_SMCAP_I56_A
R20
OPEN
OPEN
R22
0
R3
R1
0
VOUT1
1000PF
E
C015
10UF
C012
100UF
C011
100UF
C04
330UF
C09
OPEN
C03
100UF
C02
OPEN
C01
100UF
C16
1000PF
R2
1.5K
C17
OUT
PGOOD
R9
1K
OPEN
OPEN
C13
R4
665
C15
1K
1000PF
C07
100UF
C06
OPEN
C05
100UF
C010
OPEN
C016
10UF
C013
100UF
C014
100UF
BA5
C08
BA1
330UF
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ISL8240MEVAL4Z Board Schematic
R10
BA2
BA6
R14
R21
0
UNNAMED_1_ISL8240M_I230_21
IN
21
22
23
DNP
GND
VCC
IN
UNNAMED_1_ISL8240M_I230_22
24
5
DNP
25
UNNAMED_1_ISL8240M_I230_1
UNNAMED_1_ISL8240M_I230_26
26
GND
0
1
VCC
**
6
237K
D
ISL8240MIRZ
EN/FF2
VCC
EN/FF1
OUT
17
OUT
16
IN
15
IN
VMON1
CLKOUT
C14
VSEN1+
VSEN1-
PGOOD
VSEN2-
SGND
VMON1
CLKOUT
ISHARE
18
EN/FF2
EN/FF1
CLKOUT
R16
OPEN
BA4
BA8
J5
IN
C10
330UF
CIN1
CIN2
22UF
CIN3
13
N/C
GND
PHASE1
22UF
PHASE2
BA7
CIN7
9
PGND
CIN8
22UF
22UF
CIN6
22UF
CIN5
P8
D
R5
D
16.5K
PHASE1
VCC
IN
D
D
0
R19
0
COMP
IN
47PF
C3
NOTE:
47PF
C5
1000PF
JP4
4.12K
PGOOD
COMP1
IN
LED1
2
C4
EN/FF1
R6
EN/FF2
1000PF
JP5
EN2
R8
47PF
C6
4.12K
JP2
VMON
47PF
C7
3.32K
GRN
OUT
VIN2
JP3
UNNAMED_1_SMRES_I93_B
IN
EN/FF1
RED
OUT
JP1
R18
C2
UNNAMED_1_SMRES_I14_B
3.32K
ENC
IN
COMP2
D
R12
VMON1
IN
VMON2
E
R11
E
12
PHASE2
16.5K
R7
11
10
E
E
GND
**
GROUND AND GROUND ARE TIED TOGETHER AT PIN 6 OF U1.
D
4
330UF
CIN4
P4
VIN1
14
22UF
8
BA3
PGND
E
VIN1
D
D
VIN2
OUT
P7
D
4.7UF
P3
Application Note 1922
7
SYNC
OUT
19
3
RFSET
VCC
U1
VMON2
20
1
5
COMP1
ISHARE
0
SYNC
VOUT1
OPEN
OUT
VOUT2
MODE
JP7
4
COMP2
R13
OUT
3
DNP
DNP
R15
MODE
J2
C1
D
2
OUT
COMP1
ISHARE
VMON2
JP6
MODE
COMP2
VIN2
P6
E
VSEN2+
E
P2
3
UNNAMED_1_NCHANNEL_I216_D
Q1
IN
1
D
VIN1
2N7002-7-F
2
IN
E
DRAWN BY:
TIM KLEMANN
DATE:
ENGINEER:
02/19/2014
RELEASED BY:
DATE:
UPDATED BY:
DATE:
TITLE:
DATE:
TAO TAO
ISL8240M
EVALUATION BOARD
E
SCHEMATIC
TESTER
$CDS_IMAGE|intersil_color_sm.jpg|1194|282
MASK#
REV.
HRDWR ID
A
ISL8240MEVAL4Z
FILENAME:
D
~/ISL8240M/ISL8240MEVAL4ZA
FIGURE 2. ISL8240MEVAL4Z BOARD SCHEMATIC
SHEET
1
OF
1
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Layout
6
FIGURE 4. TOP LAYER COMPONENT SIDE
FIGURE 5. LAYER 2
FIGURE 6. LAYER 3
Application Note 1922
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FIGURE 3. TOP SILKSCREEN
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Layout
(Continued)
7
FIGURE 8. BOTTOM SILKSCREEN
Application Note 1922
FIGURE 7. BOTTOM LAYER SOLDER SIDE
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Bill of Materials
PART NUMBER
575-4
GRM21BR71C475KA73L
REF DES
QTY
BA1, BA2, BA3, BA4, BA5,
BA6, BA7, BA8
8
C1
1
VALUE
TOL.
(%) VOLTAGE POWER PACKAGE TYPE
CONN
4.7µF
10
JEDEC TYPE
MANUFACTURER
DESCRIPTION
CON_BAN_575
8
16V
805
CAP_0805
Murata
Ceramic Capacitor
OPEN
603
CAP_0603
Generic
Multilayer Capacitor
50V
603
CAP_0603
Generic
Multilayer Capacitor
OPEN
603
CAP_0603
Generic
Multilayer Capacitor
H1045-OPEN
C2, C3, C6, C7
4
OPEN
H1045-00102-50V10
C4, C5, C8, C9
4
1000pF
C10, C11, C12, C13, C14,
C17
6
OPEN
C15, C16
2
1000pF
10
16V
603
CAP_0603
Generic
Multilayer Capacitor
C01, C03, C05, C07, C011,
C012, C013, C014
8
100µF
20
6.3V
1210
CAP_1210
TDK
Ceramic Chip Capacitor
H1045-OPEN
H1045-00102-16V10
H1082-00107-6R3V20-T
10
C02, C06, C09, C10
4
OPEN
OPEN
1210
CAP_1210
Generic
Ceramic Chip Capacitor
6TPF330M9L
C04, C08
2
330µF
20
6.3V
SMD
CAP_7343_149
Sanyo
Tantalum Polymer
Capacitor
CIN1, CIN4
2
330µF
20
25V
SMD
CAPAE_315X402
Panasonic
CIN2, CIN3, CIN5, CIN6,
CIN7, CIN8
6
22µF
20
25V
1210
CAP_1210
Taiyo Yuden
131-4353-00
J1, J4
2
CONN
TEK131-4353-00
31-5329-52RFX
J2, J5
2
CONN
CON_BNC_31_5329_52RFX
JUMPER2_100
JP1-JP7
7
THOLE
JUMPER-1
EEVHA1E331UP
TMK325B7226MM-TR
SSL-LXA3025IGC
5002
2N7002-7-F
H2511-01001-1/10W1
Ceramic Chip Capacitor
LED1
1
SMD
P1, P2, P3, P4, P5, P6, P7,
P8
8
THOLE
LED_3X2_5MM
MTP500X
Q1
1
SOT23
SOT23
R1, R3
2
1kΩ
1
1/10W
603
RES_0603
Chip Resistor
H2511-01501-1/10W1
R2
1
1.5kΩ
1
1/10W
603
RES_0603
Chip Resistor
H2511-06650-1/10W1
R4
1
665Ω
1
1/10W
603
RES_0603
Chip Resistor
H2511-06650-1/10W1
R5, R7
2
16.5Ω
1
1/10W
603
RES_0603
Chip Resistor
H2511-06650-1/10W1
R6, R8
2
4.12kΩ
1
1/10W
603
RES_0603
Chip Resistor
H2511-06650-1/10W1
R9, R10, R13, R20, R22
5
0Ω
1
1/10W
603
RES_0603
Chip Resistor
1
1/10W
H2511-06650-1/10W1
AN1922.3
September 29, 2015
H2505-DNP-DNP-1
H2513-00R00-1/4W
H2511-02373-1/10W1
ISL8240MIRZ
R11, R12
2
3.32kΩ
R14, R15,R16, R21
4
OPEN
R18, R19
2
0Ω
1
1/4W
RFSET
1
237kΩ
1
1/10W
U1
1
603
RES_0603
Chip Resistor
603
RES_0603
Chip Resistor
1206
RES_1206
Chip Resistor
603
RES_0603
Chip Resistor
QFN
Application Note 1922
H1082-OPEN
Application Note 1922
ISL8240MEVAL4Z Performance
95
2.5VOUT
EFFICIENCY (%)
90
100mV/DIV
85
80
1.5VOUT
1.2VOUT
75
1.8VOUT
1VOUT
70
65
60
0
2
4
6
8
10
12
14
16
18
LOAD CURRENT (A)
FIGURE 9. EFFICIENCY VS LOAD CURRENT (12VIN)
20
50µs/DIV
FIGURE 10. 1VOUT TRANSIENT RESPONSE, IOUT = 0A TO 10A,
FSW = 350KHZ LOAD CURRENT SLEW RATE 10A/ΜS
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 document is current before proceeding.
For information regarding Intersil Corporation and its products, see www.intersil.com
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