isl8205meval1z user guide

User Guide 072
ISL8205MEVAL1Z Evaluation Board User Guide
The ISL8205M power module is a single channel synchronous
step-down complete power supply, capable of delivering up to
5A of continuous current. Operating from a single 2.6V to 5.5V
input power rail and integrating a controller, power inductor
and MOSFETs, ISL8205M can achieve up to 95% conversion
efficiency. It also provides fast transient response with
excellent loop stability as well as deliver output voltage as low
as 0.6V. Switching frequency is also adjustable from 680kHz
to 3.5MHz with either external resistor or SYNC clock option.
Selectable PFM mode can also be enabled to boost up light
load efficiency to extend battery life. Other features include
programmable soft-start, soft-stop, input undervoltage
lockout, 100% duty cycle operation, over-temperature,
overcurrent/short-circuit with hiccup mode, overvoltage and
negative overcurrent protection. It also has a dedicated enable
pin and power-good flag that allow for easy system power rails
sequencing.
The ISL8205MEVAL1Z evaluation board is designed to
demonstrate the performance of the ISL8205M. The board is
by default set to be 1.2V output voltage with 1.6MHz switching
frequency. Other output voltage values can be easily set by
changing the jumper position. Switching frequency can be
adjusted by changing the FS pin resistor.
Features
• 2.6V to 5.5V input voltage range
• Adjustable output voltage as low as 0.6V with ±1.6%
accuracy over line/load/temperature
• Default 1.8MHz current mode control operations
- 680kHz to 3.5MHz resistor adjustable
- External synchronization up to 3.5MHz
- Selectable light-load efficiency mode
- 100% duty cycle LDO mode
• Programmable soft-start and soft-stop output discharge
• Dedicated enable pin and power-good flag
• UVLO, over-temperature, overcurrent, overvoltage and
negative overcurrent protections
Specifications/Default Set-Up
• VIN = 2.6V to 5.5V
• VOUT options (via jumper selection): 1V, 1.2V, 2.5V, 3.3V
• MAX IOUT up to 5A
• fSW = 1.6MHz by default
References
• Set to PWM mode by default
• ISL8205M datasheet
• 1ms soft-start time by default
Ordering Information
PART NUMBER
ISL8205MEVAL1Z
DESCRIPTION
ISL8205M single 5A power module evaluation
board
FIGURE 1. ISL8205MEVAL1Z BLOCK DIAGRAM
May 3, 2016
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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.
User Guide 072
TABLE 1. ISL8205M COMPONENT SELECTION GUIDE MATRIX
VIN (V)
VOUT (V)
fSW (MHz)
CIN (µF)
COUT (µF)
R7 (kΩ)
RSET (kΩ)
CFF (pF)
5
0.6
0.8
2x22
1x100
261
OPEN
390
5
0.9
1.2
2x22
3x22
169
200
560
5
1
1.3
2x22
3x22
154
150
560
5
1
1.3
2x22
2x22
154
150
820
5
1.2
1.6
2x22
2x22
124
100
820
5
1.5
1.7
2x22
2x22
115
66.5
560
5
1.8
2
2x22
2x22
95.3
49.9
470
5
2.5
2.5
2x22
2x22
75
31.6
330
5
3.3
3
2x22
2x22
59
22.1
330
3.3
0.6
0.8
2x22
1x100
261
OPEN
390
3.3
0.9
1.2
2x22
3x22
169
200
560
3.3
1
1.3
2x22
3x22
154
150
560
3.3
1
1.3
2x22
2x22
154
150
820
3.3
1.2
1.6
2x22
2x22
124
100
820
3.3
1.5
1.7
2x22
2x22
115
66.5
560
3.3
1.8
2
2x22
2x22
95.3
49.9
470
3.3
2.5
2.5
2x22
2x22
75
31.6
330
FIGURE 2. TOP OF BOARD
Recommended Equipment
• 0V to 5.5V power supply with at least 7A source current
capability
• Electronic load capable of sinking current up to 5A
• Digital Multimeters (DMMs)
• 100MHz quad-trace oscilloscope
Functional Description
The ISL8205M is a single 5A step-down high efficiency power
module optimized for FPGA, DSP and Li-ion battery power
devices. The module switches at 1.8MHz by default when the FS
pin is shorted to VIN. The switching frequency is also adjustable
from 680kHz to 3.5MHz through a resistor from FS to SGND. To
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FIGURE 3. BOTTOM OF BOARD
boost light-load efficiency, ISL8205M can also be configured to
operate in PFM mode by pulling the SYNC pin to SGND. Peak
current mode control scheme is implemented for fast transient
response. The module utilizes internal compensation to stabilize
the system and optimize transient response, which greatly
simplifies the application. Other excellent features include
external synchronization, 100% duty cycle operation and very low
quiescent current. For further information, please refer to the
ISL8205M datasheet.
Quick Start
The ISL8205MEVAL1Z is set to be VOUT = 1.2V, fSW = 1.6MHz by
default. For other VOUT options, the recommended fSW needs to
be adjusted by changing resistor (R7) connected to the FS pin.
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1. Before applying power to input, ensure one shorting jumper
on J1 across pins 5 and 6 is present. This selects VOUT = 1.2V
option.
2. Set the ENABLE switches SW1 to the “OFF” position.
3. Connect the positive of a power supply to the VIN connector
and the negative of the power supply to the PGND connector.
Make sure the power supply is not enabled when making
connections and the input power supply voltage is set to a
value between 2.6V and 5.5V.
4. Turn the power supply on.
5. Turn ENABLE switch SW1 to the “ON” position to enable
module operation.
6. The power-good LED should illuminate in green if the module
is operating properly.
7. Measure output voltage, VOUT, at test points VOUT and PGND.
Module output should be 1.2V.
Programming the Output Voltage
The ISL8205MEVAL1Z evaluation board has several preset
output voltages, 1.0V, 1.2V, 2.5V and 3.3V, which can be selected
in J1 jumper. Other VOUT values other than on-board options can
be set by proper selection of the resistor (RSET) connecting from
FB to SGND. In this case, RSET for default options (R9, R10, R11,
R12) may need to be changed. The output voltage is governed by
Equation 1.
R SET + 100k
V OUT = V REF  ---------------------------------------R
(EQ. 1)
information on recommended switching frequency and fSW
selection range is provided in “Recommended Switching
Frequency” and “Operation Range”.
Recommended Switching Frequency
Selection of switching frequency for each VIN and VOUT
combination needs to take into account a few trade-offs.
Generally, lower switching frequency will lead to higher
efficiency. However, switching frequency should not be
decreased too low due to negative current protection limit.
Moreover, when output voltage is relatively high, low switching
frequency will result in more sub-harmonic oscillation. Therefore,
operating frequency needs to be kept relatively high under high
VOUT conditions. However, again, switching frequency cannot be
increased too much. Otherwise, the minimum on-time limit could
be violated. Based on these considerations, Figure 4 provides the
recommended switching frequency under various typical VIN and
across VOUT ranges.
4.0
SWITCHING FREQUENCY (MHz)
Please refer to Table 1 for more information. The following
operation procedure will be based on default setting.
VIN=5V
VIN=4V
Series3
VIN=2.6V
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
SET
0.6
For most popular VOUT values and corresponding RSET values,
please refer to Table 1 for more information.
1
1.4
1.8
2.2 2.6
3
3.4 3.8
OUTPUT VOLTAGE (V)
4.2
4.6
5
FIGURE 4. SWITCHING FREQUENCY RECOMMENDATION
Operation Range
Feed-Forward Capacitor Selection
In typical applications where the output capacitors are all ceramic,
a feed-forward capacitor, CFF (as annotated as C12, C13, C14, C15 in
schematic) is needed to be put in parallel with each RSET to insure
loop stability in extreme operating conditions. With internal
compensation mode enabled, the CFF values for typical operating
conditions are optimized and listed in Table 1. And that’s how C12,
C13, C14, C15 default values are selected. Please note that, for
system parameters that are different from Table 1 or external
instead of internal compensation is used, the optimized value of
CFF needs to be adjusted.
By default, the ISL8205MEVAL1Z is configured to be operating at
VOUT = 1.2V (J1 jumper position is at pins 5 and 6), fSW = 1.6MHz
conditions. VIN ranges from 2.6V to 5.5V. The board can also
support a wider operating range to meet the requirement of
specific applications. The VOUT can be adjusted from 0.6V to 5V.
Load current range is from 0A to 5A. Note that, for continuous
operation at 5A, airflow across the board may be needed. The
fSW can also be tuned. However, to ensure sufficient stability
margins, switching frequency can only be adjusted within the
safe operatiing regions represented with Figures 5 through 9.
Operating outside of these areas may lead to system instability.
Frequency Adjust
The switching frequency of ISL8205M is adjustable ranging from
680kHz to 3.5MHz via a simple resistor RFS (as shown in R7 on
ISL8205MEVAL1Z board) across FS to SGND. The switching
frequency setting is based on Equation 2:
220  10 3
R FS  k  = ------------------------------ – 14
f OSC  kHz 
(EQ. 2)
When the FS pin is directly tied to VIN, the frequency of operation
is fixed at 1.8MHz. For a recommended switching frequency with
typical operation conditions, refer to Table 1. More detailed
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4.0
SWITCHING FREQUENCY (MHz)
SWITCHING FREQUENCY (MHz)
User Guide 072
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0.6
1
1.4
1.8
2.2
2.6
3
3.4
3.8
4.2
4.6
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
5
0.6
1
1.4
1.8
OUTPUT VOLTAGE (V)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.6
3
3.4
3.8
4.2
FIGURE 6. OPERATION REGION VIN = 5.0V
SWITCHING FREQUENCY (MHz)
SWITCHING FREQUENCY (MHz)
FIGURE 5. OPERATION REGION VIN = 5.5V
0.0
2.2
OUTPUT VOLTAGE (V)
2.7
3
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
3.3
0.6
0.8
1
OUTPUT VOLTAGE (V)
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
OUTPUT VOLTAGE (V)
FIGURE 8. OPERATION REGION VIN = 3.3V
FIGURE 7. OPERATION REGION VIN = 4.0V
SWITCHING FREQUENCY (MHz)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0.6
0.8
1
1.2
1.4
1.6
1.8
2
OUTPUT VOLTAGE (V)
FIGURE 9. OPERATION REGION VIN = 2.6V
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PWM/PFM Selection
By default, ISL8205MEVAL1Z is set to operate in PWM mode.
This is achieved by connecting SYNC to VIN through R1. Pulling
the SYNC pin LOW, forces the module into PFM mode, which
enables pulse-skipping at light load to minimize the switching
loss by reducing the switching frequency. Refer to ISL8205M
datasheet for more detailed information. For ISL8205MEVAL1Z,
PFM mode can be enabled by removing R1 and shorting SYNC to
SGND by putting a 0Ω resistor on R2.
Soft Start-Up
The soft start-up reduces the inrush current during the start-up.
For ISL8205MEVAL1Z, the soft start-up time is set to 1ms by
default through C6. However, start-up time can be adjusted by
tuning the C6 value. Equation 3 can be used to determine the C6
value for the target soft-start time tSS.
C 6  F  = 3.1  t SS  S 
(EQ. 3)
Thermal Considerations and
Current Derating
Board layout is very critical in order to make the module operate
safely and deliver maximum allowable power. In order for the
board to operate properly in the high ambient temperature
environments and carry full load currents, the board layout needs
to be carefully designed to maximize thermal performance. To
achieve this, select enough trace width, copper weight and
proper connectors.
The ISL8205MEVAL1Z evaluation board is capable of operating
at 5A full load current at room temperature with plenty of safety
margin for junction temperature. However, if the board is to
operate at elevated ambient temperatures, then the available
output current may need to be derated. Refer to the derated
current curves in the ISL8205M datasheet to determine the
maximum output current the evaluation board can supply.
Evaluation Board Information
The ISL8205MEVAL1Z evaluation board is a 2x2in2 four-layer FR-4
board with 2oz. copper on all the layers. The board can be used as a
single 5A reference design. Refer to Figures 11 through 14 for
board layout information. The board is designed with mechanical
switches for ENABLE, power-good LED indicators, several
connectors, test points and jumpers, which make testing the board
easy.
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VOUT
7
8
ISL8205MIRZ
TP5
NC
NC
SW
SW
9
TP8
6
VOUT
BAN3
C9
C8
C7
C11
4
DNP
VSENSE
DNP
5
22UF
NC
0
21
22UF
U1
R15
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ISL8205MEVAL1Z Schematic
PGND
VIN
TP1
10
OUT
NC
PGND
6
VIN
11
BAN1
R1
OUT
200K
C16
4.7UF
C3
22UF
C2
22UF
C1
DNP
C10
DNP
PGOOD
12
PG
13
SYNC
PGND
BAN4
22
SW
TP6
PGND
3
PGND
E
PGND
VSENSE
UNNAMED_1_ISL8205M_I66_2
2
E
BAN2
20
TP3
1
FB
COMP
FS
16
SS
EN
PGND
15
R2
TP2
DNP
SYNC
UNNAMED_1_ISL8205M_I66_16
UNNAMED_1_ISL8205M_I66_17
19
18
17
14
PGND
UNNAMED_1_ISL8205M_I66_18
R16
8
6
4
2
4
6
8
7
5
3
1
LED1
TP7
UNNAMED_1_NCHANNEL_I17_D
Q1
PGOOD
IN
2N7002-7-F
DRAWN BY:
FIGURE 10. SCHEMATIC
DATE:
ENGINEER:
R12
150K
C15
820PF
100K
R11
C14
820PF
31.6K
R10
C13
390PF
R9
22.1K
C4
OPEN
UNNAMED_1_SMCAP_I111_A
DNP
R4
330PF
C5
124K
R7
2K
R14
R13
100K
SW1
ENABLE
UNNAMED_1_CONN8_I67_IN1
UNNAMED_1_CONN8_I67_IN3
UNNAMED_1_CONN8_I67_IN5
UNNAMED_1_CONN8_I67_IN7
0
TP4
UNNAMED_1_SMLED_I105_A
VIN
OPEN
200K
R6
EN
IN
IN
DNP
UNNAMED_1_GTSERIES_I4_NC
C6
R3
VIN
3300PF
R5
C12
E
1
3
5
7
J1
2
UNNAMED_1_CONN8_I67_IN2
DNP
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Bill of Materials
REFERENCE DESIGNATOR
QTY
C16
1
MURATA
GRM21BR71A475KA73L
C12
1
TDK
CGA2B2C0G1H331J050BA CAP, SMD, 0402, 330pF, 50V, 5%, NP0, ROHS
C6
1
PANASONIC
ECU-E1E332KBQ
CAP, SMD, 0402, 3300pF, 25V, 10%, X7R, ROHS
C13
1
YAGEO
CC0402JRNPO9BN391
CAP, SMD, 0402, 390pF, 50V, 5%, NP0, ROHS
C14, C15
2
SAMSUNG
CL05C821JB5NNNC
CAP, SMD, 0402, 820pF, 50V, 5%, NP0, ROHS
C4, C5
0
C2, C3, C7, C8
4
C1, C9
0
TP1-TP8
8
KEYSTONE
5002
CONN-MINI TEST POINT, VERTICAL, WHITE, ROHS
BAN1-BAN4
4
KEYSTONE
575-4
CONN-JACK, MINI BANANA, 0.175 PLUG,
NICKEL/BRASS, ROHS
J1
1
BERG/FCI
68000-236HLF
CONN-HEADER, 1x8, BRKAWY 1x36, 2.54mm,
ROHS
J1-Pins 5-6
1
SULLINS
SPC02SYAN
CONN-JUMPER, SHORTING, 2PIN, BLACK, GOLD,
ROHS
LED1
1
LITEON/VISHAY
LTST-C190KGKT
LED, SMD, 0603, GREEN CLEAR, 2V, 20mA,
571nm, 35mcd, ROHS
U1
1
INTERSIL
ISL8205MIRZ
IC-5A PWR MODULE, ANALOG DC/DC, 22P, QFN,
4.5x7.5, ROHS
Q1
1
DIODES, INC.
2N7002-7-F
TRANSISTOR, N-CHANNEL, 3LD, SOT-23, 60V,
115mA, ROHS
R12
1
TE CONNECTIVITY
3-1879216-2
RES, SMD, 0402, 150k, 1/16W, 0.1%, TF, ROHS
R9
1
TE CONNECTIVITY
6-1879215-6
RES, SMD, 0402, 22.1k, 1/16W, 0.1%, TF, ROHS
R11
1
TE CONNECTIVITY
9-1879208-7
RES, SMD, 0402, 100k, 1/16W, 0.1%, TF, ROHS
R4
0
R5, R15
2
VENKEL
CR0402-16W-00T
RES, SMD, 0402, 0Ω, 1/16W, 5%, TF, ROHS
R1
1
ROHM
MCR01MZPF2003
RES, SMD, 0402, 200k, 1/16W, 1%, TF, ROHS
R2, R6, R16
0
R13
1
VENKEL
CR0603-10W-1003FT
RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS
R14
1
KOA
RK73H1JTTD2001F
RES, SMD, 0603, 2k, 1/10W, 1%, TF, ROHS
R3
1
VENKEL
CR0603-10W-2003FT
RES, SMD, 0603, 200k, 1/10W, 1%, TF, ROHS
R7
1
STACKPOLE
RNCF0402DTE124K
RES, SMD, 0402, 124k, 1/16W, 0.5%, TF, ROHS
R10
1
YAGEO
RT0402BRD0731K6L
RES, SMD, 0402, 31.6k, 1/16W, 0.1%, TF, ROHS
SW1
1
ITT INDUSTRIES/C&K DIVISION GT11MSCBE
C10
0
CAP, TANT, SMD, 2917, 10V, DNP-PLACE HOLDER
C11
0
CAP, TANT POLY, SMD, 2917, 10V, DNP-PLACE
HOLDER
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MANUFACTURER
PART NUMBER
DESCRIPTION
CAP, SMD, 0805, 4.7µF, 10V, 10%, X7R, ROHS
CAP, SMD, 0402, DNP-PLACE HOLDER, ROHS
TAIYO YUDEN
LMK316AB7226KL-TR
CAP, SMD, 1206, 22µF, 10V, 10%, X7R, ROHS
CAP, SMD, 1206, DNP-PLACE HOLDER, ROHS
RES, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER
RES, SMD, 0402, DNP, DNP, DNP, TF, ROHS
7
SWITCH-TOGGLE, SMD, 6PIN, SPDT, 2POS,
ON-NONE-ON, ROHS
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Board Layout
FIGURE 11. TOP LAYER (TOP VIEW)
FIGURE 12. INNER LAYER 1 (TOP VIEW)
FIGURE 13. INNER LAYER 2 (TOP VIEW)
FIGURE 14. BOTTOM LAYER (BOTTOM VIEW)
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ISL8205MEVAL1Z Performance Data
The following data was acquired using a ISL8205MEVAL1Z evaluation
100.0
100.0
95.0
95.0
90.0
90.0
EFFICIENCY (%)
EFFICIENCY (%)
board at +25°C ambient and free air 0LFM.
85.0
80.0
Vout = 1V, Fsw = 1.3MHz
75.0
Vout = 1.2V, Fsw = 1.6MHz
70.0
Vout = 2.5V, Fsw = 2.5MHz
65.0
85.0
80.0
Vout = 1V, Fsw = 1.3MHz
75.0
Vout = 1.2V, Fsw = 1.6MHz
70.0
Vout = 2.5V, Fsw = 2.5MHz
Vout = 3.3V, Fsw = 3MHz
65.0
60.0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
60.0
5
0
0.5
1
100.0
95.0
95.0
90.0
90.0
EFFICIENCY (%)
EFFICIENCY (%)
100.0
85.0
80.0
Vout = 1V, Fsw = 1.3MHz
Vout = 1.2V, Fsw = 1.6MHz
70.0
Vout = 2.5V, Fsw = 2.5MHz
65.0
2
2.5
3
3.5
4
4.5
5
FIGURE 16. EFFICIENCY TA = +25°C, VIN = 5V PFM MODE
FIGURE 15. EFFICIENCY TA = +25°C, VIN = 3.3V PFM MODE
75.0
1.5
LOAD CURRENT (A)
LOAD CURRENT (A)
85.0
80.0
Vout = 1V, Fsw = 1.3MHz
Vout = 1.2V, Fsw = 1.6MHz
Vout = 2.5V, Fsw = 2.5MHz
Vout = 3.3V, Fsw = 3MHz
75.0
70.0
65.0
60.0
60.0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
LOAD CURRENT (A)
FIGURE 17. EFFICIENCY TA = +25°C, VIN = 3.3V PWM MODE
0.5
1
1.5
2
2.5
3.5
4
4.5
5
FIGURE 18. EFFICIENCY TA = +25°C, VIN = 5V PWM MODE
IOUT 2A/DIV
VOUT 50mV/DIV
VOUT 50mV/DIV
100µs/DIV
100µs/DIV
9
3
LOAD CURRENT (A)
IOUT 2A/DIV
FIGURE 19. LOAD TRANSIENT VIN = 5V, VOUT = 1.2V, IOUT = 0 TO 5A,
fSW = 1.6MHz, COUT = 2 x 22µF CERAMIC CAPACITORS
LOAD CURRENT SLEW RATE: 1A/µs
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FIGURE 20. LOAD TRANSIENT VIN = 5V, VOUT = 3.3V, IOUT = 0 TO 5A,
fSW = 3MHz, COUT = 2 x 22µF CERAMIC CAPACITORS,
LOAD CURRENT SLEW RATE: 1A/µs
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ISL8205MEVAL1Z Performance Data
The following data was acquired using a ISL8205MEVAL1Z evaluation
board at +25°C ambient and free air 0LFM. (Continued)
MAX=50.2°C
FIGURE 21. THERMAL IMAGE AT VIN = 5V, VOUT = 1.2V, IOUT = 5A, fSW = 1.6MHz, TA = +25°C, FREE AIR 0 LFM
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.
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May 3, 2016