an1882

Application Note 1882
Author: Billy Yang
ISL8115EVAL2Z Synchronous Buck Converter User
Guide
Introduction
ISL8115 Key Features
ISL8115EVAL2Z is a Synchronous Buck Converter
implementing Intersil’s wide input range PWM controller
ISL8115. Utilizing voltage mode control with input feed
forward, the ISL8115EVAL2Z maintains a constant loop gain
for optimal transient response, especially for applications with
a wide input voltage range. For a more detailed description of
the ISL8115 functionality, refer to the ISL8115 data sheet.
• Wide VIN range operation: 2.97V to 36V; up to 5.5V output
and 30A load current per phase.
• Integrated 5V high speed 4A MOSFET gate drivers
- Internal bootstrap diode
This application note includes the test setup, typical
performance waveforms, schematic, layout and bill of
materials (BOM).
• Oscillator programmable from 150kHz to 1.5MHz
- Frequency synchronization to external clock signal
Evaluation Board Specifications
• Diode emulation mode for light load efficiency improvement
TABLE 1. EVALUATION BOARD ELECTRICAL SPECIFICATIONS
SPEC
VIN
DESCRIPTION
Board Input Range
MIN
TYP
25
28
MAX UNIT
36
• Fast transient response
- Voltage-mode PWM leading-edge modulation with
non-linear control
- Input voltage feed-forward
V
• Output OVP/UVP; OCP and OTP
• Power-good open drain output
• Adjustable soft-start
VOUT
Output Voltage
5
V
• Pre-bias start-up function
IOUT
Output Rated Current
20
A
IOC
Overcurrent Threshold
22
A
Fsw
Switch Frequency
220
kHz
Input UVP Rising threshold
22.4
V
• Excellent output voltage regulation
- 0.6V ±1.0% internal reference (-40°C ~ +125°C)
- 0.6V ±0.7% internal reference (-40°C ~ +105°C)
- Differential voltage sensing
Falling threshold
24.2
V
Applications
92.53
%
• Power supply for datacom/telecom and POL
η
Efficiency at 50% load
• Wide input voltage range buck regulators
• High current density power supplies RF power amplifier bias
compensation
Recommended Equipment
• Input power source up to 36V supply voltage with 125W
power supply ability.
• Electronic load with 100W power sinking ability
• Voltmeters and ammeters
• 100MHz quad-trace oscilloscope
FIGURE 1. ISL8115EVAL2Z EVALUATION BOARD
February 5, 2014
AN1882.2
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2013, 2014. All Rights Reserved
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 1882
FIGURE 2. ISL8115EVAL2Z TEST SET-UP
Quick Test Setup
Design Guide
1. Ensure that the Evaluation board is correctly connected to the
power supply and the electronic load prior to applying any
power. Please refer to Figure 2 for proper set-up.
2. Set the input voltage to 28V, turn on the power supply and
observe output voltage. The output voltage should variation
should be within 5%.
3. Adjust load current within 20A. The output voltage variation
should be within 5%.
4. Use oscilloscope to observe output ripple voltage and phase
node ringing. For accurate measurement, please refer to
Figure 3 for proper set-up.
Note: Test points TP1; TP3; TP8; TP9 are for voltage
measurement only. Do not allow high current through these test
points.
The ISL8115EVAL2Z is optimized for 25V to 36V input voltage
range. However, the evaluation board can be modified to support
multiple applications due to the customer requirements. Please
refer to the datasheet for the detailed information.
Output Voltage Adjustment
The output voltage can be set by the resistor R4, R1. In order to
keep the existing compensation parameters unchanged, adjust
R4 to set the output voltage by the following Equation 1:
R4 =
0.6 V × R1
Vout − 0.6 V
(EQ. 1)
VMON monitors the output for UVP and OVP, the resistor divider
value of R11/R8 should be the same with the R1/R4.
Synchronization
Probe Set-up
ISL8115EVAL2Z board can be synchronized with an external
clock. Apply a clock signal (10% to 90% duty cycle) in the range
of 150kHz to 1.5MHz to the FSET pin makes the internal
frequency synchronized with the external clock. Please remove
R27 when the sync function is implemented.
FIGURE 3. OSCILLOSCOPE PROBE SET-UP
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Application Note 1882
Typical Performance Curves
Unless otherwise specified, the input voltage is 28V.
95
95
90
90
VIN = 24V
85
VIN = 28V
80
EFFICIENCY (%)
EFFICIENCY (%)
85
VIN = 36V
75
VIN = 24V
80
VIN = 28V
75
70
70
65
65
60
0
2
4
6
8
10
12
14
16
18
60
20
VIN = 36V
0
1
2
3
4
5
6
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
FIGURE 4. EFFICIENCY vs LOAD CURRENT AT CCM MODE
FIGURE 5. EFFICIENCY vs LOAD CURRENT AT DEM MODE
5.0080
5.0058
5.0075
5.0057
5.0056
VOUT (V)
VOUT (V)
5.0070
VIN = 28V
5.0065
5.0055
VIN = 28V
5.0054
5.0060
5.0053
5.0055
5.0050
5.0052
5.0051
0
2
4
6
8
10
12
14
16
18
20
0
2
4
6
FIGURE 6. VOUT LOAD REGULATION AT CCM MODE
12
14
16
18
20
DEM MODE
5.0068
5.0066
5.0070
5.0064
5.0068
NO LOAD
5.0066
5.0062
NO LOAD
5.0060
5.0064
VOUT (V)
VOUT (V)
10
FIGURE 7. VOUT LOAD REGULATION AT DEM MODE
CCM MODE
5.0072
5.0062
5.0060
5.0058
5.0056
5.0054
5.0058
5.0052
5.0056
5.0050
5.0054
5.0048
5.0052
24
8
LOAD CURRENT (A)
LOAD CURRENT (A)
26
28
30
32
34
36
5.0046
24
26
28
30
32
34
36
VIN (V)
VIN (V)
FIGURE 8. LINE REGULATION AT NO LOAD CONDITION
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Application Note 1882
Typical Performance Curves
Unless otherwise specified, the input voltage is 28V. (Continued)
CCM MODE
5.00562
5.00560
5.0056
5.00558
5.0055
5.0054
VOUT (V)
VOUT (V)
5.00556
5.00554
FULL LOAD 20A
5.00552
5.00550
5.0053
5.0052
FULL LOAD 20A
5.0051
5.0050
5.00548
5.0049
5.00546
5.00544
24
DEM MODE
5.0057
5.0048
26
28
30
32
34
36
5.0047
24
26
28
VIN (V)
30
32
34
36
VIN (V)
FIGURE 9. LINE REGULATION AT FULL LOAD CONDITION
VOUT
50mV/DIV
PH
20V/DIV
2µs/DIV
FIGURE 10. OUTPUT VOLTAGE RIPPLE AT 20A LOAD CONDITION
10A/DIV
OUTPUT LOAD
VOUT
10A/DIV
100mV/DIV
OUTPUT LOAD
VOUT
100mV/DIV
200µs/DIV
200µs/DIV
FIGURE 11. 5A-15A; 2A/µs AT CCM MODE
FIGURE 12. 10A -20A; 2A/µs AT CCM MODE
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Application Note 1882
Typical Performance Curves
Unless otherwise specified, the input voltage is 28V. (Continued)
2V/DIV
2V/DIV
VOUT
VOUT
OUTPUT LOAD
VIN
10A/DIV
OUTPUT LOAD
10A/DIV
20V/DIV
VIN
20V/DIV
10ms/DIV
10ms/DIV
FIGURE 13. START-UP AT 0A LOAD CONDITION
FIGURE 14. START-UP AT 20A LOAD CONDITION
VOUT
VOUT
OUTPUT LOAD
2V/DIV
2V/DIV
OUTPUT LOAD
10A/DIV
10A/DIV
VIN
VIN
20V/DIV
20V/DIV
50ms/DIV
2ms/DIV
FIGURE 15. SHUTDOWN AT 0A LOAD CONDITION
FIGURE 16. SHUTDOWN AT 20A LOAD CONDITION
VOUT
VOUT
500mV/DIV
OUTPUT LOAD
500mV/DIV
OUTPUT LOAD
10A/DIV
PH
20V/DIV
10A/DIV
PH
20V/DIV
5ms/DIV
5ms/DIV
FIGURE 17. OCP AT 27A LOAD
FIGURE 18. SHORT PROTECTION
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Schematic
TP9
RGND
PVCC
R31
4.99K
R30
4.99K
R10
0
R8
2K
2K
3
1
6
R4
3.3n
R11
14.7k
133
R9
0
Q5
2N7002LT1
1
2
PGOOD
R1
14.7k
C3
R3
3 4
2
TP4
PGOOD
C37
1uF
TP8
VOUT_S
LED1
Average OCP: 22A
Peak current limit: 25A
C17
0.22uF
C1
4.7nF
C2
100p
R17
3k
J4
23
R38
0
R26
24
113K
R27
VIN
R29
10k
R6
10
JP5
C22
2.2uF
R35
174k
8
1
2
3
DNP
Q1
4
C34
DNP
C32
5
1
L1
2.6uH
J3
1
2
Big Lug
7443556260
2.6uH 31.5A 1.58mohm
Q2
4
0.22uF
D2
C24
100uF
7
C23
100uF
DNP
R14
2
C21
2.2uF
C26
100uF
C25
100uF
C11
1uF
C15
1uF
33.2K
R12
3k
R34
2.2
TP3
PVIN
C30
10uF
Output: 5V/20A
C29
10uF
C35
100uF
C36
100uF
J1
VIN
36V
TP1
GND
C13
1uF
C10
1uF
Upper MOS: BSC039N06NS
Lower MOS: BSC039N06NS
PVCC
EVAL2Z
Input: 24V - 36V
Frequency: 220KHz
6TPF330M9L
C31
DNP
1
2
3
5
1
2
3
C16
C33
6TPF330M9L
R13
DNP
10
R33 0
Big Lug
R28
7.15k
JP7
0
9
DNP
4
R20
R36
140K
input rising shreshold: 22.4V
input falling shreshold: 21.2V
1
2
3
13
ISENA
14
ISENB
16
15
VMON
FB
BOOT
SS
1
R37
0
UGATE
CLKOUT
FSET
18.2K
CLK_IN
PHASE
ISL8115
CONF
Q4
5
11.8K
CLK_OUT
PLL_COMP
Q3
4
5
22
U1
R43
1
C6
11 PVCC
VFF
R23
PVCC
RAMP
21
LGATE
ISHARE
R16
DNP
C20
4.7uF
12
6
R25
0
ISET
PGOOD
20
5
390pF
5.11K
ISHARE_BUS
GND
PGOOD 4
19
RGND
18
25
17
R18
10.5k 1n
VCC
JP6
C19
R21
EN
C12
DNP
3
DNP
COMP
R24
JP3
2
JP4
JP1
VOUT
C4
C14
2.2nF
J2
GND
Application Note 1882
R2
13k
R22
0
AN1882.2
February 5, 2014
Application Note 1882
Bill of Materials
QTY
REFERENCE
VALUE
DESCRIPTION
1
C1
4.7nF
CAP CER 4700pF 50V 10% X7R 0603
Generic
Generic
1
C2
100p
CAP CER 100pF 50V 5% NP0 0603
Generic
Generic
1
C3
3.3n
CAP CER 3300pF 50V 10% X7R 0603
Generic
Generic
1
C4
1n
CAP CER 1000pF 50V 5% NP0 0603
Generic
Generic
5
C6, C12, R13, R16, R24
DNP
5
C10, C11, C13, C15, C37
1µF
CAP CER 1µF 10V 10% X5R 0603
Generic
Generic
1
C14
2.2nF
CAP CER 2200pF 50V 10% NP0 0603
Generic
Generic
2
C16, C17
0.22µF
CAP CER 0.22µF 16V 10% X7R 0603
Generic
Generic
1
C19
390pF
CAP CER 390pF 50V 5% NP0 0603
Generic
Generic
1
C20
4.7µF
CAP CER 4.7µF 6.3V 10% X5R 0805
Generic
Generic
1
C21
2.2µF
CAP CER 2.2µF 25V 10% X7R 1210
C3225X7R1E225K/1.60
TDK
1
C22
2.2µF
CAP CER 2.2µF 6.3V 20% X5R 0603
Generic
Generic
4
C23, C24, C25, C26
100µF
CAP CER 100µF 6.3V 20% X5R 1210
C3225X5R0J107M250AC
TDK
2
C29, C30
10µF
CAP CER 10µF 50V 10% X5R 1206
C3216X5R1H106K160AB TDK
2
C31, C34
DNP
CAP TANT 330µF 6.3V 20% 2917
6TPF330M9L
Panasonic
2
C32, C33
6TPF330M9L
CAP TANT 330µF 6.3V 20% 2917
6TPF330M9L
Panasonic
2
C35, C36
100µF
CAP ALUM 100µF 50V 20% SMD
PCV1H101MCL2GS
nichicon
1
D2
DNP
4
JP1, JP3, JP4, JP5
Jumper
JUMPER PLUG 2POS DOUBLE ROW
XG8T-0231
Omron
2
JP6, JP7
DNP
JUMPER PLUG 2POS DOUBLE ROW
1
J1
VIN
POST BINDING BANANA INSULATED RE
111-0707-001
Johnson Components
1
J2
GND
POST BINDING BANANA INSULATED BL
111-0703-001
Johnson Components
2
J3, J4
Big Lug
CONN- Big Lug TERMINAL POST
KPA8CTP
Burndy
1
LED1
VENDOR
LNJ162C3XRA
Panasonic
1
L1
2.6µH
7443556260
WE-Midcom
1
Q1
DNP
3
Q2, Q3, Q4
1
Q5
2N7002LT1
MOSFET N-CH 60V 115MA SOT-23
2N7002LT1
ON Semiconductor
2
R1, R11
14.7k
RES 14.7kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R2
13k
RES 13.0kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R3
133
RES 133Ω 1/10W 1% 0603 SMD
Generic
Generic
2
R4, R8
2k
RES 2.00kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R6
10
RES 10.0Ω 1/10W 1% 0603 SMD
Generic
Generic
8
R9, R10, R22, R25, R33, R37,
R38, R43
0
RES 0.0Ω 1/10W JUMP 0603 SMD
Generic
Generic
2
R12, R17
3k
RES 3.00kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R14
2
RES 2.00Ω 1/4W 1% 1206 SMD
Generic
Generic
1
R18
10.5k
RES 10.5kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R20
33.2k
RES 33.2kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R21
5.11k
RES 5.11kΩ 1/10W 1% 0603 SMD
Generic
Generic
DIODE SCHOTTKY 40V SOD123
LXA3025IGC-TR LED
INDUCTOR POWER 2.6µH 31.5A SMD
MOSFET N-CH 60V 19A TDSON-8
BSC039N06NS MOSFET N-CH 60V 19A TDSON-8
7
PART #
BSC039N06NS
AN1882.2
February 5, 2014
Application Note 1882
Bill of Materials
(Continued)
QTY
REFERENCE
VALUE
1
R23
11.8k
RES 11.8kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R26
18.2k
RES 18.2kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R27
113k
RES 113kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R28
7.15k
RES 7.15kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R29
10k
RES 10kΩ 1/10W 1% 0603 SMD
Generic
Generic
2
R30, R31
4.99K
RES 4.99kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R34
2.2
RES 2.2Ω 1/10W 1% 0603 SMD
Generic
Generic
1
R35
174k
RES 174kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
R36
140k
RES 140kΩ 1/10W 1% 0603 SMD
Generic
Generic
1
TP1
GND
Test point
SPCJ-123-01
Jolo
1
TP3
PVIN
Test point
SPCJ-123-01
Jolo
1
TP4
PGOOD
Test point
SPCJ-123-01
Jolo
1
TP8
VOUT_S
Test point
SPCJ-123-01
Jolo
1
TP9
RGND
Test point
SPCJ-123-01
Jolo
1
U1
ISL8115
Sync Buck PWM Controller 24Ld QFN
ISL8115FRTZ
Intersil
8
DESCRIPTION
PART #
VENDOR
AN1882.2
February 5, 2014
Assembly Drawing
9
Application Note 1882
AN1882.2
February 5, 2014
Application Note 1882
PCB Layout
FIGURE 19. TOP LAYER
FIGURE 20. LAYER 2
10
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February 5, 2014
Application Note 1882
PCB Layout
(Continued)
FIGURE 21. LAYER 3
FIGURE 22. LAYER 4
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
11
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