ISL85410DEMO1Z, ISL85418DEMO1Z User Guide

Application Note 1908
ISL85410DEMO1Z, ISL85418DEMO1Z Wide VIN 1A and
800mA Synchronous Buck Regulators
Description
Key Features
The ISL85410DEMO1Z, ISL85418DEMO1Z kits are intended
for use for Point-of-Load applications sourcing from 3V to 40V.
The kits are used to demonstrate the performance of the
ISL85410, ISL85418 Wide VIN Low Quiescent Current High
Efficiency Sync Buck Regulators with 1A (ISL85410) and
800mA (ISL85418) output current.
•
•
•
•
•
•
The ISL85410, ISL85418 are offered in a 4mmx3mm 12 Ld
DFN package with 1mm maximum height. The converter
occupies 1.516cm2 area.
Recommended Equipment
The following materials are recommended to perform testing:
• 0V to 50V Power Supply with at least 2A source current
capability
• Electronic loads capable of sinking current up to 2A
•
•
•
•
Wide input voltage range 3V to 40V
Synchronous operation for high efficiency
No compensation required
Integrated high-side and low-side NMOS devices
Selectable PFM or forced PWM mode at light loads
Internal fixed (500kHz) or adjustable switching frequency
300kHz to 2MHz
Continuous output current up to 800mA
Internal or external soft-start
Minimal external components required
Power-good and enable functions available
References
• ISL85410 Datasheet
• ISL85418 Datasheet
• Digital multimeters (DMMs)
• 100MHz quad-trace oscilloscope
Ordering Information
• Signal generator
PART NUMBER
DESCRIPTION
ISL85410DEMO1Z
Demonstration Board (1A output current)
ISL85418DEMO1Z
Demonstration Board (800mA output current)
ISL85410DEMO1Z
FIGURE 1. FRONT OF EVALUATION BOARD ISL85410DEMO1Z
March 13, 2015
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1
FIGURE 2. BACK OF EVALUATION BOARD ISL85410DEMO1Z
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Application Note 1908
Quick Setup Guide
Frequency Control
1. Ensure that the circuit is correctly connected to the supply and
loads prior to applying any power.
2. Connect the bias supply to VIN, the plus terminal to VIN (P4)
and the negative return to GND (P5).
3. Turn on the power supply.
4. Verify the output voltage is 3.3V for VOUT.
Evaluating the Other Output Voltage
The ISL85410DEMO1Z, ISL85418DEMO1Z kit outputs are preset
to 3.3V; however, output voltages can be adjusted from 0.6V to
15V. The output voltage programming resistor, R2, will depend
on the desired output voltage of the regulator and the value of
the feedback resistor R1, as shown in Equation 1.
0.6
R 2 = R 1  ------------------------------
V
– 0.6
(EQ. 1)
OUT
If the output voltage desired is 0.6V, then R1 is shorted. Please
note that if VOUT is less than 1.8V, the switching frequency and
compensation must be changed for 300kHz operation due to
minimum on-time limitation. Please refer to datasheets ISL85410
and ISL85418 for further information.
Table 1 shows the component selection that should be used for
the respective VOUT .
TABLE 1. EXTERNAL COMPONENT SELECTION
VOUT L1
(V) (µH)
C5+C6
(µF)
R1
(kΩ)
R2
(kΩ)
C4
(pF)
R12
(kΩ)
R3
(kΩ)
C7
(pF)
12
22
2x22
90.9
4.75
22
115
150
470
5
22
47+22
90.9
12.4
27
DNP
(Note 1)
100
470
3.3
22
47+22
90.9
20
27
DNP
(Note 1)
100
470
2.5
22
47+22
90.9
28.7
27
DNP
(Note 1)
100
470
1.8
12
47+22
90.9
45.5
27
DNP
(Note 1)
70
470
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The ISL85410, ISL85418 have an FS pin that controls the
frequency of operation. Programmable frequency allows for
optimization between efficiency and external component size. It
also allows low frequency operation for low VOUTs when
minimum on time would limit the operation otherwise. Default
switching frequency is 500kHz when FS is tied to VCC (R10 = 0).
By removing R10, the switching frequency could be changed
from 300kHz (R12 = 340k) to 2MHz (R12 = 32.4k). Please refer
to datasheets ISL85410 and ISL85418 for calculating the value of
R10. Do not leave this pin floating.
SYNC Control
The ISL85410, ISL85418 demo boards have a SYNC pin that
allows external synchronization frequency to be applied. Default
board configuration has R6 = 200k to VCC, which defaults to
PWM operation mode and also to the preselected switching
frequency set by R12 (see datasheet and previous section
“Frequency Control” for details). If this pin is tied to GND, the IC
will operate in PFM mode. The S2 switch allows forced PFM or
PWM modes.
Soft-start/COMP Control
R15 selects between internal (R15 = 0) and external soft-start.
R11 selects between internal (R11 = 0) and external
compensation. For applications where repetitive restarts of the
IC are required, it is recommended to add a 350kΩ resistor in
parallel to CSS in order to allow its fast discharge. Please refer to
Pin Description Table of the ISL85410 and ISL85418 datasheets.
NOTE:
1. Connect FS to Vcc
AN1908.2
March 13, 2015
Application Note 1908
ISL85410DEMO1Z Schematic
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NOTE: The input electrolytic capacitor C10 is optional and it is used to prevent transient voltages when the input test leads have large
parasitic inductance. It can be removed if the IC is used in a system application.
FIGURE 3. ISL85410DEMO1Z SCHEMATIC
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Application Note 1908
ISL85410DEMO1Z, ISL85418DEMO1Z BOM
MANUFACTURER PART
QTY UNITS
REFERENCE
DESIGNATOR
DESCRIPTION
MANUFACTURER
ISL85400EVAL2ZREVAPCB
1
ea
LABEL-RENAME
BOARD
PWB-PCB, ISL85400EVAL2Z, REVA, ROHS
INTERSIL
EEE-FK1H151P
1
ea
C10 (Optional)
CAP, SMD, 10.3mm, 150µF, 50V, 20%, ROHS, ALUM.ELEC. PANASONIC
GRM36COG270J050AQ
1
ea
C4
CAP, SMD, 0402, 27pF, 50V, 5%, NP0, ROHS
MURATA
GRM36X7R333K016AQ
1
ea
CSS
CAP, SMD, 0402, 33000pF, 16V, 10%, X7R, ROHS
MURATA
ECJ-0EB1H471K
1
ea
C7
CAP, SMD, 0402, 470pF, 50V, 10%, X7R, ROHS
PANASONIC
0
ea
C8
CAP, SMD, 0402, DNP-PLACE HOLDER, ROHS
06035C104KAT2A
1
ea
C3
CAP, SMD, 0603, 0.1µF, 50V, 10%, X7R, ROHS
AVX
GRM188R61C105KA12D
1
ea
C9
CAP, SMD, 0603, 1µF, 16V, 10%, X5R, ROHS
MURATA
C3216X5R1H106K
2
ea
C1, C2
CAP, SMD, 1206, 10µF, 50V, 10%, X5R, ROHS
TDK
GRM31CR60J226KE19L
2
ea
C6
CAP, SMD, 1206, 22µF, 6.3V, 10%, X5R, ROHS
MURATA
GRM31CR60J476KE19L
1
ea
C5
CAP, SMD, 1206, 47µF, 6.3V, 10%, X5R, ROHS
MURATA
74408943220
1
ea
L1
COIL-PWR INDUCTOR, SMD, 4.8mm, 22µH, 20%, 1.1A,
ROHS
WURTH
ELECTRONICS
5000
2
ea
P4, P7
CONN-MINI TEST PT, VERTICAL, RED, ROHS
KEYSTONE
5001
2
ea
P5, P9
CONN-MINI TEST PT, VERTICAL, BLK, ROHS
KEYSTONE
5002
2
ea
P1, P2
CONN-MINI TEST POINT, VERTICAL, WHITE, ROHS
KEYSTONE
ISL85410FRZ for ISL85410DEMO1Z
ISL85418FRZ for ISL85418DEMO1Z
1
ea
U1
IC-500mA BUCK REGULATOR, 12P, DFN, 3X4, ROHS
INTERSIL
CR0402-16W-00T
2
ea
R10, R15
RES, SMD, 0402, 0Ω, 1/16W, 5%, TF, ROHS
VENKEL
ERJ2RKF1003
1
ea
R3
RES, SMD, 0402, 100k, 1/16W, 1%, TF, ROHS
PANASONIC
ERJ2RKF2001
1
ea
R2
RES, SMD, 0402, 20k, 1/16W, 1%, TF, ROHS
PANASONIC
MCR01MZPF2003
2
ea
R6, R7
RES, SMD, 0402, 200k, 1/16W, 1%, TF, ROHS
ROHM
CRCW040290K9FKED
1
ea
R1
RES, SMD, 0402, 90.9k, 1/16W, 1%, TF, ROHS
VISHAY/DALE
0
ea
R12
RES, SMD, 0402, DNP, DNP, DNP, TF, ROHS
0
ea
R8, R9, R11
RES, SMD, 0402, DNP, DNP, DNP, TF, ROHS
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Application Note 1908
ISL85410DEMO1Z, ISL85418DEMO1Z Board Layout
FIGURE 4. SILK SCREEN TOP
FIGURE 5. SILK SCREEN BOTTOM
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Application Note 1908
ISL85410 Efficiency Curves
fSW = 500kHz, TA = +25°C
100
100
95
95
90
VIN = 24V
85
VIN = 15V
EFFICIENCY (%)
EFFICIENCY (%)
90
80
VIN = 33V
75
70
65
75
70
55
55
0.1
0.2
0.3
0.4 0.5 0.6 0.7
OUTPUT LOAD (A)
0.8
0.9
50
1.0
VIN = 33V
65
60
0
0
FIGURE 6. EFFICIENCY vs LOAD, PFM, VOUT = 12V
100
90
85
85
VIN = 15V
VIN = 24V
75
70
65
0.3
0.4
0.5
0.6
0.7
0.8
0.9
50
1.0
VIN = 15V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
OUTPUT LOAD (A)
FIGURE 9. EFFICIENCY vs LOAD, PWM, VOUT = 5V, L1 = 30µH
FIGURE 8. EFFICIENCY vs LOAD, PFM, VOUT = 5V, L1 = 30µH
100
100
VIN = 5V
95
EFFICIENCY (%)
VIN = 15V
75
70
VIN = 24V
65
VIN = 33V
85
80
65
60
55
0.2
0.3
0.4 0.5 0.6 0.7
OUTPUT LOAD (A)
0.8
0.9
FIGURE 10. EFFICIENCY vs LOAD, PFM, VOUT = 3.3V
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1.0
VIN = 33V
70
55
0.1
VIN = 15V
75
60
0
VIN = 5V
90
85
80
VIN = 12V
95
VIN = 12V
90
EFFICIENCY (%)
VIN = 6V
VIN = 24V
OUTPUT LOAD (A)
50
1.0
65
55
0.2
0.9
70
60
0.1
0.8
75
55
0
0.4 0.5 0.6 0.7
OUTPUT LOAD (A)
VIN = 12V
80
60
50
0.3
95
VIN = 6V
90
80
0.2
FIGURE 7. EFFICIENCY vs LOAD, PWM, VOUT = 12V
EFFICIENCY (%)
EFFICIENCY (%)
95
0.1
100
VIN = 12V
VIN = 15V
80
60
50
VIN = 24V
85
50
VIN = 24V
0
0.1
0.2
0.3
0.4 0.5 0.6 0.7
OUTPUT LOAD (A)
0.8
0.9
1.0
FIGURE 11. EFFICIENCY vs LOAD, PWM, VOUT = 3.3V
AN1908.2
March 13, 2015
Application Note 1908
ISL85410 Efficiency Curves
fSW = 500kHz, TA = +25°C (Continued)
100
100
95
VIN = 5V
90
85
EFFICIENCY (%)
EFFICIENCY (%)
90
80
VIN = 15V
75
70
VIN = 33V
65
VIN = 24V
60
VIN = 12V
95
VIN = 12V
VIN = 5V
85
80
75
70
VIN = 15V
65
60
VIN = 24V
55
55
50
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
50
1.0
0
0.1
0.2
0.3
5.004
0.6
0.7
0.8
0.9
1.0
5.030
5.003
5.025
VIN = 6V
VIN = 12V
5.001
OUTPUT VOLTAGE (V)
5.002
OUTPUT VOLTAGE (V)
0.5
FIGURE 13. EFFICIENCY vs LOAD, PWM, VOUT = 1.8V
FIGURE 12. EFFICIENCY vs LOAD, PFM, VOUT = 1.8V
5.000
4.999
4.998
4.997
VIN = 15V
4.996
VIN = 24V
4.995
4.993
0
0.1
0.2
0.3
VIN = 6V
5.020
VIN = 12V
5.015
5.010
5.005
VIN = 15V
5.000
4.995
4.994
0.4 0.5 0.6 0.7
OUTPUT LOAD (A)
0.8
0.9
4.990
1.0
VIN = 24V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
OUTPUT LOAD (A)
FIGURE 14. EFFICIENCY vs LOAD, PWM, VOUT = 5V, L1 = 30µH
FIGURE 15. VOUT REGULATION vs LOAD, PFM, VOUT = 5V, L1 = 30µH
3.345
3.326
VIN = 5V
VIN = 5V
3.325
3.340
3.324
OUTPUT VOLTAGE (V)
VIN = 12V
3.323
3.322
3.321
VIN = 15V
3.320
3.319
VIN = 24V
3.318
3.317
3.316
0.4
OUTPUT LOAD (A)
OUTPUT LOAD (A)
OUTPUT VOLTAGE (V)
VIN = 33V
VIN = 12V
3.335
3.330
VIN = 33V
3.320
VIN = 33V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
OUTPUT LOAD (A)
FIGURE 16. VOUT REGULATION vs LOAD, PWM, VOUT = 3.3V
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VIN = 15V
3.325
1.0
3.315
VIN = 24V
0
0.1
0.2
0.3
0.4 0.5 0.6 0.7
OUTPUT LOAD (A)
0.8
0.9
1.0
FIGURE 17. VOUT REGULATION vs LOAD, PFM, VOUT = 3.3V
AN1908.2
March 13, 2015
Application Note 1908
ISL85410 Efficiency Curves
1.810
1.816
OUTPUT VOLTAGE (V)
VIN = 12V
1.808
OUTPUT VOLTAGE (V)
1.818
VIN = 5V
VIN = 15V
1.809
fSW = 500kHz, TA = +25°C (Continued)
1.807
1.806
1.805
1.804
VIN = 33V
1.803
VIN = 24V
1.802
1.812
VIN = 12V
1.810
VIN = 15V
1.808
1.806
1.804
VIN = 33V
1.802
1.801
1.800
VIN = 5V
1.814
0
0.1
0.2
0.3
0.4 0.5 0.6 0.7
OUTPUT LOAD (A)
0.8
0.9
1.0
FIGURE 18. VOUT REGULATION vs LOAD, PWM, VOUT = 1.8V
ISL85410 Typical Performance Curves
1.800
0
0.1
0.2
0.3
VIN = 24V
0.4 0.5 0.6 0.7
OUTPUT LOAD (A)
0.8
0.9
1.0
FIGURE 19. VOUT REGULATION vs LOAD, PFM, VOUT = 1.8V
fSW = 500kHz, VIN = 24V, VOUT = 3.3V, TA = +25°C
LX 20V/DIV
LX 20V/DIV
VOUT 2V/DIV
VOUT 2V/DIV
IL 500mA/DIV
EN 20V/DIV
PG 2V/DIV
PG 2V/DIV
5ms/DIV
5ms/DIV
FIGURE 20. START-UP AT NO LOAD, PFM
FIGURE 21. START-UP AT 1A, PWM
LX 20V/DIV
LX 5V/DIV
VOUT 2V/DIV
IL 500mA/DIV
PG 2V/DIV
200µs/DIV
5ns/DIV
FIGURE 22. SHUTDOWN AT 1A, PWM
FIGURE 23. JITTER AT 1A LOAD, PWM
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Application Note 1908
ISL85410 Typical Performance Curves
fSW = 500kHz, VIN = 24V, VOUT = 3.3V, TA = +25°C (Continued)
LX 20V/DIV
LX 20V/DIV
VOUT 20mV/DIV
VOUT 20mV/DIV
IL 20mA/DIV
IL 20mA/DIV
10ms/DIV
1µs/DIV
FIGURE 24. STEADY STATE AT NO LOAD, PFM
FIGURE 25. STEADY STATE AT NO LOAD, PWM
LX 20V/DIV
LX 20V/DIV
VOUT 20mV/DIV
VOUT 50mV/DIV
IL 1A/DIV
IL 200mA/DIV
1µs/DIV
10µs/DIV
FIGURE 26. STEADY STATE AT 1A, PWM
FIGURE 27. LIGHT LOAD OPERATION AT 20mA, PFM
VOUT 100mV/DIV
VOUT 100mV/DIV
IL 1A/DIV
IL 1A/DIV
200µs/DIV
200µs/DIV
FIGURE 28. LOAD TRANSIENT, PFM
FIGURE 29. LOAD TRANSIENT, PWM
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Application Note 1908
ISL85410 Typical Performance Curves
fSW = 500kHz, VIN = 24V, VOUT = 3.3V, TA = +25°C (Continued)
LX 20V/DIV
VOUT 20mV/DIV
IL 1A/DIV
10µs/DIV
FIGURE 30. PFM TO PWM TRANSITION
LX 20V/DIV
LX 20V/DIV
VOUT 2V/DIV
VOUT 2V/DIV
IL 1A/DIV
IL 1A/DIV
PG 2V/DIV
PG 2V/DIV
10ms/DIV
50µs/DIV
FIGURE 31. OVERCURRENT PROTECTION, PWM
FIGURE 32. OVERCURRENT PROTECTION HICCUP, PWM
LX 20V/DIV
LX 20V/DIV
VOUT 5V/DIV
SYNC 2V/DIV
IL 1A/DIV
PG 2V/DIV
200ns/DIV
20µs/DIV
FIGURE 33. SYNC AT 1A LOAD, PWM
FIGURE 34. NEGATIVE CURRENT LIMIT, PWM
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Application Note 1908
ISL85410 Typical Performance Curves
fSW = 500kHz, VIN = 24V, VOUT = 3.3V, TA = +25°C (Continued)
LX 20V/DIV
VOUT 5V/DIV
VOUT 2V/DIV
IL 500mA/DIV
PG 2V/DIV
PG 2V/DIV
200µs/DIV
FIGURE 35. NEGATIVE CURRENT LIMIT RECOVERY, PWM
500µs/DIV
FIGURE 36. OVER-TEMPERATURE PROTECTION, PWM
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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