an1323

ISL8540EVAL1Z: 2A High Voltage Buck Regulator
with Integrated MOSFETs
®
Application Note
The ISL8540 is a step down DC/DC power switching
regulator which accepts a 9V to 40V input, and provides up
to 2A of output current. The output voltage can be set
between 1.21V and 35V by means of an external resistor
divider. The device uses an internal power DMOS transistor
with a typical rDS(ON) of 0.19Ω to obtain very high efficiency
and high switching speed. A switching frequency in the
range of 100kHz to 600kHz can be realized (the maximum
power dissipation of the various packages must be
observed). Notable features of this next generation DC/DC
converter include pulse-by-pulse current limit for FET
protection, hiccup-mode short circuit protection, voltage
feedforward, frequency SYNC, soft-start, low standby
current of 60µA typical in the disabled state and thermal
shut-down. The device is available in a 20 Ld HTSSOP
package.
February 13, 2008
AN1323.1
Features
• Voltage feedforward
• Step down DC/DC supporting up to 2A
• Input voltage range of 9V to 40V
• Internal reference of 1.21V ±1%
• Adjustable output voltage range of 1.21V to 35V
• Adjustable switching frequency 100kHz to 600kHz
• Frequency SYNC pin
• Zero load current operation
• Pulse-by-pulse mode current limit
• Hiccup mode short-circuit protection
• Low standby current of 60µA typical
Ordering Information
PART
NUMBER
(Note)
ISL8540IVEZ
PART
MARKING
• Thermal shut-down
TEMP.
RANGE
(°C)
PACKAGE
(Pb-free)
PKG.
DWG. #
ISL85 40IVEZ -40 to +85 20 Ld HTSSOP MDP0048
• Transient survival up at 60V for 400ms
• Pb-free (RoHS compliant)
Applications
ISL8540IVEZ-T* ISL85 40IVEZ -40 to +85 20 Ld HTSSOP MDP0048
• Industrial and automotive power supplies
ISL8540EVAL1Z Evaluation Board
• Portable computers
*Please refer to TB347 for details on reel specifications.
NOTE: These Intersil Pb-free plastic packaged products employ
special Pb-free material sets; molding compounds/die attach materials
and 100% matte tin plate PLUS ANNEAL - e3 termination finish, which
is RoHS compliant and compatible with both SnPb and Pb-free
soldering operations. Intersil Pb-free products are MSL classified at Pbfree peak reflow temperatures that meet or exceed the Pb-free
requirements of IPC/JEDEC J STD-020.
• Battery chargers
• Distributed power systems
Related Literature
• Technical Brief TB363 “Guidelines for Handling and
Processing Moisture Sensitive Surface Mount Devices
(SMDs)”
Pinouts
ISL8540
(20 LD HTSSOP)
TOP VIEW
VIN 1
19 VIN
LX 3
18 LX
LX 4
17 LX
BOOT 5
16 SS
EN 6
15 PGND
VCC5 7
14 PGOOD
SYNC 8
13 REF
RTCT 9
12 COMP
SGND 10
1
20 VIN
VIN 2
11 FB
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2007, 2008. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
Application Note 1323
What’s Inside
Evaluating the Other Output Voltage
The Evaluation Board Kit contains the following materials:
The ISL8540EVAL1Z kit output is preset to 5V. The output
voltage can be adjusted from 1.21V to 35V by Equation 1:
• The ISL8540EVAL1Z REVB board.
R 1 = ( R 2 ) ⁄ ( ( V OUT ⁄ V FB1 ) – 1 )
• The ISL8540 datasheet.
• ISL8540 Evaluation Board Application Note.
Recommended Equipment
The following equipment is recommended to evaluate the
performance of the board:
• 0V to 60V power supply with at least 5A current sourcing
capability.
• Electronic Loads capable of sinking current up to 5A.
• Digital Multimeters (DMMs.)
• 100MHz quad-trace Oscilloscope.
• Signal generator (to test the SYNC feature only).
Quick Setup Guide
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, with the positive terminal
connected to P1(VIN), and the return to P2(GND).
3. Connect the load across the output terminals, between
pins P3 (positive) and P4 (return).
4. Verify that the jumper JP1 is connected.
5. Apply a voltage between 9V and 40V across the input.
with R2 = 51.1kΩ and VFB1 = 1.21V.
Note: The inductor, output capacitors and the compensation
network may need to be tweaked, along with the
corresponding compensation network, for optimal
performance with change in output voltage and/or load. Also,
additional heatsinking or airflow may required to insure that
the junction temperature does not exceed +125°C.
Frequency
The ISL8540EVAL1Z kit is preset at 500kHz. The
ISL8540EVAL1Z can be adjusted to operate at switching
frequencies from 100kHz to 600kHz. Use C16 to program
the switching frequency using Equation 2:
6.25
1000
C 16 [ nF ] = -------------------- ⎛ ------------------------------ – 0.3⎞
⎠
R 7 [ kΩ ] ⎝ f OSC [ kHz ]
(EQ. 2)
Synchronization
The ISL8540EVAL1Z circuit may be synchronized to a TTL
signal that is set at a higher switching frequency than the
pre-set frequency. The range of the external synchronizing
frequency is from 100kHz to 600kHz. It is recommended to
use and RTCT capacitor (C16) of 2700pF in this
configuration.
6. Verify that the output voltage is 5V.
TABLE 1. SWITCH 1 SETTINGS
JP1
2
(EQ. 1)
ENABLE
OPERATING MODE
1
OPEN
Unit Disabled
2
GND
Unit Enabled
AN1323.1
February 13, 2008
Schematic
3
Application Note 1323
AN1323.1
February 13, 2008
Application Note 1323
TABLE 2. COMPONENT LIST
REF DES QTY VALUE TOL. VOLTAGE
C5, C10, C11 3
0.10µF 10%
50V
PACKAGE
0603
PART NUMBER
C1608X7R1H104K-T
C12-C14
3
150µF
20%
25V
8mmx10mm
EEE-FK1E151P-T
C1-C3
3
47µF
20
100V
12.5mmx13.5mm
EEV-FK2A470Q-T
C7, C9
2
100pF
5%
50V
0603
H1045-00101-50V5-T
C15
1
0.01µF 10%
50V
0603
H1045-00103-50V10-T
C18
1
1µF
10%
16V
0603
H1045-00105-16V10-T
C19
1
390pF
5%
50V
0603
H1045-00391-50V5-T
C8, C17
0
OPEN
-
-
-
H1045-DNP
C6
1
1.0µF
10%
25V
0805
H1046-00105-25V10-T
C4
1
0.1µF
10%
100V
1206
H1065-00104-100V10-T
C16
1
470pF
5%
100V
1206
H1065-00471-100V5-T
L1
1
22µH
20%
-
18mmx15mm
DO5010H-223MLB
JP1
1
0Ω
-
-
Header
SPC02SYAN
D1
1
5A
100V
Power DI-5
PDS5100H
U1
1
2A
-
40V
20 HTSSOP
ISL8540IEVZ
R9
1
20Ω
1%
100V
0603
H2511-0200-1/10W1-T
R5, R6, R8
3
10k
1%
100V
0603
H2511-1002-1/16W1-T
R1
1
16.2k
1%
100V
0603
H2511-1622-1/16W1-T
R4
1
301k
1%
100V
0603
H2511-3013-1/10W1-T
R2
1
51.1k
1%
100V
0603
H2511-05112-1/16W1-T
R3
1
5.62k
1%
100V
0603
H2511-5621-1/16W1-T
R7
1
20k
1%
100V
0603
H2513-02002-1/4W1-T
R10
1
0Ω
1%
100V
0603
H2515-00R00-1W-T
4
MANUFACTURER
DESCRIPTION
TDK
CAPACITOR, SMD, 0603,
0.10µF, 50V, 10%, X7R
PANASONIC
CAP, SMD,1 0.3mm, 150µF,
25V, 20%, ROHS, ALUM.
ELEC.
PANASONIC
CAPACITOR, SMD, H13, 47µF,
100V, 20%, ROHS, ALUM.
ELEC.
CAPACITOR, SMD, 0603,
AVX, Samsung,
100pF, 50V, 5%, NPO, ROHS
TDK, Murata,
Vishay
CAPACITOR, SMD, 0603,
AVX, Samsung,
0.01µF, 50V, 10%, X7R, ROHS
TDK, Murata,
Vishay
CAPACITOR, SMD, 0603, 1µF,
AVX, Samsung,
16V, 10%, X7R, ROHS
TDK, Murata,
Vishay
CAPACITOR, SMD, 0603,
AVX, Samsung,
390pF, 50V, 5%, NPO, ROHS
TDK, Murata,
Vishay
CAPACITOR, SMD, 0603,
AVX, Samsung,
DNP-PLACE HOLDER, ROHS
TDK, Murata,
Vishay
CAPACITOR, SMD, 0805,
AVX, Samsung,
1.0µF, 25V, 10%, X7R, ROHS
TDK, Murata,
Vishay
CAPACITOR, SMD, 1206,
AVX, Samsung,
0.1µF, 100V, 10%, X7R, ROHS
TDK, Murata,
Vishay
CAPACITOR, SMD, 1206,
AVX, Samsung,
470pF, 100V, 5%, NPO, ROHS
TDK, Murata,
Vishay
COILCRAFT
COIL-PWR INDUCTOR, SMD,
18x15, 22µH, 20%, 7A, ROHS,
47mΩ
SULLINS
CONN-JUMPER, 2 PIN,
SHUNT, ROHS
DIODES INC.
DIODE-RECTIFIER, SMD,
Power DI-5, 100V, 5A, ROHS,
SCHOTTKY
INTERSIL
IC-STEP DOWN DC/DC
CONVERTER, 20P, HTSSOP,
ROHS
PANASONIC
RESISTOR, SMD, 0603, 20Ω,
1/10W, 1%, TF, ROHS
PANASONIC
RESISTOR, SMD, 0603, 10k,
1/16W, 1%, TF, ROHS
PANASONIC
RESISTOR, SMD, 0603, 16.2k,
1/16W, 1%, TF, ROHS
YAGEO
RESISTOR, SMD, 0603, 301k,
1/10W, 1%, TF, ROHS
PANASONIC
RESISTOR, SMD, 0603, 51.1k,
1/16W, 1%, TF, ROHS
PANASONIC
RESISTOR, SMD, 0603, 5.62k,
1/16W, 1%, TF, ROHS
PANASONIC
RESISTOR, SMD, 1206,
20k,1/4W, 1%, TF, ROHS
VENKEL
RESISTOR, SMD, 2512, 0Ω,
1W, TF, ROHS
AN1323.1
February 13, 2008
Application Note 1323
ISL8540EVAL1Z Board Layout
ISL8540EVAL1Z Rev. B
FIGURE 1. TOP COMPONENTS
FIGURE 2. TOP LAYER ETCH
5
AN1323.1
February 13, 2008
Application Note 1323
ISL8540EVAL1Z Board Layout
(Continued)
FIGURE 3. 2ND LAYER ETCH
FIGURE 4. 3RD LAYER ETCH
6
AN1323.1
February 13, 2008
Application Note 1323
ISL8540EVAL1Z Board Layout
(Continued)
FIGURE 5. BOTTOM LAYER COMPONENTS (MIRRORED)
FIGURE 6. BOTTOM LAYER ETCH (MIRRORED)
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
7
AN1323.1
February 13, 2008
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