an1327

ISL6455EVAL1Z: 600mA Synchronous Buck
Regulator with Integrated MOSFETs
®
Application Note
The ISL6455 is a highly integrated triple output regulator
which provides a single chip solution for FPGAs and wireless
chipset power management. The device integrates a high
efficiency synchronous buck regulator (adjustable) with two
ultra low noise LDO regulators (adjustable). Either the
ISL6455 or ISL6455A can be selected based on whether
3.3V ±10% or 5V ±10% is required as an input voltage.
The synchronous current mode control PWM regulator with
integrated N-Channel and P-Channel power MOSFET
provides adjustable voltages based on external resistor
setting. Synchronous rectification with internal MOSFETs is
used to achieve higher efficiency and reduced number of
external components. Operating frequency is typically
750kHz allowing the use of smaller inductor and capacitor
values. The device can be synchronized to an external clock
signal in the range of 500kHz to 1MHz. The PG_PWM
output indicates loss of regulation on PWM output.
The ISL6455 also has two LDO adjustable regulators using
internal PMOS transistors as pass devices. LDO2 features
ultra low noise typically below 30µVRMS to aid VCO stability.
The EN_LDO pin controls LDO1 and LDO2 outputs. The
ISL6455 also integrates a RESET function, which eliminates
the need for additional RESET IC required in WLAN and
other applications. The IC asserts a RESET signal whenever
the VIN supply voltage drops below a preset threshold,
keeping it asserted for at least 25ms after VIN has risen
above the reset threshold. The PG_LDO output indicates
loss of regulation on either of the two LDO outputs. Other
features include overcurrent protection and thermal
shutdown for all the three outputs.
May 23, 2007
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Features
• Fully integrated synchronous buck regulator + dual LDO
• PWM output voltage adjustable.
- 0.8V to 2.5V with ISL6455 (VIN = 3.3V)
- 0.8V to 3.3V with ISL6455A (VIN = 5.0V)
• High output current. . . . . . . . . . . . . . . . . . . . . . . . . 600mA
• Dual LDO adjustable options
- LDO1, 1.2V to VIN - 0.3V (3.3VMAX) . . . . . . . . . 300mA
- LDO2, 1.2V to VIN - 0.3V (3.3VMAX) . . . . . . . . . 300mA
• Ultra-compact DC/DC converter design
• Stable with small ceramic output capacitors and no load
• High conversion efficiency
• Low shutdown supply current
• Low dropout voltage for LDOs
- LDO1 . . . . . . . . . . . . . . . . . . 150mV (typical) at 300mA
- LDO2 . . . . . . . . . . . . . . . . . . 150mV (typical) at 300mA
• Low output voltage noise
- <30µVRMS (typical) for LDO2 (VCO supply)
• PG_LDO and PG_PWM (PWM and LDO) outputs
• Extensive circuit protection and monitoring features
- PWM overvoltage protection
- Overcurrent protection
- Shutdown
- Thermal shutdown
• Integrated RESET output for microprocessor reset
• Proven reference design for total WLAN system solution
High integration and the thin Quad Flat No-lead (QFN)
package makes ISL6455 an ideal choice for powering
FPGAs and small form factor wireless cards such as
PCMCIA, mini-PCI and Cardbus-32.
Ordering Information
PART
NUMBER*
(Note)
ISL6455IRZ
• QFN package
- Compliant to JEDEC PUB95 MO-220 QFN - Quad Flat
No Leads - Product Outline
- Near Chip-Scale package footprint Improves PCB
efficiency and is thinner in Profile
• Pb-free plus anneal available (RoHS compliant)
PART
TEMP.
MARKING RANGE (°C)
64 55IRZ
ISL6455AIRZ 64 55AIRZ
PACKAGE
(Pb-Free)
PKG.
DWG. #
-40 to +85
24 Ld QFN 4x4 L24.4x4B
-40 to +85
24 Ld QFN 4x4 L24.4x4B
*Add “-TK” or T5K suffix for tape and reel.
NOTE: Intersil Pb-free plus anneal products employ special Pb-free
material sets; molding compounds/die attach materials and 100%
matte tin plate termination finish, which are RoHS compliant and
compatible with both SnPb and Pb-free soldering operations. Intersil
Pb-free products are MSL classified at Pb-free peak reflow
temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020.
Applications
• WLAN cards
- PCMCIA, Cardbus32, MiniPCI cards
- Compact flash cards
• Hand-held instruments
Related Literature
• TB363 - Guidelines for Handling and Processing Moisture
Sensitive Surface Mount Devices (SMDs)
• TB389 - PCB Land Pattern Design and Surface Mount
Guidelines for QFN Packages
1
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. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
Application Note 1327
Pinout
SGND
EN_LDO
PG_LDO
VIN
PVCC
LX
PGND
ISL6455, ISL6455A
(24 LD QFN)
TOP VIEW
24
23
22
21
20
19
18 GND
1
FB_LDO2 2
2
17 CT
GND_LDO
5
14 EN
VOUT1
6
13 SYNC
7
8
9
10
11
12
PG_PWM
15
FB_PWM
4
CC2
CC1
VOUT2
16 VOUT
VIN_LDO
3
VIN_LDO
FB_LDO1
RESET
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May 23, 2007
Application Note 1327
What’s Inside
Evaluating the Other Output Voltage
The Evaluation Board Kit contains the following materials:
The ISL6455 EVAL kit outputs are preset to VOUT = 2.5V;
VOUT1 = 1.8V, and VOUT2 = 1.2V. The ISL6455A EVAL kit
outputs are preset to VOUT = 3.3V; VOUT1 = 2.5V and
VOUT2 = 1.2V. Output voltages can be adjusted from 0.8V to
2.5V with ISL6455 (VIN = 3.3V), and from 0.8V to 3.3V with
ISL6455A (VIN = 5V) using the following equations:
• The ISL6455 EVAL REVD board
• The ISL6455 datasheet
• This EVAL KIT document
Recommended Equipment
The following materials are recommended to perform
testing:
• 0V to 15V power supply with at least 5A source current
capability, battery, notebook AC adapter
• Two Electronic Loads capable of sinking current up to 5A
0.45
V OUT = ----------- ( R 1 + R 2 )
R2
(EQ. 1)
1.184
V OUT1 = --------------- ( R 5 + R 6 )
R6
(EQ. 2)
1.184
V OUT2 = --------------- ( R 3 + R 4 )
R4
(EQ. 3)
• Digital Multimeters (DMMs)
• 100MHz quad-trace Oscilloscope
• Signal generator
Quick Setup Guide
Frequency
The ISL6455EVAL1Z and ISL6455AEVAL1Z can operate at
a switching frequency of 750kHZ, however, the switching
frequency can adjust from 500kHz to1MHz by using the sync
pin (P9).
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
J1(VIN) and the negative return to J2(GND).
3. Turn on the power supply. For the ISL6455, the input
voltage should be 3.3V. For the ISL6455A, the input
voltage should be 5V.
TABLE 1. SWITCH 1 SETTINGS
J1
VIN_LDO
1
Center post to right Connect VIN_LDO to VOUT
2
Center post to left
Connect VIN_LDO to P13
4. Verify the outputs voltages for ISL6455 are 2.5V for
VOUT, 1.8V for VOUT1, and 1.2V for VOUT2.
5. Verify the ouputs voltages for ISL6455A are 3.3V for
VOUT, 2.5V for VOUT1, and 1.2V for VOUT2.
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Schematic
+0.450V
R2
2.37K
R1
SEE
TABLE
VIN
SP1
P1
H1
600MA
L1B
C10
10UF
C11
0.1UF
DNP
R9
0
C8
P2
4
GND
C9
1UF
L1A
0.1UF
P3
VOUT
200MA
P4
GND
SEE
TABLE
R12
10K
C7
10UF
R8
10K
OUT
VOUT
SP2
1 22 21 20 19 18
SGND
VIN
PVCC
LX
PGND
GND
E
P8
11
12
13
14
P9
SYNC
23
C2
0.033UF
EN
PG_LDO
R7
25
EP
10K
E
VOUT
EN_LDO
U1
ISL6455/A
VOUT2
GND_LDO
VOUT1
FB_LDO1
15 17
7
8 10
E
24
P5
9
5
3
SP3
C3
10UF
2
E
C13
0.1UF
P7
LGND
P6
VOUT1
200MA
P11
LGND
E
E
E
E
P10
RESET
VOUT
VOUT2
200MA
C4
10UF
6
P12
PG_LDO
E
16
Application Note 1327
4
FB_PWM
PG_PWM
SYNC
CC1
C12
0.1UF
RESET
CT
VIN_LDO
VIN_LDO
CC2
FB_LDO2
PG_PWM
R10
0
IN
H2
R5
JP1
SEE
TABLE
+1.184V
P13
VIN_LDO
C1
0.01UF
C5
4.7UF
C6
0.033UF
E
R6
SEE
TABLE
E
E
E
+1.184V
U1
ISL6455/A
VIN
VOUT
VOUT1
+3.3V
+2.5V
+1.8V
VOUT2
+1.2V
L1A
R1
R5
8.2UH
11K
2.94K
R6
5.62K
R3
R11
80.6
0
E
R4
5.9K
H3
E
DRAWN BY:
TIM KLEMANN
RELEASED
UPDATED
BY:
BY:
DATE:
08/09/2006
DATE:
ENGINEER:
THEJU BERNARD
TITLE:
DATE:
ISL6455 - ISL6455A
EVALUATION BOARD
SCHEMATIC DRAWING
DATE:
TESTER
AN1327.0
May 23, 2007
MASK#
HRDWR ID
REV.
ISL6455_55AEVAL1Z
8
7
6
5
4
3
FILENAME:
ISL6455_55A/ISL6455_55AEVAL1ZA
2
SHEET
1
1
OF
Application Note 1327
TABLE 2. COMPONENT LIST ISL6455EVAL1Z, ISL6455AEVAL1Z
REF DES
QTY
VALUE
TOL.
VOLTAGE
PACKAGE
PART NUMBER
C1
1
0.01µF
10%
25V
0603
06032R103K8B20
PHILLIPS
CAP, SMD, 0603, 0.01µF,
25V, 10%, X7R, ROHS
C8,
C11-C13
4
0.1µF
10%
16V
0603
GRM39X7R104K016AD
MURATA
CAP, SMD, 0603, 0.1µF, 16V,
10%, X7R, ROHS
C9
1
1µF
20%
16V
0603
C2, C6
2
33000pF
10%
16V
0603
C0603X7R160-333KNE
VENKEL
CAP, SMD, 0603, 33000pF,
16V, 10%, X7R, ROHS
C3, C4, C7
3
10µF
10%
6.3V
0805
C0805X5R6R3-106KNE
VENKEL
CAP, SMD, 0805, 10µF, 6.3V,
10%, X5R, ROHS
C5
1
4.7V
10%
10V
0805
0805ZD475KAT2
AVX
CAP, SMD, 0805, 4.7µF, 10V,
10%, X5R, ROHS
C10
1
10µf
10%
10V
1206
C1206X7R100-106KNE
VENKEL
CAP, SMD, 1206, 10µF, 10V,
10%, X7R, ROHS
L1A
1
8.2µH
20%
6mmx6mm
MSS6122-822ML
COILCRAFT
COIL-PWR INDUCTOR,
SMD, 6.1mm, 8.2µH, 20%,
1.25A, SHIELDED, ROHS
U1
1
3.3V to 5.5V
4x4
ISL6455IRZ
ISL6455A EVAL1ZA use
ISL6455AIRZ
INTERSIL
IC-3.3V TRIPLE OUTPUT
REGULATOR, 24P, QFN,
4x4, ROHS
R9-R11
3
0Ω
100V
0603
ERJ-3GEY0R00V
PANASONIC
RES, SMD, 0603, 0Ω, 1/16W,
TF, ROHS
R7, R8, R12
3
10k
1%
100V
0603
ERJ-3EKF1002V
PANASONIC
RES, SMD, 0603, 10k,
1/16W, 1%, TF, ROHS
R1
1
11k
1%
100V
0603
CR0603-10W-1102FT
YAGEO
RESISTOR, SMD, 0603,
11K, 1/10W, 1%, TF, ROHS
R2
1
2.37k
1%
100V
0603
ERJ-3EKF2371V
PANASONIC
RES, SMD, 0603, 2.37k,
1/10W, 1%, TF, ROHS
R5
1
2.94k
1%
100V
0603
ERJ-3EKF2941V
PANASONIC
RES, SMD, 0603, 2.94k,
1/10W, 1%, TF, ROHS
R6
1
5.62k
1%
100V
0603
ERJ-3EKF5621V
PANASONIC
RES, SMD, 0603, 5.62k,
1/16W, 1%, TF, ROHS
R4
1
5.9k
1%
100V
0603
ERJ-3EKF5901V
PANASONIC
RES, SMD, 0603, 5.90k,
1/10W, 1%, TF, ROHS
R3
1
80.6Ω
1%
100V
0603
ERJ-3EKF80R6
PANASONIC
RES, SMD, 0603, 80.6Ω,
1/10W, 1%, TF, ROHS
5
MANUFACTURER
GRM188R61C105KA12D MURATA
DESCRIPTION
CAP, SMD, 0603, 1µF, 16V,
20%, Y5V, ROHS
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May 23, 2007
Application Note 1327
ISL6455AEVAL1Z Board Layout
FIGURE 1. TOP COMPONENTS
FIGURE 2. TOP LAYER ETCH
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Application Note 1327
ISL6455AEVAL1Z Board Layout
(Continued)
FIGURE 3. 2ND LAYER ETCH
FIGURE 4. 3RD LAYER ETCH
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Application Note 1327
ISL6455AEVAL1Z 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
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