an1326

ISL8501EVAL1Z
1A Buck Regulator with Integrated MOSFETs
®
Application Note
The ISL8501 is a high-performance, triple output controller
that provides a single, high frequency power solution for a
variety of point of load applications. The ISL8501 integrates
a 1A standard buck PWM controller and switching MOSFET
with two 500mA LDOs.
The PWM controller in the ISL8501 drives an internal
switching N-Channel power MOSFET and requires an
external Schottky diode to generate an output voltage from
0.6V to 20V. The integrated power switch is optimized for
excellent thermal performance up to 1A of output current.
The standard buck input voltage range supports a fixed 5V
or variable 6V to 25V range. The PWM regulator switches at
a fixed frequency of 500kHz and utilizes simple voltage
mode control with input voltage feed forward to provide
flexibility in component selection and minimize solution size.
Protection features include overcurrent, undervoltage, and
thermal overload protection integrated into the IC. The
ISL8501 power good signal output indicates loss of
regulation on the PWM output.
The ISL8501 features two adjustable LDO regulators using
internal PMOS transistors as pass devices. Separate enable
pins (EN_LDO1, EN_LDO2) control each LDO output. A
single power good signal output indicates loss of regulation
on either of the two LDO outputs. Independent overcurrent
and thermal fault shutdown monitors are integrated into the
LDO section.
July 10, 2007
AN1326.0
Features
• Standard Buck Controller with Integrated Switching Power
MOSFET + Dual LDOs
• Integrated Boot Diode
• Input Voltage Range
- Fixed 5V ±10%
- Variable 6V to 25V
• PWM Output Voltage Adjustable from 0.6V to 20V with
Continuous Output Current up to 1A
• Voltage Mode Control with Voltage Feed Forward
• Fixed 500kHz Switching Frequency
• Externally Adjustable Soft-Start Time
• Output Undervoltage Protection
• Dual LDO Adjustable Options
- LDO1, 0.6V to 4.2V . . . . . . . . . . . . . . . . . . . . . . 500mA
- LDO2, 0.6V to 4.2V . . . . . . . . . . . . . . . . . . . . . . 500mA
• Individual Enable Inputs
• Two PGOOD Outputs (PWM and both LDOs)
• Overcurrent Protection
• Thermal Overload Protection
• Internal 5V LDO regulator
Applications
ISL8501 is available in a small 4mmx4mm thin Quad Flat
No-Lead (QFN) package.
• General Purpose
Ordering Information
• WLAN Cards-PCMCIA, Cardbus32, MiniPCI CardsCompact Flash Cards
• Hand-Held Instruments
1
EN
24
23
22
21
20
19
FB_LDO1
1
18 VIN
VOUT1
2
17 VIN
VIN_LDO1
3
VIN_LDO2
4
VOUT2
5
14 BOOT
FB_LDO2
6
13 PVCC
16 PHASE
25
GND
7
8
9
10
11
12
EN_LDO2
GND
VCC
15 PHASE
EN_LDO1
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.
SS
*Add “-T” suffix for tape and reel
COMP
-40 to +85 24 Ld QFN 4x4 L24.4x4D
(2.7 Sq. mm Pad)
FB_PWM
Pinout
PG_PWM
PACKAGE
PKG.
DWG. #
PG_LDO
ISL8501IRZ* 85 01IRZ
TEMP.
RANGE
(°C)
CC1
PART
MARKING
CC2
PART
NUMBER
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 1326
What’s Inside
Evaluating the Other Output Voltage
The Evaluation Board Kit contains the following materials:
The ISL8501EVAL kit outputs are preset to 3.3V, 1.2V, 1.8V;
however, all of them can be programmed using resistor
dividers using Equation 1:
• The ISL8501 EVAL REV D board
R 1 ⋅ 0.6V
R 2 = ---------------------------------V OUT – 0.6V
• The ISL8501 datasheet
• This EVAL KIT document
Recommended Equipment
The following materials are recommended to perform
testing:
(EQ. 1)
The output voltage programming resistor R2 will depend on
on the feedback resistor R1, as referred to in Figure 1. The
value of R1 is typically between 1kΩ and 10kΩ. If the output
voltage desired is 0.6V, then R2 is left opened.
• 0V to 25V power supply with at least 5A source current
capability, battery, notebook AC adapter
VOUT
R1
• Three electronic loads capable of sinking current up to 5A
+
-
• Digital Multimeters (DMMs)
EA
• 100MHz quad-trace oscilloscope
• Signal generator
R2
0.6V
REFERENCE
Quick Setup Guide
1. Ensure that the circuit is correctly connected to the supply
and loads prior to applying any power.
FIGURE 1. EXTERNAL RESISTOR DIVIDER
2. Connect the bias supply to VIN, the plus terminal to TP1
(VCC) and the negative return to TP6 (GND).
TABLE 1. SWITCH 1 SETTINGS
3. Verify that SW1 is on ENABLE.
SW1
ENABLE
OPERATING MODE
1
SW1
Enable or disable the buck controller
2
SW2
Enable or disable LDO1
3
SW3
Enable or disable LDO2
4. Turn on the power supply.
5. Verify the PG_PWM LED is on and that the output voltage
is 3.3V for VOUT1 (TP3).
6. Turn on SW2 and SW3 to ENABLE. If VLDO1 is
connected to a separate power supply, remove R25 from
the bottom first, then turn on SW2 and SW3.
7. Verify the PG_LDO LED is on and LDO output voltages
are 1.2V for VOUT2 (TP7) and 1.8V for VOUT3 (TP8).
2
AN1326.0
July 10, 2007
Schematic
VCC
R29
R4
0
20K
10K
1
0.01UF
C2
R3
10PF
2
PG_PWM
GND
2.55K
TP10
R8
R27
OPEN
TP3
1
1
1
SP1
2
3
4
5
0.1UF
C21
C9
BOOT
VOUT1
1
10UH
10UF
13
PHASE
100UF
14
PVCC
4
100UH
L2
2 C13 1
BOOT
ISL8501
2
2 C12 1
15
0
OPEN
L1
1
PHASE
16
TP11
17
C14
R26
1
10UF
D2
1
18
VIN
PHASE
C8
EP
2
OPEN
R25
2
FB_LDO2
3
D1
VOUT2
6
C20
10UF
2
4.7UF
C11
2 C10 1
U1
VIN_LDO2
5
25
1
R9
Q1
TP14
EN_PWM
2
1
TP4
COMBINE INDUCTOR FOOTPRINTS
R5
10
VIN
R30
OPEN
POPULATE R30 IF VIN <6V ONLY
VCC
1
TP12
1UF
1
VCC
3
1
2
TP15
R16
C18
Q2
100K
1
10K
2
2
1000PF
1SW2
2N7002
R13
C7
3
EN_LDO1
3
EN_LDO1
EN_LDO2
PG_LDO
1
C17
10K
1000PF
1
R14
2N7002
R11
100K
3
1
+1.8V
L1
VIN
1
TP6
TP2
OPEN
1UF
VIN_LDO1
1
5.11K
TP9
22UF
VOUT3
2 C16 1
R12
100K
TP13
FB_LDO2
VCC
1SW1
3
4
R10
2
FB_LDO1
VOUT1
GND
GND
Application Note 1326
VCC
2
1
2
FB_LDO1 1
VLDO
0
23 0.1UF
22 FB
21 COMP
202 C4 SS
1
190.033UF
CC1 C5
24
1
GND
TP7
VLDO
1
TP5
100UH
R28
9
10
11
12
VOUT2
TP17
TP1
1
CC1
PG_PWM
FB_PWM
COMP
SS
EN
2
PG_LDO
1
VLDO
VIN
EN_PWM
CC2
PG_LDO
EN_LDO1
EN_LDO2
GND
VCC
0
R6
+1.2V
5.11K
R18
1
22UF
2N7002
2 C15 1
3
2
TP8
1
C6 CC27
0
R7
GND
0.1UF 8
PG_PWM
R17
1
Q4
5.11K
2N7002
3
1
1
1
TP16
3
1
3
D4
1
Q5
C3
1000PF
D3
1
10K
2
R24
301
2
R21
C1
2
10K
R20
2.43K
R2
R1
2
R23
2.43K
2.21K
2N7002
R15
1
EN_LDO2
Q3
2
10K
C19
2
1000PF
3
1SW3
ROHS COMPLIANT
8
7
6
5
4
3
TITLE:
REV:
ISL8501EVAL1
REV C
ENGINEER:
ROS
DRAWN BY:
ROS
DATE:
MAY 2
SHEET:
1
O
2
A
1
AN1326.0
July 10, 2007
Application Note 1326
TABLE 2. COMPONENT LIST
REF DES
QTY
VALUE
TOL
C5, C6, C9
3
0.10µF
10%
50V
SM 0603
C1608X7R1H104K-T
TDK
CAPACITOR, SMD, 0603,
0.10µF, 50V, 10%, X7R
C11
1
10µF
20%
25V
SM 1210
C3225X7R1E106M-T
TDK
CAP, SMD,1210,10µF,
25V, 20%, X7R, ROHS
C2
1
10pF
5%
50V
SM 0402
H1044-00100-50V5-T
VENKEL
CAP, SMD, 0402, 10pF, 50V,
5%, NPO, ROHS
C3,
C17-C19
4
1000pF
10%
50V
SM 0402
H1044-00102-50V10-T
VENKEL,
PANASONIC,
MURATA
CAP, SMD, 0402, 1000pF,
50V, 10%, X7R, ROHS
C1
1
0.01µF
10%
16V
SM 0402
H1044-00103-16V10-T
NIC COMP CORP, CAP, SMD, 0402, 0.01µF,
PHILLIPS, VENKEL, 16V, 10%,X7R, ROHS
KEMET
C4
1
33000pF
20%
16V
SM 0402
H1044-00333-16V8020-T
PANSONIC
CAP, SMD, 0402, 33000pf,
16V, +80-20%, Y5V, ROHS
C14
1
10µF
10%
6.3V
SM 0805
H1046-00106-6R3V10-T
VENKEL, AVX,
MURATA
CAP, SMD, 0805, 10µF, 6.3V,
10%, X5R, ROHS
C7
1
1µF
10%
50V
SM 1206
H1065-00105-50V10-T
VENKEL
CAP, SMD, 1206, 1µF, 50V,
10%, X7R, ROHS
C8
1
Open
10%
50V
SM 1206
H1065-00105-50V10-T
VENKEL
CAP, SMD, 1206, 1µF, 50V,
10%, X7R, ROHS
C13
1
10µF
10%
25V
SM 1206
H1065-00106-25V10-T
VENKEL
CAP, SMD, 1206, 10µF, 25V,
10%, X5R, ROHS
C15, C16
2
22µF
10%
6.3V
SM 1206
H1065-00226-6R3V10-T
MURATA, KEMET,
AVX
CAP, SMD, 1206, 22µF, 6.3V,
10%, X5R, ROHS
C10
1
4.7pF
5.40%
50V
SM 1206
H1065-004R7-50VR25-T
VENKEL
CAP, SMD, 1206, 4.7pF, 50V,
0.25pF, NPO, ROHS
C12
1
100µF
20%
6.3V
SM 1210
H1082-00107-6R3V20-T
GENERIC
CAP, SMD, 1210, 100µF,
6.3V, 20%, X5R, ROHS
L2
1
10µH
20%
102mΩ
6.9x6.5
DNP (SP1)
0
DNP
-
-
-
131-5031-00
TEKTRONIX
CONN-SCOPE PROBE
TEST PT, COMPACT, PCB
MNT
TP1-TP10
10
-
-
-
-
1514-2
KEYSTONE
CONN-TURRET, TERMINAL
POST, TH, ROHS
TP11-TP17
7
-
-
-
-
5002
KEYSTONE
CONN-MINI TEST POINT,
VERTICAL, WHITE, ROHS
D1
1
-
-
-
-
B340LB-13-F-T
DIODES INC
DIODE-SCHOTTKY, SMD,
SMB, 2P, 40V, 3A LOW VF,
Pb-free
D3, D4
2
-
-
-
-
LTST-C170CKT
LITEON, VISHAY,
ROHM, STANLEY
ELECTRIC
LED-GaAs RED, SMD,
2mmx1.25mm, 100mW,
40mA, 10mcd, ROHS
U1
1
-
-
-
QFN
ISL8501IRZ
INTERSIL
IC-2A BUCK REGULATOR,
24P, QFN, 4x4, ROHS
Q1-Q5
5
-
-
60V
SOT-23
2N7002-7-F-T
4
VOLTAGE PACKAGE
PART NUMBER
MANUFACTURER
IHLP-2525CZ-ER-10R-M01 VISHAY
DESCRIPTION
COIL-PWR INDUCTOR, SMD,
6.9mmx6.5mm, 10µH, 20%,
3A, ROHS
DIODES, INC, ON
TRANSISTOR, N-CHANNEL,
SEMICONDUCTOR 3 LD,SOT-23, 60V, 115mA,
ROHS
AN1326.0
July 10, 2007
Application Note 1326
TABLE 2. COMPONENT LIST (Continued)
REF DES
QTY
VALUE
TOL
R17, R18
2
0Ω
5%
50V
SM 0402
H2510-00R00-1/16W-T
VENKEL,
PANSONIC
RES, SMD, 0402, 0Ω, 1/16W,
5%, TF, ROHS
R2, R11,
R13, R15
4
10k
1%
50V
SM 0402
H2510-01002-1/16W1-T
PANASONIC,
VENKEL
RES, SMD, 0402, 10k, 1/16W,
1%, TF, ROHS
R12, R14,
R16
3
100k
1%
50V
SM 0402
H2510-01003-1/16W1-T
PANASONIC
RES, SMD, 0402, 100k,
1/16W, 1%, TF, ROHS
R1
1
20k
1%
50V
SM 0402
H2510-02002-1/16W1-T
PANASONIC
RES, SMD, 0402, 20k, 1/16W,
1%, TF,ROHS
R4
1
2.21k
1%
50V
SM 0402
H2510-02211-1/16W1-T
PANASONIC,
VENKEL
RES, SMD, 0402, 2.21k,
1/16W, 1%, TF, ROHS
R9
1
2.55k
1%
50V
SM 0402
H2510-02551-1/16W1-T
VENKEL, VISHAY,
DALE
RES, SMD, 0402, 2.55k,
1/16W, 1%, TF, ROHS
R3
1
301Ω
1%
50V
SM 0402
H2510-03010-1/16W1-T
PANASONIC,
VENKEL
RES, SMD, 0402, 301Ω,
1/16W, 1%, TF, ROHS
R6-R8
3
5.11k
1%
50V
SM 0402
H2510-05111-1/16W1-T
PANASONIC
RES, SMD, 0402, 5.11k,
1/16W, 1%, TF, ROHS
R5, R10,
R29
3
0Ω
1%
75V
SM 0603
H2511-00R00-1/10W-T
GENERIC
RESISTOR, SMD, 0603,
0Ω, 1/10W, TF, ROHS
R21, R24
2
10k
1%
75V
SM 0603
H2511-01002-1/10W1-T
KOA, VENKEL
RES, SMD, 0603, 10k, 1/10W,
1%, TF, ROHS
R20, R23
2
2.43k
1%
75V
SM 0603
H2511-02431-1/10W1-T
VENKEL, YAGEO
RES, SMD, 0603, 2.43k,
1/10W, 1%,TF, ROHS
R25
1
0Ω
1%
200V
SM 1206
H2513-00R00-1/4W-T
VISHAY, VENKEL
RES, SMD, 1206, 0Ω, 1/4W,
TF, ROHS
R26-R28,
R30
0
DNP
1%
200V
SM 1206
H2513-DNP
GENERIC
RES, SMD, 1206, DNP, DNP,
DNP, TF, ROHS
SW1-SW3
3
-
-
-
-
GT11MSCBE-T
C&K
COMPONENTS
SWITCH-TOGGLE, SMD,
ULTRAMINI, 1P, SPST MINI
C20, C21
0
DNP
-
-
-
DNP
DO NOT POPULATE OR
PURCHASE
D2
0
DNP
-
-
-
DNP
DO NOT POPULATE OR
PURCHASE
L1
0
DNP
-
-
-
DNP
DO NOT POPULATE OR
PURCHASE
5
VOLTAGE PACKAGE
PART NUMBER
MANUFACTURER
DESCRIPTION
AN1326.0
July 10, 2007
Application Note 1326
ISL8501 EVAL Board Layout
FIGURE 2. TOP COMPONENTS
FIGURE 3. TOP LAYER ETCH
6
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July 10, 2007
Application Note 1326
ISL8501 EVAL Board Layout
(Continued)
FIGURE 4. 2ND LAYER ETCH
FIGURE 5. 3RD LAYER ETCH
7
AN1326.0
July 10, 2007
Application Note 1326
ISL8501 EVAL Board Layout
(Continued)
FIGURE 6. BOTTOM LAYER COMPONENTS (MIRRORED)
FIGURE 7. 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
8
AN1326.0
July 10, 2007
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