an1554

Application Note 1554
Author: Huong Doan
ISL8022EVAL1Z Dual 2A/1.7A Low Quiescent
Current 2.25MHz High Efficiency Synchronous Buck
Regulator
Description
Quick Setup Guide
The ISL8022EVAL1Z kit is intended for use by
individuals with requirements for Point-of-Load
applications sourcing from 2.8V to 5.5V. The
ISL8022EVAL1Z evaluation board is used to demonstrate
the performance of the ISL8022 low quiescent current
mode converter.
The ISL8022 is offered in a 4mmx3mm 12 Ld DFN
package with 1mm maximum height. The complete
converter occupies less than 1.8cm2 area.
2. Connect the bias supply to VIN2, the plus terminal
to VIN2 and the negative return to PGND2.
3. Verify that position is ON for SW2 and SW3.
4. Turn on the power supply.
5. Verify the output voltage is 2.5V for VOUT1 and 1.8V
for VOUT2.
Evaluating the Other Output Voltage
Key Features
• Dual 2A/1.7A High Efficiency Synchronous Buck
Regulator with up to 97% Efficiency
• 180° Out-of-Phase
• Power-Goods (PG) Output with 1ms Delay
• 2.8V to 5.5V Supply Voltage
• 3% Output Accuracy Over-temperature/Load/Line
• Start-up with Pre-biased Output
• Internal Digital Soft-Start - 5ms
• Soft-Stop Output Discharge During Disabled
• 40µA Quiescent Supply Current in PFM Mode
• Selectable Forced PWM Mode and PFM Mode
• External Synchronization up to 8MHz
• Typical 6.5µA Logic Controlled Shutdown Current
• 100% Maximum Duty Cycle for Lowest Dropout
• Internal Current Mode Compensation
• Peak Current Limiting, Hiccup Mode Short Circuit
Protection and Over-temperature Protection
• Negative Current Detection and Protection
Recommended Equipment
The following materials are recommended to perform
testing:
• 0V to 10V Power Supply with at least 3A source
current capability or 5V battery
• Electronic Loads capable of sinking current up to 3A
• Digital Multimeters (DMMs)
• 100MHz quad-trace oscilloscope
• Signal generator
October 27, 2010
AN1554.1
1. Ensure that the circuit is correctly connected to the
supply and loads prior to applying any power.
1
The ISL8022EVAL1Z kit output is preset to 2.5V for
VOUT1 and 1.8V for VOUT2; however, output voltages
can be adjusted from 0.6V to 3.3V. The output voltage
programming resistor, R2 (or R5 in Channel 2), will
depend on the desired output voltage of the regulator.
The value for the feedback resistor is typically between
0Ω and 750kΩ as shown in Equation 1.
Let’s set R3/R6 = 100kΩ, then R2/R5 will be:
VOUT
R2 = R3 ⎛ ------------------ – 1⎞
⎝ VFB
⎠
(EQ. 1)
If the output voltage desired is 0.6V, then R3 is left
unpopulated and short R2. For faster response
performance, add 10pF in parallel to R2.
Mode Control
The ISL8022 has a SYNC pin that controls the operation
mode. The SYNC pin connects to logic high or input
voltage VIN for PFM mode; connect to logic low or
ground for forced PWM mode. Connect to an external
function generator for Synchronization. Negative edge
trigger. Do not leave this pin floating.
TABLE 1. SWITCH SETTINGS
SW2, SW3
ENABLE
ON/OFF CONTROL
1
OFF
Disable VOUT
3
ON
Enable VOUT
SW1
SKIP
1
PWM
Fixed PWM frequency at light load
3
PFM
Force continuous mode
FUNCTION
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. 2010. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
ISL8022EVAL1Z Schematic
R15
VIN1
VIN2
1
2
C1
10UF
C8
OPEN
A
1.2UH
2
VIN2
1
VOUT1
0
SYNC
2
3
S1 1
3
C7
OPEN
C9
OPEN
A
LX1
5
13
FB1
EN1
PG
VIN1
LX1
PGND1
EP
R14
20
C3
10PF
PGND
A
2
6
C2
22UF
PGND1
A
PGND2
FB2
EN2
SYNC
VIN2
LX2
PGND2
12
11
10
9
8
FB2
EN2
SYNC
L2
LX2 1
2
1.2UH
7
ISL8022IRZ
A
C4
22UF
R13
20
C6
OPEN
VIN2
A
C5
10PF
R5
200K
PGND3
PGND3
A
R6
100K
VIN2
A
R7
100K
R10
2K
2
R4
100K
4
VOUT2_S
R2
316K
VIN2
VOUT2
VOUT2_S
1
2
A
R3
100K
A
VOUT2
VOUT2
A
A
PFM
PWM
C10
10UF
Application Note 1554
SYNC
R11
4
VOUT1
VOUT1
VOUT1_S
SYNC
L1
VIN2
3
FB1 1
EN1 2
PG 3
A
1
2
C11
OPEN
A
U1
PGND
VOUT1_S 4
LX2
PGND2
PGND
R1
100K
4
3
4 LX1
3
VIN
0
LX1_S
1
2
SGND
2
3
S2 1
ON/EX
OFF
EN1
SGND
EN2
2
3
S3 1
R9
OPEN
ON/EX
OFF
EN2
PG
EN2
1
PG
2N7002
Q2
2
EN1
D2
31
EN1
A
NOTE:
PLEASE KEEP FB1, FB2 PINS TRACES SHORT
A
A
A
DRAWN BY:
RELEASED BY:
DATE:
04/29/2008
DATE:
UPDATED BY
DATE
HUONG DOAN
TU BUI / HUONG DOAN
ENGINEER:
HUONG DOAN
TITLE:
ISL8022
DATE:
4/29/08
AN1554.1
Application Note 1554
TABLE 2. BILL OF MATERIALS
PART
NUMBER
QTY UNITS
REFERENCE
DESIGNATOR
DESCRIPTION
PWB-PCB,
ISL8022EVAL1Z,
REVA, ROHS
MANUFACTURER
TBD
ISL8022EVAL1ZREVAPCB
1
ea
C2012X5R0J226M-T
2
ea
C2, C4
TDK
CAP, SMD, 0805,
22µF, 6.3V, 20%, X5R,
ROHS
H1045-00100-50V5-T
2
ea
C3, C5
CAP, SMD, 0603,
10pF, 50V, 5%, COG,
ROHS
MANUFACTURER
PART
ISL8022EVAL1ZREVAPCB
C2012X5R0J226M
YAGEO
CC0603JRNP09BN100
VENKEL
C0603COG500-100JNE
KEMET
C0603C100J5GACTU
MURATA
GRM1885C1H100JA01D
AVX
06035A100JAT2A
H1045-DNP
0
ea
C9
CAP, SMD, 0603,
DNP-PLACE HOLDER,
ROHS
H1046-00106-6R3V10-T
2
ea
C1, C10
VENKEL
CAP, SMD, 0805,
10µF, 6.3V, 10%, X5R,
KEMET
ROHS
C0805X5R6R3-106KNE
C0805C106K9PACTU
AVX
08056D106KAT2A
MURATA
GRM21BR60J106KE19L
TAIYO YUDEN
JMK212BJ106KD-T
PANASONIC
ECJ-2FB0J106K
TDK
C2012X5R0J106K
JOHANSON DIELECTRICS 6R3R15X106KV4E
INC
H1046-DNP
0
ea
C6-C8, C11
CAP, SMD, 0805,
DNP-PLACE HOLDER,
ROHS
VLCF-4028T-1R2N2R7-2
2
ea
L1, L2
COIL-PWR
INDUCTOR, WW,
SMD, 4mm, 1.2µH,
30%, 2.7A, ROHS
131-4353-00
4
ea
1514-2
8
1514-2
TDK
VLCF4028T-1R2N2R7-2
CONN-SCOPE PROBE
LX1, LX2,
TEST PT, COMPACT,
VOUT1_S,
PCB MNT, ROHS
VOUT2_S *(SEE
ASSEMBLY NOTE)
TEKTRONIX
131-4353-00
ea
a) PGND, PGND1- CONN-TURRET,
TERMINAL POST, TH,
PGND3, VIN,
ROHS
VIN2
KEYSTONE
1514-2
0
ea
b) VOUT1, VOUT2 CONN-TURRET,
TERMINAL POST, TH,
ROHS
KEYSTONE
1514-2
5000
4
ea
EN1, EN2, PG,
SYNC
CONN-MINI TEST PT,
VERTICAL, RED,
ROHS
KEYSTONE
5000
5001
1
ea
SGND
CONN-MINI TEST PT, KEYSTONE
VERTICAL, BLK, ROHS
5001
3
AN1554.1
Application Note 1554
TABLE 2. BILL OF MATERIALS (Continued)
PART
NUMBER
LTST-C170CKT
QTY UNITS
1
ea
REFERENCE
DESIGNATOR
D2
DESCRIPTION
MANUFACTURER
LED-GaAs RED, SMD,
2mmX1.25mm,
100mW, 40mA,
10mcd, ROHS
LITEON/VISHAY
LTST-C170CKT
ROHM
SML-210LTT86
STANLEY ELECTRIC
BR112H-TR
INTERSIL
ISL8022IRZ
ISL8022IRZ
1
ea
U1
IC-2A/1.7A BUCK
REGULATOR, 12P,
DFN, 4X3, ROHS
2N7002-7-F-T
1
ea
Q2
DIODES, INC.
TRANSISTOR,
N-CHANNEL, 3LD,
ON SEMICONDUCTOR
SOT-23, 60V, 115mA,
ROHS
H2511-00200-1/10W1-T
H2511-00R00-1/10W-T
2
ea
1
ea
R13, R14
R11
RES, SMD, 0603,
20Ω, 1/10W, 1%, TF,
ROHS
RES, SMD, 0603, 0Ω,
1/10W, TF, ROHS
YAGEO
RC0603FR-0720RL
VENKEL
CR0603-10W-20R0FT
VENKEL
CR0603-10W-000T
KOA
RK73Z1JTTD-T
ROHM
MCR03EZPJ000
PANASONIC
ERJ-3GEY0R00V
YAGEO
RC0603JR-070RL
VISHAY/DALE
CRCW06030000Z0EA
ea
R1, R3, R4, R6,
R7
RES, SMD, 0603,
100k, 1/10W, 1%, TF,
ROHS
H2511-02001-1/10W1-T
1
ea
R10
RES, SMD, 0603, 2k, KOA
1/10W, 1%, TF, ROHS
VENKEL
H2511-03163-1/10W1-T
ea
1
ea
R5
R2
2N7002LT1G
ERJ-3EKF20R0V
5
1
2N7002-7-F
PANASONIC
H2511-01003-1/10W1-T
H2511-02003-1/10W1-T
MANUFACTURER
PART
VENKEL
RES, SMD, 0603,
200k, 1/10W, 1%, TF,
YAGEO
ROHS
RK73H1JTTD2001F
CR0603-10W-2001FT
CR0603-10W-2003FT
RC0603FR-07200KL
VISHAY/DALE
CRCW0603200KFKEA
PANASONIC
ERJ-3EKF2003V
ROHM
MCR03EZPFX2003
PANASONIC
RES, SMD, 0603,
316k, 1/10W, 1%, TF,
VENKEL
ROHS
ERJ-3EKF3163V
CR0603-10W-3163FT
ROHM
MCR03EZPFX3163
YAGEO
RC0603FR-07316KL
VISHAY/DALE
CRCW0603316KFKEA
H2511-DNP
0
ea
R9
RES, SMD, 0603,
DNP-PLACE HOLDER,
ROHS
H2514-00R00-1/4W-T
1
ea
R15
RES, SMD, 1210, 0Ω,
1/4W, TF, ROHS
VENKEL
CR1210-4W-000
GT11MSCBE-T
3
ea
S1-S3
SWITCH-TOGGLE,
SMD, 6PIN, SPDT,
2POS, ON-ON, ROHS
ITT INDUSTRIES/C&K
DIVISION
GT11MSCBE
4
AN1554.1
Application Note 1554
TABLE 2. BILL OF MATERIALS (Continued)
PART
NUMBER
QTY UNITS
REFERENCE
DESIGNATOR
DESCRIPTION
MANUFACTURER
MANUFACTURER
PART
SJ-5003-BLACK
4
ea
Bottom four
corners
BUMPONS, 0.44’ W x
0.20’ H, DOMETOP,
BLACK
3M
SJ-5003SPBL
5X8-STATIC-BAG
1
ea
Place assy in bag
BAG, STATIC, 5X8,
ZIP LOC
INTERSIL
212403-013
ASSEMBLY-NOTE
1
ea
ASSEMBLY NOTE
a) LX1, LX2,
VOUT1_S,
VOUT2_S - Install
ASSEMBLY-NOTE
0
ea
b) on bottom of
PCB
ASSEMBLY NOTE
ISL8022EVAL1Z Board Layout
FIGURE 1. TOP COMPONENTS
5
FIGURE 2. TOP LAYER ETCH
AN1554.1
Application Note 1554
ISL8022EVAL1Z Board Layout (Continued)
FIGURE 3. 2ND LAYER ETCH
FIGURE 4. 3RD LAYER ETCH
FIGURE 5. BOTTOM LAYER COMPONENTS (MIRRORS)
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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
6
AN1554.1
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