AN1360: ISL8012EVAL1Z

Application Note 1360
ISL8012EVAL1Z: 2A Synchronous Buck Regulator
with Integrated MOSFETs
2A Low Quiescent Current 1MHz
High Efficiency Synchronous Buck
Regulator
ISL8012 is an integrated power controller rate for the 2A,
1MHz step-down regulator, which is ideal for any low
power, low-voltage application. It is optimized for
generating low output voltages down to 0.8V. The supply
voltage range is from 2.7V to 5.5V, allowing for the use of
a single Li+ cell, three NiMH cells or a regulated 5V input.
It has a guaranteed minimum output current of 2A.
1MHz pulse-width modulation (PWM) switching
frequency allows using small external components. It has
flexible operation mode selection of forced PWM mode
and PFM mode with as low as 35µA quiescent current for
highest light load efficiency to maximize battery life.
The ISL8012 includes a pair of low ON-resistance
P-Channel and N-Channel internal MOSFETs to
maximize efficiency and minimize external component
count. 100% duty-cycle operation allows less than
400mV dropout voltage at 2A.
Features
• High Efficiency Synchronous Buck Regulator with up
to 95% Efficiency
• 1ms Reset Timer
• Soft Discharge Output Cap During Enable
• 2.7V to 5.5V Supply Voltage
• 3% Output Accuracy Over-Temperature/Load/Line
• 2A Guaranteed Output Current
• 25µA Quiescent Supply Current in PFM Mode
• Selectable Forced PWM Mode and PFM Mode
• Less Than 1µA Logic Controlled Shutdown Current
• 100% Maximum Duty Cycle for Lowest Dropout
• Internal Current Mode Compensation
• Internal Digital Soft-Start
• Peak Current Limiting, Short Circuit Protection
• Over-Temperature Protection
• Enable
• Small 10 Ld 3mmx3mm DFN
The ISL8012 offers a 1ms Power-On-Reset (PG) timer at
power-up. The timer output can be reset by RSI. When
shutdown, ISL8012 discharges the output capacitor.
Other features include internal digital soft-start, enable
for power sequence, overcurrent protection and thermal
shutdown.
• Pb-Free (RoHS Compliant)
The ISL8012 is offered in a 3mmx3mm 10 Ld DFN
package with 1mm maximum height. The complete
converter occupies less than 1cm2 area.
• Plug-in DC/DC Modules for Routers and Switchers
Ordering Information
Pinout
PART
NUMBER
PART
(Notes 1, 2, 3) MARKING
ISL8012IRZ
012Z
TEMP.
RANGE
(°C)
PACKAGE
(Pb-Free)
Applications
• DC/DC POL Modules
• µC/µP, FPGA and DSP Power
• PGtable Instruments
• Test and Measurement Systems
ISL8012
(10 LD DFN)
TOP VIEW
PKG.
DWG. #
-40 to +85 10 Ld 3x3 DFN L10.3x3C
NOTES:
1. Add “-T” or suffix for tape and reel. Please refer to TB347 for
details on reel specifications.
2. 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 Pb-free peak reflow
temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020.
VIN
1
10 LX
VCC
2
9
PGND
EN
3
8
SGND
PG
4
7
VFB
MODE
5
6
RSI
3. For Moisture Sensitivity Level (MSL), please see device
information page for ISL8012. For more information on MSL
please see techbrief TB363.
November 4, 2009
AN1360.1
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, 2009. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
Application Note 1360
What’s Inside
Evaluating the Other Output Voltage
The Evaluation Board Kit contains the following
materials:
• The ISL8012EVAL1Z REVC Board
• The ISL8012 Data Sheet
• This EVAL KIT Application Note
Recommended Equipment
The following materials are recommended to perform
testing:
• 0V to 10V power supply with at least 3A source
current capability, battery and notebook AC
adapter
• Two electronic loads capable of sinking current up
to 5A
• Digital multimeters (DMMs)
• 100MHz quad-trace oscilloscope
• Signal generator
Quick Setup Guide
The ISL8012EVAL1Z kit output is preset to 1.8V;
however, output voltages can be adjusted from 0.8V
to 3.3V using Equations 1 and 2:
R 1⎞
⎛
VOUT = 0.8 ⎜ 1 + -------⎟
R 2⎠
⎝
(EQ. 1)
Let’s set R2 = 100kΩ
VOUT
R 1 = R 2 ⎛ ------------------ – 1⎞
⎝ 0.8
⎠
(EQ. 2)
If the desired output is 0.8V, short R1 and open R2.
Mode Control
The ISL8012 has a MODE pin that controls the
operation mode. When the MODE pin is driven to low
or shorted to ground, the regulator operates in a forced
PWM mode. The forced PWM mode remains the fixed
PWM frequency at light load instead of entering the
skip mode.
TABLE 1. SWITCH SETTINGS
SW2
SKIP
FUNCTION
PWM
Fixed PWM Frequency at Light
Load
PFM
Force Continuous Mode
ENABLE
ON/OFF CONTROL
4. Turn on the power supply.
OFF
Disable VOUT
5. Verify the output voltage is 1.8V for VOUT
ON
Enable VOUT
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 P4 (VIN) and the negative return to P5 (GND).
3. Verify that SW1 is in the ON position.
2
SW1
AN1360.1
November 4, 2009
ISL8012EVAL1Z Schematic
1
J1
2
5
4
3
1
P5
11
10
1
P7
1
P8
1
1
1
9
C5
10UF
C4
R1
124K 220PF
6
C6
10UF
2
A
7
2
8
2
EN 3
PG 4
SKIP 5
LX
PGND
GND
VFB
RSI
2
2
C2
10UF
2
C1
10UF
1
1
3
VIN
VCC
EN
POR
SKIP
EP
2
1
1
2
RSI
A ISL8012IRZ
Application Note 1360
A
2
VIN
1
P4
L1
L1
2.2UH
1.5UH
A
5
4
3
U1
1
J2
R2
100K
1
A
A
RSI
1
P1
R3
100K
A
VIN
2N7002
1
P6
R9
OPEN
2
3
ON/EX
SW1 1 OFF
1
R8
OPEN
1
AN1360.1
November 4, 2009
Q1
EN
1
31
1
PFM
2
P2
3
SW2 1 PWM
2
PG
2
2
D1
1
1
SKIP
21
2
R4
100K
P3
1
R5
2K
R7
100K
1
R6
100K
2
VIN
2
2
VIN
A
A
A
TABLE 2. BILL OF MATERIALS
PART
NUMBER
QTY UNITS
4
ISL8012EVAL1ZREVCPCB
1
ea
GRM31CR71A106KA01L-T
4
ea
H1045-00221-50V5-T
1
DR73-2R2-R
REFERENCE
DESIGNATOR
DESCRIPTION
MANUFACTURER
MANUFACTURER
PART
IMAGINEERING
INC
ISL8012EVAL1ZREVCPCB
C1, C2, C5, C6
CAP, SMD, 1206, 10µF, 10V, 10%, X7R, ROHS,
MONOLITHIC
MURATA
GRM31CR71A106KA01L
ea
C4
CAP, SMD, 0603, 220pF, 50V, 5%, C0G, ROHS
VENKEL
C0603COG500-221JNE
1
ea
L1
COIL-PWR INDUCTOR, SMD, 7.6X6, 2.2uH, 20%,
4.15A, ROHS
COOPER
ELECTRONIC
TECH.
DR73-2R2-R
131-5031-00
2
ea
J1, J2
CONN-SCOPE PROBE TEST PT, COMPACT,
PCB MNT, ROHS
TEKTRONIX
131-5031-00
1514-2
4
ea
P4, P5, P7, P8
CONN-TURRET, TERMINAL POST, TH, ROHS
KEYSTONE
1514-2
5002
4
ea
P1-P3, P6
CONN-MINI TEST POINT, VERTICAL, WHITE, ROHS
KEYSTONE
5002
LTST-C170CKT
1
ea
D1
LED-GaAs RED, SMD, 2mmX1.25mm, 100mW, 40mA, LITEON/VISHAY
10mcd, ROHS
LTST-C170CKT
ISL8012IRZ
1
ea
U1
IC-2A SYNCH. BUCK REGULATOR, 10P, DFN, 2X3,
ROHS
INTERSIL
ISL8012IRZ
2N7002-7-F-T
1
ea
Q1
TRANSISTOR, N-CHANNEL, 3LD, SOT-23, 60V,
115mA, ROHS
DIODES, INC.
2N7002-7-F
H2511-01003-1/10W1-T
5
ea
R2-R4, R6, R7
RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS
H2511-01243-1/10W1-T
1
ea
R1
RES, SMD, 0603, 124k, 1/10W, 1%, TF, ROHS
YAGEO
9C06031A1243FKHFT
H2511-02001-1/10W1-T
1
ea
R5
RES,SMD,0603, 2k, 1/10W, 1%, TF, ROHS
KOA
RK73H1JTTD2001F
H2511-DNP
0
ea
R8, R9
RES, SMD, 0603, DNP-PLACE HOLDER, ROHS
GT11MSCBE-T
2
ea
SW1, SW2
SWITCH-TOGGLE, SMD, 6PIN, SPDT, 2POS, ON-ON,
ROHS
ITT INDUSTRIES/
C&K DIVISION
GT11MSCBE
4-40X1/2-SCREW
4
ea
Four corners.
SCREW, 4-40X1/2in, PAN, NYLON, PHILLIPS, ROHS
4-40X3/4-STANDOFF
4
ea
Four corners.
STANDOFF, 4-40X3/4in, F/F, HEX, NYLON
KEYSTONE
1902D
5X8-STATIC-BAG
1
ea
Place assy in bag.
BAG, STATIC, 5X8, ZIP LOC
INTERSIL
212403-013
LABEL-SERIAL NUMBER
1
ea
LABEL, FOR SERIAL NUMBER AND BOM REV #
Application Note 1360
PWB-PCB, ISL8012EVAL1Z, REVC, ROHS
AN1360.1
November 4, 2009
Application Note 1360
ISL8012EVAL1Z Board Layout
FIGURE 1. TOP COMPONENTS
FIGURE 2. TOP LAYER ETCH
5
AN1360.1
November 4, 2009
Application Note 1360
ISL8012EVAL1Z Board Layout
(Continued)
FIGURE 3. BOTTOM LAYER COMPONENTS (MIRRORED)
FIGURE 4. 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
6
AN1360.1
November 4, 2009