AN1803

Application Note 1803
Author: Huong Doan
1.5A/2A Low Quiescent Current High Efficiency
Synchronous Buck Regulator
Description
Key Features
The ISL8002, ISL8002A and ISL80019, ISL80019A kits are
intended for use by individuals with requirements for point-of-load
applications sourcing from 2.7V to 5.5V. The ISL8002, ISL8002A
and ISL80019, ISL80019A evaluation boards are used to
demonstrate the performance of the ISL8002 and ISL80019, low
quiescent current high efficiency synchronous buck regulator.
• High efficiency synchronous buck regulator with up to 95%
efficiency
The ISL8002, ISL8002A and ISL80019, ISL80019A are offered
in a 2mmx2mm 8 Ld μTDFN package with 1mm maximum
height. The complete area that the converter occupies can be
as small as 0.10in2.
• Soft-stop output discharge during disable
IOUT
(Max)
(A)
FSW
RANGE
(MHz)
ISL80019
1.5
1
ISL80019A
1.5
2
ISL8002
2
1
ISL8002A
2
2
• Start-up with pre-biased output
• Internal soft-start - 1ms
• 1MHz, 2MHz default frequency
• Negative OC protection
Evaluating the Other Output
Voltage
TABLE 1. SUMMARY OF KEY DIFFERENCES
PART
NUMBER
• 0.8% reference accuracy over-temperature/load/line
VIN RANGE
(V)
VOUT
RANGE
(V)
PART SIZE
(mm sq.)
2.7 to 5.5
0.6 to 5.5
2x2
The ISL8002, ISL8002A and ISL80019, ISL80019A kits outputs
are preset to 1.8V for V0, however, the output voltages can be
adjusted from 0.6V to 5V. The output voltage programming
resistor, R1, will depend on the desired output voltage of the
regulator. The value for the feedback resistor is typically
between 0Ω and 200kΩ, as shown in Equation 1.
VO
R 1 = R 2 ⎛ ---------- – 1⎞
⎝ VFB
⎠
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, the plus terminal to VIN (P4)
and the negative return to PGND (P5).
3. Connect the output load to V0, the plus terminal to V0 (P7)
and the negative return to PGND (P8).
4. Verify that the position is PWM or PFM for SW2.
5. Verify that the position is ON for SW1.
6. Turn on the power supply.
(EQ. 1)
If the output voltage desired is 0.6V, then R2 is left
unpopulated and R1 is shorted. For faster response
performance, add 10pF to 47pF in parallel to R1. Check
bode plot to insure optimum performance.
Switch Control
The ISL8002, ISL8002A and ISL80019, ISL80019A evaluation
board contains SW1 and SW2 for various controls of the
ISL8002, ISL8002A and ISL80019, ISL80019A circuitries.
Table 2 details this function.
TABLE 2. SWITCH SETTINGS
7. Verify the output voltage is 1.8V for V0.
SW1
ENABLE
Recommended Equipment
1
OFF
Disable V0
The following materials are recommended to perform testing:
3
ON
Enable V0
SW2
MODE
1
PFM
Force continuous mode
3
PWM
Fixed PWM frequency at light load
• 0V to 10V power supply with at least 10A source current
capability or 5V battery
• Electronic loads capable of sinking current up to 7A
• Digital multimeters (DMMs)
• 100MHz quad-trace oscilloscope
FUNCTION
FUNCTION
• Signal generator
December 13, 2012
AN1803.0
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas Inc. 2012. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
Application Note 1803
lSL8002, ISL8002A, ISL80019, ISL80019EVAL1Z Schematic
J1
J2
PHASE
VIN
P4
L1
A
VO
2
1
1.2UH
U1
1
EN
C1
C2
MODE
C3
220UF 22UF 22UF
PG
2
3
4
9
C5
VIN
PHASE
EN
PGND
MODE
PG
FB
COMP
8
C6
22UF 22UF
R3
20
7
P8
R2
100K
6
A
C4
22PF
5
EP
P5
P7
A
R1
ISL80019
CH8
200K
A
C7
220PF
C8
OPEN
R11
VIN
DNP
VIN
R14
100K
R7
200K
A
2
EN
EDGE FINGERS TO DUT
-VOS
A
A
VO
VO
VO
VO
-VI2S_A
EN2_A
VCC
CH6
CH7
PG
CH9
CH10 BOOT
2
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
B12
B13
B14
B15
B16
B17
B18
B19
B20
B21
B22
B23
B24
B25
B26
B27
B28
B29
B30
VIN
VIN
VIN
VIN
VIN
VIN
ON
OFF
R8
OPEN
2
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
R5
2K
1
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
KEY2
D1
+VOS
VO
PG
VO
A
VO
VO
P1
VO
VO
VIN
+VI2S_A
MODE
EN
TRACKREF CH1
CH2
SYNCOUT CH3
SS
CH4
CH5
A
VIN
R4
200K
R6
200K
3
KEY1
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
A22
A23
A24
A25
A26
A27
A28
A29
A30
Q1
1
2N7002
MODE
2
2
-VINS
VIN
VIN
VIN
VIN
1
P6
3
SW1 1
A
P2
3
SW2 1
PWM
PFM
R9
OPEN
A
AN1803.0
December 13, 2012
Application Note 1803
TABLE 3. BILL OF MATERIALS
PART NUMBER
REFERENCE
DESIGNATOR
QTY UNITS
DESCRIPTION
MANUFACTURER
MANUFACTURER PART
10TPB220M
1
ea
C1
CAP-POSCAP, SMD, D4, SANYO
220µF, 10V, 20%,
ROHS
10TPB220M
H1045-00220-50V5-T
1
ea
C4
CAP, SMD, 0603, 22pF, VENKEL, KEMET, TDK
50V, 5%, C0G, ROHS
MURATA, ROHM
C0603C0G500-220JNE,
C0603C220J5GACTU,
C1608C0G1H220J,
GRM1885C1H220JA01D,
MCH185A220JK
H1045-00221-50V10-T
1
ea
C7
MURATA, VENKEL,
CAP, SMD, 0603,
220pF, 50V, 10%, X7R, AVX, TDK, YAGEO,
ROHM, KEMET
ROHS
GRM188R71H221KA01D,
C0603X7R500-221KNE,
06035C221KAT2A,
C1608X7R1H221K,
MCH185CN221KK,
CC0603KRX7R9BB221,
C0603C221K5RACTU
H1045-DNP
0
ea
C8
CAP, SMD, 0603,
DNP-PLACE HOLDER,
ROHS
H1065-00226-6R3V20-T
4
ea
C2, C3, C5, C6
CAP, SMD, 1206, 22µF, PANASONIC, TAIYO
6.3V, 20%, X5R, ROHS YUDEN, TDK, AVX
VLCF-4028T-1R2N2R7-2
1
ea
L1 for ISL8002A,
ISL80019A, 2MHz
COIL-PWR INDUCTOR,
WW, SMD, 4mm,
1.2µH, 30%, 2.7A,
ROHS
74437324022
1
ea
L1 for ISL8002,
ISL80019, 1MHz
COIL-PWR INDUCTOR, Wurth Electronics
SMD, 4.45x4.6, 2.2µH,
20%, 3.25A, ROHS
LTST-C170CKT
1
ea
D1
LED-GaAs RED, SMD,
2x1.25mm, 100mW,
40mA, 10mcd, ROHS
LITEON/VISHAY,
ROHM, STANLEY
ELECTRIC
LTST-C170CKT, SML-210LTT86,
BR112H-TR
ISL8002AIRZ
1
ea
U1
IC-2A BUCK
REGULATOR, 8P,
µTDFN, 2x2, ROHS
INTERSIL
ISL8002AIRZ
2N7002-7-F-T
1
ea
Q1
TRANSISTOR,
N-CHANNEL, 3 LD,
SOT-23, 60V, 115mA,
ROHS
DIODES, INC., ON
SEMICONDUCTOR
2N7002-7-F, 2N7002LT1G
H2511-00200-1/10W1-T
1
ea
R3
RES, SMD, 0603, 20Ω, PANASONIC, YAGEO,
1/10W, 1%, TF, ROHS VENKEL
ERJ-3EKF20R0V,
RC0603FR-0720RL,
CR0603-10W-20R0FT
H2511-01003-1/10W1-T
2
ea
R2, R14
RES, SMD, 0603, 100k, VENKEL, PANASONIC,
1/10W, 1%, TF, ROHS ROHM, YAGEO,
STACKPOLE,
VISHAY/DALE
CR0603-10W-1003FT,
ERJ-3EKF1003V,
MCR03EZPFX1003,
RC0603FR-07100KL, RMCF 1/16
100K 1% R, CRCW0603100KFKEA
H2511-02001-1/10W1-T
1
ea
R5
RES, SMD, 0603, 2k,
1/10W, 1%, TF, ROHS
RK73H1JTTD2001F,
CR0603-10W-2001FT
3
TDK
KOA, VENKEL
ECJ-DV50J226M,
JMK316BJ226ML,
C3216X5R0J226M,
12066D226MAT2A
VLCF4028T-1R2N2R7-2
74437324022
AN1803.0
December 13, 2012
Application Note 1803
TABLE 3. BILL OF MATERIALS (Continued)
PART NUMBER
QTY UNITS
REFERENCE
DESIGNATOR
DESCRIPTION
MANUFACTURER
MANUFACTURER PART
CR0603-10W-2003FT,
RC0603FR-07200KL,
CRCW0603200KFKEA,
ERJ-3EKF2003V,
MCR03EZPFX2003
H2511-02003-1/10W1-T
4
ea
R1, R4, R6, R7
RES, SMD, 0603, 200k, VENKEL, YAGEO,
1/10W, 1%, TF, ROHS VISHAY/DALE,
PANASONIC, ROHM
H2511-DNP
0
ea
R8, R9, R11
RES, SMD, 0603,
DNP-PLACE HOLDER,
ROHS
GT11MSCBE-T
2
ea
SW1, SW2
SWITCH-TOGGLE, SMD, ITT INDUSTRIES/C&K GT11MSCBE
DIVISION
6 PIN, SPDT, 2 POS,
ON-ON, ROHS
4
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December 13, 2012
Application Note 1803
ISL8002, ISL8002A, ISL80019, ISL80019AEVAL1Z Layout
FIGURE 1. TOP LAYER COMPONENTS
FIGURE 2. SILKSCREEN TOP
5
AN1803.0
December 13, 2012
Application Note 1803
ISL8002, ISL8002A, ISL80019, ISL80019AEVAL1Z Layout
(Continued)
FIGURE 3. TOP LAYER ETCH
FIGURE 4. SECOND LAYER ETCH
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AN1803.0
December 13, 2012
Application Note 1803
ISL8002, ISL8002A, ISL80019, ISL80019AEVAL1Z Layout
(Continued)
FIGURE 5. THIRD LAYER ETCH
FIGURE 6. BOTTOM LAYER ETCH
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AN1803.0
December 13, 2012
Application Note 1803
ISL8002, ISL8002A, ISL80019, ISL80019AEVAL1Z Layout
(Continued)
FIGURE 7. BOTTOM LAYER COMPONENTS
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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AN1803.0
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