DATASHEET
ISL8026, ISL8026A
Compact Synchronous Buck Regulators
The
ISL8026, ISL8026A
are highly efficient, monolithic,
synchronous step-down DC/DC converters that can deliver 6A of
continuous output current from a 2.5V to 5.5V input supply. The
devices use current mode control architecture to deliver a very low
duty cycle operation at high frequency with fast transient
response and excellent loop stability.
The ISL8026, ISL8026A integrate a very low ON-resistance
P-channel (36mΩ) high-side FET and N-channel (13mΩ)
low-side FET to maximize efficiency and minimize external
component count. The 100% duty-cycle operation allows less
than 180mV dropout voltage at 6A output current. The
operation frequency of the Pulse-width Modulator (PWM) is
adjustable from 500kHz to 4MHz. The default switching
frequency, which is set by connecting the FS pin high, is 1MHz
for the ISL8026 and 2MHz for the ISL8026A.
The ISL8026, ISL8026A can be configured for discontinuous or
forced continuous operation at light load. Forced continuous
operation reduces noise and RF interference, while
discontinuous mode provides higher efficiency by reducing
switching losses at light loads.
Fault protection is provided by internal hiccup mode current
limiting during short-circuit and overcurrent conditions. Other
protection, such as overvoltage and over-temperature, are also
integrated into the device. A power-good output voltage
monitor indicates when the output is in regulation.
The ISL8026, ISL8026A offer a 1ms Power-Good (PG) timer at
power-up. When in shutdown, the ISL8026, ISL8026A
discharge the output capacitor through an internal soft-stop
switch. Other features include internal fixed or adjustable
soft-start and internal/external compensation.
The ISL8026, ISL8026A are offered in a space saving 16 Ld
3x3 Pb-free TQFN package with an exposed pad for improved
thermal performance and 0.8mm maximum height. The
complete converter occupies less than 142mm
2
.
FN8736
Rev 2.00
October 28, 2016
Features
• 2.5V to 5.5V input voltage range
• Very low ON-resistance FETs - P-channel 36mΩ and
N-channel 13mΩ typical values
• High efficiency synchronous buck regulator with up to 95%
efficiency
• 1.0% reference accuracy over load/line/temperature (-40°C
to +85°C)
• 1.5% reference accuracy over load/line/temperature (-40°C
to +125°C)
• Internal soft-start: 1ms or adjustable
• Soft-stop output discharge during disable
• Adjustable frequency from 500kHz to 4MHz - default at
1MHz (ISL8026) or 2MHz (ISL8026A)
• External synchronization up to 4MHz
• Over-temperature, overcurrent, overvoltage and negative
overcurrent protection
Applications
• DC/DC POL modules
•
μC/µP,
FPGA and DSP power
• Video processor/SOC power
• Li-ion battery powered devices
• Routers and switchers
• Portable instruments
• Test and measurement systems
• Industrial PCs
Related Literature
•
UG033,
“ISL8026xEVAL3Z Evaluation Board User Guide”
L1
1.0μH
C2
2 x 22μF
+1.8V/6A
100
VOUT
16
PHASE
PHASE
PHASE
VIN
13
15
14
VIN
GND
+2.5V
…+5.5V
C1
2 x 22μF
R1
100k
:
GND
PGND
R2
200k
:
C3*
22pF
90
EFFICIENCY (%)
80
3.3V
OUT
PFM
1
VIN
ISL8026
2
VIN
PGND
PG
3
PG
PGND/
SGND
FB
COMP
PAD
R3
100k
:
3.3V
OUT
PWM
70
60
50
40
4
SYNC
EN
FS
SS
17
5
8
6
7
*C3 IS OPTIONAL. IT IS
RECOMMENDED TO PUT A
PLACEHOLDER FOR IT AND CHECK
LOOP ANALYSIS BEFORE USE.
VO
-
R 2 = R 3
----------- –
1
VFB
EN
(EQ. 1)
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
OUTPUT LOAD (A)
FIGURE 1. TYPICAL APPLICATION CIRCUIT CONFIGURATION (INTERNAL
COMPENSATION OPTION)
FIGURE 2. EFFICIENCY vs LOAD 1MHz 5V
IN
FN8736 Rev 2.00
October 28, 2016
Page 1 of 23
ISL8026, ISL8026A
Table of Contents
Pin Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Typical Operating Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PWM Control Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SKIP Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frequency Adjust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Negative Current Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UVLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Soft Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Discharge Mode (Soft-Stop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power MOSFETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
100% Duty Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Derating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Inductor and Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loop Compensation Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
17
17
18
18
18
18
18
18
18
18
18
18
18
19
19
19
19
19
19
PCB Layout Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
About Intersil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
FN8736 Rev 2.00
October 28, 2016
Page 2 of 23
ISL8026, ISL8026A
Pin Configuration
ISL8026, ISL8026A
(16 LD TQFN)
TOP VIEW
PHASE
PHASE
PHASE
13
16
VIN
15
14
VIN 1
VIN 2
PG 3
SYNC 4
12
11
10
9
PGND
PGND
PGND/SGND
FB
EPAD
5
EN
6
FS
7
SS
8
COMP
Pin Descriptions
PIN NUMBER
1, 2, 16
3
4
SYMBOL
VIN
PG
SYNC
DESCRIPTION
Input supply voltage. Place a minimum of two 22µF ceramic capacitors from VIN to PGND as close as possible to the IC
for decoupling.
Power-good is an open-drain output. Use a 10kΩ to 100kΩ pull-up resistor connected between VIN and PG. At power-up or
EN HI, PG rising edge is delayed by 1ms once the output voltage reaches regulation.
Mode Selection pin. Connect to logic high or input voltage VIN for PWM mode. Connect to logic low or ground for PFM
mode. Connect to an external function generator for synchronization with the positive edge trigger. There is an internal
1MΩ pull-down resistor to prevent an undefined logic state in case the SYNC pin is floating.
Regulator enable pin. Enable the output when driven high. Shut down the chip and discharge output capacitor when driven
low.
This pin sets the oscillator switching frequency using a resistor, R
FS
, from the FS pin to GND. The frequency of operation
may be programmed between 500kHz to 4MHz. The default frequency is 1MHz (ISL8026), 2MHz (ISL8026A) if FS is
connected to VIN.
SS is used to adjust the soft-start time. Connect to SGND for internal 1ms rise time. Connect a capacitor from SS to SGND to
adjust the soft-start time. Do not use more than 33nF per IC.
The feedback network of the regulator, FB, is the negative input to the transconductance error amplifier. The output
voltage is set by an external resistor divider connected to FB. With a properly selected divider, the output voltage can be
set to any voltage between the power rail (reduced by converter losses) and the 0.6V reference.
COMP is the output of the amplifier if COMP is not tied to VIN. Otherwise, COMP is disconnected through a MOSFET for
internal compensation. Must connect COMP to VIN in internal compensation mode to meet a typical application.
Additional external networks across COMP and SGND might be required to improve the loop compensation of the amplifier
operation.
In addition, the regulator power-good and undervoltage protection circuitry use FB to monitor the regulator output voltage.
Power ground
Switching node connections. Connect to one terminal of the inductor. This pin is discharged by a 100Ω resistor when the
device is disabled. See
“Block Diagram” on page 5
for more detail.
The exposed pad must be connected to the SGND pin for proper electrical performance. Place as many vias as possible
under the pad connecting to the SGND plane for optimal thermal performance.
5
6
EN
FS
7
8, 9
SS
COMP, FB
10
11, 12
13, 14, 15
Exposed Pad
PGND/SGND Power/signal ground
PGND
PHASE
-
FN8736 Rev 2.00
October 28, 2016
Page 3 of 23
ISL8026, ISL8026A
Ordering Information
PART NUMBER
(Notes
1, 2, 3)
ISL8026IRTAJZ
ISL8026AIRTAJZ
ISL8026FRTAJZ
ISL8026AFRTAJZ
ISL8026EVAL3Z
ISL8026AEVAL3Z
NOTES:
1. Add “-T” suffix for 6k unit or “-T7A” suffix for 250 unit Tape and Reel options. 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.
3. For Moisture Sensitivity Level (MSL), please see device information page for
ISL8026, ISL8026A.
For more information on MSL please see techbrief
TB363.
026A
26AA
026F
026AF
Evaluation board for ISL8026
Evaluation board for ISL8026A
PART
MARKING
OPERATION FREQUENCY
(MHz)
1
2
1
2
TEMP. RANGE
(°C)
-40 to +85
-40 to +85
-40 to +125
-40 to +125
PACKAGE
(RoHS COMPLIANT)
16 Ld 3x3 TQFN
16 Ld 3x3 TQFN
16 Ld 3x3 TQFN
16 Ld 3x3 TQFN
PKG.
DWG. #
L16.3x3D
L16.3x3D
L16.3x3D
L16.3x3D
TABLE 1. SUMMARY OF KEY DIFFERENCES
PART
NUMBER
ISL8026
ISL8026A
I
OUT
(MAX)
(A)
6
f
SW
RANGE
(MHz)
Programmable 0.5MHz to 4MHz
Programmable 1MHz to 4MHz
V
IN
RANGE
(V)
2.5 to 5.5
V
OUT
RANGE
(V)
0.6 to 5.5
PART SIZE
(mm)
3x3
TABLE 2. ISL8026 COMPONENT SELECTION
V
OUT
C
1
C
2
C
3
L
1
R
2
R
3
0.8V
2 x 22µF
4 x 22µF
22pF
0.47~1µH
33kΩ
100kΩ
1.2V
2 x 22µF
2 x 22µF
22pF
0.47~1µH
100kΩ
100kΩ
1.5V
2 x 22µF
2 x 22µF
22pF
0.47~1µH
150kΩ
100kΩ
1.8V
2 x 22µF
2 x 22µF
22pF
0.68~1.5µH
200kΩ
100kΩ
2.5V
2 x 22µF
2 x 22µF
22pF
0.68~1.5µH
316kΩ
100kΩ
3.3V
2 x 22µF
2 x 22µF
22pF
1~2.2µH
450kΩ
100kΩ
3.6V
2 x 22µF
2 x 22µF
22pF
1~2.2µH
500kΩ
100kΩ
TABLE 3. ISL8026A COMPONENT SELECTION
V
OUT
C
1
C
2
C
3
L
1
R
2
R
3
0.8V
22µF
3 x 22µF
22pF
0.22~0.47µH
33kΩ
100kΩ
1.2V
22µF
2 x 22µF
22pF
0.22~0.47µH
100kΩ
100kΩ
1.5V
22µF
2 x 22µF
22pF
0.22~0.47µH
150kΩ
100kΩ
1.8V
22µF
2 x 22µF
22pF
0.33~0.68µH
200kΩ
100kΩ
2.5V
22µF
2 x 22µF
22pF
0.33~0.68µH
316kΩ
100kΩ
3.3V
22µF
2 x 22µF
22pF
0.47~1µH
450kΩ
100kΩ
3.6V
22µF
2 x 22µF
22pF
0.47~1µH
500kΩ
100kΩ
FN8736 Rev 2.00
October 28, 2016
Page 4 of 23
ISL8026, ISL8026A
Block Diagram
COMP
SS
SHUTDOWN
Soft
SOFT-
START
+
55pF
100kΩ
OSCILLATOR
PWM/PFM
LOGIC
CONTROLLER
PROTECTION
HS DRIVER
P
PHASE
LS
DRIVER
N
PGND
VIN
FS
SYNC
SHUTDOWN
EN
-
3pF
+
FB
6kΩ
0.8V
-
+
OV
SLOPE
Slope
COMP
0.85*VREF
+
PG
SGND
0.5V
FN8736 Rev 2.00
October 28, 2016
+
-
-
BANDGAP VREF
EAMP
+
COMP
-
+
CSA
-
+
OCP
-
ISET
THRESHOLD
UV
+
SKIP
-
1ms
DELAY
NEG CURRENT
SENSING
ZERO-CROSS
SENSING
SCP
+
SHUTDOWN
100Ω
FIGURE 3. FUNCTIONAL BLOCK DIAGRAM
Page 5 of 23
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