DATASHEET
ISL85413
Wide V
IN
300mA Synchronous Buck Regulator
The ISL85413 is a 300mA synchronous buck regulator with an
input range of 3.5V to 40V. It provides an easy to use, high
efficiency low BOM count solution for a variety of applications.
The ISL85413 integrates both high-side and low-side NMOS
FETs and features a PFM mode for improved efficiency at light
loads. This feature can be disabled if forced PWM mode is
desired. The part switches at a default frequency of 700kHz.
By integrating both NMOS devices and providing internal
configuration, minimal external components are required,
reducing BOM count and complexity of design.
With the wide V
IN
range and reduced BOM, the part provides
an easy to implement design solution for a variety of
applications while giving superior performance. It will provide
a very robust design for high voltage industrial applications as
well as an efficient solution for battery powered applications.
The part is available in a small Pb-free 3mmx3mm TDFN
plastic package with an operation junction temperature range
of -40°C to +125°C.
FN8379
Rev 1.00
March 13, 2015
Features
• Wide input voltage range of 3.5V to 40V
• Synchronous operation for high efficiency
• No compensation required
• Integrated high-side and low-side NMOS devices
• Selectable PFM or forced PWM mode at light loads
• Internal switching frequency 700kHz
• Continuous output current up to 300mA
• Internal soft-start
• Minimal external components required
• Power-good and enable functions available
Applications
• Industrial control
• Medical devices
• Portable instrumentation
• Distributed power supplies
•
Cloud infrastructure
Related Literature
•
AN1929,
“ISL85413EVAL1Z, ISL85412EVAL1Z Evaluation
Boards”
•
AN1931,
“ISL85413DEMO1Z, ISL85412DEMO1Z Wide VIN
Synchronous Buck Regulator - Short Form”
100
V
OUT
U1
MODE
C6
0.1µF
1
2
3
4
f
SW
= 700kHz
VOUT
GND
MAX 300mA
C8
L1
MODE
BOOT
VIN
PGND
PHASE
ISL85413
FB
VCC
PG
EN
8
7
6
5
R2
C5
1µF
PG
EN
R1
C4
90
EFFICIENCY (%)
80
70
60
50
1.0V
OUT
VIN
GND
+3.5 ... +40V
C1
20µF
1.5V
OUT
1.2V
OUT
3.3V
OUT
1.8V
OUT
2.5V
OUT
5.0V
OUT
Device must be
connected to GND
plane with Vias.
9
40
0
0.03 0.06 0.09 0.12 0.15 0.18 0.21 0.24 0.27 0.30
OUTPUT LOAD (A)
FIGURE 1. TYPICAL APPLICATION
FIGURE 2. EFFICIENCY vs LOAD, PFM, V
IN
= 12V
FN8379 Rev 1.00
March 13, 2015
Page 1 of 20
ISL85413
Table of Contents
Pin Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Efficiency Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Typical Performance Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Soft-Start. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power-Good . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PWM Control Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Light Load Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Protection Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Negative Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Over-Temperature Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Boot Undervoltage Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Application Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Simplifying the Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Inductor Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Buck Regulator Output Capacitor Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Layout Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
15
15
15
15
15
16
16
16
16
17
17
17
17
17
17
17
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
About Intersil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
FN8379 Rev 1.00
March 13, 2015
Page 2 of 20
ISL85413
Pin Configuration
ISL85413
(8 LD 3x3 TDFN)
TOP VIEW
MODE 1
BOOT 2
VIN 3
PHASE 4
GND
8
7
6
5
FB
VCC
PG
EN
Pin Descriptions
PIN NUMBER
1
SYMBOL
MODE
PIN DESCRIPTION
Mode Selection pin. Connect to logic high or VCC for PWM mode. Connect to logic low or ground for PFM
mode. Logic ground enables the IC to automatically choose PFM or PWM operation. There is an internal
5MΩ pull-down resistor to prevent an undefined logic state if MODE is left floating.
Floating bootstrap supply pin for the power MOSFET gate driver. The bootstrap capacitor provides the
necessary charge to turn on the internal N-Channel MOSFET. Connect an external 100nF capacitor from this
pin to PHASE.
The input supply for the power stage of the regulator and the source for the internal linear bias regulator.
Place a minimum of 10µF ceramic capacitance from VIN to GND and close to the IC for decoupling.
Switch node output. It connects the switching FETs with the external output inductor.
Regulator enable input. The regulator and bias LDO are held off when the pin is pulled to ground. When the
voltage on this pin rises above 1V, the chip is enabled. Connect this pin to VIN for automatic start-up. Do not
connect EN pin to VCC since the LDO is controlled by EN voltage.
Open drain power-good output that is pulled to ground when the output voltage is below regulation limits
or during the soft-start interval. There is an internal 5MΩ internal pull-up resistor.
Output of the internal 5V linear bias regulator. Decouple to PGND with a 1µF ceramic capacitor at the pin.
Feedback pin for the regulator. FB is the inverting input to the voltage loop error amplifier. COMP is the
output of the error amplifier. The output voltage is set by an external resistor divider connected to FB. In
addition, the PWM regulator’s power-good and UVLO circuits use FB to monitor the regulator output voltage.
Signal ground connections. Connect to application board GND plane with at least 5 vias. All voltage levels
are measured with respect to this pin. The EPAD MUST not float.
2
BOOT
3
4
5
VIN
PHASE
EN
6
7
8
PG
VCC
FB
EPAD
GND
TABLE 1. EXTERNAL COMPONENT SELECTION (Refer To
Figure 1)
V
OUT
(V)
1.0
1.2
1.5
1.8
2.5
3.3
5.0
12.0
C
4
(pF)
100
100
100
100
100
100
100
100
C
8
(µF)
2x22
2x22
2x22
2x22
22
22
22
22
L
1
(µH)
10
10
16
16
22
33
47
100
R
1
(kΩ)
90.9
90.9
90.9
90.9
90.9
90.9
90.9
90.9
R
2
(kΩ)
137
90.9
60.4
45.3
28.7
20
12.4
4.75
FN8379 Rev 1.00
March 13, 2015
Page 3 of 20
ISL85413
Functional Block Diagram
EN
PG
VIN
FB
POWER-
GOOD
LOGIC
EN/SOFT-
START
FB
600mV VREF
FAULT
LOGIC
5M
VCC
BIAS
LDO
BOOT
930mV/A
CURRENT SENSE
GATE
DRIVE
AND
PWM DEADTIME
MODE
OSCILLATOR
PFM
CURRENT
SET
PWM/PFM
SELECT LOGIC
FB
s Q
R Q
PWM
PHASE
5M
ZERO CURRENT
DETECTION
450mV/T Slope
Compensation
(PWM only)
g
m
INTERNAL = 50µs
150k
PGND
INTERNAL
54pF COMPENSATION
PACKAGE
PADDLE
GND
Ordering Information
PART NUMBER
(Notes
1, 2, 3)
ISL85413FRTZ
ISL85413EVAL1Z
ISL85413DEMO1Z
NOTES:
1. Add “-T*” 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.
3. For Moisture Sensitivity Level (MSL), please see device information page for
ISL85413.
For more information on MSL please see techbrief
TB363.
5413
Evaluation Board
Demonstration Board
PART
MARKING
TEMP. RANGE
(°C)
-40 to +125
PACKAGE
(RoHS Compliant)
8 Ld TDFN
PKG.
DWG. #
L8.3x3H
FN8379 Rev 1.00
March 13, 2015
Page 4 of 20
ISL85413
Absolute Maximum Ratings
VIN to GND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +43V
PHASE to GND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VIN + 0.3V (DC)
PHASE to GND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -2V to 44V (20ns)
EN to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +43V
BOOT to PHASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +5.5V
COMP, FS, PG, MODE, SS, VCC to GND. . . . . . . . . . . . . . . . . . -0.3V to +5.9V
FB to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +2.95V
Junction Temperature Range at 0A . . . . . . . . . . . . . . . . . . . . . . . . . .+150°C
ESD Rating
Human Body Model (Tested per JESD22-A114) . . . . . . . . . . . . . . . .2.5kV
Charged Device Model (Tested per JESD22-C101E). . . . . . . . . . . . . . 1kV
Machine Model (Tested per JESD22-A115). . . . . . . . . . . . . . . . . . . . 200V
Latch-up (Tested per JESD-78A; Class 2, Level A) . . . . . . . . . . . . . . 100mA
Thermal Information
Thermal Resistance
JA
(°C/W)
JC
(°C/W)
TDFN Package (Notes
4, 5)
. . . . . . . . . . . . .
47
4
Maximum Junction Temperature (Plastic Package) . . . . . . . . . . . .+150°C
Maximum Storage Temperature Range . . . . . . . . . . . . . .-65°C to +150°C
Operating Junction Temperature Range . . . . . . . . . . . . . .-40°C to +125°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see
TB493
Recommended Operating Conditions
Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40°C to +125°C
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +3.5V to +40V
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
4.
JA
is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
Brief
TB379
for details.
5. For
JC
, the “case temp” location is the center of the exposed metal pad on the package underside.
T
J
= -40°C to +125°C, V
IN
= 3.5V to 40V, unless otherwise noted. Typical values are at T
A
= +25°C. Boldface
limits apply across the junction temperature range, -40°C to +125°C
PARAMETER
SUPPLY VOLTAGE
V
IN
Voltage Range
V
IN
Quiescent Supply Current
V
IN
Shutdown Supply Current
V
CC
Voltage
POWER-ON RESET
V
CC
POR Threshold
OSCILLATOR
Nominal Switching Frequency
Minimum Off-Time
Minimum On-Time
ERROR AMPLIFIER
Error Amplifier Transconductance Gain
FB Leakage Current
Current Sense Amplifier Gain
FB Voltage
R
T
T
A
= -40°C to +125°C
gm
V
FB
= 0.6V
0.84
0.589
50
1
0.93
0.599
100
1.02
0.606
µA/V
nA
V/A
V
f
SW
t
OFF
t
ON
V
IN
= 3.5V
(Note
9)
600
700
130
90
784
kHz
ns
ns
Rising Edge
Falling Edge
2.76
3.3
3
3.46
V
V
V
IN
I
Q
I
SD
V
CC
V
FB
= 0.7V, MODE = 0V
EN = 0V, V
IN
= 40V (Note
6)
V
IN
= 40V
V
IN
= 12V; I
OUT
= 0A to 10mA
4.5
4.35
3.5
50
1.8
5.1
5
2.5
5.5
5.45
40
V
µA
µA
V
V
SYMBOL
TEST CONDITIONS
MIN
(Note
8)
TYP
MAX
(Note
8)
UNITS
Electrical Specifications
FN8379 Rev 1.00
March 13, 2015
Page 5 of 20
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