DATASHEET
ISL8117
Synchronous Step-Down PWM Controller
The
ISL8117
is a synchronous buck controller used to generate
POL voltage rails and bias voltage rails for a wide variety of
applications in industrial and general purpose segments. Its
wide input and output voltage ranges make it suitable for
telecommunication and after-market automotive applications.
The ISL8117 uses the valley current modulation technique to
bring hassle-free power supply design with a minimal number
of components and complete protection from unwanted
events.
The ISL8117 offers programmable soft-start and enable
functions along with a power-good indicator for ease of supply
rail sequencing and other housekeeping requirements. In ideal
situations, a complete power supply circuit can be designed
with 10 external components and provide OV/OC/OT
protections in a space conscious 16 Ld 4mmx4mm QFN or
easy to assemble 6.4mmx5mm 16 Ld HTSSOP package. Both
packages use an EPAD to improve thermal dissipation and
noise immunity. Low pin count, fewer external components,
and default internal values makes the ISL8117 an ideal
solution for quick to market simple power supply designs. The
ISL8117 uses internal loop compensation and single resistor
settings for other functions such as operating frequency and
overcurrent protection. Its current mode control with V
IN
feed-
forward enables it to cover various applications even with fixed
internal compensations. The unique DEM/Skipping mode at
light-load dramatically lowers standby power consumption
with consistent output ripple over different load levels.
FN8666
Rev 4.00
Apr 19, 2018
Features
• Wide input voltage range: 4.5V to 60V
• Wide output voltage range: 0.6V to 54V
• Light-load efficiency enhancement
- Low ripple Diode Emulation mode with pulse skipping
• Programmable soft-start
• Supports prebiased output with SR soft-start
• Programmable frequency: 100kHz to 2MHz
• External sync
• PGOOD indicator
• Forced PWM
• Adaptive shoot-through protection
• No external current sense resistor
- Use lower MOSFET r
DS(ON)
• Complete protection
- Overcurrent, overvoltage, over-temperature, undervoltage
• Pb-free (RoHS compliant)
Applications
• PLC and factory automation
• Amusement machines
• Security surveillance
• Servers and data centers
• Switchers and routers
• Telecom and datacom
• LED panels
Related Literature
For a full list of related documents, visit our website
•
ISL8117
product page
VIN
1 EXTBIAS
VIN 16
100
98
96
EFFICIENCY (%)
VOUT
2 EN
BOOT 15
3 CLKOUT
4 MOD
SYNC
SGND
5 PGOOD
UGATE 14
PHASE 13
94
92
90
88
86
84
0
2
4
V
IN
= 18V
V
IN
= 24V
V
IN
= 60V
V
IN
= 36V V = 48V
IN
ISEN 12
6 RT
VCC5V 11
LGATE
10
OCS
PGND 9
7 SS/TRK
8 FB
6
8
10
OUTPUT CURRENT (A)
12
14
16
FIGURE 1. TYPICAL APPLICATION
FIGURE 2. EFFICIENCY
FN8666 Rev 4.00
Apr 19, 2018
Page 1 of 24
ISL8117
Table of Contents
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin Configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Typical Application Schematics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Typical Performance Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Voltage Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Internal 5V Linear Regulator (VCC5V) and External VCC Bias Supply (EXTBIAS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enable and Soft-Start Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Voltage Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tracking Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Light-Load Efficiency Enhancement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Prebiased Power-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frequency Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frequency Synchronization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gate Control Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gate Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adaptive Dead Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Internal Bootstrap Diode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power-Good Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
14
14
14
14
14
15
15
15
15
15
15
16
16
16
16
Protection Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Undervoltage Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Overvoltage Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Over-Temperature Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Feedback Loop Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Layout Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Layout Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
General PowerPAD Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Component Selection Guideline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MOSFET Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Inductor Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Capacitor Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
19
19
19
20
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
L16.4x4A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
M16.173A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
FN8666 Rev 4.00
Apr 19, 2018
Page 2 of 24
ISL8117
Ordering Information
PART NUMBER
(Notes
2, 3)
ISL8117FRZ
ISL8117FRZ-T
ISL8117FRZ-T7A
ISL8117FVEZ
ISL8117FVEZ-T
ISL8117FVEZ-T7A
ISL8117EVAL1Z
ISL8117DEMO1Z
ISL8117EVAL2Z
ISL8117DEMO2Z
ISL8117DEMO3Z
ISL8117DEMO4Z
NOTES:
1. Refer to
TB347
for details about reel specifications.
2. These 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). 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), refer to the
ISL8117
product information page. For more information about MSL, refer to
TB363.
PART
MARKING
81 17FRZ
81 17FRZ
81 17FRZ
8117 FVEZ
8117 FVEZ
8117 FVEZ
TEMP. RANGE
(°C)
-40 to +125
-40 to +125
-40 to +125
-40 to +125
-40 to +125
-40 to +125
TAPE AND REEL
(Units) (Note
1)
-
6k
250
-
2.5k
250
PACKAGE
(RoHS Compliant)
16 Ld 4x4 QFN
16 Ld 4x4 QFN
16 Ld 4x4 QFN
16 Ld HTSSOP
16 Ld HTSSOP
16 Ld HTSSOP
PKG.
DWG. #
L16.4x4A
L16.4x4A
L16.4x4A
M16.173A
M16.173A
M16.173A
Evaluation Board for HTSSOP
Demonstration Board for HTSSOP
Evaluation Board for QFN
Demonstration Board for QFN
Demonstration Board for QFN
Demonstration Board for QFN
Pin Configurations
ISL8117
16 LD 4x4 QFN
TOP VIEW
EXTBIAS
BOOT
ISL8117
16 LD HTSSOP
TOP VIEW
VIN
EN
EXTBIAS
EN
12 UGATE
11 PHASE
CLKOUT
MOD/SYNC
PGOOD
RT
SS/TRK
FB
1
2
3
4
5
6
7
8
SGND
16 VIN
15 BOOT
14 UGATE
13 PHASE
12 ISEN
11
VCC5V
16
CLKOUT
MOD/SYNC
PGOOD
RT
1
2
3
4
5
SS/TRK
15
14
13
SGND
10 ISEN
9
VCC5V
6
FB
7
PGND
8
LGATE/OCS
10 LGATE/OCS
9
PGND
Pin Descriptions
PIN # PIN #
(HTSSOP) (QFN)
3
4
1
2
PIN
NAME
CLKOUT
FUNCTION
Clock signal output. The frequency of the clock signal is the switching frequency set by the resistor from RT to ground.
MOD/SYNC Dual function pin. Connect this pin to VCC5V to select Diode Emulation mode with pulse skipping at light-load. While
connected to ground or floating, the controller operates in PWM mode at light-load.
Connect this pin to an external clock for synchronization. The controller operates in PWM mode at light-load when
synchronized with an external clock.
PGOOD
Open-drain logic output used to indicate the status of output voltage. This pin is pulled down when the output is not within
±11% of the nominal voltage or the EN pin is pulled LOW.
5
3
FN8666 Rev 4.00
Apr 19, 2018
Page 3 of 24
ISL8117
Pin Descriptions
(Continued)
PIN # PIN #
(HTSSOP) (QFN)
6
4
PIN
NAME
RT
FUNCTION
A resistor from this pin to ground adjusts the switching frequency from 100kHz to 2MHz. The switching frequency of the
PWM controller is determined by the resistor, R
T
as shown in
Equation 1.
39.2
-
R
T
=
---------- –
1.96
k
f
SW
(EQ. 1)
Where f
SW
is the switching frequency in MHz.
When this pin is tied to ground, the output frequency is set to 300kHz.
When this pin is tied to VCC5V or floating, the output frequency is set to 600kHz.
7
5
SS/TRK
Dual function pin. When used for soft-starting control, a soft-start capacitor is connected from this pin to ground. A
regulated 2μA soft-starting current charges up the soft-start capacitor. Value of the soft-start capacitor sets the output
voltage ramp.
When used for tracking control, an external supply rail is configured as the master and the output voltage of the master
supply is applied to this pin using a resistor divider. The output voltage will track the master supply voltage.
Output feedback input. Connect FB to a resistive voltage divider from the output to SGND to adjust the output voltage.
Power ground connection. This pin should be connected to the sources of the lower MOSFETs and the (-) terminals of the
external input capacitors.
8
9
10
6
7
8
FB
PGND
LGATE/OCS Low-side MOSFET gate driver output and OC set pin. Connect a 1k to 30k resistor between this pin and ground to set the
overcurrent threshold. If there is no resistor connected from this pin to GND, the overcurrent threshold is automatically
set to the same point as a 10k resistor.
VCC5V
Output of the internal 5V linear regulator. This output supplies bias for the IC, the low-side gate driver and the internal
boot circuitry for the high-side gate driver. The VCC5V pin must always be decoupled to power ground with a minimum of
4.7µF ceramic capacitor placed very close to the pin. Do not allow the voltage at VCC5V to exceed VIN at any time. To
prevent excessive current through the VCC5V pin to the VIN pin, a resistor can be connected from the VIN pin to the power
supply.
Current sense signal input. This pin is used to monitor the voltage drop across the lower MOSFET for current loop feedback
and overcurrent protection.
Phase node connection. This pin is connected to the junction of the upper MOSFET’s source, output filter inductor, and lower
MOSFET’s drain.
High-side MOSFET gate driver output.
Bootstrap pin to provide bias for high-side driver. The positive terminal of the bootstrap capacitor connects to this pin. The
bootstrap diode is integrated to help reduce total cost and reduce layout complexity.
This pin should be tied to the input rail. It provides power to the internal linear drive circuitry and is also used by the
feed-forward controller to adjust the amplitude of the PWM sawtooth. Decouple this pin with a small ceramic capacitor
(0.1µF to 1µF) to ground.
Input from an optional external 5V bias supply. There is an internal switch from this pin to VCC5V. This switch closes and
supplies the IC power, bypassing the internal linear regulator, when voltage at EXTBIAS is higher than 4.7V (typ). Do not
allow voltage at the EXTBIAS pin to exceed VIN at any time. To prevent excessive current through the EXTBIAS pin to the
VIN pin, a resistor can be connected from the VIN pin to the power supply.
Decouple this pin to ground with a small ceramic capacitor (0.1µF to 1µF) when it is in use, otherwise tie this pin to
ground. DO NOT float this pin.
This pin provides an enable/disable function. The output is disabled when the pin is pulled to ground. When the voltage
on the pin reaches 1.6V, the output becomes active. When the pin is floating, it will be enabled in default by internal
pull-up.
This is the small-signal ground common to all control circuitry. It is suggested to route this separately from the high
current ground (PGND). SGND and PGND can be tied together if there is one solid ground plane with no noisy currents
around the chip. All voltage levels are measured with respect to this pin.
EPAD at ground potential. EPAD is connected to SGND internally. However, it is highly recommended to solder it directly
to ground plane for better thermal performance and noise immunity.
11
9
12
13
14
15
16
10
11
12
13
14
ISEN
PHASE
UGATE
BOOT
VIN
1
15
EXTBIAS
2
16
EN
-
-
SGND
EPAD
FN8666 Rev 4.00
Apr 19, 2018
Page 4 of 24
ISL8117
Block Diagram
BOOT
5VCC
UGATE
PHASE
ADAPTIVE
DEAD TIME
V/I SAMPLE TIMING
SS/TRK
POR
ENABLE
BIAS SUPPLIES
REFERENCE
FAULT LATCH
SEE
Note 6
PGOOD EN
VIN
VCC5V
EXTBIAS
SW THRES.
5VCC
LGATE/OCS
PGND LGATE/OCS
PGND
FB
OC
OV/UV
_
+
+ 0.6V
_ REF
SS/TRK
2µA
SS/TRK
PWM
FB
5VCC
VIN
CLKOUT
ISEN
CURRENT
SAMPLE
CURRENT
SAMPLE
DUTY CYCLE
RAMP GENERATOR
CLOCK
MOD/SYNC
LGATE/OCS
+ 1.75V
_ REFERENCE
OC
SAME STATE FOR
2 CLOCK CYCLES
REQUIRED TO LATCH
OVERCURRENT FAULT
RT
SGND
FIGURE 3. BLOCK DIAGRAM
FN8666 Rev 4.00
Apr 19, 2018
Page 5 of 24
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
