DATASHEET

High Efficiency Synchronous Boost Converter with
4.2A Switches and Output Disconnect
ISL91117
Features
The ISL91117 is a highly-integrated boost switching regulator
for battery powered applications. The device provides a power
supply solution for products using dual-cell or three-cell
alkaline, NiCd or NiMH, or one-cell Li-ion or Li-polymer battery.
• Input voltage range: 1.8V to 4.8V
This device is capable of delivering an output current of 1.5A
with PVIN = 3.3V and VOUT = 5V. The use of a synchronous
rectifier maximizes efficiency at high loads. No-load quiescent
current of only 35µA optimizes efficiency under light-load
conditions. Forced PWM and/or synchronization to an external
clock may also be selected for noise sensitive applications.
The ISL91117 is designed for standalone applications and
supports 5V fixed output voltage or variable output voltages
with an external resistor divider. Power supply solution size is
minimized by a 2.34mm x 1.72mm WLCSP and a 2.6MHz
switching frequency, which allows for the use of tiny,
low-profile inductors and ceramic capacitors to minimize the
size of the solution.
Related Literature
• Output current: up to 1.5A (PVIN = 3.3V, VOUT = 5V)
• High efficiency: up to 96%
• 35µA quiescent current maximizes light-load efficiency
• True input-output disconnect when disabled
• 2.6MHz switching frequency minimizes external component
size
• Selectable forced-PWM mode and external synchronization
• Fully protected for short-circuit, over-temperature and
undervoltage
• Small 2.34mm x 1.72mm WLCSP
Applications
• Smart phones and tablets
• Wireless communication devices
• AN1918, ISL91117II7-EVZ, ISL91117IIA-EVZ Evaluation
Boards
L1
• Fixed 5V or adjustable output
• Products including portable HDMI and USB-OTG
1µH
100
VIN = 4.2V
95
PVIN
VOUT = 5V
VOUT
VIN
EN
ISL91117
FB
GND
MODE
C2
2x22µF
EFFICIENCY (%)
BLKG
PGND
C1
22µF
90
LX
VIN =
1.8V TO 4.8V
85
VIN = 3.6V
80
VIN = 3.0V
75
VIN = 2.7V
70
65
60
55
50
0.1
1
10
100
1000
LOAD CURRENT (mA)
FIGURE 1. TYPICAL FIXED OUTPUT APPLICATION
March 7, 2014
FN8569.3
1
FIGURE 2. EFFICIENCY vs LOAD CURRENT (VOUT = 5V)
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2014. 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.
ISL91117
Block Diagram
BLKG
A2 B2 C2
LX
A4 B4 C4
A5
A1
PVIN B1
B5 VOUT
Blocking FET
C1
EN D2
REVERSE
CURRENT
GATE
DRIVERS
& ANTISHOOT THRU
C5
SOFT
DISCHARGE
EN
A3
EN
B3 PGND
VREF
VIN D1
C3
PVIN
MONITOR
THERMAL
SHUTDOWN
MODE D3
VOUT
CLAMP
PWM
CONTROL
CURRENT
DETECT
EN
VOUT
MONITOR
EN
EN
OSC
D5 FB
PWM
COMP
REF
ERROR
AMP
VOLTAGE
PROG.
D4
GND
Pin Configuration
Pin Descriptions
ISL91117
(4x5 WLCSP)
TOP VIEW
A1
B1
C1
D1
A2
B2
C2
D2
A3
B3
C3
D3
A4
B4
C4
D4
A5
B5
C5
D5
PIN #
PIN
NAMES
A5, B5, C5
VOUT
A4, B4, C4
LX
2
Boost output. Connect 2x22µF capacitor to
PGND.
Switching node of the boost converter.
A3, B3, C3
PGND Power ground for high switching current.
A2, B2, C2
BLKG
Blocking FET terminal. Connect the input side of
the inductor.
A1, B1, C1
PVIN
Power input. Range: 1.8V to 4.8V. Connect a 22µF
capacitor to PGND.
D1
VIN
Supply input. Range: 1.8V to 4.8V.
D2
EN
Logic input, drive HIGH to enable device.
D3
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DESCRIPTION
MODE Logic input, HIGH for auto PFM mode. LOW for
forced PWM operation. Also, this pin can be used
with an external clock sync input. Range:
2.75MHz to 3.25MHz. Maximum voltage on this
pin should be limited to VIN.
D4
GND
D5
FB
Analog ground pin.
Voltage feedback pin.
FN8569.3
March 7, 2014
ISL91117
Ordering Information
PART NUMBER
(Notes 1, 2, 3)
PART
MARKING
VOUT
(V)
TEMP RANGE
(°C)
PACKAGE
(Pb-free)
PKG.
DWG. #
ISL91117II7Z-T (Note 4)
GAXC
5
-40 to +85
20 Ball WLCSP
W4x5.20F
ISL91117II7Z-T7A (Note 4)
GAXC
5
-40 to +85
20 Ball WLCSP
W4x5.20F
ISL91117IIAZ-T
GAXB
ADJ.
-40 to +85
20 Ball WLCSP
W4x5.20F
ISL91117IIAZ-T7A
GAXB
ADJ.
-40 to +85
20 Ball WLCSP
W4x5.20F
ISL91117II7-EVZ (Note 4)
Evaluation Board for ISL91117II7Z
ISL91117IIA-EVZ
Evaluation Board for ISL91117IIAZ
NOTES:
1. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free WLCSP and BGA packaged products employ special Pb-free material sets; molding compounds/die attach materials and
SnAgCu - e1 solder ball terminals, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free
WLCSP and BGA packaged 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 ISL91117 For more information on MSL please see techbrief TB363.
4. Contact Intersil for Availability.
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FN8569.3
March 7, 2014
ISL91117
Absolute Maximum Ratings
Thermal Information
PVIN, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
LX (Note 7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
FB (ISL91117IIAZ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.7V
FB (ISL91117II7Z) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
MODE/SYNC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VIN+0.3V
GND, PGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 0.3V
All Other Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
ESD Rating
Human Body Model (Tested per JESD22-A114E) . . . . . . . . . . . . . . .2.5kV
Machine Model (Tested per JESD22-A115-A) . . . . . . . . . . . . . . . . . . 200V
Latch Up (Tested per JESD-78B; Class 2, Level A) . . . . . . . . . . . . . . 100mA
Thermal Resistance (Typical)
θJA (°C/W) θJC (°C/W)
20 Ball WLCSP (Notes 5, 6). . . . . . . . . . . . .
66
1.0
Maximum Junction Temperature (Plastic Package) . . . . . . . . . . . .+125°C
Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Recommended Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
Supply Voltage Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8V to 4.8V
Load Current Range (DC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0A to 1.5A
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:
5. θJA 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
6. For θJC, the “case temp” location is taken at the package top center.
7. LX pin can withstand switching transients of -1.5V for 100ns, and 7V for 20ms.
Analog Specifications
VIN = PVIN = EN = 3.6V, VOUT = 5V, L1 = 1µH, C1 = 22µF, C2 = 2 x 22µF, TA = +25°C. Boldface limits apply over
the operating temperature range, -40°C to +85°C and input voltage range (1.8V to 4.8V).
SYMBOL
PARAMETER
TEST CONDITIONS
MIN
(Note 8)
TYP
MAX
(Note 8) UNITS
POWER SUPPLY
VIN
Input Voltage Range
1.8
V
1.775
V
VIN Undervoltage Lockout Threshold
Rising
IVIN
VIN Supply Current
PFM mode, no external load on VOUT (Note 9)
27.5
60
µA
ISD
VIN Supply Current, Shutdown
EN = GND, VIN = 3.6V
0.4
1.0
µA
VUVLO
Falling
1.725
4.8
1.550
1.650
V
OUTPUT VOLTAGE REGULATION
Output Voltage Accuracy
IOUT = 0mA, PWM mode
-2
+2
%
IOUT = 1mA, PFM mode
-3
+4
%
VFB
FB Pin Voltage Regulation
For adjustable output version (ISL91117IIAZ)
IFB
FB Pin Bias Current
For adjustable output version (ISL91117IIAZ)
0.788
0.80
0.812
V
0.2
µA
ΔVOUT/ Line Regulation, PWM Mode
ΔVIN
IOUT = 500mA, MODE = GND, VIN step from 2.3V to 4.8V
±0.005
mV/mV
ΔVOUT/ Load Regulation, PWM Mode
ΔIOUT
VIN = 3.7V, MODE = GND, IOUT step from 0mA to 500mA
±0.005
mV/mA
ΔVOUT/ Line Regulation, PFM Mode
ΔVIN
IOUT = 100mA, MODE = VIN, VIN step from 2.3V to 4.8V
±12.5
mV/V
ΔVOUT/ Load Regulation, PFM Mode
ΔIOUT
VIN = 3.7V, MODE = VIN, IOUT step from 0mA to 100mA
±0.4
mV/mA
VCLAMP Output Voltage Clamp
Rising
5.25
Output Voltage Clamp Hysteresis
5.95
400
V
mV
DC/DC SWITCHING SPECIFICATIONS
fSW
Oscillator Frequency
2.4
tONMIN Minimum On Time
2.9
MHz
+0.5
µA
80
INFETLEAK LX Pin Leakage Current
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2.6
-0.5
4
ns
FN8569.3
March 7, 2014
ISL91117
Analog Specifications
VIN = PVIN = EN = 3.6V, VOUT = 5V, L1 = 1µH, C1 = 22µF, C2 = 2 x 22µF, TA = +25°C. Boldface limits apply over
the operating temperature range, -40°C to +85°C and input voltage range (1.8V to 4.8V). (Continued)
SYMBOL
PARAMETER
TEST CONDITIONS
MIN
(Note 8)
TYP
MAX
(Note 8) UNITS
SOFT-START and SOFT DISCHARGE
Time from when EN signal asserts to when output voltage
ramp starts.
1
ms
Time from when output voltage ramp starts to when
output voltage reaches 95% of its nominal value.
VIN = 2V, IOUT = 200mA
2
ms
EN < VIL
120
Ω
RDSON_P P-Channel MOSFET ON-Resistance
IOUT = 200mA
90
mΩ
RDSON_N N-Channel MOSFET ON-Resistance
IOUT = 200mA
tSS
Soft-start Time
RDISCHG VOUT Soft-Discharge ON-Resistance
POWER MOSFET
IPK_LMT P-Channel MOSFET Peak Current Limit
75
3.7
4.2
mΩ
4.7
A
PFM/PWM TRANSITION
Load Current Threshold, PFM to PWM
200
mA
Load Current Threshold, PWM to PFM
75
mA
External Synchronization Frequency Range
2.75
3.25
MHz
Thermal Shutdown
150
°C
Thermal Shutdown Hysteresis
35
°C
LOGIC INPUTS
ILEAK
Input Leakage
VIH
Input HIGH Voltage
VIL
Input LOW Voltage
0.03
0.5
µA
V
1.4
0.4
V
NOTES:
8. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization
and are not production tested.
9. Quiescent current measurements are taken when the output is not switching.
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FN8569.3
March 7, 2014
ISL91117
Typical Performance Curves
100
90
3.0
80
2.5
EFFICIENCY (%)
MAXIMUM OUTPUT CURRENT (A)
3.5
2.0
1.5
1.0
VIN = 2.7V
70
VIN = 3.0V
60
VIN = 3.6V
VIN = 4.2V
50
40
30
20
0.5
0
1.5
10
2.0
2.5
3.0
3.5
4.0
4.5
0
0.1
5.0
1
VIN (V)
10
100
LOAD CURRENT (mA)
1000
FIGURE 4. EFFICIENCY vs LOAD CURRENT
(VOUT = 5V, MODE = LOW, TA = +25°C)
FIGURE 3. MAXIMUM OUTPUT CURRENT vs INPUT VOLTAGE (VOUT = 5V)
100
140
LOAD = 500mA
95
130
LOAD = 100mA
INPUT CURRENT (µA)
EFFICIENCY (%)
90
LOAD = 10mA
85
LOAD = 1000mA
80
75
70
120
110
100
+85°C
90
80
65
70
60
1.8
60
1.8
+25°C
-40°C
2.3
2.8
3.3
3.8
4.3
4.8
2.3
2.8
3.3
3.8
FIGURE 5. EFFICIENCY vs INPUT VOLTAGE (MODE = HIGH, TA = +25°C)
4.8
FIGURE 6. INPUT CURRENT vs INPUT VOLTAGE (MODE = HIGH)
30
5.01
25
5.00
VIN = 4.2V
VIN = 2.7V
-40°C
+85°C
4.99
20
+25°C
VOUT (V)
INPUT CURRENT (mA)
4.3
VIN (V)
VIN (V)
15
4.98
VIN = 3.0V
4.97
VIN = 3.6V
10
4.96
5
0
1.8
4.95
2.3
2.8
3.3
3.8
4.3
VIN (V)
FIGURE 7. INPUT CURRENT vs INPUT VOLTAGE (MODE = LOW)
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4.8
4.94
0.1
1
10
100
1000
LOAD CURRENT (mA)
FIGURE 8. OUTPUT VOLTAGE vs LOAD CURRENT
(MODE = HIGH, TA = +25°C)
FN8569.3
March 7, 2014
ISL91117
Typical Performance Curves
(Continued)
5.00
5.02
4.99
5.01
4.98
5.00
LOAD = 100mA
4.97
VOUT (V)
VOUT (V)
4.99
VIN = 4.2V
VIN = 2.7V
4.96
4.95
4.94
VIN = 3.6V
4.93
4.98
LOAD = 10mA
4.97
LOAD = 500mA
4.96
VIN = 3.0V
4.95
4.92
4.91
4.94
4.90
4.93
1.8
1
10
100
1000
LOAD = 1000mA
2.3
2.8
3.3
3.8
4.3
4.8
VIN (V)
LOAD CURRENT (mA)
FIGURE 10. OUTPUT VOLTAGE vs INPUT VOLTAGE
(MODE = HIGH, TA = +25°C)
FIGURE 9. OUTPUT VOLTAGE vs LOAD CURRENT
(MODE = LOW, TA = +25°C)
LX (5V/DIV)
LX (5V/DIV)
INDUCTOR CURRENT (500mA/DIV)
INDUCTOR CURRENT (500mA/DIV)
VOUT, 5V OFFSET (20mV/DIV)
VOUT, 5V OFFSET (20mV/DIV)
TIMESCALE (2µs/DIV)
FIGURE 11. PFM MODE OPERATION
(VIN = 3.6V, VOUT = 5V, 10mA LOAD)
VIN (1V/DIV)
VIN (1V/DIV)
VOUT, 5V OFFSET (50mV/DIV)
LOAD CURRENT (20mA/DIV)
VOUT, 5V OFFSET (200mV/DIV)
0mA – 50mA
LOAD TRANSIENT
INDUCTOR CURRENT (1A/DIV)
TIMESCALE (200µs/DIV)
FIGURE 13. LOAD TRANSIENT (VIN = 3.0V, VOUT = 5V)
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TIMESCALE (0.5µs/DIV)
FIGURE 12. PWM MODE OPERATION
(VIN = 3.6V, VOUT = 5V, 200mA LOAD)
7
10mA – 1A LOAD TRANSIENT
(240mA/µs SLEW RATE)
TIMESCALE (200µs/DIV)
FIGURE 14. LOAD TRANSIENT (VIN = 3.0V, VOUT = 5V)
FN8569.3
March 7, 2014
ISL91117
Typical Performance Curves
(Continued)
4.2V – 3.6V
LINE TRANSIENT
3.8V – 3.2V
LINE TRANSIENT
VIN (1V/DIV)
VIN (1V/DIV)
VOUT, 5V OFFSET (200mV/DIV)
VOUT, 5V OFFSET (100mV/DIV)
TIMESCALE (1ms/DIV)
TIMESCALE (500µs/DIV)
FIGURE 15. LINE TRANSIENT (VOUT = 5V)
FIGURE 16. LINE TRANSIENT (VOUT = 5V)
EN (2V/DIV)
EN (2V/DIV)
VOUT (1V/DIV)
VOUT (1V/DIV)
INDUCTOR CURRENT (500mA/DIV)
INDUCTOR CURRENT (500mA/DIV)
TIMESCALE (500µs/DIV)
FIGURE 17. START-UP WITH NO LOAD (VIN = 3.6V, VOUT = 5V)
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TIMESCALE (500µs/DIV)
FIGURE 18. START-UP WITH 25Ω (VIN = 3.6V, VOUT = 5V)
FN8569.3
March 7, 2014
ISL91117
Functional Description
Functional Overview
Refer to the “Block Diagram” on page 2. The ISL91117
implements a complete boost switching regulator, with PWM
controller, internal switches, references, protection circuitry, and
control inputs.
Internal Supply and References
Referring to the “Block Diagram” on page 2, the ISL91117 provides
two power input pins. The PVIN pin supplies input power to the
DC/DC converter, while the VIN pin provides the operating voltage
source required for stable VREF generation. Separate ground pins
(GND and PGND) are provided to avoid problems caused by ground
shift due to the high switching currents.
Enable Input
A master enable pin EN allows the device to be enabled. Driving
the EN pin LOW invokes a power-down mode, where most
internal device functions, including input and output power-good
detection, are disabled.
Soft Discharge
When the device is disabled by driving EN LOW, an internal
resistor between VOUT and GND is activated. This internal
resistor has typical 120Ω resistance.
POR Sequence and Soft-start
Bringing the EN pin HIGH allows the device to power-up. A
number of events occur during the start-up sequence. The
internal voltage reference powers up, and stabilizes. The device
then starts operating. There is a typical 1ms delay between
assertion of the EN pin and the start of switching regulator
soft-start ramp.
The soft-start feature minimizes output voltage overshoot and
input in-rush currents. During soft-start, the reference voltage is
ramped up to provide a ramping VOUT voltage. While the output
voltage is lower than approximately 20% of the target output
voltage, switching frequency is reduced to a fraction of the
normal switching frequency to aid in producing low duty cycles
necessary to avoid input in-rush current spikes. Once the output
voltage exceeds that threshold, switching frequency is increased
to its nominal value.
The soft-start time is typically 3ms. Increasing the load current
will increase these typical soft-start times.
Short Circuit Protection
The ISL91117 provides short-circuit protection by monitoring the
feedback voltage. When feedback voltage is sensed to be lower
than a certain threshold, the PWM oscillator frequency is reduced
in order to protect the device from damage. The P-Channel
MOSFET peak current limit remains active during this state.
Undervoltage Lockout
The undervoltage lockout (UVLO) feature prevents abnormal
operation in the event that the supply voltage is too low to
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9
guarantee proper operation. When the VIN voltage falls below the
UVLO threshold, the regulator is disabled.
Thermal Shutdown
A built-in thermal protection feature protects the ISL91117 if the
die temperature reaches +150°C (typical). At this die
temperature, the regulator is completely shut down. The die
temperature continues to be monitored in this thermal-shutdown
mode. When the die temperature falls to +125°C (typical), the
device will resume normal operation.
When exiting thermal shutdown, the ISL91117 will execute its
soft-start sequence.
External Synchronization
An external sync feature is provided. Applying a clock signal with
a frequency between 2.75MHz and 3.25MHz at the MODE input,
forces the ISL91117 to synchronize to this external clock. The
MODE input supports standard logic levels.
PWM Operation
The control scheme of the device is based on the peak current
mode control, and the control loop is compensated internally.
The peak current of the N-channel MOSFET switch is sensed to
limit the maximum current flowing through the switch and the
inductor.
The control circuit includes ramp generator, slope compensator,
error amplifier, PWM comparator (see “Block Diagram” on page 2).
The ramp signal is derived from the inductor current. This ramp
signal is then compared to the error amplifier output to generate
the PWM gating signals for driving both N-channel and P-channel
MOSFETs. The PWM operation is initialized by the clock from the
internal oscillator (typical 2.6MHz). The N-channel MOSFET is
turned ON at the beginning of a PWM cycle, the P-channel MOSFET
remains OFF, and the current starts ramping up. When the sum of
the ramp and the slope compensator output reaches the error
amplifier output voltage, the PWM comparator outputs a signal to
turn OFF the N-channel MOSFET. Here, both MOSFETs remain OFF
during the dead-time interval, and then the P-channel MOSFET is
turned ON and remains ON until the end of this PWM cycle. During
this time, the inductor current ramps down until the next clock. At
this point, following a short dead time, the N-channel MOSFET is
again turned ON, repeating as previously described.
PFM Operation
The boost converter enters the PFM mode of operation under light
load conditions. When the inductor current is sensed to cross zero,
the converter enters PFM mode. In this mode, each pulse cycle is
still synchronized by the PWM clock. The N-channel MOSFET is
turned ON at the rising edge of the clock and turned OFF when the
inductor peak current reaches a certain current limit. Then the
P-channel MOSFET is turned ON, and it stays ON until the inductor
current goes to zero. Subsequently, both N-channel and P-channel
MOSFETs are turned OFF until the next clock cycle starts, at which
time the N-channel MOSFET is turned ON again.
In most operating conditions, there will be multiple PFM pulses
to charge up the output capacitor. In addition to the inductor
current limit for PFM operation, the PFM pulses are also
controlled by output voltage. These pulses continue until VOUT
FN8569.3
March 7, 2014
ISL91117
Applications Information
Non-Adjustable Version FB Pin Connection
The fixed output version of the ISL91117 does not require
external resistors or a capacitor on the FB pin. Simply connect
VOUT to FB, as shown in Figure 20.
L1
The fixed-output version of the ISL91117 requires only three
external power components to implement the boost converter:
an inductor, an input capacitor, and an output capacitor.
VIN =
1.8V TO 4.8V
C1
22µF
ISL91117
C2
2x
22µF
FB
GND
MODE
FIGURE 20. TYPICAL ISL91117II7Z APPLICATION
BLKG
PVIN
Inductor Selection
VOUT = 5V
VOUT
VIN
EN
VOUT = 5V
VOUT
1µH
ISL91117
C3
R1
320k 22pF
FB
GND
MODE
PGND
VIN = 1.8V
TO 4.8V
PVIN
VIN
EN
LX
L1
BLKG
C1
22µF
The adjustable ISL91117 versions require three additional
components to program the output voltage. Two external
resistors program the output voltage, and a small capacitor is
added to improve stability and response.
1µH
LX
Component Selection
PGND
has achieved the upper threshold of the PFM hysteretic
controller. Switching then stops, and remains stopped until VOUT
decays to the lower threshold of the hysteretic PFM controller.
R2
60.4k
An inductor with high frequency core material (e.g., ferrite core)
should be used to minimize core losses and provide good
efficiency. The inductor must be able to handle the peak
switching currents without saturating.
C2
2x
22µF
A 1µH inductor with ≥4A saturation current rating is
recommended. Select an inductor with low DCR to provide good
efficiency. In applications where radiated noise must be
minimized, a toroidal or shielded inductor can be used.
FIGURE 19. TYPICAL ISL91117IIAZ APPLICATION
TABLE 1. INDUCTOR VENDOR INFORMATION
Output Voltage Programming, Adjustable
Version
MANUFACTURER
Setting and controlling the output voltage of the ISL91117IIAZ
(adjustable output version) can be accomplished by selecting the
external resistor values.
Equation 1 can be used to derive the R1 and R2 resistor values:
R1
V OUT = 0.8V • ⎛ 1 + --------⎞
⎝
R2⎠
(EQ. 1)
When designing a PCB, include a GND guard band around the
feedback resistor network to reduce noise and improve accuracy
and stability. Resistors R1 and R2 should be positioned close to
the FB pin.
Feed-Forward Capacitor Selection
A small capacitor (C3 in Figure 19) in parallel with resistor R1 is
required to provide the specified load and line regulation. The
suggested value of this capacitor is 22pF for R1 = 320kΩ. An
NPO type capacitor is recommended.
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SERIES
WEBSITE
Coilcraft
XFL4020-102ME
www.coilcraft.com
Murata
LQH5BPN1R0NT0 www.murata.com
PVIN and VOUT Capacitor Selection
The input and output capacitors should be ceramic X5R type with
low ESL and ESR. The recommended input capacitor value is
22µF. The recommended VOUT capacitor value is 2x22µF or
47µF.
TABLE 2. CAPACITOR VENDOR INFORMATION
MANUFACTURER
SERIES
WEBSITE
AVX
X5R
www.avx.com
Murata
X5R
www.murata.com
Taiyo Yuden
X5R
www.t-yuden.com
TDK
X5R
www.tdk.com
FN8569.3
March 7, 2014
ISL91117
Recommended PCB Layout
Correct PCB layout is critical for proper operation of the
ISL91117. The input and output capacitors should be positioned
as closely to the IC as possible. The ground connections of the
input and output capacitors should be kept as short as possible,
and should be on the component layer to avoid problems that are
caused by high switching currents flowing through PCB vias.
FIGURE 21. RECOMMENDED LAYOUT
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to web to make sure you
have the latest revision.
DATE
REVISION
CHANGE
March 7, 2014
FN8569.3
Updated Related Literature.
Figure 18 on page 8 Title changed from START-UP WITH NO LOAD (VIN = 3.6V, VOUT = 5V) to START-UP WITH
25Ω (VIN = 3.6V, VOUT = 5V).
February 4, 2014
FN8569.2
Initial Release.
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FN8569.3
March 7, 2014
ISL91117
Package Outline Drawing
W4x5.20F
20 BALL WAFER LEVEL CHIP SCALE PACKAGE (WLCSP 0.4mm PITCH)
Rev 0, 5/13
X
Y
1.200
1.72±0.030
0.400
5
20x 0.265±0.035
2.335±0.030
4
1.600
3
2
1
0.3675
(4X)
0.10
A
B
C
D
0.260
0.200
PIN 1 (A1 CORNER)
TOP VIEW
BOTTOM VIEW
0.05 Z
PACKAGE OUTLINE
Z SEATING PLANE
3
0.240
0.040 BSC
(BACKSIDE COATING)
0.400
0.290
0.265±0.035
x20
0.10M Z X Y
0.05M Z
0.200±0.030
0.540±0.050
RECOMMENDED LAND PATTERN
SIDE VIEW
NOTES:
1. Dimensions and tolerance per ASME Y 14.5M - 1994.
2. Dimension is measured at the maximum bump diameter
parallel to primary datum Z .
3. Primary datum Z and seating plane are defined by the spherical
crowns of the bump.
4. Bump position designation per JESD 95-1, SPP-010.
5. There shall be a minimum clearance of 0.10mm between
the edge of the bump and the body edge.
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FN8569.3
March 7, 2014