DATASHEET
ISL91108
High Efficiency Buck-Boost Regulator with 4.2A Switches
The ISL91108 is a highly-integrated buck-boost switching
regulator that accepts input voltages either above or below the
regulated output voltage. Unlike other buck-boost regulators,
this regulator automatically transitions between operating
modes without significant output disturbance.
This device is capable of delivering up to 2.7A of burst current
(PVIN = 3V, V
OUT
= 3.3V), and provides excellent efficiency due
to its fully synchronous 4-switch architecture. No load
quiescent current of only 27.5µA also optimizes efficiency
under light-load conditions. Forced PWM and/or
synchronization to an external clock may also be selected for
noise sensitive applications.
The ISL91108 is designed for standalone applications and
supports a 3.3V fixed output voltage or variable output
voltages with an external resistor divider. Output voltages as
low as 1V or as high as 5.2V are supported using an external
resistor divider.
The ISL91108 requires only a single inductor and very few
external components. Power supply solution size is minimized
by a 2.34mmx1.72mm WLCSP and a 2.6MHz switching
frequency, which further reduces the size of external
components.
FN8448
Rev 1.00
November 12, 2014
Features
• Accepts input voltages above or below regulated output
voltage
• Automatic and seamless transitions between buck and
boost modes
• Input voltage range: 1.8V to 5.5V
• Output current: up to 1.6A DC (PVIN = 2.8V, V
OUT
= 3.3V)
• Burst current: up to 2.7A (PVIN = 3V, V
OUT
= 3.3V, t
ON
<600µs, t = 4.6ms)
• High efficiency: up to 95%
• 27.5µA quiescent current maximizes light load efficiency
• 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
• Smartphones and tablets
• Wireless communication devices
• 2G/3G/4G power amplifiers
Related Literature
•
AN1903
“ISL91108IIA-EVZ/ISL91108IIN-EVZ Evaluation
Board User Guide”
100
95
V
IN
=
1.8V TO 5.5V
C
1
2x10µF
ISL91108IINZ
EFFICIENCY (%)
PVIN
LX1
L1
1µH
VIN
MODE
EN
LX2
VOUT
FB
PGND
GND
V
OUT
= 3.3V
C2
2x22µF
90
85
80
75
70
65
60
55
50
0.001
0.01
0.1
I
OUT
(A)
1
3.5VIN
3.0VIN
2.7VIN
2.5VIN
4.5VIN
FIGURE 1. TYPICAL FIXED OUTPUT APPLICATION
FIGURE 2. ISL91108IINZ EFFICIENCY vs OUTPUT CURRENT
FN8448 Rev 1.00
November 12, 2014
Page 1 of 9
ISL91108
Block Diagram
LX1
A2 B2 C2
A1
PVIN B1
C1
REVERSE
CURRENT
EN
GATE
DRIVERS
& ANTI-
SHOOT THRU
EN
VIN D1
V
REF
PVIN
MONITOR
THERMAL
SHUTDOWN
MODE D3
VOUT
CLAMP
PWM
CONTROL
CURRENT
DETECT
EN
EN
EN
D5 FB
EN
OSC
REF
ERROR
AMP
VOUT
MONITOR
SOFT
DISCHARGE
EN
A3
B3 PGND
C3
LX2
A4 B4
C4
A5
B5 VOUT
C5
EN D2
VOLTAGE
PROG.
D4
GND
Pin Configuration
ISL91108
(20 BUMP WLCSP)
TOP VIEW
A1
A2
A3
A4
A5
B1
B2
B3
B4
B5
C1
C2
C3
C4
C5
D1
D2
D3
D4
D5
Pin Descriptions
PIN #
A5, B5, C5
A4, B4, C4
A3, B3, C3
A2, B2, C2
A1, B1, C1
D1
D2
D3
PIN NAMES
VOUT
LX2
PGND
LX1
PVIN
VIN
EN
MODE/
SYNC
DESCRIPTION
Buck-boost output. Connect 2x22µF
capacitor to PGND.
Inductor connection, output side.
Power ground for high switching current.
Inductor connection, input side.
Power input. Range: 1.8V to 5.5V. Connect
2x 10µF capacitor to PGND.
Supply input. Range: 1.8V to 5.5V.
Logic input, drive HIGH to enable device.
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.
Analog ground pin.
Voltage feedback pin.
D4
D5
GND
FB
FN8448 Rev 1.00
November 12, 2014
Page 2 of 9
ISL91108
Ordering Information
PART NUMBER
(Notes
1, 2, 3)
ISL91108IINZ-T
ISL91108IINZ-T7A
ISL91108IIAZ-T
ISL91108IIAZ-T7A
ISL91108IIN-EVZ
ISL91108IIA-EVZ
NOTES:
1. 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
ISL91108.
For more information on MSL please see techbrief
TB363.
PART
MARKING
GAZA
GAZA
GAXA
GAXA
VOUT
(V)
3.3
3.3
ADJ.
ADJ.
TEMP RANGE
(°C)
-40 to +85
-40 to +85
-40 to +85
-40 to +85
PACKAGE
Tape and Reel
(Pb-free)
20 Bump WLCSP
20 Bump WLCSP
20 Bump WLCSP
20 Bump WLCSP
PKG.
DWG. #
W4x5.20F
W4x5.20F
W4x5.20F
W4x5.20F
Evaluation Board for ISL91108IINZ
Evaluation Board for ISL91108IIAZ
FN8448 Rev 1.00
November 12, 2014
Page 3 of 9
ISL91108
Absolute Maximum Ratings
PVIN, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
LX1, LX2 (Note
6)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
FB (ISL91108IIAZ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.7V
FB (ISL91108IINZ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
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
Charged Device Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV
Latch Up (Tested per JESD-78B; Class 2, Level A) . . . . . . . . . . . . . . 100mA
Thermal Information
Thermal Resistance (Typical)
JA
(°C/W)
JC
(°C/W)
2.34x1.72 WLCSP (Notes
4, 5).
. . . . . . . . .
66
1.0
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . .+125°C
Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see
TB493
Recommended Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
Supply Voltage (V
IN
) Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8V to 5.5V
Load Current (I
OUT
) Range (DC) . . . . . . . . . . . . . . . . . . . . . . . . . . 0A to 1.6A
Maximum Burst Current (t
ON
<600µs, t = 4.6ms) . . . . . . . . . . . . . . . . .2.7A
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
5. For
JC
, the “case temp” location is the center of the exposed metal pad on the package underside.
6. LX1 and LX2 pins can withstand switching transients of -1.5V for 100ns, and 7V for 20ms.
Analog Specifications
V
IN
= PVIN = EN = 3.6V, V
OUT
= 3.3V, L
1
= 1µH, C
1
= 2x 10µF, C
2
= 2x 22µF, T
A
= +25°C. Boldface limits apply
across the recommended operating temperature range, -40°C to +85°C and input voltage ranges.
SYMBOL
POWER SUPPLY
VIN
V
UVLO
I
VIN
I
SD
VOUT
Input Voltage Range
V
IN
Undervoltage Lockout Threshold
V
IN
Supply Current
V
IN
Supply Current, Shutdown
Output Voltage Range
Output Voltage Accuracy
V
FB
I
FB
VOUT
/
VIN
VOUT
/
I
OUT
VOUT/
VIN
VOUT/
I
OUT
V
CLAMP
FB Pin Voltage Regulation
FB Pin Bias Current
Line Regulation, PWM Mode
Load Regulation, PWM Mode
Line Regulation, PFM Mode
Load Regulation, PFM Mode
Output Voltage Clamp
Output Voltage Clamp Hysteresis
DC/DC SWITCHING SPECIFICATIONS
f
SW
t
ONMIN
I
PFETLEAK
I
NFETLEAK
Oscillator Frequency
Minimum On Time
LX1 Pin Leakage Current
LX2 Pin Leakage Current
-0.5
-0.5
V
IN
= 3.6V
2.4
2.6
80
+0.5
+0.5
2.9
MHz
ns
µA
µA
Rising
Falling
PFM mode, no external load on V
OUT
(Note
8)
EN = GND
ISL91108IIAZ, I
OUT
= 100mA
I
OUT
= 0mA, PWM mode
I
OUT
= 1mA, PFM mode
For adjustable output version (ISL91108IIAZ)
For adjustable output version (ISL91108IIAZ)
I
OUT
= 500mA, MODE = GND, V
IN
step from 2.3V to
5.5V
V
IN
= 3.7V, MODE = GND, I
OUT
step from 0mA to
500mA
I
OUT
= 100mA, MODE = V
IN
, V
IN
step from 2.3V to
5.5V
V
IN
= 3.7V, MODE = V
IN
, I
OUT
step from 0mA to
100mA
Rising
5.25
400
±0.005
±0.005
±12.5
±0.4
5.95
1.00
-2
-3
0.788
0.80
1.550
1.8
1.725
1.650
27.5
0.4
60
1.0
5.20
+2
+4
0.812
0.2
5.5
1.775
V
V
V
µA
µA
V
%
%
V
µA
mV/mV
mV/mA
mV/V
mV/mA
V
mV
PARAMETER
TEST CONDITIONS
MIN
(Note
7)
TYP
MAX
(Note
7)
UNITS
OUTPUT VOLTAGE REGULATION
FN8448 Rev 1.00
November 12, 2014
Page 4 of 9
ISL91108
V
IN
= PVIN = EN = 3.6V, V
OUT
= 3.3V, L
1
= 1µH, C
1
= 2x 10µF, C
2
= 2x 22µF, T
A
= +25°C. Boldface limits apply
across the recommended operating temperature range, -40°C to +85°C and input voltage ranges. (Continued)
SYMBOL
t
SS
Soft-start Time
PARAMETER
TEST CONDITIONS
Time from when EN signal asserts to when output
voltage ramp starts.
Time from when output voltage ramp starts to
when output voltage reaches 95% of its nominal
value with device operating in buck mode.
V
IN
= 4V, I
OUT
= 200mA
Time from when output voltage ramp starts to
when output voltage reaches 95% of its nominal
value with device operating in boost mode.
V
IN
= 2V, I
OUT
= 200mA
R
DISCHG
R
DSON_P
R
DSON_N
I
PK_LMT
VOUT Soft-Discharge ON-Resistance
P-Channel MOSFET ON-Resistance
N-Channel MOSFET ON-Resistance
P-Channel MOSFET Peak Current Limit
Load Current Threshold, PFM to PWM
Load Current Threshold, PWM to PFM
External Synchronization Frequency Range
Thermal Shutdown
Thermal Shutdown Hysteresis
LOGIC INPUTS
I
LEAK
V
IH
V
IL
NOTES:
7. 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.
8. Quiescent current measurements are taken when the output is not switching.
Input Leakage
Input HIGH Voltage
Input LOW Voltage
1.4
0.4
0.03
0.5
µA
V
V
±2%
2.75
150
35
EN < V
IL
I
OUT
= 200mA
I
OUT
= 200mA
3.7
POWER MOSFET
90
75
4.2
200
75
3.25
4.7
mΩ
mΩ
A
mA
mA
MHz
°C
°C
MIN
(Note
7)
TYP
MAX
(Note
7)
UNITS
ms
ms
Analog Specifications
SOFT-START and SOFT DISCHARGE
1
1
2
ms
110
Ω
PFM/PWM TRANSITION
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in the quality certifications found at
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Intersil products are sold by description only. Intersil may modify the circuit design and/or specifications of products at any time without notice, provided that such
modification does not, in Intersil's sole judgment, affect the form, fit or function of the product. Accordingly, the reader is cautioned to verify that datasheets are
current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its
subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or
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For information regarding Intersil Corporation and its products, see
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FN8448 Rev 1.00
November 12, 2014
Page 5 of 9
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