DATASHEET
ISL8013A
3A Low Quiescent Current 1MHz High Efficiency Synchronous Buck Regulator
FN7526
Rev 2.01
Dec 3, 2021
The ISL8013A is a high efficiency, monolithic, synchronous
step-down DC/DC converter that can deliver up to 3A
continuous output current from a 2.8V to 5.5V input supply. It
uses a current control architecture to deliver very low duty
cycle operation at high frequency with fast transient response
and excellent loop stability.
Features
The ISL8013A integrates a pair of low ON-resistance
P-Channel and N-Channel internal MOSFETs to maximize
efficiency and minimize external component count. The 100%
duty-cycle operation allows less than 300mV dropout voltage
at 3A output current. High 1MHz pulse-width modulation
(PWM) switching frequency allows for the use of small external
components and the SYNC input enables multiple ICs to
synchronize out-of-phase to reduce ripple and eliminate beat
frequencies.
• 3% output accuracy over temperature, load, line
The ISL8013A can be configured for discontinuous or forced
continuous operation at light load. Forced continuous
operation reduces noise and RF interference while
discontinuous mode provides high efficiency by reducing
switching losses at light loads.
• External synchronization up to 4MHz
Fault protection is provided by internal hiccup mode current
limiting during short circuit and overcurrent conditions, an
output overvoltage comparator and over-temperature monitor
circuit. A power-good output voltage monitor indicates when
the output is in regulation.
• Peak current limiting and hiccup mode short-circuit
protection
The ISL8013A is offered in a space saving 4mmx4mm, Pb-free
QFN package with exposed pad leadframes for low thermal
resistance.
• High efficiency synchronous buck regulator with up to 97%
efficiency
• Power-good (PG) output with a 1ms delay
• 2.8V to 5.5V supply voltage
• 3A output current
• Start-up with prebiased output
• Internal soft-start - 1ms
• Soft-stop output discharge during disable
• 35µA quiescent supply current in PFM mode
• Selectable forced PWM mode and PFM mode
• Less than 1µA logic controlled shutdown current
• 100% maximum duty cycle
• Internal current mode compensation
• Over-temperature protection
• Small 16 Ld 4mmx4mm QFN
• Pb-Free (RoHS compliant)
Applications
• DC/DC POL modules
The ISL8013A includes a pair of low ON-resistance P-Channel
and N-Channel internal MOSFETs to maximize efficiency and
minimize external component count. The 100% duty-cycle
operation allows less than 300mV dropout voltage at 3A.
• µC/µP, FPGA and DSP power
The ISL8013A offers a 1ms Power-Good (PG) timer at
power-up. When shut down, ISL8013A discharges the output
capacitor. Other features include internal soft-start, internal
compensation, overcurrent protection, and thermal shutdown.
• Test and measurement systems
The ISL8013A is offered in a 4mmx4mm 16 Ld QFN package
with 1mm maximum height. The complete converter occupies
less than 0.4in2 area.
FN7526 Rev 2.01
Dec 3, 2021
• Plug-in DC/DC modules for routers and switchers
• Portable instruments
• Li-ion battery powered devices
• Small form factor (SFP) modules
• Barcode readers
Page 1 of 17
© 2009 Renesas Electronics
ISL8013A
Table of Contents
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Typical Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Absolute Maximum Ratings (Reference to GND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Typical Operating Performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PWM Control Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SKIP Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Synchronization Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short-Circuit Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UVLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Soft Start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Discharge Mode (Soft-Stop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power MOSFETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
100% Duty Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
12
13
13
13
13
14
14
14
14
14
14
14
14
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Inductor and Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
15
15
15
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
FN7526 Rev 2.01
Dec 3, 2021
Page 2 of 17
ISL8013A
Ordering Information
PART NUMBER
(Notes 2, 3)
PART
MARKING
ISL8013AIRZ
PACKAGE DESCRIPTION
(RoHS Compliant)
PKG.
DWG. #
CARRIER TYPE
(Note 1)
TEMP. RANGE
16 Ld 4x4 QFN
L16.4x4
Tube
-40 to +85°C
80
13AIRZ
ISL8013AIRZ-T
Reel, 6k
ISL8013AIRZ-T7A
Reel, 250
ISL8013AEVAL2Z
Evaluation Board
NOTES:
1. See 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), see the ISL8013A device information page. For more information about MSL, see TB363.
Pin Configuration
VDD
3
SYNCH
4
LX
LX
LX
13
12 PGND
11 PGND
PAD
10 SGND
9
5
6
7
8
VFB
2
14
PG
VIN
15
NC
1
16
EN
VIN
NC
ISL8013A
(16 LD QFN)
TOP VIEW
SGND
REFER TO AN1365 FOR MORE LAYOUT SUGGESTIONS.
Pin Descriptions
PIN NUMBER
PIN NAME
1, 2
VIN
Input supply voltage. Connect a 10µF ceramic capacitor to power ground.
DESCRIPTION
3
VDD
Input supply voltage for the analog circuitry. Connect to VIN pin.
5
EN
Regulator enable pin. Enable the output when driven to high. Shut down the chip and discharge output capacitor
when driven to low. Do not leave this pin floating.
7
PG
1ms timer output. At power-up or EN HI, this output is a 1ms delayed power-good signal for the output voltage.
4
SYNCH
Mode Selection pin. Connect to logic high or input voltage VDD for PWM mode. Connect to logic low or ground
for PFM mode. Connect to an external function generator for synchronization with the negative edge trigger. Do
not leave this pin floating.
13, 14, 15
LX
11, 12
PGND
Power ground
9, 10
SGND
Signal ground
8
VFB
Buck regulator output feedback. Connect to the output through a resistor divider for adjustable output voltage.
For 0.8V output voltage, connect this pin to the output.
6
NC
Pin 6 is used for ISL8013A production test only. It can be connected to GND for noise immunity in applications.
16
-
Switching node connection. Connect to one terminal of the inductor.
No connect pins.
Exposed Pad
FN7526 Rev 2.01
Dec 3, 2021
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 SGND plane for optimal thermal performance.
Page 3 of 17
ISL8013A
Typical Application
INPUT
2.8V TO 5.5V
VIN
OUTPUT
1.8V
L
1.5µH
LX
C2
2 x 22µF
VDD
C1
2 x 22µF
R2
124k
PGND
C3
47pF
ISL8013A
EN
R1
100k
VFB
R3
100k
PG
SYNCH
SGND
FIGURE 1. TYPICAL APPLICATION DIAGRAM
Block Diagram
SYNCH
SHUTDOWN
SOFTSoft
START
SHUTDOWN
27pF
390k
BANDGAP 0.8V
+
EN
VIN
OSCILLATOR
+
COMP
-
EAMP
-
PWM/PFM
LOGIC
CONTROLLER
PROTECTION
DRIVER
3pF
LX
+
PGND
VFB
SLOPE
Slope
COMP
6k
+
CSA
+
OCP
-
+
0.736V
-
1.4V
+
SKIP
PG
-
-
1ms
DELAY
SGND
0.5V
ZERO-CROSS
SENSING
0.2V
SCP
+
FIGURE 2. FUNCTIONAL BLOCK DIAGRAM
FN7526 Rev 2.01
Dec 3, 2021
Page 4 of 17
ISL8013A
Absolute Maximum Ratings (Reference to GND)
Thermal Information
VIN, VDD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V (DC) or 7V (20ms)
EN, SYNCH, PG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VIN + 0.3V
LX . . . . . . . . . . . . . . . . -1.5V (100ns)/-0.3V (DC) to 6.5V (DC) or 7V (20ms)
VFB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.8V
Thermal Resistance (Typical, Notes 4, 5)
JA (°C/W) JC (°C/W)
16 Ld 4x4 QFN Package . . . . . . . . . . . . .
39
3
Junction Temperature Range . . . . . . . . . . . . . . . . . . . . . . .-55°C to +125°C
Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see TB493
Recommended Operating Conditions
VIN Supply Voltage Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8V to 5.5V
Load Current Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0A to 3A
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions can 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 TB379.
5. JC, case temperature location is at the center of the exposed metal pad on the package underside.
Electrical Specifications
Unless otherwise noted, all parameter limits are established over the recommended operating conditions and
the typical specification are measured at the following conditions unless otherwise noted: TA = -40°C to +85°C, VIN = 3.6V, EN = VDD. Typical values are
at TA = +25°C. Boldface limits apply across the operating temperature range, -40°C to +85°C.
PARAMETER
MIN
(Note 7)
TYP
MAX
(Note 7)
UNITS
Rising, no load
-
2.6
2.8
V
Falling, no load
2.15
2.35
-
V
SYNCH = GND, no load at the output
-
35
-
µA
SYNCH = GND, no load at the output and no switches
switching
-
30
45
µA
SYNCH = VDD, FS = 1MHz, no load at the output
-
6.5
10
mA
VIN = 5.5V, EN = low
-
0.1
2
µA
0.790
0.8
0.810
V
VFB = 0.75V
-
0.1
-
µA
VIN = VO + 0.5V to 5.5V (minimal 2.8V)
-
0.2
-
%/V
-
1
-
ms
SYMBOL
TEST CONDITIONS
INPUT SUPPLY
VIN Undervoltage Lockout Threshold
Quiescent Supply Current
Shut Down Supply Current
VUVLO
IVIN
ISD
OUTPUT REGULATION
Reference Voltage
VREF
VFB Bias Current
IVFB
Line Regulation
Soft-Start Ramp Time Cycle
OVERCURRENT PROTECTION
Current Limit Blanking Time
tOCON
-
17
-
Clock pulses
Overcurrent and Auto Restart Period
tOCOFF
-
4
-
SS cycle
Switch Current Limit
ILIMIT
(Note 6)
4.0
4.8
5.9
A
Peak Skip Limit
ISKIP
(Note 6)
-
1.2
-
A
-
20
-
µA/V
0.213
0.25
0.287
Ω
VIN = 5V, IO = 200mA
-
50
75
mΩ
VIN = 2.8V, IO = 200mA
-
70
100
mΩ
COMPENSATION
Error Amplifier Transconductance
Trans-Resistance
RT
LX
P-Channel MOSFET ON-resistance
FN7526 Rev 2.01
Dec 3, 2021
Page 5 of 17
ISL8013A
Electrical Specifications
Unless otherwise noted, all parameter limits are established over the recommended operating conditions and
the typical specification are measured at the following conditions unless otherwise noted: TA = -40°C to +85°C, VIN = 3.6V, EN = VDD. Typical values are
at TA = +25°C. Boldface limits apply across the operating temperature range, -40°C to +85°C. (Continued)
PARAMETER
MIN
(Note 7)
TYP
MAX
(Note 7)
UNITS
VIN = 5V, IO = 200mA
-
50
75
mΩ
VIN = 2.8V, IO = 200mA
-
70
100
mΩ
-
100
-
0.80
1.00
1.20
MHz
SYNCH = High
-
-
140
ns
Sinking 1mA
-
-
0.3
V
0.65
1
1.35
ms
-
0.01
0.1
µA
SYMBOL
N-Channel MOSFET ON-Resistance
TEST CONDITIONS
LX Maximum Duty Cycle
PWM Switching Frequency
fS
LX Minimum On-Time
PG
Output Low Voltage
Delay Time (Rising Edge)
PG Pin Leakage Current
PG = VIN = 3.6V
PGOOD Rising Threshold
Percentage of regulation voltage
89
92
95
%
PGOOD Falling Threshold
Percentage of regulation voltage
85
88
91.5
%
-
15
-
µs
Logic Input Low
-
-
0.4
V
Logic Input High
1.4
-
-
V
-
0.1
1
µA
-
0.1
1
µA
Thermal Shutdown
-
140
-
°C
Thermal Shutdown Hysteresis
-
25
-
°C
PGOOD Delay Time (Falling Edge)
EN, SYNCH
Synch Logic Input Leakage Current
ISYNCH
Enable Logic Input Leakage Current
IEN
Pulled up to 5.5V
NOTES:
6. Limits established by characterization and are not production tested.
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.
FN7526 Rev 2.01
Dec 3, 2021
Page 6 of 17
ISL8013A
Typical Operating Performance Unless otherwise noted, operating conditions are: TA = +25°C, VIN = 2.5V to 5.5V, EN = VIN,
SYNCH = 0V, L = 1.5µH, C1 = 2x22µF, C2 = 2x22µF, IOUT = 0A to 3A.
100
100
90
2.5VOUT-PWM
80
1.8VOUT-PWM
70
EFFICIENCY (%)
EFFICIENCY (%)
90
1.5VOUT-PWM
1.2VOUT-PWM
60
50
2.5VOUT-PFM
80
1.8VOUT-PFM
1.2VOUT-PFM
70
60
50
40
0.0
0.5
1.0
1.5
2.0
2.5
40
3.0
0.0
0.1
0.2
0.3
OUTPUT LOAD (A)
90
0.9
2.5VOUT-PWM
70
1.8VOUT-PWM
EFFICIENCY (%)
1.0
EFFICIENCY (%)
100
80
1.5VOUT-PWM
1.2VOUT-PWM
3.3VOUT-PWM
60
50
0.8 2.5VOUT-PFM
0.8
0.9
1.0
3.3VOUT-PFM
1.5VOUT-PFM
1.8VOUT-PFM
0.7
1.2VOUT-PFM
0.6
0.5
0.0
0.5
1.0
1.5
2.0
2.5
0.4
0.0
3.0
0.1
0.2
0.3
OUTPUT LOAD (A)
2.00
POWER DISSIPATION (mW)
1.50
1.25
1.00
3.3VIN-PFM
5VIN-PWM
0.75
0.25
0
0.0
0.8
0.9
1.0
125
1.75
0.50
0.4
0.5
0.6
0.7
OUTPUT LOAD (A)
FIGURE 6. EFFICIENCY vs LOAD (1MHz 5VIN PFM)
FIGURE 5. EFFICIENCY vs LOAD (1MHz 5VIN PWM)
POWER DISSIPATION (W)
0.4
0.5
0.6
0.7
OUTPUT LOAD (A)
FIGURE 4. EFFICIENCY vs LOAD (1MHz 3.3 VIN PFM)
FIGURE 3. EFFICIENCY vs LOAD (1MHz 3.3 VIN PWM)
40
1.5VOUT-PFM
3.3VIN-PWM
0.5
5VIN-PFM
1.0
1.5
2.0
2.5
3.0
OUTPUT LOAD (A)
FIGURE 7. POWER DISSIPATION vs LOAD (1MHz, VOUT = 1.8V)
FN7526 Rev 2.01
Dec 3, 2021
100
75
50
25
0
2.0
2.5
3.0
3.5
4.0
VIN (V)
4.5
5.0
FIGURE 8. POWER DISSIPATION WITH NO LOAD vs VIN
(PWM VOUT = 1.8V)
Page 7 of 17
5.5
ISL8013A
Typical Operating Performance Unless otherwise noted, operating conditions are: TA = +25°C, VIN = 2.5V to 5.5V, EN = VIN,
SYNCH = 0V, L = 1.5µH, C1 = 2x22µF, C2 = 2x22µF, IOUT = 0A to 3A. (Continued)
1.55
1.24
1.54
3.3VIN-PFM
1.22
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.23
1.21
1.20
1.19
5VIN-PWM
1.18
5VIN-PFM
3.3VIN-PWM
1.52
1.51
1.50
5VIN-PFM
1.49
0.0
0.5
1.0
1.5
2.0
2.5
1.47
3.0
0.0
0.5
OUTPUT LOAD (A)
3.3VIN-PWM
1.0
1.5
2.0
2.5
FIGURE 10. VOUT REGULATION vs LOAD (1MHz, VOUT = 1.5V)
1.83
2.52
2.51
OUTPUT VOLTAGE (V)
3.3VIN-PFM
5VIN-PWM
1.81
1.80
1.79
1.78 3.3V
IN-PWM
1.77
5VIN-PFM
3.3VIN-PFM
2.50
0.5
1.0
1.5
2.0
OUTPUT LOAD (A)
2.5
3.0
FIGURE 11. VOUT REGULATION vs LOAD (1MHz, VOUT = 1.8V)
3.3VIN-PWM
2.49
2.48
2.47
5VIN-PWM
2.46
5VIN-PFM
2.45
1.76
1.75
0.0
2.44
0.0
0.5
1.0
1.5
2.0
OUTPUT LOAD (A)
2.5
FIGURE 12. VOUT REGULATION vs LOAD (1MHz, VOUT = 2.5V)
3.36
OUTPUT VOLTAGE (V)
3.35
4.5VIN-PWM
5VIN-PWM
3.34
3.33
3.32
3.31
3.30
4.5VIN-PFM
5VIN-PFM
3.29
3.28
0.0
0.5
1.0
1.5
2.0
OUTPUT LOAD (A)
2.5
3.0
FIGURE 13. VOUT REGULATION vs LOAD (1MHz, VOUT = 3.3V)
FN7526 Rev 2.01
Dec 3, 2021
3.0
OUTPUT LOAD (A)
FIGURE 9. VOUT REGULATION vs LOAD (1MHz, VOUT = 1.2V)
1.82
OUTPUT VOLTAGE (V)
5VIN-PWM
1.48
1.17
1.16
3.3VIN-PFM
1.53
Page 8 of 17
3.0
ISL8013A
Typical Operating Performance Unless otherwise noted, operating conditions are: TA = +25°C, VIN = 2.5V to 5.5V, EN = VIN,
SYNCH = 0V, L = 1.5µH, C1 = 2x22µF, C2 = 2x22µF, IOUT = 0A to 3A. (Continued)
1.830
1.830
1.820
0A LOAD PWM
3A LOAD PWM
1.810
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.820
1.800
1.790
1.780
1.770
1.760
1.750
3A LOAD
1.810
0A LOAD
1.800
1.790
1.780
1.770
1.760
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.750
2.0
2.5
3.0
FIGURE 14. OUTPUT VOLTAGE REGULATION vs VIN
(PWM VOUT = 1.8 )
3.5
4.0
4.5
5.0
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
FIGURE 15. OUTPUT VOLTAGE REGULATION vs VIN
(PFM VOUT = 1.8V)
LX 2V/DIV
LX 2V/DIV
VOUT RIPPLE 20mV/DIV
VOUT RIPPLE 20mV/DIV
IL 0.5A/DIV
IL 0.5A/DIV
FIGURE 16. STEADY STATE OPERATION AT NO LOAD (PWM)
FIGURE 17. STEADY STATE OPERATION AT NO LOAD (PFM)
LX 2V/DIV
LX 2V/DIV
IL 1A/DIV
VOUT RIPPLE 20mV/DIV
FIGURE 18. STEADY STATE OPERATION WITH FULL LOAD
FN7526 Rev 2.01
Dec 3, 2021
VOUT RIPPLE 50mV/DIV
IL 1A/DIV
FIGURE 19. MODE TRANSITION CCM TO DCM
Page 9 of 17
5.5
ISL8013A
Typical Operating Performance Unless otherwise noted, operating conditions are: TA = +25°C, VIN = 2.5V to 5.5V, EN = VIN,
SYNCH = 0V, L = 1.5µH, C1 = 2x22µF, C2 = 2x22µF, IOUT = 0A to 3A. (Continued)
LX 2V/DIV
VOUT RIPPLE 50mV/DIV
VOUT RIPPLE 50mV/DIV
IL 1A/DIV
IL 1A/DIV
FIGURE 20. MODE TRANSITION DCM TO CCM
LX 2V/DIV
FIGURE 21. LOAD TRANSIENT (PWM)
EN 5V/DIV
VOUT 0.5V/DIV
VOUT RIPPLE 50mV/DIV
IL 1A/DIV
FIGURE 22. LOAD TRANSIENT (PFM)
EN 5V/DIV
IL 1A/DIV
PG 5V/DIV
FIGURE 23. SOFT-START WITH NO LOAD (PWM)
EN 5V/DIV
VOUT 0.5V/DIV
VOUT 0.5V/DIV
IL 5A/DIV
IL 1A/DIV
PG 5V/DIV
FIGURE 24. SOFT-START AT NO LOAD (PFM)
FN7526 Rev 2.01
Dec 3, 2021
PG 5V/DIV
FIGURE 25. SOFT-START WITH PREBIASED 1V
Page 10 of 17
ISL8013A
Typical Operating Performance Unless otherwise noted, operating conditions are: TA = +25°C, VIN = 2.5V to 5.5V, EN = VIN,
SYNCH = 0V, L = 1.5µH, C1 = 2x22µF, C2 = 2x22µF, IOUT = 0A to 3A. (Continued)
EN 5V/DIV
EN 5V/DIV
VOUT 0.5V/DIV
VOUT 0.5V/DIV
IL 1A/DIV
IL 1A/DIV
PG 5V/DIV
PG 5V/DIV
FIGURE 26. SOFT-START AT FULL LOAD
LX 2V/DIV
FIGURE 27. SOFT-DISCHARGE SHUTDOWN
LX 2V/DIV
IL 1A/DIV
SYNCH 2V/DIV
VOUT RIPPLE 20mV/DIV
IL 1A/DIV
FIGURE 28. STEADY STATE OPERATION AT NO LOAD WITH
FREQUENCY = 2MHz
LX 2V/DIV
SYNCH 2V/DIV
VOUT RIPPLE 20mV/DIV
FIGURE 29. STEADY STATE OPERATION AT FULL LOAD WITH
FREQUENCY = 2MHz
LX 2V/DIV
IL 1A/DIV
SYNCH 2V/DIV
SYNCH 2V/DIV
VOUT RIPPLE 20mV/DIV
IL 1A/DIV
FIGURE 30. STEADY STATE OPERATION AT NO LOAD WITH
FREQUENCY = 4MHz
FN7526 Rev 2.01
Dec 3, 2021
VOUT RIPPLE 20mV/DIV
FIGURE 31. STEADY STATE OPERATION AT FULL LOAD (PWM)
WITH FREQUENCY = 4MHz
Page 11 of 17
ISL8013A
Typical Operating Performance Unless otherwise noted, operating conditions are: TA = +25°C, VIN = 2.5V to 5.5V, EN = VIN,
SYNCH = 0V, L = 1.5µH, C1 = 2x22µF, C2 = 2x22µF, IOUT = 0A to 3A. (Continued)
LX 2V/DIV
PHASE 2V/DIV
VOUT 1V/DIV
VOUT 0.5V/DIV
IL 2A/DIV
IL 2A/DIV
PG 5V/DIV
PG 5V/DIV
FIGURE 33. OUTPUT SHORT-CIRCUIT RECOVERY
FIGURE 32. OUTPUT SHORT-CIRCUIT
5.000
OUTPUT CURRENT (A)
4.875
4.750
OCP_3.3VIN
4.625
4.500
4.375
OCP_5VIN
4.250
4.125
4.000
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
FIGURE 34. OUTPUT CURRENT LIMIT vs TEMPERATURE
Theory of Operation
The ISL8013A is a step-down switching regulator optimized for
battery-powered handheld applications. The regulator operates at
1MHz fixed switching frequency under heavy load conditions to
allow smaller external inductors and capacitors to be used for
minimal printed-circuit board (PCB) area. At light load, the regulator
reduces the switching frequency, unless forced to the fixed
frequency, to minimize the switching loss and to maximize the
battery life. The quiescent current, when the output is not loaded, is
typically only 35µA. The supply current is typically only 0.1µA when
the regulator is shut down.
PWM Control Scheme
Pulling the SYNCH pin HI (>2.5V) forces the converter into PWM
mode, regardless of output current. The ISL8013A employs the
current-mode pulse-width modulation (PWM) control scheme for
fast transient response and pulse-by-pulse current limiting. Figure 2
shows the block diagram. The current loop consists of the oscillator,
the PWM comparator, current sensing circuit and the slope
compensation for the current loop stability. The gain for the current
sensing circuit is typically 250mV/A. The control reference for the
current loops comes from the error amplifier's (EAMP) output.
FN7526 Rev 2.01
Dec 3, 2021
The PWM operation is initialized by the clock from the oscillator.
The P-Channel MOSFET is turned on at the beginning of a PWM
cycle and the current in the MOSFET starts to ramp up. When the
sum of the current amplifier CSA and the slope compensation
(237mV/µs) reaches the control reference of the current loop, the
PWM comparator COMP sends a signal to the PWM logic to turn
off the P-MOSFET and turn on the N-Channel MOSFET. The
N-MOSFET stays on until the end of the PWM cycle. Figure 35
shows the typical operating waveforms during the PWM operation.
The dotted lines illustrate the sum of the slope compensation
ramp and the current-sense amplifier’s CSA output.
The output voltage is regulated by controlling the VEAMP voltage
to the current loop. The bandgap circuit outputs a 0.8V reference
voltage to the voltage loop. The feedback signal comes from the
VFB pin. The soft-start block only affects the operation during the
start-up and will be discussed separately. The error amplifier is a
transconductance amplifier that converts the voltage error signal
to a current output. The voltage loop is internally compensated
with the 27pF and 390kΩ RC network. The maximum EAMP
voltage output is precisely clamped to 1.6V.
Page 12 of 17
ISL8013A
Synchronization Control
VEAMP
The frequency of operation can be synchronized up to 4MHz by an
external signal applied to the SYNCH pin. The falling edge on the
SYNCH triggers the rising edge of the LX pulse. Make sure that the
minimum on time of the LX node is greater than 140ns.
VCSA
DUTY
CYCLE
Overcurrent Protection
The overcurrent protection is realized by monitoring the CSA
output with the OCP comparator, as shown in Figure 2. The current
sensing circuit has a gain of 250mV/A, from the P-MOSFET current
to the CSA output. When the CSA output reaches 1.4V, which is
equivalent to 4.8A for the switch current, the OCP comparator is
tripped to turn off the P-MOSFET immediately. The overcurrent
function protects the switching converter from a shorted output by
monitoring the current flowing through the upper MOSFET.
IL
VOUT
FIGURE 35. PWM OPERATION WAVEFORMS
SKIP Mode
Pulling the SYNCH pin LO (
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