ISL8002A [RENESAS]
Compact Synchronous Buck Regulators;
| 型号： | ISL8002A |
| 厂家： | 
RENESAS TECHNOLOGY CORP |
| 描述： | Compact Synchronous Buck Regulators |
| 文件： | 总23页 (文件大小：1828K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DATASHEET
ISL8002, ISL8002A, ISL80019, ISL80019A
Compact Synchronous Buck Regulators
FN7888
Rev 4.00
July 31, 2014
The ISL8002, ISL8002A, ISL80019 and ISL80019A are highly
efficient, monolithic, synchronous step-down DC/DC converters
that can deliver up to 2A of continuous output current from a 2.7V
to 5.5V input supply. They use peak current mode control
architecture to allow very low duty cycle operation. They operate
at either 1MHz or 2MHz switching frequency, thereby providing
superior transient response and allowing for the use of small
inductors. They also have excellent stability and provide both
internal and external compensation options.
Features
• V range 2.7V to 5.5V
IN
• V
range is 0.6V to V
OUT
IN
maximum is 1.5A or 2A (see Table 1 on page 3)
• I
OUT
• Switching frequency is 1MHz or 2MHz (see Table 1 on page 3)
• Internal or external compensation option
• Selectable PFM or PWM operation option
• Overcurrent and short circuit protection
The ISL8002, ISL8002A, ISL80019 and ISL80019A integrate
very low r
MOSFETs in order to maximize efficiency. In
DS(ON)
addition, since the high-side MOSFET is a PMOS, the need for a
Boot capacitor is eliminated, thereby reducing external
component count. They can operate at 100% duty cycle (at 1MHz)
with a dropout of 200mV at 2A output current.
• Over-temperature/thermal protection
• V Undervoltage Lockout and V
IN
Overvoltage Protection
OUT
• Up to 95% peak efficiency
These devices can be configured for either PFM (discontinuous
conduction) or PWM (continuous conduction) operation at light
load. PFM provides high efficiency by reducing switching losses at
light loads and PWM reduces noise susceptibility and RF
interference.
Applications
• General purpose point of load DC/DC
• Set-top boxes and cable modems
• FPGA power
These devices are offered in a space saving 8 pin 2mmx2mm
TDFN lead free package with exposed pad for improved thermal
performance. The complete converter occupies less than
• DVD, HDD drives, LCD panels, TV
Related Literature
• See AN1803, “1.5A/2A Low Quiescent Current High
Efficiency Synchronous Buck Regulator”
2
0.10in area.
ISL8002
L1
100
90
1.2μH
+1.8V/2A
+2.7V …+5.5V
1
2
3
4
8
7
6
5
VIN
PHASE
PGND
FB
VOUT
GND
VIN
C1
C5
C6
22μF
22μF
22μF
GND
EN
80
R1
200k 1%
+0.6V
EN
PG
MODE
PG
70
R2
100k 1%
2.5V
1.8V
1.5V
1.2V
0.9V
0.8V
OUT
OUT
OUT
OUT
OUT
OUT
COMP
PAD
60
50
40
9
V
O
(EQ. 1)
-----------
R
= R
– 1
0.0 0.2
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
OUTPUT LOAD (A)
1
2
VFB
FIGURE 1. TYPICAL APPLICATION CIRCUIT CONFIGURATION
(INTERNAL COMPENSATION OPTION)
FIGURE 2. EFFICIENCY vs LOAD
F
= 1MHz, V = 3.3V, MODE = PFM, T = +25°C
SW
IN
A
FN7888 Rev 4.00
July 31, 2014
Page 1 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Table of Contents
Pin Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Pin Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Typical Performance Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
PWM Control Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
PFM Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Short-Circuit Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Negative Current Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
PG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
UVLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Enable, Disable, and Soft-Start Up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Discharge Mode (Soft-Stop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
100% Duty Cycle (1MHz Version). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Thermal ShutDown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Power Derating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Output Inductor and Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Output Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Output Capacitor Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Loop Compensation Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Layout Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
About Intersil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
FN7888 Rev 4.00
July 31, 2014
Page 2 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
TABLE 1. SUMMARY OF KEY DIFFERENCES
I
(MAX)
F
V
RANGE
(V)
V
OUT
RANGE
(V)
PACKAGE
SIZE
OUT
(A)
SW
IN
PART#
ISL80019
ISL80019A
ISL8002
(MHz)
1.5
1.5
2
1
2
1
2
2.7 to 5.5
0.6 to 5.5
8 pin 2mmx2mm TDFN
ISL8002A
2
NOTE: In this datasheet, the parts in the table above are collectively called "device".
TABLE 2. COMPONENT VALUE SELECTION TABLE
V
C1
(µF)
C5, C6
(µF)
C4
(pF)
L1
(µH)
R1
(kΩ)
R2
(kΩ)
OUT
(V)
0.8
1.2
1.5
1.8
2.5
3.3
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
1.0~2.2
1.0~2.2
1.0~2.2
1.0~3.3
1.5~3.3
1.5~4.7
33
100
100
100
100
100
100
100
150
200
316
450
FN7888 Rev 4.00
July 31, 2014
Page 3 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Pin Configuration
ISL8002, ISL8002A, ISL80019, ISL80019A
(8 LD 2x2 TDFN)
TOP VIEW
VIN
EN
1
2
3
4
8
7
6
5
PHASE
PGND
FB
THERMAL
PAD
(GND)
PIN 9
MODE
PG
COMP
Pin Descriptions
PIN #
PIN NAME
PIN DESCRIPTION
1
VIN
The input supply for the power stage of the PWM regulator and the source for the internal linear regulator that provides
bias for the IC. Place a minimum of 10µF ceramic capacitance from VIN to GND and as close as possible to the IC for
decoupling.
2
3
EN
Device enable input. When the voltage on this pin rises above 1.4V, the device is enabled. The device is disabled when
the pin is pulled to ground. When the device is disabled, a 100Ω resistor discharges the output through the PHASE pin.
See Figure 3, “FUNCTIONAL BLOCK DIAGRAM” on page 5 for details.
MODE
Mode selection pin. Connect to logic high or input voltage VIN for PWM mode. Connect to logic low or ground for PFM
mode. There is an internal 1MΩ pull-down resistor to prevent an undefined logic state in case the MODE pin is left
floating, however, it is not recommended to leave this pin floating.
4
5
PG
Power-good output is pulled to ground during the soft-start interval and also when the output voltage is below regulation
limits. There is an internal 5MΩ internal pull-up resistor on this pin.
COMP
COMP is the output of the error amplifier. When COMP is tied high to VIN, compensation is internal. When COMP is
connected with a series resistor and capacitor to GND, compensation is external. See “Loop Compensation Design” on
page 20 for more detail.
6
FB
Feedback pin for the regulator. FB is the negative input to the voltage loop error amplifier. The output voltage is set by
an external resistor divider connected to FB. In addition, the power-good PWM regulator’s power-good and undervoltage
protection circuits use FB to monitor the output voltage.
7
8
PGND
Power and analog ground connections. Connect directly to the board GROUND plane.
PHASE
Power stage switching node for output voltage regulation. Connect to the output inductor. This pin is discharged by an
100Ω resistor when the device is disabled. See Figure 3, “FUNCTIONAL BLOCK DIAGRAM” on page 5 for details.
9
THERMAL PAD Power ground. This thermal pad provides a return path for the power stage and switching currents, as-well-as a thermal
(T-PAD) path for removing heat from the IC to the board. Place thermal vias to the PGND plane in this pad.
FN7888 Rev 4.00
July 31, 2014
Page 4 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Functional Block Diagram
COMP
MODE
27pF
SOFT-
SHUTDOWN
*
START
200kΩ
+
+
VIN
OSCILLATOR
EN
VREF
BANDGAP
+
EAMP
COMP
-
P
N
-
PWM/PFM
LOGIC
SHUTDOWN
PHASE
PGND
CONTROLLER
PROTECTION
HS DRIVER
3pF
+
FB
SLOPE
COMP
1.15*VREF
6kΩ
+
-
-
CSA
OV
+
+
-
OCP
SKIP
-
0.85*VREF
VIN
5MΩ
+
UV
+
-
PG
1ms
DELAY
NEG CURRENT
SENSING
ZERO-CROSS
SENSING
-
SCP
+
0.3V
100Ω
SHUTDOWN
By default, when COMP is tied to VIN, the voltage loop is internally compensated with the 27pF and 200kΩ RC network.
*
Page 4
Please see "COMP" pin in the “Pin Descriptions” table on
for more details.
FIGURE 3. FUNCTIONAL BLOCK DIAGRAM
FN7888 Rev 4.00
July 31, 2014
Page 5 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Ordering Information
PACKAGE
Tape and Reel
(Pb-Free)
PART NUMBER
(Notes 1, 2, 3)
TAPE AND REEL
QUANTITY
PART
MARKING
TECHNICAL
SPECIFICATIONS
TEMP. RANGE
(°C)
PKG.
DWG. #
ISL8002IRZ-T
1000
250
002
002
02A
02A
019
019
19A
19A
02F
02F
2AF
2AF
19F
19F
9AF
9AF
2A, 1MHz
2A, 1MHz
-40 to +85
-40 to +85
-40 to +85
-40 to +85
-40 to +85
-40 to +85
-40 to +85
-40 to +85
-40 to +125
-40 to +125
-40 to +125
-40 to +125
-40 to +125
-40 to +125
-40 to +125
-40 to +125
8 Ld TDFN
L8.2x2C
ISL8002IRZ-T7A
ISL8002AIRZ-T
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
8 Ld TDFN
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
L8.2x2C
1000
2A, 2MHz
ISL8002AIRZ-T7A
ISL80019IRZ-T
250
2A, 2MHz
1000
1.5A, 1MHz
1.5A, 1MHz
1.5A, 2MHz
1.5A, 2MHz
2A, 1MHz
ISL80019IRZ-T7A
ISL80019AIRZ-T
ISL80019AIRZ-T7A
ISL8002FRZ-T
250
1000
250
1000
ISL8002FRZ-T7A
ISL8002AFRZ-T
ISL8002AFRZ-T7A
ISL80019FRZ-T
ISL80019FRZ-T7A
ISL80019AFRZ-T
ISL80019AFRZ-T7A
ISL8002EVAL1Z
ISL8002AEVAL1Z
250
2A, 1MHz
1000
2A, 2MHz
250
2A, 2MHz
1000
1.5A, 1MHz
1.5A, 1MHz
1.5A, 2MHz
1.5A, 2MHz
250
1000
250
Evaluation Board
Evaluation Board
ISL80019AEVAL1Z Evaluation Board
ISL80019EVAL1Z
NOTES:
Evaluation Board
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 ISL8002, ISL8002A, ISL80019, ISL80019A. For more information on
MSL please see techbrief TB363.
FN7888 Rev 4.00
July 31, 2014
Page 6 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Absolute Maximum Ratings
Thermal Information
VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V (DC) or 7V (20ms)
PHASE . . . . . . . . . . . . . . -1.5V (100ns)/-0.3V (DC) to 6V (DC) or 7V (20ms)
EN, COMP, PG, MODE. . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VIN + 0.3V
FB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.7V
Junction Temperature Range at 0A . . . . . . . . . . . . . . . . . . . . . . . . . .+150°C
Thermal Resistance (Typical, Notes 4, 5)
2x2 TDFN Package . . . . . . . . . . . . . . . . . . .
Junction Temperature Range . . . . . . . . . . . . . . . . . . . . . . .-55°C to +125°C
Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see TB493
(°C/W)
71
(°C/W)
7
JA
JC
Recommended Operating Conditions
VIN Supply Voltage Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7V to 5.5V
Load Current Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0A to 2A
Junction Temperature Range . . . . . . . . . . . . . . . . . . . . . . .-40°C to +125°C
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. is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
JA
Brief TB379 for details.
5. For , the “case temp” location is the center of the exposed metal pad on the package underside.
JC
Electrical Specifications T = -40°C to +125°C, V = 2.7V to 5.5V, unless otherwise noted. Typical values are at T = +25°C. Boldface
J
IN
A
limits apply across the operating temperature range, -40°C to +85°C.
MIN
MAX
PARAMETER
INPUT SUPPLY
Undervoltage Lockout Threshold
SYMBOL
TEST CONDITIONS
(Note 6)
TYP
(Note 6)
UNITS
V
V
Rising, no load
2.5
2.4
35
2.7
V
V
IN
UVLO
Falling, no load
2.2
Quiescent Supply Current
I
MODE = PFM (GND), F
the output
= 2MHz, no load at
= 1MHz, no load at
= 2MHz, no load at
60
15
22
10
µA
VIN
SW
SW
SW
MODE = PWM (VIN), F
the output
7
10
5
mA
mA
µA
MODE = PWM (VIN), F
the output
Shut Down Supply Current
OUTPUT REGULATION
Feedback Voltage
I
MODE = PFM (GND), V = 5.5V, EN = low
IN
SD
V
0.595
0.589
-120
0.600
0.605
0.605
350
V
V
FB
T = -40°C to +125°C
J
VFB Bias Current
Line Regulation
I
V
= 2.7V. T = -40°C to +125°C
50
nA
%/V
VFB
FB
IN
J
V
= V + 0.5V to 5.5V (minimal 2.7V)
-0.2
-0.05
0.1
O
T = -40°C to +125°C
J
Load Regulation
See Note 7
< -0.2
1
%/A
ms
Soft-Start Ramp Time Cycle
PROTECTIONS
Positive Peak Current Limit
IPLIMIT
2A application
3
3.5
2.5
4
A
A
1.5A application
2.1
2.9
Peak Skip Limit
I
V
= 3.6, V
IN OUT
= 1.8V (See “Applications
450
mA
SKIP
Information” on page 19 for more detail)
Zero Cross Threshold
Negative Current Limit
Thermal Shutdown
-170
-2.3
-70
-1.5
150
30
-1
mA
A
INLIMIT
Temperature rising
°C
FN7888 Rev 4.00
July 31, 2014
Page 7 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Electrical Specifications T = -40°C to +125°C, V = 2.7V to 5.5V, unless otherwise noted. Typical values are at T = +25°C. Boldface
J
IN
A
limits apply across the operating temperature range, -40°C to +85°C. (Continued)
MIN
MAX
PARAMETER
Thermal Shutdown Hysteresis
COMPENSATION
SYMBOL
TEST CONDITIONS
Temperature falling
(Note 6)
TYP
25
(Note 6)
UNITS
°C
Error Amplifier Trans-Conductance
COMP tied VIN
COMP with RC
40
120
0.3
µA/V
µA/V
Ω
Trans-Resistance
RT
0.24
0.40
LX
P-Channel MOSFET ON-Resistance
N-Channel MOSFET ON-Resistance
LX Maximum Duty Cycle
LX Minimum On-Time
OSCILLATOR
V
V
= 5V, I = 200mA
117
86
mΩ
mΩ
IN
O
= 5V, I = 200mA
IN
O
100
60
MODE = PWM (High) 1MHz
80
ns
Nominal Switching Frequency
F
ISL8002, ISL80019
850
1000
2000
1150
2300
kHz
kHz
SW
ISL8002A, ISL80019A
1700
PG
Output Low Voltage
Delay Time (Rising Edge)
PGOOD Delay Time (Falling Edge)
PG Pin Leakage Current
OVP PG Rising Threshold
OVP PG Hysteresis
UVP PG Rising Threshold
UVP PG Hysteresis
EN AND MODE LOGIC
Logic Input Low
1mA sinking current
0.3
2
V
ms
µs
µA
%
0.5
1
15
0.01
115
5
PG = V
0.1
IN
110
80
120
%
85
5
90
%
%
0.4
8
V
V
Logic Input High
1.4
Logic Input Leakage Current
NOTES:
I
Pulled up to 5.5V
5.5
µA
MODE
6. 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.
7. Not tested in production. Characterized using evaluation board. Refer to Figures 12 through 14 load regulation diagrams. +105°C T represents near
A
worst case operating point.
FN7888 Rev 4.00
July 31, 2014
Page 8 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Typical Performance Curves
100
100
90
80
70
60
50
40
90
80
70
2.5V
1.8V
1.5V
1.2V
0.9V
0.8V
2.5V
1.8V
1.5V
1.2V
0.9V
0.8V
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
60
50
40
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.0 0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
OUTPUT LOAD (A)
OUTPUT LOAD (A)
FIGURE 4. EFFICIENCY vs LOAD
FIGURE 5. EFFICIENCY vs LOAD
F
= 2MHz, V = 3.3V, MODE = PFM, T = +25°C
F
= 2MHz, V = 3.3V, MODE = PWM, T = +25°C
SW
IN
A
SW
IN
A
100
90
80
70
60
50
40
100
90
80
70
60
50
40
2.5V
1.8V
1.5V
1.2V
0.9V
0.8V
OUT
OUT
OUT
OUT
OUT
OUT
2.5V
1.8V
1.5V
1.2V
0.9V
0.8V
OUT
OUT
OUT
OUT
OUT
OUT
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
OUTPUT LOAD (A)
OUTPUT LOAD (A)
FIGURE 6. EFFICIENCY vs LOAD
FIGURE 7. EFFICIENCY vs LOAD
F
= 1MHz, V = 3.3V, MODE = PFM, T = +25°C
F
= 1MHz, V = 3.3V, MODE = PWM, T = +25°C
SW
IN
A
SW
IN
A
100
90
80
70
60
50
40
100
90
80
70
60
50
40
3.3V
2.5V
1.8V
1.5V
1.2V
0.9V
3.3V
2.5V
1.8V
1.5V
1.2V
0.9V
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.0 0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
OUTPUT LOAD (A)
OUTPUT LOAD (A)
FIGURE 8. EFFICIENCY vs LOAD
= 2MHz, V = 5V, MODE = PFM, T = +25°C
FIGURE 9. EFFICIENCY vs LOAD
F
F
= 2MHz, V = 5V, MODE = PWM, T = +25°C
SW
IN
A
SW
IN
A
FN7888 Rev 4.00
July 31, 2014
Page 9 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Typical Performance Curves (Continued)
100
100
90
80
70
60
50
40
90
80
70
60
50
40
3.3V
2.5V
1.8V
1.5V
1.2V
0.9V
0.8V
3.3V
2.5V
1.8V
1.5V
1.2V
0.9V
0.8V
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
0.0 0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
OUTPUT LOAD (A)
OUTPUT LOAD (A)
FIGURE 10. EFFICIENCY vs LOAD
= 1MHz, V = 5V, MODE = PFM, T = +25°C
FIGURE 11. EFFICIENCY vs LOAD
= 1MHz, V = 5V, MODE = PWM, T = +25°C
F
F
SW
SW
IN
A
IN
A
0.1
0.0
0.1
0.0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.1
-0.2
-0.3
AVERAGE
HIGH
AVERAGE
HIGH
-0.4
-0.5
-0.6
LOW
LOW
6 SIGMA
6 SIGMA
-0.6
0.5
0.5
1.0
LOAD CURRENT
1.0
LOAD CURRENT
0
1.5
2.0
0
1.5
2.0
FIGURE 12. LOAD REGULATION, T = +105°C, 2.7V , 0.6V
, 1MHz
FIGURE 13. LOAD REGULATION, T = +105°C, 3.3V , 0.6V
, 1MHz
A
IN
OUT
A
IN OUT
0.0
-0.1
-0.2
-0.3
-0.4
AVERAGE
HIGH
LOW
-0.5
-0.6
6 SIGMA
0.5
1.0
LOAD CURRENT
1.5
2.0
0
FIGURE 14. LOAD REGULATION, T = +105°, 5.5V , 0.6V
, 1MHz
A
IN OUT
FN7888 Rev 4.00
July 31, 2014
Page 10 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Typical Performance Curves (Continued)
1.230
1.225
1.220
1.215
1.210
1.205
1.200
0.925
5V PFM
IN
5V PWM
IN
3.3V PWM
IN
3.3V PFM
IN
5V PFM
IN
5V PWM
IN
3.3V PWM
IN
3.3V PFM
IN
0.920
0.915
0.910
0.905
0.900
0.895
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
OUTPUT LOAD (A)
OUTPUT LOAD (A)
FIGURE 16. V
F
REGULATION vs LOAD,
FIGURE 15. V
F
REGULATION vs LOAD,
OUT
SW
OUT
SW
= 2MHz, V
= 1.2V, T = +25°C
= 2MHz, V
= 0.9V, T = +25°C
OUT
A
OUT
A
1.520
1.515
1.510
1.505
1.500
1.495
1.490
1.810
1.805
5V PFM
IN
5V PWM
IN
3.3V PWM
IN
3.3V PFM
IN
5V PFM
IN
5V PWM
IN
3.3V PWM
IN
3.3V PFM
IN
1.800
1.795
1.790
1.785
1.780
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8 2.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
OUTPUT LOAD (A)
OUTPUT LOAD (A)
FIGURE 17. V
F
REGULATION vs LOAD,
FIGURE 18. V
F
REGULATION vs LOAD,
OUT
SW
OUT
SW
= 2MHz, V
= 1.5V, T = +25°C
= 2MHz, V
= 1.8V, T = +25°C
OUT
A
OUT A
3.335
3.330
3.325
3.320
3.315
3.310
3.305
2.505
2.500
2.495
2.490
2.485
2.480
2.475
5V PFM MODE
5V PFM
IN
5V PWM
IN
3.3V PWM
IN
3.3V PFM
IN
IN
5V PWM MODE
IN
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
OUTPUT LOAD (A)
OUTPUT LOAD (A)
FIGURE 19. V
F
REGULATION vs LOAD,
FIGURE 20. V
F
REGULATION vs LOAD,
OUT
SW
OUT
SW
= 2MHz, V
= 2.5V, T = +25°C
= 2MHz, V = 3.3V, T = +25°C
OUT
A
OUT A
FN7888 Rev 4.00
July 31, 2014
Page 11 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Typical Performance Curves (Continued)
LX 5V/DIV
1V/DIV
LX 5V/DIV
V
1V/DIV
V
OUT
OUT
VEN 1V/DIV
PG 5V/DIV
VEN 2V/DIV
PG 5V/DIV
1ms/DIV
1ms/DIV
FIGURE 21. START-UP AT NO LOAD
FIGURE 22. START-UP AT NO LOAD
F
= 2MHz, V = 5V, MODE = PFM, T = +25°C
SW
IN
A
F
= 2MHz, V = 5V, MODE = PWM, T = +25°C
SW
IN
A
LX 5V/DIV
LX 5V/DIV
V
1V/DIV
V
1V/DIV
OUT
OUT
VEN 2V/DIV
PG 5V/DIV
VEN 2V/DIV
PG 5V/DIV
1ms/DIV
FIGURE 23. SHUTDOWN AT NO LOAD
= 2MHz, V = 5V, MODE = PFM, T = +25°C
1ms/DIV
FIGURE 24. SHUTDOWN AT NO LOAD
= 2MHz, V = 5V, MODE = PWM, T = +25°C
F
F
SW
SW
IN
A
IN
A
LX 5V/DIV
LX 5V/DIV
V
1V/DIV
OUT
V
1V/DIV
OUT
VEN 2V/DIV
PG 5V/DIV
VEN 2V/DIV
PG 5V/DIV
1ms/DIV
FIGURE 25. START-UP AT 2A LOAD
= 2MHz, V = 5V, MODE = PWM, T = +25°C
1ms/DIV
FIGURE 26. SHUTDOWN AT 2A LOAD
F
F
= 2MHz, V = 5V, MODE = PWM, T = +25°C
SW
IN
A
SW
IN
A
FN7888 Rev 4.00
July 31, 2014
Page 12 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Typical Performance Curves (Continued)
LX 5V/DIV
LX 5V/DIV
VOUT 1V/DIV
VEN 2V/DIV
V
1V/DIV
OUT
PG 5V/DIV
VEN 2V/DIV
PG 5V/DIV
1ms/DIV
1ms/DIV
FIGURE 27. START-UP AT 2A LOAD
FIGURE 28. SHUTDOWN AT 2A LOAD
F
= 2MHz, V = 5V, MODE = PFM, T = +25°C
F
= 2MHz, V = 5V, MODE = PFM, T = +25°C
SW
IN
A
SW
IN
A
VEN 5V/DIV
VEN 5V/DIV
V
1V/DIV
OUT
V
1V/DIV
OUT
I
1A/DIV
L
PG 5V/DIV
I
1A/DIV
L
PG 5V/DIV
1ms/DIV
FIGURE 29. START-UP AT 1.5A LOAD
= 2MHz, V = 5V, MODE = PWM, T = +25°C
1ms/DIV
FIGURE 30. SHUTDOWN AT 1.5A LOAD
= 2MHz, V = 5V, MODE = PWM, T = +25°C
F
F
SW
SW
IN
A
IN
A
VEN 5V/DIV
VEN 5V/DIV
V
1V/DIV
OUT
V
1V/DIV
OUT
I
1A/DIV
L
PG 5V/DIV
I
1A/DIV
L
PG 5V/DIV
1ms/DIV
FIGURE 31. START-UP AT 1.5A LOAD
= 2MHz, V = 5V, MODE = PFM, T = +25°C
1ms/DIV
FIGURE 32. SHUTDOWN AT 1.5A LOAD
F
= 2MHz, V = 5V, MODE = PFM, T = +25°C
F
SW
IN
A
SW
IN
A
FN7888 Rev 4.00
July 31, 2014
Page 13 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Typical Performance Curves (Continued)
V
5V/DIV
V
5V/DIV
1V/DIV
IN
IN
V
1V/DIV
V
OUT
OUT
I
1A/DIV
I
1A/DIV
L
L
PG 5V/DIV
PG 5V/DIV
500µs/DIV
500µs/DIV
FIGURE 33. START-UP V AT 2A LOAD
FIGURE 34. START-UP V AT 2A LOAD
IN
= 2MHz, V = 5V, MODE = PFM, T = +25°C
IN
= 2MHz, V = 5V, MODE = PWM, T = +25°C
F
F
SW
IN
A
SW
IN
A
V
IN
5V/DIV
V
5V/DIV
IN
I
1A/DIV
1V/DIV
I
1A/DIV
1V/DIV
L
L
V
V
OUT
OUT
PG 5V/DIV
PG 5V/DIV
1ms/DIV
1ms/DIV
FIGURE 35. SHUTDOWN V AT 2A LOAD
IN
FIGURE 36. SHUTDOWN V AT 2A LOAD
IN
F
= 2MHz, V = 5V, MODE = PFM, T = +25°C
F
= 2MHz, V = 5V, MODE = PWM, T = +25°C
SW
IN
A
SW
IN
A
LX 5V/DIV
1V/DIV
LX 5V/DIV
V
V
1V/DIV
OUT
OUT
V
5V/DIV
V
5V/DIV
IN
IN
PG 5V/DIV
PG 5V/DIV
500µs/DIV
500µs/DIV
FIGURE 38. START-UP V AT NO LOAD
FIGURE 37. START-UP V AT NO LOAD
IN
= 2MHz, V = 5V, MODE = PFM, T = +25°C
IN
F
F
= 2MHz, V = 5V, MODE = PFM, T = +25°C
SW
IN
A
SW
IN
A
FN7888 Rev 4.00
July 31, 2014
Page 14 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Typical Performance Curves (Continued)
LX 5V/DIV
LX 5V/DIV
V
1V/DIV
5V/DIV
V
1V/DIV
5V/DIV
OUT
OUT
V
V
IN
IN
PG 5V/DIV
PG 5V/DIV
100ms/DIV
50ms/DIV
FIGURE 39. SHUTDOWN V AT NO LOAD
IN
FIGURE 40. SHUTDOWN V AT NO LOAD
IN
F
= 2MHz, V = 5V, MODE = PFM, T = +25°C
F
= 2MHz, V = 5V, MODE = PWM, T = +25°C
SW
IN
A
SW
IN
A
LX 1V/DIV
LX 1V/DIV
10ns/DIV
FIGURE 41. JITTER AT NO LOAD
= 2MHz, V = 5V, MODE = PWM, T = +25°C
10ns/DIV
FIGURE 42. JITTER AT FULL LOAD
= 2MHz, V = 5V, MODE = PWM, T = +25°C
F
F
SW
SW
IN
A
IN
A
LX 5V/DIV
10mV/DIV
LX 5V/DIV
20mV/DIV
V
OUT
V
OUT
I
0.5A/DIV
L
I
0.5A/DIV
L
500ns/DIV
FIGURE 44. STEADY STATE AT NO LOAD
50ms/DIV
FIGURE 43. STEADY STATE AT NO LOAD
= 2MHz, V = 5V, MODE = PFM, T = +25°C
F
= 2MHz, V = 5V, MODE = PWM, T = +25°C
F
SW
IN
A
SW
IN
A
FN7888 Rev 4.00
July 31, 2014
Page 15 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Typical Performance Curves (Continued)
V
RIPPLE 50mV/DIV
OUT
V
RIPPLE 50mV/DIV
OUT
I
1A/DIV
L
I
1A/DIV
L
200µs/DIV
FIGURE 45. LOAD TRANSIENT
= 2MHz, V = 5V, MODE = PFM, T = +25°C
200µs/DIV
FIGURE 46. LOAD TRANSIENT
F
F
= 2MHz, V = 5V, MODE = PWM, T = +25°C
SW
IN
A
SW
IN
A
LX 5V/DIV
V
0.5V/DIV
OUT
I
1A/DIV
L
I
2A/DIV
L
V
1V/DIV
OUT
PG 5V/DIV
PG 5V/DIV
5µs/DIV
FIGURE 47. OUTPUT SHORT-CIRCUIT
= 2MHz, V = 5V, MODE = PFM, T = +25°C
500µs/DIV
FIGURE 48. OVERCURRENT PROTECTION
= 2MHz, V = 5V, MODE = PWM, T = +25°C
F
F
SW
SW
IN
A
IN
A
LX 5V/DIV
LX 5V/DIV
675mA MODE TRANSITION, COMPLETELY
ENTER TO PWM AT 770mA
BACK TO PFM AT 121mA
RIPPLE 20mV/DIV
V
V
RIPPLE 20mV/DIV
OUT
OUT
I
2A/DIV
L
I
1A/DIV
L
2µs/DIV
FIGURE 50. PWM TO PFM TRANSITION
2µs/DIV
FIGURE 49. PFM TO PWM TRANSITION
= 2MHz, V = 5V, MODE = PFM, T = +25°C
F
= 2MHz, V = 5V, MODE = PWM, T = +25°C
F
SW
IN
A
SW
IN
A
FN7888 Rev 4.00
July 31, 2014
Page 16 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Typical Performance Curves (Continued)
LX 5V/DIV
I
2A/DIV
2V/DIV
L
V
0.5V/DIV
OUT
V
OUT
PG 2V/DIV
PG 5V/DIV
10µs/DIV
1ms/DIV
FIGURE 51. OVERVOLTAGE PROTECTION
FIGURE 52. OVER-TEMPERATURE PROTECTION
F
= 2MHz, V = 5V, MODE = PFM, T = +25°C
F
= 2MHz, V = 5V, MODE = PWM, T = +163°C
SW
IN
A
SW
IN
A
Theory of Operation
V
EAMP
The device is a step-down switching regulator optimized for battery
powered applications. It operates at high switching frequency (1MHz
or 2MHz), which enables the use of smaller inductors resulting in
small form factor, while also providing excellent efficiency. Further,
at light loads while in PFM mode, the regulator reduces the
switching frequency, thereby minimizing the switching loss and
maximizing battery life. The quiescent current when the output is
not loaded is typically only 35µA. The supply current is typically only
5µA when the regulator is shut down.
V
CSA
DUTY
CYCLE
I
L
V
OUT
PWM Control Scheme
Pulling the MODE pin HI (>2.5V) forces the converter into PWM
mode, regardless of output current. The device employs the
current-mode pulse-width modulation (PWM) control scheme for
fast transient response and pulse-by-pulse current limiting. See
“Functional Block Diagram” on page 5. The current loop consists of
the oscillator, the PWM comparator, current sensing circuit and the
slope compensation for the current loop stability. The slope
compensation is 900mV/Ts, which changes with frequency. The
gain for the current sensing circuit is typically 300mV/A. The control
reference for the current loops comes from the error amplifier's
(EAMP) output.
FIGURE 53. PWM OPERATION WAVEFORMS
The output voltage is regulated by controlling the V
EAMP
voltage
to the current loop. The bandgap circuit outputs a 0.6V 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 200kΩ RC network. The maximum EAMP
voltage output is precisely clamped to 1.6V.
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
reaches the control reference of the current loop, the PWM
comparator COMP sends a signal to the PWM logic to turn off the
P-FET and turn on the N-Channel MOSFET. The N-FET stays on until
the end of the PWM cycle. Figure 53 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.
PFM Mode
Pulling the MODE pin LO (<0.4V) forces the converter into PFM
mode. The device enters a pulse-skipping mode at light load to
minimize the switching loss by reducing the switching frequency.
Figure 54 illustrates the skip-mode operation. A zero-cross
sensing circuit shown in Figure 54 monitors the N-FET current for
zero crossing. When 16 consecutive cycles of the inductor current
crossing zero are detected, the regulator enters the skip mode.
During the eight detecting cycles, the current in the inductor is
allowed to become negative. The counter is reset to zero when
the current in any cycle does not cross zero.
FN7888 Rev 4.00
July 31, 2014
Page 17 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
PWM
PFM
PWM
CLOCK
16 CYCLES
PFM CURRENT LIMIT
LOAD CURRENT
I
L
0
NOMINAL +1.5%
V
OUT
NOMINAL -1.5%
NOMINAL
FIGURE 54. SKIP MODE OPERATION WAVEFORMS
Once the skip mode is entered, the pulse modulation starts being
controlled by the SKIP comparator as shown in the “Functional
Block Diagram” on page 5. Each pulse cycle is still synchronized
by the PWM clock. The P-FET is turned on at the clock's rising
edge and turned off when the output is higher than 1.5% of the
nominal regulation or when its current reaches the peak Skip
current limit value. Then the inductor current is discharges to 0A
and stays at zero. The internal clock is disabled. The output
voltage reduces gradually due to the load current discharging the
output capacitor. When the output voltage drops to the nominal
voltage, the P-FET will be turned on again at the rising edge of
the internal clock as it repeats the previous operations.
cycles, both P-FET and N-FET shut off. The 100Ω in parallel to the
N-FET will activate discharging the output into regulation. The
control will begin to switch when output is within regulation. The
regulator will be in PFM for 20µs before switching to PWM if
necessary.
PG
PG is an output of a window comparator that continuously monitors
the buck regulator output voltage. PG is actively held low when EN is
low and during the buck regulator soft-start period. After 1ms delay
of the soft-start period, PG becomes high impedance as-long-as the
output voltage is within nominal regulation voltage set by VFB.
When VFB drops 15% below or raises 15% above the nominal
regulation voltage, the device pulls PG low. Any fault condition forces
PG low until the fault condition is cleared by attempts to soft-start.
There is an internal 5MΩ pull-up resistor to fit most applications. An
external resistor can be added from PG to VIN for more pull-up
strength.
The regulator resumes normal PWM mode operation when the
output voltage drops 1.5% below the nominal voltage.
Overcurrent Protection
The overcurrent protection is realized by monitoring the CSA
output with the OCP comparator, as shown in the “Functional
Block Diagram” on page 5. The current sensing circuit has a gain
of 300mV/A, from the P-FET current to the CSA output. When the
CSA output reaches a threshold, the OCP comparator is tripped to
turn off the P-FET immediately. The overcurrent function protects
the switching converter from a shorted output by monitoring the
current flowing through the upper MOSFET.
UVLO
When the input voltage is below the undervoltage lock-out (UVLO)
threshold, the regulator is disabled.
Enable, Disable, and Soft-Start Up
After the VIN pin exceeds its rising POR trip point (nominal 2.7V),
the device begins operation. If the EN pin is held low externally,
nothing happens until this pin is released. Once the EN is
released and above the logic threshold, the internal default
soft-start time is 1ms.
Upon detection of overcurrent condition, the upper MOSFET will
be immediately turned off and will not be turned on again until
the next switching cycle. If the overcurrent condition goes away,
the output will resume back into regulation point.
Short-Circuit Protection
Discharge Mode (Soft-Stop)
When a transition to shutdown mode occurs or the VIN UVLO is set,
the outputs discharge to GND through an internal 100Ω switch.
The short-circuit protection (SCP) comparator monitors the VFB
pin voltage for output short-circuit protection. When the VFB is
lower than 0.3V, the SCP comparator forces the PWM oscillator
frequency to drop to 1/3 of the normal operation value. This
comparator is effective during start-up or an output short-circuit
event.
100% Duty Cycle (1MHz Version)
The device features 100% duty cycle operation to maximize the
battery life. When the battery voltage drops to a level that the
device can no longer maintain the regulation at the output, the
regulator completely turns on the P-FET. The maximum dropout
voltage under the 100% duty cycle operation is the product of the
load current and the ON-resistance of the P-FET.
Negative Current Protection
Similar to the overcurrent, the negative current protection is
realized by monitoring the current across the low-side N-FET, as
shown in the “Functional Block Diagram” on page 5. When the
valley point of the inductor current reaches -1.5A for 2 consecutive
FN7888 Rev 4.00
July 31, 2014
Page 18 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
voltage 3.3V application, in order to decrease the inductor ripple
current and output voltage ripple, the output inductor value can
be increased. It is recommended to set the inductor ripple
current to be approximately 30% of the maximum output current
for optimized performance. The inductor ripple current can be
expressed as shown in Equation 4:
Thermal ShutDown
The device has built-in thermal protection. When the internal
temperature reaches +150°C, the regulator is completely
shutdown. As the temperature drops to +125°C, the device
resumes operation by stepping through the soft-start.
V
O
Power Derating Characteristics
To prevent the ISL8002 from exceeding the maximum junction
temperature, some thermal analysis is required. The
temperature rise is given by Equation 2:
---------
V
1 –
O
(EQ. 4)
V
IN
--------------------------------------
I =
L F
SW
The inductor’s saturation current rating needs to be at least
larger than the peak current.
(EQ. 2)
T
= PD
JA
RISE
The device uses internal compensation network and the output
capacitor value is dependent on the output voltage. The ceramic
capacitor is recommended to be X5R or X7R.
where PD is the power dissipated by the regulator and θ is the
thermal resistance from the junction of the die to the ambient
JA
temperature. The junction temperature, T , is given by
J
Equation 3:
Output Voltage Selection
(EQ. 3)
The output voltage of the regulator can be programmed via an
external resistor divider that is used to scale the output voltage
relative to the internal reference voltage and feed it back to the
inverting input of the error amplifier (see Figure 35).
T
= T + T
RISE
RISE
A
where T is the ambient temperature. For the DFN package, the
A
θ
is +71°C/W.
JA
The output voltage programming resistor, R , will depend on the
2
The actual junction temperature should not exceed the absolute
maximum junction temperature of +125°C when considering
the thermal design.
value chosen for the feedback resistor and the desired output
voltage of the regulator. The value for the feedback resistor is
typically between 10kΩ and 100kΩas shown in Equation 5.
V
The ISL8002 delivers full current at ambient temperatures up to
+85°C; if the thermal impedance from the thermal pad
maintains the junction temperature below the thermal shutdown
level, depending on the input voltage/output voltage
O
VFB
(EQ. 5)
-----------
R
= R
– 1
1
2
If the output voltage desired is 0.6V, then R is left unpopulated
2
combination and the switching frequency. The device power
dissipation must be reduced to maintain the junction
temperature at or below the thermal shutdown level. Figure 55
illustrates the approximate output current derating versus
ambient temperature for the ISL8002 EVAL1Z kit.
and R is shorted. There is a leakage current from VIN to LX. It is
recommended to preload the output with 10µA minimum. For
1
better performance, add 22pF in parallel with R Check loop
1
analysis before use in application.
Input Capacitor Selection
2.5
The main functions for the input capacitor are to provide
decoupling of the parasitic inductance and to provide filtering
function to prevent the switching current flowing back to the
battery rail. At least two 22µF X5R or X7R ceramic capacitors are
a good starting point for the input capacitor selection.
2.0
1V
1.5
1.5V
1.0
0.5
0
2.5V
3.3V
Output Capacitor Selection
An output capacitor is required to filter the inductor current.
Output ripple voltage and transient response are 2 critical factors
when considering output capacitance choice. The current mode
control loop allows for the usage of low ESR ceramic capacitors
and thus smaller board layout. Electrolytic and polymer
capacitors may also be used.
V
= 5V, OLFM
IN
50
60
70
80
90
100
110
120
130
TEMPERATURE (°C)
FIGURE 55. DERATING CURVE vs TEMPERATURE
Additional consideration applies to ceramic capacitors. While
they offer excellent overall performance and reliability, the actual
in-circuit capacitance must be considered. Ceramic capacitors
are rated using large peak-to-peak voltage swings and with no DC
bias. In the DC/DC converter application, these conditions do not
reflect reality. As a result, the actual capacitance may be
considerably lower than the advertised value. Consult the
manufacturers data sheet to determine the actual in-application
capacitance. Most manufacturers publish capacitance vs DC bias
so this effect can be easily accommodated. The effects of AC
Applications Information
Output Inductor and Capacitor Selection
To consider steady state and transient operations,
ISL8002A/ISL80019A typically requires a 1.2µH and
ISL8002/ISL80019 typically requires a 2.2µH output inductor.
Higher or lower inductor value can be used to optimize the total
converter system performance. For example, for higher output
FN7888 Rev 4.00
July 31, 2014
Page 19 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
voltage are not frequently published, but an assumption of ~20%
further reduction will generally suffice. The result of these
considerations can easily result in an effective capacitance 50%
lower than the rated value. Nonetheless, they are a very good
choice in many applications due to their reliability and extremely
low ESR.
^
^
^
L
R
LP
i
P
i
L
v
in
o
^
d
V
in
^
^
1:D
I d
V
L
in
Rc
Co
+
R
T
Ro
The following equations allow calculation of the required
capacitance to meet a desired ripple voltage level. Additional
capacitance may be used.
T (S)
i
^
d
For the ceramic capacitors (low ESR) =
K
I
Fm
--------------------------------------
V
=
(EQ. 6)
is the
OUTripple
C
OUT
8 F
SW
T (S)
+
v
He(S)
where I is the inductor’s peak-to-peak ripple current, F
SW
switching frequency and C
is the output capacitor.
OUT
^
v
comp
-Av(S)
If using electrolytic capacitors then:
FIGURE 56. SMALL SIGNAL MODEL OF SYNCHRONOUS BUCK
REGULATOR
V
= I*ESR
(EQ. 7)
OUTripple
Regarding transient response needs, a good starting point is to
determine the allowable overshoot in V if the load is suddenly
OUT
removed. In this case, energy stored in the inductor will be
transferred to C causing its voltage to rise. After calculating
V
OUT
OUT
capacitance required for both ripple and transient needs, choose
the larger of the calculated values. The following equation
determines the required output capacitor value in order to
achieve a desired overshoot relative to the regulated voltage.
2
R
R
1
2
C
4
V
FB
-
V
COMP
GM
V
REF
I
L
*
+
OUT
--------------------------------------------------------------------------------------------
=
C
(EQ. 8)
OUT
2
2
V
V
V
– 1
R
*
14
OUT
OUTMAX
OUT
C
8
where V is the relative maximum overshoot
allowed during the removal of the load. For an overshoot of 5%,
/V
OUTMAX OUT
C
7
the equation becomes as follows:
2
I
L
*
OUT
-----------------------------------------------------
=
C
(EQ. 9)
OUT
2
2
V
1.05 – 1
*
OUT
FIGURE 57. TYPE II COMPENSATOR
Loop Compensation Design
Figure 57 shows the type II compensator and its transfer function
is expressed as Equation 10:
When COMP is not connected to VDD, the COMP pin is active for
external loop compensation. The ISL8002, ISL8002A, ISL80019,
and ISL80019A use constant frequency peak current mode
control architecture to achieve fast loop transient response. An
accurate current sensing pilot device in parallel with the upper
MOSFET is used for peak current control signal and overcurrent
protection. The inductor is not considered as a state variable
since its peak current is constant, and the system becomes a
single order system. It is much easier to design a type II
compensator to stabilize the loop than to implement voltage
mode control. Peak current mode control has an inherent input
voltage feed-forward function to achieve good line regulation.
Figure 56 shows the small signal model of the synchronous buck
regulator.
S
S
------------
------------
1 +
1 +
ˆ
GM R
v
comp
2
cz1
cz2
---------------- -------------------------------------------------------- --------------------------------------------------------------
A S=
=
v
ˆ
C + C R + R
S
S
v
7
8
1
2
FB
-------------
-------------
S 1 +
1 +
cp1
cp2
(EQ. 10)
where,
C
+ C
R + R
1 2
C R R
4 1 2
1
-----------------
1
7
8
--------------
-------------------------
----------------------
=
=
,
=
=
cp2
cz1
cz2
cp1
R
C
R C
R
C C
14
7
1
4
14
7
8
FN7888 Rev 4.00
July 31, 2014
Page 20 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
COMPENSATOR DESIGN GOAL
60
45
30
15
0
• High DC gain
• Choose Loop bandwidth f less than 100kHz
c
• Gain margin: >10dB
• Phase margin: >50°
The compensator design procedure is as follows:
The loop gain at crossover frequency of f has unity gain.
c
Therefore, the compensator resistance R is determined by
14
Equation 11.
-15
-30
2f V C R
(EQ. 11)
3
c
o o t
---------------------------------
= 2610 f V C
c o o
R
=
14
GM V
FB
100
1k
10k
100k
1M
FREQUENCY (Hz)
Where GM is the trans-conductance of the voltage error
amplifier.
Compensator capacitors C and C are then given by
Equations 12 and 13.
180
150
120
90
7
8
R C
V C
o o
I R
o 14
o
o
(EQ. 12)
(EQ. 13)
-------------- ---------------
C
=
=
7
R
14
R C
1
c
o
C = max(--------------,------------------)
8
R
f R
s 14
14
60
An optional zero can boost the phase margin. CZ2 is a zero due
to R and C
30
1
4
Put compensator zero 2 to 5 times f :
c
0
100
1k
10k
100k
1M
1
(EQ. 14)
---------------
C =
FREQUENCY (Hz)
4
f R
c
1
FIGURE 58. SIMULATED LOOP GAIN
Example: V = 5V, V
IN OUT
= 1.8V, I = 2A, F
= 1MHz,
O
SW
R = 200k, R = 100k, C = 2x22µF/3mΩ, L = 2.2µH,
OUT
Layout Considerations
The PCB layout is a very important converter design step to make
sure the designed converter works well. The power loop is
1
2
f = 100kHz, then compensator resistance R
:
c
14
3
(EQ. 15)
R
= 2610 100kHz 1.8V 44F = 205k
14
composed of the output inductor L’s, the output capacitor C ,
OUT
the PHASE’s pins, and the PGND pin. It is necessary to make the
power loop as small as possible and the connecting traces
among them should be direct, short and wide. The switching
node of the converter, the PHASE pins, and the traces connected
to the node are very noisy, so keep the voltage feedback trace
away from these noisy traces. The input capacitor should be
placed as closely as possible to the VIN pin and the ground of the
input and output capacitors should be connected as closely as
possible. The heat of the IC is mainly dissipated through the
thermal pad. Maximizing the copper area connected to the
thermal pad is preferable. In addition, a solid ground plane is
helpful for better EMI performance. It is recommended to add at
least 4 vias ground connection within the pad for the best
thermal relief.
Using the closest standard value for R value is fine (200k.
14
1.8V 44F
2A 200k
(EQ. 16)
-------------------------------
= 198pF
C
=
7
3m 44F
200k
1
(EQ. 17)
C = max(--------------------------------,------------------------------------------------ )= (1pF,2.3pF)
8
1MHz200k
The closest standard values for C and C are also fine. There is
7
8
approximately 3pF parasitic capacitance from V
to GND;
Therefore, C is optional. Use C = 220pF and C = OPEN.
COMP
8
7
8
1
(EQ. 18)
-----------------------------------------------
C =
= 16pF
4
100kHz 200k
Use C = 15pF. Note that C may increase the loop bandwidth
4
4
from previously estimated value. Figure 58 shows the simulated
voltage loop gain. It is shown that it has 114kHz loop bandwidth
with 52° phase margin and 10dB gain margin. It may be more
desirable to achieve more phase margin. This can be
accomplished by lowering R by 20% to 50%.
14
FN7888 Rev 4.00
July 31, 2014
Page 21 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
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
July 31, 2014
FN7888.4 Page 18 under overcurrent protection: removed a text, which read “after the hiccup mode expires”.
Added ISL80019AEVAL1Z and ISL80019EVAL1Z to ordering information table on Page 6.
November 26, 2013
July 30, 2013
FN7888.3 Added Eval boards to “Ordering Information” on Page 6.
Added Curve and “Power Derating Characteristics” on page 19.
FN7888.2 Updated ordering information table on Page 6.
Added Figures 12, 13 and 14 to “Typical Performance Curves” on page 9.
Electrical Specifications on Page 7 under output regulation section removed duplicate of "T = -40°C to +125°C"
J
from VFB Bias Current to in place Line Regulation.
June 13, 2013
Functional Block Diagram on page 5 - changed VFB to VREF
Changed part number in ordering information on page 6 from ISL80019FRZ-T TO ISL80019FZ-T
Changed on page 7 Recommend Operating Conditions the word "Ambient" to "Junction"
Changed in Electrical Spec on page 7
conditions from TA -40 to +85 to TJ -40 to +125
VFB Bias Current under Output Regulation Test condition from 0.75V and TYP from 0.1 to 2.7V
MIN -120 TYP 50 MAX 350
Type II Compensator graphic on page 20 - changed VFB to VREF
May 10, 2013
Pin Descriptions on Page 4: EN section, changed pin rises from 0.6V to 1.4V.
January 7, 2013
FN7888.1 Initial release.
About Intersil
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address some of the largest markets within the industrial and infrastructure, mobile computing and high-end consumer markets.
For the most updated datasheet, application notes, related documentation and related parts, please see the respective product
information page found at www.intersil.com.
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Intersil products are manufactured, assembled and tested utilizing ISO9001 quality systems as noted
in the quality certifications found at www.intersil.com/en/support/qualandreliability.html
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
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FN7888 Rev 4.00
July 31, 2014
Page 22 of 23
ISL8002, ISL8002A, ISL80019, ISL80019A
Package Outline Drawing
L8.2x2C
8 LEAD THIN DUAL FLAT NO-LEAD PLASTIC PACKAGE (TDFN) WITH E-PAD
Rev 0, 07/08
2.00
6
A
PIN #1 INDEX AREA
6
B
PIN 1
INDEX AREA
8
1
0.50
1.45±0.050
Exp.DAP
(4X)
0.15
0.25
( 8x0.30 )
0.10
C A B
M
TOP VIEW
0.80±0.050
Exp.DAP
BOTTOM VIEW
( 8x0.20 )
( 8x0.30 )
Package Outline
SEE DETAIL "X"
( 6x0.50 )
C
0.10
C
0 . 75 ( 0 . 80 max)
1.45
2.00
BASE PLANE
SEATING PLANE
0.08
C
SIDE VIEW
( 8x0.25 )
0.80
2.00
TYPICAL RECOMMENDED LAND PATTERN
0 . 2 REF
C
0 . 00 MIN.
0 . 05 MAX.
DETAIL "X"
NOTES:
1. Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2. Dimensioning and tolerancing conform to AMSE Y14.5m-1994.
3. Unless otherwise specified, tolerance : Decimal ± 0.05
4. Dimension b applies to the metallized terminal and is measured
between 0.15mm and 0.30mm from the terminal tip.
Tiebar shown (if present) is a non-functional feature.
5.
6.
The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 identifier may be
either a mold or mark feature.
FN7888 Rev 4.00
July 31, 2014
Page 23 of 23
相关型号：
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