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PDF ISL8014 Data sheet ( Hoja de datos )
| Número de pieza | ISL8014 | |
| Descripción | 4A Low Quiescent Current 1MHz High Efficiency Synchronous Buck Regulator | |
| Fabricantes | Intersil Corporation | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de ISL8014 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
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ISL8014
The ISL8014 is a high efficiency, monolithic, synchronous
step-down DC/DC converter that can deliver up to 4A
continuous output current from a 2.7V 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.
The ISL8014 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 400mV
dropout voltage at 4A output current. High 1MHz
pulse-width modulation (PWM) switching frequency
allows the use of small external components and SYNC
input enables multiple ICs to synchronize out of phase to
reduce ripple and eliminate beat frequencies.
The ISL8014 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.
Fault protection is provided by internal hiccup mode
current limiting during short circuit and overcurrent
conditions, an output over voltage comparator and
over-temperature monitor circuit. A power good output
voltage monitor indicates when the output is in
regulation.
The ISL8014 is offered in a space saving 4x4 QFN lead
free package with exposed pad lead frames for low
thermal.
The ISL8014 offers a 1ms Power-Good (PG) timer at
power-up. When shutdown, ISL8014 discharges the
output capacitor. Other features include internal
soft-start, internal compensation, overcurrent protection,
and thermal shutdown.
The ISL8014 is offered in a 16 Ld 4mmx4mm QFN
package with 1mm maximum height. The complete
converter occupies less than 0.4in2 area.
Features
• High Efficiency Synchronous Buck Regulator with up
to 97% Efficiency
• Power-Good (PG) Output with a 1ms Delay
• 2.7V to 5.5V Supply Voltage
• 3% Output Accuracy Over-Temperature/Load/Line
• 4A Output Current
• Pin Compatible to ISL8013
• Start-up with Pre-Biased Output
• Internal Soft-Start - 1ms
• Soft-Stop Output Discharge During Disabled
• 35µA Quiescent Supply Current in PFM Mode
• Selectable Forced PWM Mode and PFM Mode
• External Synchronization up to 4MHz
• Less than 1µA Logic Controlled Shutdown Current
• 100% Maximum Duty Cycle
• Internal Current Mode Compensation
• Peak Current Limiting and Hiccup Mode Short Circuit
Protection
• Over-Temperature Protection
• Small 16 Ld 4mmx4mm QFN
• Pb-Free (RoHS Compliant)
Applications
• DC/DC POL Modules
• µC/µP, FPGA and DSP Power
• Plug-in DC/DC Modules for Routers and Switchers
• Portable Instruments
• Test and Measurement Systems
• Li-ion Battery Powered Devices
• Small Form Factor (SFP) Modules
• Bar Code Readers
November 23, 2009
FN6576.4
1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2007-2009. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
1 page  
ISL8014
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:
TA = -40°C to +85°C, VIN = 3.6V, EN = VDD, unless otherwise noted. Typical values are at
TA = +25°C. Boldface limits apply over the operating temperature range,
-40°C to +85°C. (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
MAX
(Note 7) TYP (Note 7)
UNITS
LX
P-Channel MOSFET
ON-Resistance
N-Channel MOSFET
ON-Resistance
LX Maximum Duty Cycle
VIN = 5V, IO = 200mA
VIN = 2.7V, IO = 200mA
VIN = 5V, IO = 200mA
VIN = 2.7V, IO = 200mA
- 50 75
- 70 100
- 50 75
- 70 100
- 100 -
mΩ
mΩ
mΩ
mΩ
%
PWM Switching Frequency
LX Minimum On-Time
fS
SYNCH = High
0.80 1.0 1.20
- - 140
MHz
ns
PG
Output Low Voltage
Sinking 1mA
- - 0.3
V
Delay Time (Rising Edge)
0.65 1 1.35
ms
PG Pin Leakage Current
PGOOD Rising Threshold
PG = VIN = 3.6V
Percentage of regulation voltage
- 0.01 0.1
89 92 95
µA
%
PGOOD Falling Threshold
Percentage of regulation voltage
85 88 91
%
PGOOD Delay Time (Falling Edge)
- 15 -
µs
EN, SYNCH
Logic Input Low
- - 0.4
V
Logic Input High
1.4 -
-
V
Synch Logic Input Leakage
Current
ISYNCH Pulled up to 5.5V
- 0.1 1
µA
Enable Logic Input Leakage
Current
IEN
- 0.1 1
µA
Thermal Shutdown
- 140 -
°C
Thermal Shutdown Hysteresis
- 25 -
°C
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.
5 FN6576.4
November 23, 2009
5 Page 
ISL8014
Typical Operating Performance
(Unless otherwise noted, operating conditions are: TA = +25°C,
VVIN = 2.5V to 5.5V, EN = VIN, SYNCH = 0V, L = 1.5µH,
C1 = 2x22µF, C2 = 2x22µF, IOUT = 0A to 4A). (Continued)
LX 2V/DIV
IL 2A/DIV
LX 2V/DIV
VOUT 0.5V/DIV
PG 5V/DIV
VOUT 1V/DIV
PG 5V/DIV
IL 2A/DIV
FIGURE 33. OUTPUT SHORT CIRCUIT
FIGURE 34. OUTPUT SHORT CIRCUIT RECOVERY
5.500
5.375
5.250
OCP_3.3VIN
5.125
5.000
4.875
4.750
OCP_5VIN
4.625
4.500-50
-25
0 25 50
TEMPERATURE (°C)
75 100
FIGURE 35. OUTPUT CURRENT LIMIT vs TEMPERATURE
Theory of Operation
The ISL8014 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
ISL8014 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
200mV/A. The control reference for the current loops
comes from the error amplifier's (EAMP) output.
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 36 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
11 FN6576.4
November 23, 2009
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet ISL8014.PDF ] | |
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