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PDF ISL8025A Data sheet ( Hoja de datos )
| Número de pieza | ISL8025A | |
| Descripción | Compact Synchronous Buck Regulators | |
| Fabricantes | Intersil | |
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Compact Synchronous Buck Regulators
ISL8025, ISL8025A
The ISL8025, ISL8025A are highly efficient, monolithic,
synchronous step-down DC/DC converters that can deliver 5A of
continuous output current from a 2.7V to 5.5V input supply. The
devices use current mode control architecture to deliver a very low
duty cycle operation at high frequency with fast transient
response and excellent loop stability.
The ISL8025, ISL8025A integrates a very low ON-resistance
P-Channel (36mΩ) high-side FET and N-Channel (13mΩ)
low-side FET to maximize efficiency and minimize external
component count. The 100% duty-cycle operation allows less
than 180mV dropout voltage at 5A output current. The
operation frequency of the pulse-width modulator (PWM) is
adjustable from 500kHz to 4MHz. The default switching
frequency, which is set by connecting the FS pin high, is 1MHz
for the ISL8025 and 2MHz for the ISL8025A.
The ISL8025, ISL8025A can be configured for discontinuous or
forced continuous operation at light load. Forced continuous
operation reduces noise and RF interference, while
discontinuous mode provides higher efficiency by reducing
switching losses at light loads.
Fault protection is provided by internal hiccup mode current
limiting during short circuit and overcurrent conditions. Other
protection, such as overvoltage and over-temperature, are also
integrated into the device. A power-good output voltage
monitor indicates when the output is in regulation.
The ISL8025, ISL8025A offers a 1ms Power-good (PG) timer
at power-up. When in shutdown, the ISL8025, ISL8025A
discharges the output capacitor through an internal soft-stop
switch. Other features include internal fixed or adjustable
soft-start and internal/external compensation.
The ISL8025, ISL8025A are offered in a space saving 16 Ld
3x3 Pb-free QFN package with an exposed pad for improved
thermal performance and 1mm maximum height. The
complete converter occupies less than 0.22 in2 area.
Features
• 2.7V to 5.5V input voltage range
• Very low ON-resistance FET’s - P-channel 36mΩ and
N-channel 13mΩ typical values
• High efficiency synchronous buck regulator with up to 95%
efficiency
• Pin-to-pin compatible with ISL8023 and ISL8024
• 0.8% reference accuracy over-temperature/load/line
• Internal soft-start: 1ms or adjustable
• Soft-stop output discharge during disable
• Adjustable frequency from 500kHz to 4MHz - default at
1MHz (ISL8025), 2MHz (ISL8025A)
• External synchronization up to 4MHz
• Over-temperature, overcurrent, overvoltage and negative
overcurrent protection
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
Related Literature
• See AN1806, “5A Low Quiescent Current High Efficiency
Synchronous Buck Regulator”
VIN
+2.7V …+5.5V
C1
2 x 22µF
GND R1
100kΩ
PG
1 VIN
2 VDD
3 PG
4 SYNC
ISL8025, ISL8025A
L1
1.0µH C2
2 x 22µF
+1.8V/5A
PGND 12
PGND 11
R2
200kΩ
C3*
22pF
SGND 10
FB 9
R3
100kΩ
+0.6V
VOUT
GND
*C3 IS OPTIONAL. IT IS
RECOMMENDED TO PUT A
PLACEHOLDER FOR IT AND CHECK
LOOP ANALYSIS BEFORE USE.
R2
=
R3
⎛
⎝
--V-----O----
VFB
– 1⎠⎞
(EQ. 1)
FIGURE 1. TYPICAL APPLICATION CIRCUIT CONFIGURATION
(INTERNAL COMPENSATION OPTION)
100
90
80
70
60 3.3VOUT
2.5VOUT
50
1.8VOUT
1.5VOUT
1.2VOUT
40
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT LOAD (A)
FIGURE 2. EFFICIENCY vs LOAD
FSW = 1MHz, VIN = 5V, MODE = PFM, TA = +25°C
December 19, 2013
FN8357.1
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2013. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
1 page  
ISL8025, ISL8025A
SS SOSFoTft-
START
SHUTDOWN
COMP
55pF
100kΩ
FS SYNC
SHUTDOWN
VDD
EN BANDGAP VREF
EAMP
-
FB
6kΩ
3pF
+
0.8V
-
+
SLSOloPpEe
COMP
OV
-
0.85*VREF
+
UV
PG
SGND
1ms
DELAY
OSCILLATOR
+
COMP
-
PWM/PFM
LOGIC
CONTROLLER
PROTECTION
HS DRIVER
+
OCP
-
+
SKIP
-
+
CSA
-
ISET
THRESHOLD
NEG CURRENT
SENSING
VIN
P
PHASE
LS
DRIVER
N
PGND
0.5V
-
SCP
+
ZERO-CROSS
SENSING
SHUTDOWN
100Ω
FIGURE 3. FUNCTIONAL BLOCK DIAGRAM
5 FN8357.1
December 19, 2013
5 Page 
ISL8025, ISL8025A
Typical Operating Performance Unless otherwise noted, operating conditions are: TA = +25°C, VVIN = 5V, EN = VIN,
SYNC = VIN, L = 1.0µH, C1 = 22µF, C2 = 2 x 22µF, IOUT = 0A to 5A) Resistor load is used in the test.
PHASE 5V/DIV
PHASE 5V/DIV
VOUT 1V/DIV
VEN 5V/DIV
PG 5V/DIV
500µs/DIV
FIGURE 19. START-UP AT NO LOAD (PFM)
PHASE 5V/DIV
VOUT 1V/DIV
VEN 5V/DIV
PG 5V/DIV
500µs/DIV
FIGURE 20. START-UP AT NO LOAD (PWM)
PHASE 5V/DIV
VOUT 1V/DIV
VEN 5V/DIV
PG 5V/DIV
500µs/DIV
FIGURE 21. SHUTDOWN AT NO LOAD (PFM)
VOUT 1V/DIV
VEN 5V/DIV
PG 5V/DIV
500µs/DIV
FIGURE 22. SHUTDOWN AT NO LOAD (PWM)
PHASE 5V/DIV
VOUT 1V/DIV
VEN 5V/DIV
PG 5V/DIV
500µs/DIV
FIGURE 23. START-UP AT 5A LOAD (PWM)
11
PHASE 5V/DIV
VOUT 1V/DIV
VEN 5V/DIV
PG 5V/DIV
500µs/DIV
FIGURE 24. SHUTDOWN AT 5A LOAD (PWM)
FN8357.1
December 19, 2013
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet ISL8025A.PDF ] | |
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