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ACT4082A の電気的特性と機能

ACT4082AのメーカーはActive-Semiです、この部品の機能は「1.4MHz Step-Down DC/DC Converter」です。


製品の詳細 ( Datasheet PDF )

部品番号 ACT4082A
部品説明 1.4MHz Step-Down DC/DC Converter
メーカ Active-Semi
ロゴ Active-Semi ロゴ 




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ACT4082A Datasheet, ACT4082A PDF,ピン配置, 機能
Active-Semi
ACT4082A
Rev0, 16-May-08
16V, 1.2A, 1.4MHz Step-Down DC/DC Converter in SOT23-6
FEATURES
Wide 4.5V to 16V Input Voltage Range
1.2A Output Current (12VIN to 5VOUT)
Output Adjustable Down to 0.81V
0.3Internal Power MOSFET
Up to 92% Efficiency
Stable with Low ESR Ceramic Output Capacitors
Fixed 1.4MHz Operating Frequency
Internal Soft-Start Function
Over Current Protection with Hiccup-Mode
Thermal Shutdown
Available in a SOT23-6 Package
APPLICATIONS
TFT LCD Monitors
Portable DVDs, Headphones, MP3 Players, etc.
Car-Powered or Battery-Powered Equipment
Set-Top Boxes
Telecom Power Supplies
DSL and Cable Modems and Routers
GENERAL DESCRIPTION
The ACT4082A is a current-mode step-down
DC/DC converter that supplies up to 1.2A into 5V
from a 12V input. 1.4MHz switching frequency al-
lows the use of tiny external components, and inter-
nal loop compensation provides simple, stable
power supplies with a minimum of external compo-
nents. Optimized for use with ceramic input and
output capacitors, the ACT4082A provides a very
compact 1.2A power supply for space constrained
mobile and consumer applications.
The ACT4082A operates over a wide input voltage
range and utilizes current-mode operation to pro-
vide excellent line and load transient response
while requiring no external compensation compo-
nents. Fault protection includes cycle-by-cycle cur-
rent limiting, frequency fold-back, hiccup mode, and
thermal shutdown. Internal soft-start provides a
controlled startup with no overshoot, even at light
loads.
The ACT4082A is available in a tiny SOT23-6 pack-
age and requires very few external components.
TYPICAL APPLICATION CIRCUIT
4.5V to 16V
VIN
ON
OFF
IN BST
Active-Semi
ACT4082A SW
EN
FB
G
VOUT
Innovative PowerTM
- 1 - www.active-semi.com
Copyright © 2008 Active-Semi, Inc.

1 Page





ACT4082A pdf, ピン配列
Active-Semi
ACT4082A
Rev0, 16-May-08
ABSOLUTE MAXIMUM RATINGSc
PARAMETER
IN Supply Voltage
SW Voltage
BST Voltage
EN, FB Voltage
Continuous SW Current
Junction to Ambient Thermal Resistance (θJA)
Maximum Power Dissipation
Operating Junction Temperature
Storage Temperature
Lead Temperature (Soldering, 10 sec)
VALUE
-0.3 to 20
-1 to VIN + 1
VSW - 0.3 to VSW + 7
-0.3 to 6
Internally Limited
220
0.5
-40 to 150
-55 to 150
300
UNIT
V
V
V
V
A
°C/W
W
°C
°C
°C
c: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may
affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = 12V, TA = 25°C, unless otherwise specified.)
PARAMETER
SYMBOL
TEST CONDITIONS
Input Voltage
Under Voltage Lockout Voltage
Under Voltage Lockout Hysteresis
Feedback Voltage
Frequency Foldback Threshold
High-side Switch On Resistance
Low-side Switch On Resistance
SW Leakage
Current Limit
Switching Frequency
Foldback Switching Frequency
Maximum Duty Cycle
Minimum On-Time
EN Threshold Voltage
EN Hysteresis
EN Internal Pull-up Current
Supply Current in Shutdown
Supply Current in Operation
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
VIN
VUVLO
VOUT = 3.3V, ILOAD = 0A to 1.2A
Input Voltage Rising
VFB 4.75V VIN 16V, VCOMP = 1.5V
RONH
RONH
ILTM
fSW
DMAX
VEN = 0, VSW = 0V
VIN = 12V, VOUT = 5V, or
EN = G, SW = G
VFB = 0V, or FB = G
VFB = 0.6V
EN Rising
EN Rising
VEN = 0V or EN = G
VEN = 2V, VFB = 1.0V
MIN
4.5
4
0.78
TYP MAX
16
4.2 4.49
250
0.81 0.84
250
0.300
15
1 10
UNIT
V
V
mV
V
mV
µA
1.8 A
1.1 1.4 1.7 MHz
467 kHz
92 %
75 ns
1.12 1.24 1.36
V
100 mV
2 µA
15 30
µA
1 2 mA
160 °C
10 °C
Innovative PowerTM
- 3 - www.active-semi.com
Copyright © 2008 Active-Semi, Inc.


3Pages


ACT4082A 電子部品, 半導体
Active-Semi
FUNCTIONAL BLOCK DIAGRAM
IN
EN
REGULATOR
& UVLO
OSCILLATOR
REFERENCE
& THERMAL
SHUTDOWN
FB
EA
CONTROL
SOFT-START
PWM Comparator
ILIM Comparator
HICCUP
COMPENSATION
G
ACT4082A
Rev0, 16-May-08
CSA
BST
DRIVER
Q1
SW
FUNCTIONAL DESCRIPTION
The ACT4082A is a current-mode step-down
DC/DC converter that provides excellent transient
response with no extra external compensation com-
ponents. This device contains an internal, low-
resistance, high-voltage power MOSFET, and oper-
ates at a high 1.4MHz operating frequency to en-
sure a compact, high-efficiency design with excel-
lent AC and DC performance.
Setting the Output Voltage
An external voltage divider is used to set the output
voltage, as well as provide a known impedance
from VOUT to FB for compensation purposes. Con-
nect a 50kresistor from the output to FB to ensure
stable compensation, and select the bottom resistor
to provide the desired regulation voltage.
Figure 1:
Output Voltage Setting
ACT4082A
FB
VOUT
RFB1
RFB2
The feedback resistor (RFB1) interacts with the inter-
nal compensation network, and plays an important
in setting the ACT4082A's transient response and
ensuring stability. For most applications, choosing
RFB1 = 49.9kprovides good results. For applica-
tions with output voltages of 1.8V or lower, use a
larger RFB1 value such as 80.6k. Once RFB1 is
chosen, use the following equation to choose RFB2:
RFB2
=
⎜⎛
RFB1
VOUT 1⎟⎞
0.81V
(1)
Selecting the Inductor
The ACT4082A was optimized for use with a 4.7µH
inductor. When choosing an inductor, choose one
with a DC resistance of less than 250mand a DC
current rating that is typically 30% higher than the
maximum load current.
During typical operation, the inductor maintains a
continuous current to output load. The inductor
current has a ripple that is dependent on the
inductance value.
Higher inductance reduces the peak-to-peak ripple
current. The trade off for high inductance value is
the increase in inductor core size and series
resistance, and a reduction in current handling
capability.
If efficiency at light loads (such as less than 100mA)
is critical in the application, a larger inductor is
recommended.
Innovative PowerTM
- 6 - www.active-semi.com
Copyright © 2008 Active-Semi, Inc.

6 Page



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部品番号部品説明メーカ
ACT4082A

1.4MHz Step-Down DC/DC Converter

Active-Semi
Active-Semi


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