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Número de pieza | ACT6391 | |
Descripción | (ACT6390 / ACT6391) 1.7A/2.5A PWM Step-Up DC/DC Converters | |
Fabricantes | Active-Semi | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de ACT6391 (archivo pdf) en la parte inferior de esta página. Total 11 Páginas | ||
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ACT6390/ACT6391
Rev0, 13-May-08
1.7A/2.5A PWM Step-Up DC/DC Converters In MSOP
FEATURES
• Greater than 90% Efficiency
• Adjustable Output Voltage Up to 12V
• Internal 14V Power MOSFET
• Two Peak Current Options:
− ACT6390: 1.7A, 0.2Ω
− ACT6391: 2.5A, 0.15Ω
• Selectable 700kHz/1.3MHz Frequency
• Integrated Over-Voltage Protection (OVP)
• Programmable Soft-Start Function
• Thermal Shutdown
• Cycle-by-Cycle Over-Current Protection
• Small MSOP-8 Package
APPLICATIONS
• TFT LCD Monitors
• Battery-Powered Equipment
• Set-Top Boxes
• DSL and Cable Modems and Routers
GENERAL DESCRIPTION
The ACT6390/ACT6391 are high-performance,
fixed-frequency, current-mode PWM step-up
DC/DC converters that incorporate internal power
MOSFETs. The ACT6390 includes an integrated
0.2Ω power MOSFET that supports peak currents
of up to 1.7A, while the ACT6391’s integrated
0.15Ω power MOSFET supports currents of up to
2.5A.
The ACT6390 and ACT6391 both utilize simple ex-
ternal loop compensation and a pin-selectable
fixed-frequency of either 700kHz or 1.3MHz, allow-
ing optimization between component size, cost, and
AC performance across a wide range of applica-
tions. Additional functions include an externally pro-
grammable soft-start function for easy inrush cur-
rent control, internal over-voltage protection (OVP),
cycle-by-cycle current limit protection, and thermal
shutdown.
Both the ACT6390 and the ACT6391 are available
in the small 8-pin MSOP-8 package.
SIMPLIFIED APPLICATION CIRCUIT
VIN
2.7V to 5.5V
IN
ON
OFF
1.3MHz
700kHz
ACT6390
ACT6391
EN
SW
VOUT
FREQ
R1
SS
COMP
FB
G R2
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Copyright © 2008 Active-Semi, Inc.
1 page ACT6390/ACT6391www.DataSheet4U.com
Rev0, 13-May-08
FUNCTIONAL BLOCK DIAGRAM
EN
COMP
FB
1.24V
ERROR
AMPLIFIER
-
+
ERROR
COMPARATOR
CLOCK
SOFT
START
CONTROL
AND
DRIVE
LOGIC
4.5µA
IN
SS
SW
FREQ
OSCILLATOR
5.5µA
SLOPE
COMPENSATION
+
CURRENT SENSE
AMPLIFIER
G
FUNCTIONAL DESCRIPTION
The ACT6390 and ACT6391 are highly efficient
step-up DC/DC converters that employ a current-
mode, fixed frequency pulse-width modulation
(PWM) architecture with excellent line and load
regulation.
The ACT6390 and ACT6391 operate at constant
switching frequency under medium to high load cur-
rent conditions. At light loads, these devices oper-
ate in a pulse-skipping mode in order to improve
light-load efficiency.
Soft-Start
The ACT6390 and ACT6391 both offer a program-
mable soft-start function which minimizes inrush
current during startup. The soft-start period is pro-
grammed by connecting a capacitor (CSS) between
SS and G. Operation of the soft-start function is as
follows: when the IC is disabled, SS is actively dis-
charged to G. Upon enabling the IC, CSS is charged
with a 4.5µA current so that the voltage at SS in-
creases in a controlled manner. The peak inductor
current is limited by the voltage at SS, so that the
input current is limited until the soft-start period ex-
pires, and the regulator can achieve its full output
current rating.
The soft-start period can be calculated as a simple
function of the soft-start capacitor using the equa-
tion:
t SS = 2.2 × 10 5 × C SS
(1)
Frequency Selection
The ACT6390 and ACT6391 include a pin-
selectable operating frequency drive FREQ to a
logic high for 1.3MHz operation, drive FREQ to a
logic low for 700kHz operation.
Selectable operating frequency, in combination with
the external compensation network, allows a wide
range of flexibility in optimizing total solution size
and cost.
FREQ is internally pulled down by 5.5µA, this pin
may be left unconnected to achieve a 700kHz oper-
ating frequency.
Setting the Output Voltage
The ACT6390 and ACT6391 both feature external
adjustable output voltages of up to 12V. To program
the output voltage, simply connect a resistive volt-
age divider between the output, FB, and G, with
resistors set according to the following equation:
R1
=
R
2
×
⎢⎣⎡⎜⎜⎝⎛
VOUT
VFB
⎟⎟⎠⎞
−
1⎥⎤
⎦
Where VFB is 1.24V.
(2)
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Copyright © 2008 Active-Semi, Inc.
5 Page ACT6390/ACT6391www.DataSheet4U.com
Rev0, 13-May-08
PACKAGE OUTLINE
MSOP-8 PACKAGE OUTLINE AND DIMENSIONS
be
D
C
A2
θA
DIMENSION IN
SYMBOL MILLIMETERS
MIN MAX
DIMENSION
IN INCHES
MIN MAX
A 0.820 1.100 0.032 0.043
A1 0.020 0.150 0.001 0.006
A2 0.750 0.950 0.030 0.037
b 0.250 0.380 0.010 0.015
C 0.090 0.230 0.004 0.009
D 2.900 3.100 0.114 0.122
E 2.900 3.100 0.114 0.122
E1 4.750 5.050 0.187 0.199
e
0.650 TYP
0.026 TYP
L 0.400 0.800 0.016 0.031
θ 0° 6° 0° 6°
Active-Semi, Inc. reserves the right to modify the circuitry or specifications without notice. Users should evaluate each product to make
sure that it is suitable for their applications. Active-Semi products are not intended or authorized for use as critical components in life-
support devices or systems. Active-Semi, Inc. does not assume any liability arising out of the use of any product or circuit described in
this datasheet, nor does it convey any patent license.
Active-Semi and its logo are trademarks of Active-Semi, Inc. For more information on this and other products, contact sales@active-
semi.com or visit http://www.active-semi.com. For other inquiries, please send to:
1270 Oakmead Parkway, Suite 310, Sunnyvale, California 94085-4044, USA
Innovative PowerTM
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www.active-semi.com
Copyright © 2008 Active-Semi, Inc.
11 Page |
Páginas | Total 11 Páginas | |
PDF Descargar | [ Datasheet ACT6391.PDF ] |
Número de pieza | Descripción | Fabricantes |
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