Datasheet.kr   

ACT4050 데이터시트 PDF




Active-Semi에서 제조한 전자 부품 ACT4050은 전자 산업 및 응용 분야에서
광범위하게 사용되는 반도체 소자입니다.


 

PDF 형식의 ACT4050 자료 제공

부품번호 ACT4050 기능
기능 Wide Input 3.5A Step Down Converter
제조업체 Active-Semi
로고 Active-Semi 로고


ACT4050 데이터시트 를 다운로드하여 반도체의 전기적 특성과 매개변수에 대해 알아보세요.




전체 13 페이지수

미리보기를 사용할 수 없습니다

ACT4050 데이터시트, 핀배열, 회로
Active-Semi
ACT4050
Rev 2, 01-Jul-11
Wide Input 3.5A Step Down Converter
FEATURES
3.5A Output Current
Up to 96% Efficiency
4.5V to 15V Input Range
12µA Shutdown Supply Current
400kHz Switching Frequency
Adjustable Output Voltage From 0.817V
Cycle-by-Cycle Current Limit Protection
Thermal Shutdown Protection
Frequency Fold-Back at Short Circuit
Stability with Wide Range of Capacitors,
Including Low ESR Ceramic Capacitors
SOP-8/EP (Exposed Pad) Package
APPLICATIONS
Digital TV
Portable DVDs
Car-Powered or Battery-Powered Equipments
Set-Top Boxes
Telecom Power Supplies
Consumer Electronics
GENERAL DESCRIPTION
The ACT4050 is a current-mode step-down DC/DC
converter that provides up to 3.5A of output current
at 400kHz switching frequency. The device utilizes
Active-Semi’s proprietary high voltage process for
operation with input voltages up to 15V.
The ACT4050 provides fast transient response and
eases loop stabilization while providing excellent
line and load regulation. This device features a very
low ON-resistance power MOSFET which provides
peak operating efficiency up to 96%. In shutdown
mode, the ACT4050 consumes only 12μA of supply
current.
This device also integrates protection features
including cycle-by-cycle current limit, thermal
shutdown and frequency fold-back at short circuit.
The ACT4050 is available in a SOP-8/EP (Exposed
Pad) package and requires very few external
devices for operation.
TYPICAL APPLICATION CIRCUIT
Efficiency vs. Load Current
100
VIN = 7V
90
VIN = 12V
80
70
60
50 VOUT = 5V
0 500 1000 1500 2000 2500 3000 3500
Load Current (mA)
Innovative PowerTM
- 1 - www.active-semi.com
Copyright © 2011 Active-Semi, Inc.




ACT4050 pdf, 반도체, 판매, 대치품
Active-Semi
FUNCTIONAL BLOCK DIAGRAM
ACT4050
Rev 2, 01-Jul-11
FUNCTIONAL DESCRIPTION
As seen in Functional Block Diagram, the ACT4050
is a current mode pulse width modulation (PWM)
converter. The converter operates as follows:
A switching cycle starts when the rising edge of the
Oscillator clock output causes the High-Side Power
Switch to turn on and the Low-Side Power Switch to
turn off. With the SW side of the inductor now
connected to IN, the inductor current ramps up to
store energy in the magnetic field. The inductor
current level is measured by the Current Sense
Amplifier and added to the Oscillator ramp signal. If
the resulting summation is higher than the COMP
voltage, the output of the PWM Comparator goes
high. When this happens or when Oscillator clock
output goes low, the High-Side Power Switch turns
off and the Low-Side Power Switch turns on. At this
point, the SW side of the inductor swings to a diode
voltage below ground, causing the inductor current
to decrease and magnetic energy to be transferred
to output. This state continues until the cycle starts
again.
The High-Side Power Switch is driven by logic using
BS as the positive rail. This pin is charged to VSW + 6V
when the Low-Side Power Switch turns on.
The COMP voltage is the integration of the error
between FB input and the internal 0.817V
reference. If FB is lower than the reference voltage,
COMP tends to go higher to increase current to the
output. Current limit happens when COMP reaches
its maximum clamp value of 2.15V.
The Oscillator normally switches at 400kHz.
However, if FB voltage is less than 0.7V, then the
switching frequency decreases until it reaches a
typical value of 60kHz at VFB = 0.5V.
Shutdown Control
The ACT4050 EN pin contains a precision 1.1V
comparator with 100mV hysteresis, as well as a
2µA pull-up current source. This combination can
be used to control the on/off operation of
ACT4050 using several methods:
1) First, "always-on" operation can be enabled
simply by floating the EN pin. Any time power is
applied to VIN, the EN pull-up current source will
bring the pin above 1.1V and enable the IC. In
this case, under-voltage lockout will be controlled
by an internal 4.2V comparator on VIN.
2) Second, an open-drain or open-collector logic
device can be used to pull the EN pin low to
provide digital ON/OFF control. When the logic
pull-down is disabled, the internal 2µA pull-up
current will bring the EN pin high and enable the
chip.
3) Third, a known startup delay time can be created
by adding a small capacitor from EN to GND in
Innovative PowerTM
- 4 - www.active-semi.com
Copyright © 2011 Active-Semi, Inc.

4페이지










ACT4050 전자부품, 판매, 대치품
Active-Semi
ACT4050
Rev 2, 01-Jul-11
STABILITY COMPENSATION
Figure 2:
Stability Compensation
COMP
ACT4050
CCOMP
RCOMP
CCOMP2c
c: CCOMP2 is needed only for high ESR output capacitor
The feedback loop of the IC is stabilized by the
components at the COMP pin, as shown in Figure 2.
The DC loop gain of the system is determined by
the following equation:
AVDC
0 .82 V
= IOUT
AVEA G COMP
The dominant pole P1 is due to CCOMP:
fP1
=
G EA
2π AVEA C COMP
(7)
(8)
The second pole P2 is the output pole:
fP 2
=
I OUT
2πVOUT C OUT
(9)
The first zero Z1 is due to RCOMP and CCOMP:
fZ1
=
1
2 πR COMP
C COMP
(10)
And finally, the third pole is due to RCOMP and
CCOMP2 (if CCOMP2 is used):
fP3
=
1
2πRCOMP CCOMP2
(11)
The following steps should be used to compensate
the IC:
STEP 1. Set the cross over frequency at 1/10 of the
switching frequency via RCOMP:
R COMP
=
2πVOUT COUT fSW
10 GEAGCOMP × 0.82V
= 1 .88
× 10
V8
OUT
C OUT
()
(12)
but limit RCOMP to 15kmaximum.
STEP 2. Set the zero fZ1 at 1/4 of the cross over
frequency. If RCOMP is less than 15k, the equation
for CCOMP is:
CCOMP
=
1.6 ×10
RCOMP
5
(F) (13)
If RCOMP is limited to 15k, then the actual cross
over frequency is 3.4 / (VOUTCOUT). Therefore:
CCOMP = 1.2 ×10 5VOUTCOUT
(F) (14)
STEP 3. If the output capacitor’s ESR is high
enough to cause a zero at lower than 4 times the
cross over frequency, an additional compensation
capacitor CCOMP2 is required. The condition for using
CCOMP2 is:
R ESRCOUT
Min
⎜⎜⎝⎛
1
.1 ×10
COUT
6
,0.012
× VOUT
⎟⎟⎠⎞
()
(15)
And the proper value for CCOMP2 is:
CCOMP 2
=
C ROUT ESRCOUT
RCOMP
(16)
Though CCOMP2 is unnecessary when the output
capacitor has sufficiently low ESR, a small value
CCOMP2 such as 100pF may improve stability against
PCB layout parasitic effects.
Table 3 shows some calculated results based on
the compensation method above.
Table 2:
Typical Compensation for Different Output
Voltages and Output Capacitors
VOUT
2.5V
3.3V
5V
2.5V
3.3V
5V
2.5V
3.3V
5V
COUT
2x22μF Ceramic
2x22μF Ceramic
2x22μF Ceramic
47μF SP CAP
47μF SP CAP
47μF SP CAP
470μF/6.3V/30m
470μF/6.3V/30m
470μF/6.3V/30m
RCOMP
8.2k
12k
15k
15k
15k
15k
15k
15k
15k
CCOMP
2.2nF
1.5nF
1.5nF
1.5nF
1.8nF
2.7nF
15nF
22nF
27nF
CCOMP2c
None
None
None
None
None
None
1nF
1nF
None
c: CCOMP2 is needed for high ESR output capacitor.
Figure 3 shows an example ACT4050 application circuit
generating a 2.5V/3.5A output.
Innovative PowerTM
- 7 - www.active-semi.com
Copyright © 2011 Active-Semi, Inc.

7페이지


구       성 총 13 페이지수
다운로드[ ACT4050.PDF 데이터시트 ]

당사 플랫폼은 키워드, 제품 이름 또는 부품 번호를 사용하여 검색할 수 있는

포괄적인 데이터시트를 제공합니다.


구매 문의
일반 IC 문의 : 샘플 및 소량 구매
-----------------------------------------------------------------------

IGBT, TR 모듈, SCR 및 다이오드 모듈을 포함한
광범위한 전력 반도체를 판매합니다.

전력 반도체 전문업체

상호 : 아이지 인터내셔날

사이트 방문 :     [ 홈페이지 ]     [ 블로그 1 ]     [ 블로그 2 ]



관련 데이터시트

부품번호상세설명 및 기능제조사
ACT4050

Wide Input 3.5A Step Down Converter

Active-Semi
Active-Semi

DataSheet.kr       |      2020   |     연락처      |     링크모음      |      검색     |      사이트맵