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UC3844A 데이터시트 PDF




ETC에서 제조한 전자 부품 UC3844A은 전자 산업 및 응용 분야에서
광범위하게 사용되는 반도체 소자입니다.


PDF 형식의 UC3844A 자료 제공

부품번호 UC3844A 기능
기능 High Performance Current Mode PWM Controller
제조업체 ETC
로고 ETC 로고


UC3844A 데이터시트 를 다운로드하여 반도체의 전기적 특성과 매개변수에 대해 알아보세요.




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UC3844A 데이터시트, 핀배열, 회로
Replacement of
UC3842A/43A/44A/45A
High Performance Current
Mode PWM Controller
MIK3842A/43A/44A/45A
July 1995 –revised July 2002
Description
The MIK3842A(AM)/43A(AM)/44A(AM)/45A(AM) are fixed frequency current mode PWM controller. They are specially designed for
OFFLine and DC to DC converter applications with a minimal external components. Internally implemented circuits include a trimmed
oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator,
and a high current totempole output ideally suited for driving a power MOSFET. Protection circuitry includes built undervoltage lockout
and current limiting. The MIK3842A(AM) and MIK3844A(AM) have UVLO thresholds of 16 V (on) and 10 V (off). The corresponding
thresholds for the MIK3843A(AM)/45A(AM) are 8.4V (on) and 7.6V (off). The MIK3842A(AM) and MIK3843A(AM) can operate within 100%
duty cycle. The MIK3844A(AM) and UC3845A(AM) can operate within 50% duty cycle.
The MIK384XA(AM) has Start-Up Current 0.17mA (typ).
Features
Low Start-Up and Operating Current
High Current Totem Pole Output
Undervoltage Lockout With Hysteresis
Operating Frequency Up To 300KHz (MIK384XA)
500KHz (MIK384XAM)
Pin Connection
VREF
8
Block diagram
(toggle flip flop used only in MIK3844, MIK3845)
5V
VREF
SET/
RESET
UVLO
Top view
VCC 7
36V GND
5
INTERNAL
BIAS
VREF GOOD
LOGIC
2 VFB
1/2 VREF
+ ERR
- AMP
COMP
1
CURRENT
SENSE
3
2R
R
C.S.
COMP
1V
4 RT/CT
OSCILLATOR
R
PWM
LATCH
S
T
POWER VCC
7
OUT
6
5
POWER GND
Absolute Maximum Ratings
Symbol
Parameter
VCC
IO
VI
ISINK (E.A)
PO
Tstg
TL
Supply Voltage (low impedance source)
Output Current
Input Voltage (Analog Inputs pins 2,3)
Error Amp Output Sink Current
Power Dissipation (TA=250C)
Storage Temperature Range
Lead Temperature (soldering 5 sec.)
Maximum
30
±1
0.3 to 5.5
10
1
-65 to150
260
Units
V
A
V
mA
W
oC
oC
Page 1 of 8




UC3844A pdf, 반도체, 판매, 대치품
Replacement of
UC3842A/43A/44A/45A
High Performance Current
Mode PWM Controller
MIK3842A/43A/44A/45A
RT
RSLOPE
IS
R1
RS
VREF
8
RT /CT 4 MIK3842
ISENSE 3
5
GND
July 1995 –revised July 2002
VREF 8
RT
RSLOPE
IS
RT /CT 4
MIK3842
R1 ISENSE 3
RS
5
GND
Figure 4. Slope Compensation Techniques
SCR must be selected for a holding current of less than 0.5mA.
The simple two transistor circuit can be used in place of the SCR as shown.
Figure 5. Latched Shutdown
From V0
RI
Rd Cf
2.5 V
VFB
2
Rf
+
- EA
+
1mA
1
COMP
2R
R
5
Error Amp compensation circuit for stabilizing any current-mode topology except
for boost and flyback converters operating with continuous inductor current.
From V0
Rp
RI
Cp
2.5 V
Cf
Rd
VFB
+
-
2 EA
Rf
COMP 1
+
1mA
2R
R
5
Error Amp compensation circuit for stabilizing current-mode boost and flyback
topologies operating with continuous inductor current.
Figure 6. Error Amplifier Compensation
Page 4 of 8

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UC3844A 전자부품, 판매, 대치품
Replacement of
UC3842A/43A/44A/45A
MIK3842A/43A/44A/45A
Vsa t
(V)
Sourse Satura tion
-1 (Load to Ground)
VCC = 15 V
-2 80 µs Pulsed Load 120Hz Ra te
3
High Performance Current
Mode PWM Controller
July 1995 –revised July 2002
ICC
(m A)
20
15
2
1
Sink Sa turation
(Lo ad to VCC )
0
0 200 400 600 IO (m A)
Figure 7.Output Saturation Voltage vs. Load Current
TA= 25C.
10
5
0
0
ISe nse = 0V
VFB = 0V
RT= 10K
TA = 25 OC
CT= 3.3nF
10 20
30 VCC (V)
Figure 8. Supply Current vs. Supply Voltage.
Vref 8
RT
RT/CT
4
CT
VCC
7
5V REG
PWM
CLOCK
RT/CT
OUTPUT
6
OUTPUT
LARGE RT/ SMALL CT
OSCILLATOR
ID
RT/CT
OUTPUT
5
GND
Figure 9. Oscillator and Output Waveforms
SMALL RT / LARGE CT
Page 7 of 8

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관련 데이터시트

부품번호상세설명 및 기능제조사
UC3844

Current Mode PWM Controller (Rev. C)

Texas Instruments
Texas Instruments
UC3844

(UC3844 / UC3845) HIGH PERFORMANCE CURRENT MODE PWM CONTROLLERS

Unisonic Technologies
Unisonic Technologies

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