參數(shù)資料
型號(hào)： UC3845A
廠商： 意法半導(dǎo)體
英文描述： High Performance Current Mode PWM Controller(高性能電流模式PWM控制器)
中文描述： 高性能電流模式PWM控制器（高性能電流模式的PWM控制器）
文件頁(yè)數(shù)： 1/15頁(yè)
文件大小： 138K
代理商： UC3845A
UC2842A/3A/4A/5A
UC3842A/3A/4A/5A
September 1998
HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER
.
TRIMMED OSCILLATOR DISCHARGE CUR-
RENT
.
CURRENT MODE OPERATION TO 500kHz
.
AUTOMATIC FEED FORWARD COMPENSA-
TION
.
LATCHING PWM FOR CYCLE-BY-CYCLE
CURRENT LIMITING
.
INTERNALLY TRIMMED REFERENCE WITH
UNDERVOLTAGELOCKOUT
.
HIGH CURRENT TOTEM POLEOUTPUT
.
UNDERVOLTAGE LOCKOUT WITH HYSTER-
ESIS
.
LOWSTART-UP CURRENT (< 0.5mA)
.
DOUBLEPULSESUPPRESSION
DESCRIPTION
TheUC384xAfamilyofcontrolICsprovidesthenec-
essary features to implement off-line or DC to DC
fixedfrequencycurrent modecontrolschemeswith
a minimal external parts count. Internally imple-
mentedcircuits includea trimmedoscillatorfor pre-
cise DUTY CYCLE CONTROL under voltagelock-
outfeaturingstart-upcurrentlessthan0.5mA,a pre-
cision reference trimmed for accuracy at the error
ampinput,logicto insurelatchedoperation,a PWM
comparatorwhichalsoprovidescurrentlimitcontrol,
and a totem pole output stage designed to source
orsinkhighpeakcurrent.Theoutputstage,suitable
for driving N-Channel MOSFETs, is low in the off-
state.
Differencesbetweenmembers of this family arethe
under-voltagelockoutthresholdsandmaximum duty
cycle ranges. The UC3842A and UC3844A have
UVLO thresholds of 16V (on) and 10V (off), ideally
suitedoff-lineapplicationsThecorrespondingthresh-
olds for the UC3843A and UC3845A are 8.5 V and
7.9V. The UC3842A and UC3843A can operateto
dutycyclesapproaching100%.Arangeofthezeroto
<50%isobtainedbytheUC3844AandUC3845Aby
theadditionofaninternaltoggleflipflopwhichblanks
theoutputoffeveryotherclockcycle.
BLOCK DIAGRAM
(toggle flip flop used only in UC3844A and UC3845A)
UVLO
S/R
5V
REF
34V
INTERNAL
BIAS
VREF GOOD
LOGIC
2.50V
T
S
R
OSC
R
1V
CURRENT
SENSE
COMPARATOR
2R
+
-
PWM
LATCH
7
5
4
2
1
3
8
6
ERROR AMP.
Vi
GROUND
RT/CT
VFB
COMP
CURRENT
SENSE
VREF
5V 50mA
OUTPUT
D95IN331
Minidip
SO8
UC3842A
1/15
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
UC3845A-BW 制造商:FCI 制造商全稱:First Components International 功能描述:Current Mode PWM Controller Low Start-Up and Operating Current
UC3845AD 功能描述:電流型 PWM 控制器 Current Mode RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
UC3845AD1 功能描述:電流型 PWM 控制器 RO 511-UC3845BD 9/04 RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
UC3845AD1013TR 制造商:STMicroelectronics 功能描述:
UC3845AD8 功能描述:電流型 PWM 控制器 Current Mode RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
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