UC3842D8TR ,Current-Mode PWM ControllerFeatures... 19 Application and Implementation...... 212 Applications..... 19.1 Application Informat ..
UC3842J ,Current-Mode PWM Controller
UC3842J ,Current-Mode PWM Controller
UC3842N ,SMPS ControllerTable of Contents8.4 Device Functional Modes.... 201
UC3842NG4 ,Current-Mode PWM Controller 8-PDIP 0 to 70Block Diagrams. 11Information..... 368.3 Feature Description.... 124 Revision HistoryChanges from R ..
UC3842Q , CURRENT-MODE PWM CONTROLLERFeaturesThe UCx84x family offers a variety of package• Optimized for Off-Line and DC-to-DC Converte ..
UMX1/N/TN , General purpose transistors (dual transistors)
UMX18N , General purpose transistors (dual transistors)
UMX1N TN , General purpose transistors (dual transistors)
UMX1N TN , General purpose transistors (dual transistors)
UMX1NTN , General purpose transistors (dual transistors)
UMX1NTN , General purpose transistors (dual transistors)
UC3842D-UC3842D8-UC3842D8TR-UC3842N-UC3842NG4
SMPS Controller
VIN
VCC
VREF
RT/CT
GROUND
VFB
ISENSE
OUTPUT
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UC1842, UC2842, UC3842, UC1843, UC2843, UC3843
UC1844, UC2844, UC3844, UC1845, UC2845, UC3845SLUS223E –APRIL 1997–REVISED JANUARY
UCx84x Current-Mode PWM Controllers Features Optimized for Off-Line and DC-to-DC Converters Low Start-Up Current(<1 mA) Automatic Feedforward Compensation Pulse-by-Pulse Current Limiting Enhanced Load-Response Characteristics Undervoltage Lockout With Hysteresis Double-Pulse Suppression High-Current Totem-Pole Output Internally Trimmed Bandgap Reference Upto 500-kHz Operation Error Amplifier With Low Output Resistance
Applications Switching Regulatorsof Any Polarity Transformer-Coupled DC-DC Converters
DescriptionThe UCx84x series of control integrated circuits
provide the features that are necessaryto implement
off-line or DC-to-DC fixed-frequency current-mode
control schemes, witha minimum numberof external
components. The internally implemented circuits
include an undervoltage lockout (UVLO), featuringa
start-up currentof less than1 mA, anda precision
reference trimmed for accuracyat the error amplifier
input. Other internal circuits include logicto ensure
latched operation,a pulse-width modulation (PWM)
comparator that also provides current-limit control,
anda totem-pole output stage thatis designedto
sourceor sink high-peak current. The output stage,
suitable for driving N-channel MOSFETs,is low whenisin theoff state.
The UCx84x family offersa variety of package
options, temperature range options, choice
maximum duty cycle, and choiceof turnon and turnoff
thresholds and hysteresis ranges. Devices
higher turnonor turnoff hysteresis are ideal choices
for off-line power supplies, while the devices with
narrower hysteresis range are suited for DC-DC
applications. The UC184x devices are specified
operation from –55°Cto 125°C, the UC284x series
specified for operation from –40°Cto 85°C, and
UC384x seriesis specified for operation from 0°C
70°C.
Device Information(1)(1) Forall available packages, see the orderable addendum
the endofthe datasheet.
Simplified Application
