Motor de Búsqueda de Datasheet de Componentes Electrónicos
  Spanish  ▼
ALLDATASHEET.ES

X  

UC3837 Datasheet(PDF) 6 Page - Unisonic Technologies

No. de pieza UC3837
Descripción Electrónicos  LOW COST POWER-SAVING MODE PWM CONTROLLER
Download  10 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricante Electrónico  UTC [Unisonic Technologies]
Página de inicio  http://www.utc-ic.com
Logo UTC - Unisonic Technologies

UC3837 Datasheet(HTML) 6 Page - Unisonic Technologies

Back Button UC3837_15 Datasheet HTML 2Page - Unisonic Technologies UC3837_15 Datasheet HTML 3Page - Unisonic Technologies UC3837_15 Datasheet HTML 4Page - Unisonic Technologies UC3837_15 Datasheet HTML 5Page - Unisonic Technologies UC3837_15 Datasheet HTML 6Page - Unisonic Technologies UC3837_15 Datasheet HTML 7Page - Unisonic Technologies UC3837_15 Datasheet HTML 8Page - Unisonic Technologies UC3837_15 Datasheet HTML 9Page - Unisonic Technologies UC3837_15 Datasheet HTML 10Page - Unisonic Technologies  
Zoom Inzoom in Zoom Outzoom out
 6 / 10 page
background image
UC3837
Preliminary
LINEAR INTEGRATED CIRCUIT
UNISONICTECHNOLOGIESCO.,LTD
6 of 10
www.unisonic.com.tw
QW-R103-069.B
OPERATION DESCRIPTION (Cont.)
Frequency Hopping For EMI Improvement
The Frequency hopping is implemented in the IC; there are two oscillators built-in the IC. The first oscillator is to
set the normal switching frequency; the switching frequency is modulated with a period signal generated by the 2nd
oscillator. The relation between the first oscillator and the 2nd oscillator as followed Fig.2. So the tone energy is
evenly spread out, the spread spectrum minimizes the conduction band EMI and therefore eases the system design
in meeting stringent EMI requirement.
Fig.2 Frequency Hopping
Built-in Slope Compensation
Built-in slope compensation circuit greatly improves the close loop stability at CCM and prevents the
sub-harmonic oscillation.
Leading-Edge Blanking
Each time the power MOSFET is switched on, a turn-on spike will inevitably occur at the sense-resistor. To avoid
premature termination of the switching pulse, a 400ns leading-edge blanking time is built in. Conventional RC
filtering can therefore be omitted. During this blanking period, the current-limit comparator is disabled and it cannot
switch off the gate driver.
Constant Output Power Limit
When the SENSE voltage, across the sense resistor RS, reaches the threshold voltage, around 0.8V, the output
GATE drive will be turned off after a small propagation delay tD. This propagation delay will introduce an additional
current proportional to tD×VIN/Lp. Since the propagation delay is nearly constant regardless of the input line voltage
VIN. Higher input line voltage will result in a larger additional current and hence the output power limit is also higher
than that under low input line voltage. To compensate this variation for wide AC input range, the threshold voltage is
adjusted by the VIN current. Since VIN pin is connected to the rectified input line voltage through a resistor RVIN, a
higher line voltage will generate higher VIN current into the VIN pin. The threshold voltage is decreased if the VIN
current is increased. Smaller threshold voltage, forces the output GATE drive to terminate earlier, thus reduce the
total PWM turn-on time and make the output power equal to that of low line input. This proprietary internal
compensation ensures a constant output power limit for wide AC input voltage from 90VAC to 264VAC.
Under Voltage Lockout (UVLO)
The turn-on and turn-off thresholds of the UC3837 are fixed internally at VTHD(ON)/VDD(MIN) During start-up, the
hold-up capacitor must be charged to VTHD(ON) through the start-up resistor, so that the UC3837 will be enabled. The
hold-up capacitor will continue to supply VDD until power can be delivered from the auxiliary winding of the main
transformer. VDD must not drop below VDD(MIN) during this start-up process. This UVLO hysteresis window ensures
that hold-up capacitor will be adequate to supply VDD during start-up.
Gate Output
The UC3837 output stage is a fast totem pole gate driver. Cross conduction has been avoided to minimize heat
dissipation, increase efficiency, and enhance reliability. A good tradeoff is achieved through dead time control. The
low idle loss and good EMI system design is easier to achieve with this dedicated control scheme. An internal 15V
clamp is added for MOSFET gate protection at higher than expected VDD input.


Número de pieza similar - UC3837_15

Fabricante ElectrónicoNo. de piezaDatasheetDescripción Electrónicos
logo
Unisonic Technologies
UC3837G-AG6-R UTC-UC3837G-AG6-R Datasheet
366Kb / 11P
   LOW COST POWER-SAVING MODE PWM CONTROLLER FOR FLYBACK CONVERTERS
UC3837L UTC-UC3837L Datasheet
332Kb / 11P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3837L-AG6-R UTC-UC3837L-AG6-R Datasheet
366Kb / 11P
   LOW COST POWER-SAVING MODE PWM CONTROLLER FOR FLYBACK CONVERTERS
UC3837LG-AG6-R UTC-UC3837LG-AG6-R Datasheet
332Kb / 11P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3837L UTC-UC3837L_16 Datasheet
332Kb / 11P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
More results

Descripción similar - UC3837_15

Fabricante ElectrónicoNo. de piezaDatasheetDescripción Electrónicos
logo
Unisonic Technologies
UC3800 UTC-UC3800_18 Datasheet
221Kb / 10P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3873A UTC-UC3873A Datasheet
309Kb / 10P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3973 UTC-UC3973 Datasheet
353Kb / 10P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3800 UTC-UC3800 Datasheet
225Kb / 10P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3873 UTC-UC3873_16 Datasheet
263Kb / 10P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
US4651S UTC-US4651S Datasheet
363Kb / 9P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3875C UTC-UC3875C Datasheet
295Kb / 9P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3863A UTC-UC3863A Datasheet
342Kb / 10P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3875A UTC-UC3875A Datasheet
333Kb / 10P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3863 UTC-UC3863_17 Datasheet
262Kb / 9P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
UC3856 UTC-UC3856_17 Datasheet
358Kb / 10P
   LOW COST POWER-SAVING MODE PWM CONTROLLER
More results


Html Pages

1 2 3 4 5 6 7 8 9 10


Datasheet Descarga

Go To PDF Page


Enlace URL




Política de Privacidad
ALLDATASHEET.ES
¿ALLDATASHEET es útil para Ud.?  [ DONATE ] 

Todo acerca de Alldatasheet   |   Publicidad   |   Contáctenos   |   Política de Privacidad   |   Intercambio de Enlaces   |   Lista de Fabricantes
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com