Moteur de recherche de fiches techniques de composants électroniques
  French  ▼
ALLDATASHEET.FR

X  

UC2851 Fiches technique(PDF) 4 Page - Texas Instruments

Click here to check the latest version.
No de pièce UC2851
Description  All Control, Driving, Monitoring, and Protection Functions Included
Download  12 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricant  TI1 [Texas Instruments]
Site Internet  http://www.ti.com
Logo TI1 - Texas Instruments

UC2851 Fiches technique(HTML) 4 Page - Texas Instruments

  UC2851 Datasheet HTML 1Page - Texas Instruments UC2851 Datasheet HTML 2Page - Texas Instruments UC2851 Datasheet HTML 3Page - Texas Instruments UC2851 Datasheet HTML 4Page - Texas Instruments UC2851 Datasheet HTML 5Page - Texas Instruments UC2851 Datasheet HTML 6Page - Texas Instruments UC2851 Datasheet HTML 7Page - Texas Instruments UC2851 Datasheet HTML 8Page - Texas Instruments UC2851 Datasheet HTML 9Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 4 / 12 page
background image
UC1851
UC2851
UC3851
PWM CONTROL
1. Oscillator
Generates a fixed-frequency internal clock from an external RT and CT.
Frequency =
KC
RTCT
where KC is a first-order correction factor
≈ 0.3 log (CT x 1012).
2. Ramp Generator:
Develops linear ramp with slope defined externally by
dV
dT
=
sense voltage
RRCR
.
CR is normally selected
≤ CT and its value will have some effect upon valley duty cycle.
Limiting the minimum value for ISENSE into pin 11 will establish a maximum duty cycle clamp.
CR terminal can be used as an input port for current mode control.
3. Error Amplifier
Conventional operational amplifier for closed-loop gain and phase compensation.
Low output impedance; unity-gain stable.
The output is held low by the slow start voltage at turn on in order to minimize overshoot.
4. Reference Generator:
Precision 5.0V for internal and external usage to 50mA.
Tracking 3.0V reference for internal usage only with nominal accuracy of
±2%.
40V clamp zener for chip OV protection, 100mA maximum current.
5. PWM Comparator:
Generates output pulse which starts at termination of clock pulse and ends when the ramp input
crosses the lowest of two positive inputs.
6. PWM Latch:
Terminates the PWM output pulse when set by inputs from either the PWM comparator, the
pulse-by-pulse comparator, or the error latch. Resets with each internal clock pulse.
7. PWM Output Switch:
Totem pole output stage capable of sourcing and sinking 1 amp peak current. The active "on" state
is high.
SEQUENCING FUNCTIONS
1. Start/UV Sense:
With an increasing voltage, this comparator generates a turn-on signal and releases the slow start
clamp at a start threshold.
With a decreasing voltage, it generates a turn-off command at a lower level separated by a 200
µA
hysteresis current.
2. Drive Switch:
Disables most of the chip to hold internal current consumption low, and Driver Bias OFF, until input
voltage reaches start threshold.
3. Driver Bias:
Supplies drive to external circuitry upon start-up.
4. Slow Start:
Clamps low to hold PWM OFF. Upon release, rises with rate controlled by RSCS for slow increase of
output pulse width.
Can also be used as an alternate maximum duty cycle clamp with an external voltage divider.
PROTECTION FUNCTIONS
1. Error Latch:
When set by momentary input, this latch insures immediate PWM shutdown and hold off until reset.
Inputs to Error Latch are:
a. OV > 3.2V (Typically 3V)
b. Stop > 2.4V (Typically 1.6V)
c. Current Sense 400mV over threshold. (Typical).
Error Latch resets when slow start voltage falls to 0.4V if Reset Pin < 2.8V. With Pin 5 > 3.2V,
Error Latch will remain set.
2. Current Limiting:
Differential input comparator terminates individual output pulses each time sense voltage rises
above threshold.
When sense voltage rises to 400mV (typical) above threshold, a shutdown signal is sent to Error
Latch.
3. External Stop:
A voltage over 2.4 will set the Error Latch and hold the output off.
A voltage less than 0.8V will defeat the error latch and prevent shutdown.
A capacitor here will slow the action of the error latch for transient protection by providing a Typical
Delay of 13ms/
µF.
FUNCTIONAL DESCRIPTION
4


Numéro de pièce similaire - UC2851

FabricantNo de pièceFiches techniqueDescription
logo
Texas Instruments
UC2851 TI-UC2851 Datasheet
576Kb / 7P
[Old version datasheet]   Programmable, Off-Line, PWM Controller
UC2851DW TI1-UC2851DW Datasheet
772Kb / 11P
[Old version datasheet]   Programmable, Off-Line, PWM Controller
UC2851DWG4 TI1-UC2851DWG4 Datasheet
772Kb / 11P
[Old version datasheet]   Programmable, Off-Line, PWM Controller
UC2851N TI1-UC2851N Datasheet
772Kb / 11P
[Old version datasheet]   Programmable, Off-Line, PWM Controller
UC2851NG4 TI1-UC2851NG4 Datasheet
772Kb / 11P
[Old version datasheet]   Programmable, Off-Line, PWM Controller
More results

Description similaire - UC2851

FabricantNo de pièceFiches techniqueDescription
logo
List of Unclassifed Man...
NLA-PM100D ETC2-NLA-PM100D Datasheet
145Kb / 2P
   Multi-functions Power Monitoring and Control Terminal
logo
Analog Devices
AD5593R AD-AD5593R Datasheet
986Kb / 34P
   Control and monitoring
AD5592R AD-AD5592R Datasheet
1,002Kb / 42P
   Control and monitoring
logo
Texas Instruments
ADS131E04 TI1-ADS131E04 Datasheet
1Mb / 56P
[Old version datasheet]   Analog Front-End for Power Monitoring, Control, and Protection
logo
Suntsu Electronics, Inc...
SATPC-35A7AF-ISB5 SUNTSU-SATPC-35A7AF-ISB5 Datasheet
381Kb / 3P
   Industrial Monitoring And Control
logo
STMicroelectronics
STS1TX STMICROELECTRONICS-STS1TX Datasheet
2Mb / 70P
   Industrial monitoring and control
August 2013 Rev 1
logo
Texas Instruments
ADS131E04 TI1-ADS131E04_14 Datasheet
2Mb / 60P
[Old version datasheet]   Analog Front-End for Power Monitoring, Control, and Protection
ADS131E08IPAGR TI1-ADS131E08IPAGR Datasheet
1Mb / 60P
[Old version datasheet]   Analog Front-End for Power Monitoring, Control, and Protection
logo
Suntsu Electronics, Inc...
SATPC-35A7AB5-ISB5 SUNTSU-SATPC-35A7AB5-ISB5 Datasheet
379Kb / 3P
   Industrial Monitoring And Control
logo
Texas Instruments
AMC7820 TI1-AMC7820_15 Datasheet
1Mb / 32P
[Old version datasheet]   ANALOG MONITORING AND CONTROL
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12


Fiches technique Télécharger

Go To PDF Page


Lien URL




Politique de confidentialité
ALLDATASHEET.FR
ALLDATASHEET vous a-t-il été utile ?  [ DONATE ] 

À propos de Alldatasheet   |   Publicité   |   Contactez-nous   |   Politique de confidentialité   |   Echange de liens   |   Fabricants
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