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

X  

UC2844N Fiches technique(PDF) 9 Page - Motorola, Inc

No de pièce UC2844N
Description  HIGH PERFORMANCE CURRENT MODE CONTROLLERS
Download  14 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricant  MOTOROLA [Motorola, Inc]
Site Internet  http://www.freescale.com
Logo MOTOROLA - Motorola, Inc

UC2844N Fiches technique(HTML) 9 Page - Motorola, Inc

Back Button UC2844N Datasheet HTML 5Page - Motorola, Inc UC2844N Datasheet HTML 6Page - Motorola, Inc UC2844N Datasheet HTML 7Page - Motorola, Inc UC2844N Datasheet HTML 8Page - Motorola, Inc UC2844N Datasheet HTML 9Page - Motorola, Inc UC2844N Datasheet HTML 10Page - Motorola, Inc UC2844N Datasheet HTML 11Page - Motorola, Inc UC2844N Datasheet HTML 12Page - Motorola, Inc UC2844N Datasheet HTML 13Page - Motorola, Inc Next Button
Zoom Inzoom in Zoom Outzoom out
 9 / 14 page
background image
UC3844, 45 UC2844, 45
9
MOTOROLA ANALOG IC DEVICE DATA
Undervoltage Lockout
Two undervoltage lockout comparators have been
incorporated to guartantee that the IC is fully functional before
the output stage is enabled. The positive power supply
terminal (VCC and the reference output (Vref) are each
monitored by separate comparators. Each has built–in
hysteresis to prevent erratic output behavior as their
respective thresholds are crossed. The VCC comparator
upper and lower thresholds are 16 V/10 V for the UCX844,
and 8.4 V/7.6 V for the UCX845. The Vref comparator upper
and lower thresholds are 3.6 V/3/4 V. The large hysteresis
and low startup current of the UCX844 makes it ideally suited
in off–line converter applications where efficient bootstrap
startup techniques later required (Figure 29). The UCX845 is
intended for lower voltage dc–to–dc converter applications. A
36 V zener is connected as a shunt regulator from VCC to
ground. Its purpose is to protect the IC from excessive
voltage that can occur during system startup. The minimum
operating voltage for the UCX844 is 11 V and 8.2 V for the
UCX845.
Output
These devices contain a single totem pole output stage
that was specifically designed for direct drive of power
MOSFETs. It is capable of up to
± 1.0 A peak drive current
and has a typical rise and fall time of 50 ns with a 1.0 nF load.
Additional internal circuitry has been added to keep the
Output in a sinking mode whenever and undervoltage lockout
is active. This characteristic eliminates the need for an
external pull–down resistor.
The SO–14 surface mount package provides separate
pins for VC (output supply) and Power Ground. Proper
implementation will significantly reduce the level of switching
transient noise imposed on the control circuitry. This
becomes particularly useful when reducing the Ipk(max) clamp
level. The separate VC supply input allows the designer
added flexibility in tailoring the drive voltage independent of
VCC. A zener clamp is typically connected to this input when
driving power MOSFETs in systems where VCC is greater the
20 V. Figure 22 shows proper power and control ground
connections in a current sensing power MOSFET
application.
Reference
The 5.0 V bandgap reference is trimmed to
± 1.0%
tolerance at TJ = 25°C on the UC284X, and ± 2.0% on the
UC384X. Its primary purpose is to supply charging current to
the oscillator timing capacitor. The reference has short circuit
protection and is capable of providing in excess of 20 mA for
powering additional control system circuitry.
Design Considerations
Do not attempt to construct the converter on
wire–wrap or plug–in prototype boards. High frequency
circuit layout techniques are imperative to prevent pulsewidth
jitter. This is usually caused by excessive noise pick–up
imposed on the Current Sense or Voltage Feedback inputs.
Noise immunity can be improved by lowering circuit
impedances at these points. The printed circuit layout should
contain a ground plane with low–current signal and
high–current switch and output grounds returning on
separate paths back to the input filter capacitor. Ceramic
bypass capacitors (0.1
µF) connected directly to VCC, VC,
and Vref may be required depending upon circuit layout. This
provides a low impedance path for filtering the high frequency
noise. All high current loops should be kept as short as
possible using heavy copper runs to minimize radiated EMI.
The Error Amp compensation circuitry and the converter
output voltage divider should be located close to the IC and
as far as possible from the power switch and other noise
generating components.
Figure 17. External Clock Synchronization
Figure 18. External Duty Cycle Clamp and
Multi–Unit Synchronization
The diode clamp is required if the Sync amplitude is large enough to
cause the bottom side of CT to go more than 300 mV below ground.
External
Sync
Input
47
5(9)
R
R
Bias
Osc
Vref
RT
8(14)
4(7)
2(3)
1(1)
0.01
CT
2R
R
EA
+
+
5(9)
R
R
Bias
Osc
8(14)
4(7)
2(3)
1(1)
2R
R
EA
+
+
7
5.0k
3
8
6
5
1
C
R
S
MC1455
2
RA
+
+
4
Q
5.0k
RB
To Additional
UCX84XA’s
f =
1.44
(RA + 2RB)C
Dmax =
RB
RA + 2RB


Numéro de pièce similaire - UC2844N

FabricantNo de pièceFiches techniqueDescription
logo
ON Semiconductor
UC2844N ONSEMI-UC2844N Datasheet
376Kb / 14P
   HIGH PERFORMANCE CURRENT MODE CONTROLLERS
1996 REV 1
logo
Texas Instruments
UC2844N TI1-UC2844N Datasheet
3Mb / 56P
[Old version datasheet]   Current-Mode PWM Controllers
logo
STMicroelectronics
UC2844N STMICROELECTRONICS-UC2844N Datasheet
96Kb / 11P
   CURRENTMODE PWM CONTROLLER
logo
Texas Instruments
UC2844N TI-UC2844N Datasheet
937Kb / 3P
[Old version datasheet]   Current Mode PWM Controller
logo
ON Semiconductor
UC2844N ONSEMI-UC2844N Datasheet
617Kb / 16P
   High Performance Current Mode Controllers
July, 2006 ??Rev. 7
More results

Description similaire - UC2844N

FabricantNo de pièceFiches techniqueDescription
logo
Motorola, Inc
UC3842B MOTOROLA-UC3842B Datasheet
401Kb / 16P
   HIGH PERFORMANCE CURRENT MODE CONTROLLERS
logo
Freescale Semiconductor...
MC34129EF FREESCALE-MC34129EF Datasheet
444Kb / 16P
   high performance current mode controllers
logo
ON Semiconductor
UC3844BNG ONSEMI-UC3844BNG Datasheet
399Kb / 19P
   High Performance Current Mode Controllers
August, 2013 ??Rev. 11
UC3845BDR2G ONSEMI-UC3845BDR2G Datasheet
387Kb / 19P
   High Performance Current Mode Controllers
December, 2012 ??Rev. 11
UC3845BVDG ONSEMI-UC3845BVDG Datasheet
399Kb / 19P
   High Performance Current Mode Controllers
August, 2013 ??Rev. 11
UC3845BVDR2G ONSEMI-UC3845BVDR2G Datasheet
399Kb / 19P
   High Performance Current Mode Controllers
August, 2013 ??Rev. 11
UC3844BVDG ONSEMI-UC3844BVDG Datasheet
399Kb / 19P
   High Performance Current Mode Controllers
August, 2013 ??Rev. 11
logo
Unisonic Technologies
UC3842B UTC-UC3842B_08 Datasheet
518Kb / 11P
   HIGH PERFORMANCE CURRENT MODE CONTROLLERS
logo
ON Semiconductor
UC3842A ONSEMI-UC3842A Datasheet
399Kb / 14P
   HIGH PERFORMANCE CURRENT MODE CONTROLLERS
1996 REV 1
UC3844 ONSEMI-UC3844 Datasheet
376Kb / 14P
   HIGH PERFORMANCE CURRENT MODE CONTROLLERS
1996 REV 1
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14


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