Power BJT Switching With Speed-Up Capacitor

14
Favorite
90
copy
Copy
25828
Views
Power BJT Switching With Speed-Up Capacitor

Circuit Description

Graph image for Power BJT Switching With Speed-Up Capacitor

Circuit Graph

This circuit demonstrates how to improve the switching speed of BJTs using a speed-up capacitor. Both the turn-on and turn-off times of the BJT are reduced. The speed-up capacitor works as follows: When the input is at low state and the capacitor is fully discharged, the voltage across its plates is 0 V. When the input is switched to high state, the capacitor initially bypasses (shorts) the base resistor Rb, the current that goes to the base of the transistor is (very) high, limited only by the base current limiting resistor Rbcl and other parasitic resistors in series with it. This initial high current quickly turns on the transistor. As the capacitor accumulates charge the voltage across its plates increases, thus the base current decreases until it reaches the value if the capacitor is open. With the input at high state and the circuit settled to steady state, the capacitor is charged to the voltage across Rb. The voltage is approximately the logic high voltage at the input minus the transistor base voltage (also base to emitter voltage in this case). The terminal of the capacitor towards the input is more positive than its terminal towards the base of the transistor. When the input transitions to logic low, the previously more positive terminal of the capacitor is now connected to a voltage very near ground potential. The other terminal of the capacitor now applies a negative potential to Rbcl. This negative voltage results to larger initial reverse-bias to the transistor and larger initial reverse current to discharge the parasitic capacitances across the base-emitter terminal. As the capacitor loses charge, the reverse bias to the base of the transistor subsides to approximately the logic low voltage level of the input, just enough to maintain the transistor off. The voltage probe at the junction of Rb, Rbcl, and the switch to capacitor captures the spikes as the input switches logic states. It is also interesting to probe the current, it's just not included in the saved circuit to avoid clutter in the graph. Note: I prefer to use smaller power transistor such as TIP29, TIP31, MJE243, MJE15034, etc. for this simulation. The MJ15024 used in the circuit is a very high power BJT for the purpose of this demonstration but it is the only available model in the Free Subscription version of Multisim Live. In the circuit, the ON collector current was set to just 0.5 A and the base current is about 25 mA to get a clean reference waveforms.

There are currently no comments

Profile image for nasti06

nasti06

1 favorites
Profile image for user-633094

user-633094

21 favorites
Profile image for CharlesAbe

CharlesAbe

7 favorites
Profile image for adroca

adroca

1 favorites
Profile image for josepvillalba

josepvillalba

2 favorites
Profile image for luimarf1

luimarf1

2 favorites
Profile image for StefanoGiaccaglia

StefanoGiaccaglia

3 favorites
Profile image for jash27

jash27

20 favorites
Profile image for jai87

jai87

1 favorites
Profile image for Wissa

Wissa

2 favorites
Profile image for Deedido

Deedido

1 favorites
Profile image for nani91

nani91

16 favorites
Profile image for agaelema

agaelema

23 favorites
Profile image for danteregianifreitas

danteregianifreitas

1 favorites
Profile image for veeresh1

Copy of Power BJT Switching With Speed-Up Capacitor

veeresh1
Profile image for Aditya1101

NPN transistor made more efficient using capacitor

Aditya1101
Profile image for Elron.d

Power BJT Switching With Speed-Up Capacitor

Elron.d
Profile image for higopi

Power BJT Switching With Speed-Up Capacitor

higopi
Profile image for narcinev

Power BJT Switching With Speed-Up Capacitor

narcinev
Profile image for percy2020

Power BJT Switching With Speed-Up Capacitor

percy2020
Profile image for narcinev

Power BJT Switching With Speed-Up Capacitor

narcinev
Profile image for Timkos

Power BJT Switching With Speed-Up Capacitor

Timkos
Profile image for teo_ju_teng

Power BJT Switching With Speed-Up Capacitor

teo_ju_teng
Profile image for fleb72

Influence Speed-Up Capacitor

fleb72
Profile image for rsmit32

Power BJT Switching With Speed-Up Capacitor

rsmit32
Profile image for S004

Power BJT Switching With Speed-Up Capacitor

S004
Profile image for avaris

Copy of Power BJT Switching With Speed-Up Capacitor

avaris
Profile image for slzw

Power BJT Switching With Speed-Up Capacitor

slzw
Profile image for livefreest

Power BJT Switching With Speed-Up Capacitor

livefreest
Profile image for mikel789

Power BJT Switching With Speed-Up Capacitor

mikel789
Profile image for joaod

Copy of Power BJT Switching With Speed-Up Capacitor

joaod
Profile image for c4lig0

Power BJT Switching With Speed-Up Capacitor

c4lig0
Profile image for blue_led

Power BJT Switching With Speed-Up Capacitor

blue_led
Profile image for Johndoe221

Copy of Power BJT Switching With Speed-Up Capacitor

Johndoe221
Profile image for Giuseppe

Power BJT Switching With Speed-Up Capacitor

Giuseppe
Profile image for ksank7

Power BJT Switching With Speed-Up Capacitor

ksank7
Profile image for Prof.Massimo

DC10_RC circuit in DC

Prof.Massimo
Profile image for Clemente_05

Power BJT Switching With Speed-Up Capacitor

Clemente_05
Profile image for Croust

Power BJT Switching With Speed-Up Capacitor

Croust
Profile image for Ainaa99

Power BJT Switching With Speed-Up Capacitor

Ainaa99
Profile image for amoreirasilva

Power_BJT_SwitchingSpeedUp_Cap

amoreirasilva
Profile image for icg0511

Power BJT Switching With Speed-Up Capacitor

icg0511
Profile image for admasta

Copy of Power BJT Switching With Speed-Up Capacitor

admasta
Profile image for mireia99

PRÁCTICA 3- Power BJT Switching With Speed-Up Capacitor

mireia99
Profile image for BUGARINJM

Copy of Power BJT Switching With Speed-Up Capacitor

BUGARINJM
Profile image for Eran2004

Power BJT Switching With Speed-Up Capacitor

Eran2004
Profile image for mackyykcam

Power BJT Switching With Speed-Up Capacitor

mackyykcam
Profile image for jogarta6

Copy of Power BJT Switching With Speed-Up Capacitor

jogarta6
Profile image for Eedmundo

Switching BJT UNAQ

Eedmundo
Profile image for MohitS27

Copy of Power BJT Switching With Speed-Up Capacitor

MohitS27
Profile image for vladimir.tanasiev

Power BJT Switching With Speed-Up Capacitor

vladimir.tanasiev
Profile image for adroca

Copy of Power BJT Switching With Speed-Up Capacitor

adroca
Profile image for yabari

Power BJT Switching With Speed-Up Capacitor

yabari
Profile image for betofraus

Power BJT Switching With Speed-Up Capacitor

betofraus
Profile image for fluque

sb Power BJT Switching With Speed-Up Capacitor

fluque
Profile image for mackyykcam

Copy of Power BJT Switching With Speed-Up Capacitor

mackyykcam
Profile image for stephanePerissutti74

Power BJT Switching With Speed-Up Capacitor

stephanePerissutti74
Profile image for YuMERA

Copy of Power BJT Switching With Speed-Up Capacitor

YuMERA
Profile image for rado123456

Copy of Power BJT Switching With Speed-Up Capacitor

rado123456
Profile image for neelpatel96433

Copy of Power BJT Switching With Speed-Up Capacitor

neelpatel96433
Profile image for picaxe2021

Power BJT Switching With Speed-Up Capacitor

picaxe2021
Profile image for trssnchz

Power BJT Switching With Speed-Up Capacitor

trssnchz
Profile image for hussam786

Transistor as a Switch

hussam786
Profile image for pchpch

Power BJT Switching With Speed-Up Capacitor

pchpch
Profile image for almasfaisal4

Power BJT Switching With Speed-Up Capacitor

almasfaisal4
Profile image for henrique.armand

Power BJT Switching With Speed-Up Capacitor

henrique.armand
Profile image for Leonmzzhang

Power BJT Switching With Speed-Up Capacitor

Leonmzzhang
Profile image for Pallavi20

Power BJT Switching With Speed-Up Capacitor

Pallavi20
Profile image for Isroilxan

Power BJT Switching With Speed-Up Capacitor

Isroilxan
Profile image for 20ru1a0414@ruce.ac.in

voltage series

20ru1a0414@ruce.ac.in
Profile image for STPN

Copy of Power BJT Switching With Speed-Up Capacitor

STPN
Profile image for 20ru1a0414@ruce.ac.in

current shunt feedback amplifier

20ru1a0414@ruce.ac.in
Profile image for AbelMcRop

Power BJT Switching With Speed-Up Capacitor

AbelMcRop
Profile image for giovanni.andreoli

Power BJT Switching With Speed-Up Capacitor

giovanni.andreoli
Profile image for alvaro.rodriguez.c02

Power BJT Switching With Speed-Up Capacitor

alvaro.rodriguez.c02
Profile image for CharlesAbe

Copy of Power BJT Switching With Speed-Up Capacitor

CharlesAbe
Profile image for CarlosPatricio

Power BJT Switching With Speed-Up Capacitor

CarlosPatricio
Profile image for evelyn.f.c.26@gmail.com

EVELYN

evelyn.f.c.26@gmail.com
Profile image for JoshuaCute

Power BJT Switching With Speed-Up Capacitor

JoshuaCute
Profile image for Lare

Copy of Power BJT Switching With Speed-Up Capacitor

Lare
Profile image for айтишник

ллллллл

айтишник
Profile image for Jessen-li

Power BJT Switching with 2 BJTs

Jessen-li
Profile image for evelyn.f.c.26@gmail.com

Power BJT Switching With Speed-Up Capacitor

evelyn.f.c.26@gmail.com
Profile image for Aarthivpmb

Copy of Power BJT Switching With Speed-Up Capacitor

Aarthivpmb
Profile image for ZhangKF

Power BJT Switching With Speed-Up Capacitor

ZhangKF
Profile image for naveenramana460@gmail.com

Power BJT Switching With Speed-Up Capacitor

naveenramana460@gmail.com
Profile image for Radmir00070

11

Radmir00070
Profile image for Henrique79

Copy of Power BJT Switching With Speed-Up Capacitor

Henrique79
Profile image for Doniiiii

dondon

Doniiiii
Profile image for CaitlinH

E1 l3

CaitlinH
Profile image for Itzel_Juarez

Prac 8

Itzel_Juarez
Profile image for Talapula

Copy of Power BJT Switching With Speed-Up Capacitor

Talapula
Profile image for jollyaaa

Power BJT Switching With Speed-Up Capacitor

jollyaaa
Profile image for Talapula

Copy of Power BJT Switching With Speed-Up Capacitor

Talapula
Profile image for Camiloacero10

Fase 6 Circuito Final

Camiloacero10
Profile image for AlexDaniel56

Power BJT With Speed-Up Capacitor

AlexDaniel56
Profile image for selva96

Power BJT Switching With Speed-Up Capacitor

selva96
Profile image for khahoan1985

Copy of Power BJT Switching With Speed-Up Capacitor

khahoan1985
Profile image for kamaldeepmehra

Power mosfet Switching With Speed-Up Capacitor

kamaldeepmehra
Profile image for maiker.torres

Power BJT Switching With Speed-Up Capacitor

maiker.torres
Profile image for cnandes

circuit sw2

cnandes
Profile image for J0va

Power BJT Switching With Speed-Up Capacitor

J0va
Profile image for user-38902

Copy of Power BJT Switching With Speed-Up Capacitor

user-38902
Profile image for private copy

Private Copy

Creator

GGoodwin

1116 Circuits

Date Created

7 years, 3 months ago

Last Modified

7 years, 3 months ago

Tags

  • circuit fundamentals
  • bjt switching
  • bjt inverter
  • bjt inverter with speed-up capacitor
  • power bjt switching with speed-up capacitor
  • switching bjts
  • bjt switching speed-up capacitor
  • power bjts