Power Diode Recovered Charge(Qr) & Reverse Recovery Time(trr) || Diode Switching Loss Explanation
Summary
TLDRIn this educational lecture, the presenter delves into the concept of stored charge and reverse recovery in diodes. They explain the functioning of a diode under forward and reverse bias, highlighting the role of minority charge carriers and junction capacitance. The lecture further discusses the process of removing stored charges and the significance of reverse recovery time (tRR). It explores power loss in diodes due to stored charges and reverse recovery, and contrasts different types of diodes, such as the IN4007 and SBD, in terms of their reverse recovery characteristics.
Takeaways
- 🔌 Diodes function by allowing current flow when forward-biased and blocking current when reverse-biased.
- 🌊 The depletion region in a diode expands when reverse-biased, which helps to block current flow.
- ⚡ The process of removing stored charges in a diode's junction capacitance is crucial for its operation.
- 🕒 Reverse recovery time (tRR) is the time it takes for a diode to remove all stored charges and become capable of blocking reverse voltage.
- 📉 The waveform of voltage and current across a diode can illustrate the diode's behavior during forward and reverse bias conditions.
- 🔋 The stored charge in the junction capacitance affects the diode's ability to block reverse voltage, which is significant for its performance.
- 💡 The minority charge carriers' diffusion from the P-region to the N-region and vice versa is key to the diode's conduction.
- 🔗 The slope of the current during the diode's operation influences the diode's charge and discharge dynamics.
- 🛑 The removal of stored charges is achieved by applying a reverse voltage, which initiates the reverse recovery process.
- 📚 Different types of diodes, such as Schottky or standard silicon diodes, have varying reverse recovery times and stored charge characteristics.
Q & A
What is the main topic of the lecture?
-The main topic of the lecture is the stored charge and reverse recovery in diodes, including power loss due to stored charges and the concept of reverse recovery time (t_rr) in diodes.
What happens when a diode is forward biased?
-When a diode is forward biased, the depletion region reduces, allowing current to flow through it due to the diffusion of minority charge carriers from the P region to the N region and vice versa.
How does the depletion region change when a diode is reverse biased?
-When a diode is reverse biased, the depletion region spreads towards the PN junction, and the minority carrier charges are pulled out, preventing current flow until the diode is capable of blocking the reverse voltage.
What is meant by stored charge in a diode?
-Stored charge in a diode refers to the minority charge carriers that accumulate at the junction capacitance when the diode is forward biased.
What is reverse recovery?
-Reverse recovery is the process of removing the stored charges from the junction capacitance when the diode transitions from forward bias to reverse bias.
How is the reverse recovery time (t_rr) defined?
-The reverse recovery time (t_rr) is the time required for a diode to remove all stored charges and block the applied reverse voltage after transitioning from forward bias to reverse bias.
What is the significance of the current slope during reverse recovery?
-The current slope during reverse recovery is significant as it determines the rate at which the stored charges are removed and the diode's ability to block the reverse voltage.
What are the power losses in a diode during reverse recovery?
-Power losses in a diode during reverse recovery include conduction losses when the diode is forward biased and switching losses when the diode transitions to reverse bias.
Why is it important to know the reverse recovery time for diodes?
-Knowing the reverse recovery time is important because it affects the efficiency and performance of circuits, especially in applications involving fast switching.
How do different types of diodes compare in terms of reverse recovery time?
-Different types of diodes have different reverse recovery times. For example, Schottky diodes typically have faster reverse recovery times compared to silicon diodes, which is an important consideration in high-speed switching applications.
Outlines
🔬 Introduction to Stored Charge and Diode Operations
This paragraph introduces the topic of stored charge and diode behavior, particularly focusing on reverse recovery and power loss due to stored charges. The speaker begins by inviting viewers to subscribe to the channel and engage with the content. The main discussion revolves around the functioning of a diode, explaining how a forward bias leads to the diffusion of minority charge carriers and the resulting current flow. The concept of junction capacitance charging and the role of the depletion region in a PN junction diode are also covered. The paragraph sets the stage for a deeper dive into the technical aspects of diode operation and the challenges associated with stored charges and reverse recovery.
🔋 Reverse Bias and Diode Recovery Process
The second paragraph delves into the process of reverse biasing a diode and the subsequent removal of stored charges. It describes how applying a reverse voltage leads to the depletion of minority charge carriers and the expansion of the depletion region. The speaker uses a waveform diagram to illustrate the voltage and current changes over time, highlighting the intervals during which the diode transitions from forward to reverse bias. The concept of reverse recovery time (tRR) is introduced, explaining the time it takes for a diode to remove all stored charges and become capable of blocking reverse voltage. The paragraph also touches on the impact of the slope of the current on the diode's behavior, providing a technical explanation of the recovery process.
⏱ Understanding Reverse Recovery Time and Diode Types
The final paragraph discusses the reverse recovery time (TRR) in detail, emphasizing its significance in determining the diode's ability to block negative voltage after charge removal. The speaker contrasts different types of diodes, such as the IN4001 and Schottky diodes, highlighting their respective TRR characteristics. The paragraph concludes with a summary of the lecture's key points and a thank you to the viewers for their attention. It reinforces the importance of understanding the technical specifications of diodes for applications involving rapid switching and voltage blocking.
Mindmap
Keywords
💡Stored Charge
💡Diode
💡Reverse Recovery
💡Power Loss
💡tRR (Reverse Recovery Time)
💡QR (Recovery Charge)
💡PN Junction
💡Depletion Region
💡Forward Bias
💡Reverse Bias
💡Diode Types
Highlights
Introduction to stored charge and diode reverse recovery
Explanation of power loss in diodes due to stored charges and reverse recovery
Definition of tRR (reverse recovery time) and QR (reverse recovery charge)
Types of diodes and their reverse recovery times
How to subscribe and receive notifications for upcoming lectures
Basic functioning of a diode under forward bias
The role of minority charge carriers in diode operation
How the depletion region changes under reverse bias
Process of removing stored charges in the junction capacitance
Waveform analysis of voltage and current across a diode
Minority charge distribution during reverse recovery
Interval analysis of diode operation from on to off state
Impact of current slope on diode performance
Explanation of how depletion region width increases after removing stored charges
Blocking of reverse voltage by diodes after charge removal
Calculation of power loss in diodes during conduction and switching
Detailed discussion on reverse recovery time (TRR) and its significance
Comparison of reverse recovery times for different types of diodes
Conclusion and appreciation for watching the lecture
Transcripts
hello friends hope you are doing well in
today's lecture I'm going to talk about
the stored charge and diode and diode
reverse recovery okay power loss in
diode due to store charts and reverse
recovery and then what is t RR win diode
what is QR n diode types of diode and
their reverse recovery time so okay so
before I start my lecture I would
request you if you haven't subscribe my
channel please subscribe it and press
the bell icon so that you get
notifications of all my upcoming lecture
please like share with your friends and
family members okay watch the video till
the end so that you get all the lecture
notes ok now let's talk about the diode
store charts removal and reverse
recovery ok
I'm not going much more in detail how
diode is functioning but let's talk
about a bit a little bit how the hood is
working now so if you apply a positive
voltage to P reason and negative voltage
to n reason okay so what happens is if
you apply positive voltage to P reason
and negative voltage to n vision there
is a magnetic diffusion of a minority
carry a charge carrier minority charge
carrier from P reason to and reason and
indecent to P reason okay
minority it's the charge carrier
diffuses from P reason to and isn't due
to that the junction
capacitance charges and because of that
the current start flowing through the
through it okay so if you apply a
forward bias diode in a foul road for
advice
okay so depletion region of PN Junction
diode a diode reduces because of that
current start flowing through it okay
okay all right so if you bias a diode in
a reverse fashion okay how would you
guys it if you apply negative voltage to
be terminal of PN Junction and positive
voltage to end a zone of PN Junction
diode becomes a reverse biased reverse
bias condition in that particular
condition the depletion region spreads
towards towards PN and reason and the
minority carrier charges now pulls out
okay
so that is how a diode is working so now
let's talk about the store charts in
removal and reverse recovery means how
you how you remove the stored charges in
junction capacitance and what is reverse
recovery
okay let's talk a bit about that so now
okay
I have drawn a drawn a waveform this is
VD voltage across diode okay over a
period of time this is ID current across
the diode over a period of time okay and
this one I have drawn here minority
charge distribution during reverse
recovery in diode okay so let's talk
about now okay during interval or during
interval T equals to zero here
to t equals to t0 here okay during
interval T equals to 0 to T equals to t0
diode is on condition and there is some
current current flowing through it okay
so that is ID
okay so diode is there is some voltage
across the diode and some current
flowing through it so voltage across
diode is VD on and some current across
the diode is flowing through it is ID on
right okay means diode is in forward
bias condition now
during interval t equals 2t 0 to t
equals to t1 okay t equals 2t 0 to t
equals to t1 you have applied the
reverse voltage across the PN Junction
and diode is in reverse bias condition
so now in diode is in reverse bias
condition so what happens when the diode
is in reverse bias condition means we
start removing minority charges with a
negative current okay okay so we start
removing negative charges from negative
current so you can see here there is
some negative current flowing through
the diode okay now what happens during
interval of T equals 2 T 1 2 T equals 2
T 2 okay during this interval T equals 2
T 1 2 T equals 2 T 2 okay in this
interval a diode is off and if we
removed the enough charge okay and that
point of time voltage across depletion
region start decreasing and go negative
okay at that point of time voltage
across depletion region okay start
decreasing and go negative
okay during t equals to this point of
time okay now let's have a look off
minority charge distribution how it is
functioning when diode is in forward
bias let's say T equals 2t 0 time
Junction capacitance fully charged okay
there is chards concept a concentration
profile over here the junction minority
charges are minority charge carriers
stored in a junction capacitance over T
equals to zero
during the period of T equals 2t one
start removing some charges from you
start pulling out some charges from the
from Junction capacitance okay over P
and n region so now here the now here
you have less charge stored in in the
junction capacitance okay all right
nothing one more thing
the there is a some current slope okay
okay this is some slope current slope
right that the slope determines the
diffusion did and charge and the current
okay so at the point of 2 T 2 you have
reduced some more charges you have
reduced enough charges you have reduced
enough charges and that point of time
voltage across depletion region start
decreasing and go negative so okay
during two teeth okay during this period
t three okay during this period t three
you removed all stored charge in
Junction capacitance right so let's say
here here okay let's say here let's say
here earlier your depletion width reason
width is that much only okay that much
only now once you removed all charge
stored in Junction capacitance okay so
your depletion region
width increases earlier it was that much
now it was that much because you removed
all stool charts from the new Junction
capacitance so you remove all minority
carrier charges from your Junction
capacitance so the depletion region
width increases because of that diode is
now able to block the reverse voltage
okay
okay diode is now able to block the
reverse voltage okay here beauty of -
negative voltage okay and there is no
current flowing through it so alright
hope you understood that much and now
let's talk about much more and this
interval I've already explained during
this now let's talk about loss in power
loss in diode what is power loss P
equals to B into y at time T equals 2 T
0 - 2 equals 2t to zero here it is so
nice conduction loss at T equals to G T
0 and T equals to t4 you have switching
losses right so now what is a reverse
recovery time time required to diode to
remove all Stuart charts and block the
apply negative voltage okay this one is
TR from T equals to 0 to P equals to 2
for that much time required diode to
remove all its two charges that time is
called reverse recovery time now what is
recovered charge negative diode current
area during reverse recovery let's say I
will overlook here diode stored charge
okay so this one is a recovered charges
area okay let's example I n400 say one
the TR are not specified then FASTA
comedy diode the example is I n for one
for it it's TR r equals two now
a Schottky diode let's say SB 180 and no
recovered charts okay so my question is
now while does I even four zero zero
seven and SB 1 at T does not have it TRR
the reverse recovery time okay okay
thank you watching this lecture hope you
enjoyed the lecture I wish you a very
happy learning
thank you so much
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