Reading transistor datasheet ... need help

how to read transistor datasheet

Hi
I'm a newbie in electronic.
And I just read a transistor datasheet. I need help understandng the value.
This are some value from the data sheet :

---------------------------
IC (cont.) (A) 4.0
---------------------------
hFE
Min. 300
Max. 1200
@IC(mA) 1000
@VCE(V) 2
----------------------------
VCE(sat)
Max.(V) 0.19
@IC(mA) 4000
@IB(mA) 20
----------------------------

My questions are
1. What is hFE @VCE ?
2. What is hFE @IC ?
3. How to calculate the power dissipation (which VCE to use ?)
Thank you
Sundi

how to read a transistor datasheet

for understandin HFE and VCE you need to know the transistor's internals

HFE is the Gain of the transistor
VCE is the collector to emitter voltage
IC is the collector current

and the power dissipation is calculated on the basis of the current you are applying at the base and the voltage the transistor is operating at

Which transistor it is?
and where you want to use it??

reading transistor data sheets

What is different between hFE VCE and VCE Sat ?

PD formula is VCE * IC, correct ? Which VCE ?

Thank you

reading transistor

You are combining spec's of different transistors together which makes it confusing.
You should ask about the datasheet of one transistor and say which transistor.

Your first description has a high collector current of 4A for a big power transistor but the very high hFE of a little low current transistor.

My example is a TIP41 power transistor (look at its datasheet) with a max allowed continuous collector current of 6A.
1) Its hFE at a collector current of 3A and a VCE of 4V is from 15 to 75. Therfore its base current must be from 40mA to 200mA.
2) Its VCE sat (saturation voltage loss) is a max of 1.5V when its collector current is 6A and its base current is 600mA. Its VCE sat voltage loss is less at lower currents. hFE is not used for a saturated transistor since the collector to emitter voltage is as low as it can be.
3) The power dissipation is the VCE times the IC. The max allowed dissipation of the TIP41 is 2.0W without a heatsink at a 25 degrees C ambient. Its max allowed dissipation is 65W if its case is cooled to 25 degrees C somehow.

how to read transistor datasheets

The spec is from one transistor, ZTX1047A-ND.

I get the data from digikey catalog. The link is :
**broken link removed**

The ZTX1047A-ND datasheet link is :
**broken link removed**

I need a transistor with minimum PD with high Ic.

Thank you

Sundi

transistor reading

Sundi said:

Hi

---------------------------
IC (cont.) (A) 4.0
---------------------------
hFE
Min. 300
Max. 1200
@IC(mA) 1000
@VCE(V) 2
----------------------------
VCE(sat)
Max.(V) 0.19
@IC(mA) 4000
@IB(mA) 20
----------------------------

My questions are
1. What is hFE @VCE ?
2. What is hFE @IC ?
3. How to calculate the power dissipation (which VCE to use ?)
Thank you
Sundi

Click to expand...

Put it simple, hFE is the current gain of the transistor. When there is Ib current pass into the base of the transister, there will be Ib x hFE current pass through the collector and emitter. VCE is the voltage across the C and E of the transistor. Lets presume the C and E of transistor as two leads of a resistor, when there is current IC pass through it there will be a voltage different between the two leads (V = I x R).

According to the spec, the transister should have the mininum current gain of 300 and a maximun gain of 1200, (different in devices) under the testing condition of IC = 1000 ma and VCE= 2V.

When the transister is under this testing condition as
IB=20ma, IC=4000ma then
VCE will be 0.19 volt max.
the current gain = IC/IB = 4000/20 = 200.

power dissipation = VCE x IC of your circuit under operation condition.
You can limit the power dissipation by 1) putting a large resistor in series of the collector, 2) limit the IB corrent, 3) Lower the supply voltage.

Regards.

what is hfe

The Zetex transistor is amazing.
It has a very high max current for a little transistor.
It has a high current gain.
It has a low saturation voltage loss.
But its max allowed collector-emitter voltage is only 10V.

how to read transistor data sheet

Apparently, your question is related to saturated operation, the hFE related data can be ignored in this respect.

If the datsheet's numeric values don't fit your intended operation point, you may want to consult the diagrams for saturated operation.

Basically, to lower Vce,sat, you have to provide more base current than required by the current gain, that's simply the definition of saturation. You also have to consider gain variation between exemplars.

how to read datasheet transistor

Audioguru said:

The Zetex transistor is amazing.
It has a very high max current for a little transistor.
It has a high current gain.
It has a low saturation voltage loss.
But its max allowed collector-emitter voltage is only 10V.

Click to expand...

Zetex is renowned for transistors like this. You will often find that they also have rather higher Hfe at high Ic than many other small transistors. If you can find one to suit your application they can be an absolute saviour.

JD