# BJT's VCE.

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#### alphacat

##### New Member
Hey,

There's something which i dont quite understand about VCE in BJT's datasheet.
I take for example the P2N2222A datasheet.

1.
in the hFE category, for IC = 150mA & VCE = 10V* (2% pulse), hFE is guaranteed to be between 100 to 300.
If I apply continuous 10V voltage on VCE, would hFE remain between 100 to 300?
Do they apply a voltage pulse insead of continuous voltage to keep the BJT cool, and measuring hFE only when the
pulse is at its on state?

2.
In the VCEsat row, they claim that for IC=150mA & VCE = 10V*, VCEsat is 0.3V max.
I dont understand, if they apply 2% 10V pulse on the CE junction, shouldnt VCE be the exact applied pulse?
I dont understand how they reached 0.3V.

Thanks.

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#### crutschow

##### Well-Known Member
1. hFE will be at the values stated for 10V Vce and the indicated collector current and temperature, yes.
They pulse test to limit the power dissipation so it doesn't heat up during the the test, and also to perform the test rapidly in production.

2. You caught an error in the data sheet. The Vce(sat) should be specified at a specific collector and base current. See http://www.electro-tech-online.com/custompdfs/2009/08/2N2222.pdf for example.

Thank you C

#### audioguru

##### Well-Known Member
I looked at 25 datasheets but did not see the one with the errors about saturation voltages.
I asked before but nobody replied: Whose datasheet is wrong?

#### mneary

##### New Member
I looked at 25 datasheets but did not see the one with the errors about saturation voltages.
I asked before but nobody replied: Whose datasheet is wrong?
All of them (except Microsemi). This one is Fairchild PN2222A/MMBT2222A/PZT2222A Rev. 1.0.0 February 2009. Note that Vce cannot be 10V and 0.3V at the same time.
Code:
Collector-Emitter Sat Voltage * IC = 150mA, VCE = 10V    0.3
* IC = 500mA, VCE = 10V    1.0

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#### audioguru

##### Well-Known Member
I looked at one dozen Fairchild datasheets for their PN2222A transistor and found a wrong saturation voltage spec in 2004.
They shouldn't let school kid NOOBs do their datasheets.

#### Hero999

##### Banned
They've probably outsourced their datasheet department to India.

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