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Antonio

Sat May 03 2014, 03:15PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

I obtained some FGH60N60SMD IGBTs to use in a DRSSTC driver and was testing them. They appear to work (in low voltage at least), but I found strange the input capacitance measured with a capacitance meter between gate and emitter. By the datasheet I should see a bit more than 2 nF, but in most of by devices I am reading about 8 nF, and in others I measure just 1 nF. I know that the capacitance is nonlinear and the meter may be inventing something, but I was expecting something more consistent with the datasheet. Could someone with these devices at hand verify?

Artlav

Sat May 03 2014, 10:30PM

Registered Member #8120 Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94

Just tried 4 of them, date code (line above the name?) is 1C32AH.
4.4 to 4.6 nF with a multimeter, 4.0 to 4.2 nF with an LCR meter (any frequency).
Don't have ones from another batch.

I thought that the gate have a specific amount of charge, not capacitance, so C will be very voltage dependent?
However, it does not add up anyway.

Antonio

Sun May 04 2014, 01:07AM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

The capacitances depend on the applied voltages (probably incremental capacitances), so what a meter will read depends on how it measures the capacitance. What I find strange is the large variation in the ten that I have, with cies (between gate and emmiter and collector short-circuited) between 1.59 nF and 9.72 nF, with half of them above 8.36 nF and the others below 6.20 nF. The curves are from the datasheet.

Uspring

Tue May 06 2014, 09:39AM

Registered Member #3988 Joined: Thu Jul 07 2011, 03:25PM
Location:
Posts: 711

I just measured my only left over IXGN60N60C2D1. It has 5.8nF with open CE, which is close to the datasheet value.

Steve Conner

Tue May 06 2014, 10:09AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Antonio, where did you get your IGBTs? Is it possible they might be counterfeit parts? Can you post some high resolution pictures of the packages and markings? (put them in a flatbed scanner)

Antonio

Thu May 08 2014, 01:03AM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

I bought them from a chinese site, for a suspiciously low price

I didn't test them at power yet. They behave as should at low power, but may be really counterfeit.

Mads Barnkob

Thu May 08 2014, 06:27AM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

According to fairchild the marking is coded as follow:
Line 1:$Y (Fairchild logo) &Z (Plant Code) &3 (3-Digit Date Code) &K
Line 2:FGH60N60
Line 3:SMD

So according to:

We have the Fairchild logo, looks okay.

B is the plant code for Bangkok, Thailand (Subcontractor)

The next 6 digits have me puzzled. It should be 5 as its "3-Digit Date code format" and "2-Digits Lot Run Traceability Code"

but...

"When marking info does not have &K or &T, the following trace code assignment logic will apply.
When date code type is "S1" or "S2" - Lot Code will be assigned as Trace Code."

Since its given to be a S1 marking, there might be something else and I am not too sure what the trace code is.

But atleast the surface does not look like it was milled down, so maybe they bought packages without text on to start with and did a little crude laser job.

Some other F markings seems to just be a thin line all around.

Antonio

Sun May 18 2014, 10:52PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

An update: I tested a pair in a small drsstc with a half-bridge driver. They worked perfectly, switching up to 100 A without even getting warm. I see, however, a lot of noise in the primary current at each switching, what I was not seing with mosfets in a similar driver. Maybe just because the switching is faster, even at 300 kHz. Investigating.

Dr. Dark Current

Tue May 20 2014, 08:08AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Figure 9 in this data sheet should answer your original question:

Antonio

Wed May 21 2014, 12:43AM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Dr. Dark Current wrote ...

Figure 9 in this data sheet should answer your original question:

I posted this curve above. The capacitances are nonlinear, and so the value read in a capacitance meter depends on how the meter works. I am using two that read around 3 nF. The others I will use in a driver with several in parallel, but this requires a redesign of everything that I have, starting with the secondary coil that is too lossy.

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