TIDA-010242: about MIL-STD-1275E

Yuta Nishie

Part Number: TIDA-010242

Tool/software:

Hi,

Can this reference design also protect "5.1.1.2 Voltage ripple" and "5.1.2 Starting operation" as specified in MIL-STD-1275E?

https://www.sullivanuv.com/wp-content/uploads/2017/12/MIL-STD-1275E.pdf

The design guide "TIDA-010242" states "The standard characteristics three main events that occur during operation of a military vehicle, and any equipment connected to the 28-V main power supply must be protected against these three events. These events are: reverse polarity, voltage spike, and voltage surge event."

I would like to know if 5.1.1.2 voltage ripple and 5.1.2 Starting operation are also applicable.

Best Regards,

Nishie

1 month ago

0 Bart Basile 1 month ago

TI__Intellectual 2880 points

Nishie,

We didn't design or test the design to either of the two sections you listed. For 5.1.1.2, I cannot confirm if the input diodes are sufficient. There is a PSpice model attached to the design, which you could simulate the ripple with.

Regarding 5.1.2, the system does not operate in boost mode, so startup transients must be handled by the downstream converter if necessary, depending on the system needs.

0 Yuta Nishie 1 month ago in reply to Bart Basile

Genius 3440 points

Hi Bart,

Thank you for your support.

I will confirm about 5.1.1.2 using simulation.

Regarding 5.1.2, could you tell us what kind of circuit the converter in the latter stage will be? If you have a document with an example circuit, would you please share it with me?

Best Regards,

Nishie

0 Bart Basile 29 days ago in reply to Yuta Nishie

TI__Intellectual 2880 points

Nishie,

Apologies for the delay.

What you're potentially looking for is a pre-boost circuit if you're system won't operate down to the 12V level during the cranking stage.

This is dependent on your system power input however. You could also use a hold up capacitor depending on your power requirements.

0 Yuta Nishie 29 days ago in reply to Bart Basile

Genius 3440 points

Hi Bart-san,

I apologize for my lack of knowledge.

Am I correct in understanding that "the downstream converter" and "a pre-boost circuit" in your answer are different circuits?

Also, where are these circuits added in the reference design?

Best Regards,

Nishie

+1 Bart Basile 28 days ago in reply to Yuta Nishie

TI__Intellectual 2880 points

The surge protection would typically sit at the primary input of your system. This will clamp the input of the system to 34V, as well as prevent reverse polarity connections.

The DC/DC converter that takes the output from the surge protection and powers the rest of the system will need to be able to handle the low voltage during cranking operation, but it will be protected from any surge inputs. This is what I meant as downstream, as it is after the surge protection.

A pre-boost circuit is typically used in automotive applications to ensure that the voltage going to your system buck converters stays above the converter outputs. Your buck converter outputs are system dependent, so I cannot say for sure that you would need one, but here is an excellent article describing it for automotive systems, the voltages would just have to be adapted for Mil-Std-1275: https://www.electronicspecifier.com/products/power/optimising-automotive-pre-boost-power-supplies

So, if your buck converters can operate down to the low voltage at cranking, you would just need the surge protection, then the buck converters.

If they cannot, then you would insert a pre-boost circuit between the surge protection and the bucks in order to keep the voltage at an appropriate level.

0 Yuta Nishie 24 days ago in reply to Bart Basile

Genius 3440 points

Hi Bart-san,

I tried to simulate with PSpice model, but an error like the image occurred. Could you tell me the countermeasure?

Best Regards,

Nishie

+1 Bart Basile 24 days ago in reply to Yuta Nishie

TI__Intellectual 2880 points

Nishie,

This looks to be a type of license error. Can you try the steps that David outlines in this thread and let me know if it resolves it?

https://e2e.ti.com/support/tools/simulation-hardware-system-design-tools-group/sim-hw-system-design/f/simulation-hardware-system-design-tools-forum/1361023/pspice-for-ti-after-one-time-usage-license-error-lmc-022071-occurs

0 Yuta Nishie 16 days ago in reply to Bart Basile

Genius 3440 points

Hi Bart-san,

Sorry for the late reply. I solved it by referring to the link you gave me.

Best Regards,

Nishie

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TIDA-010242: about MIL-STD-1275E