TSD05: How to Use and Select a TVS

user5163865

Genius 4040 points

Part Number: TSD05
Other Parts Discussed in Thread: , TVS0500

Tool/software:

Hi,

I have a question about how to use and select a TVS.

Target parts: TSD05, TSD05C

Things to check
①. Is it okay to use it for the following purposes?

- Between the signal and GND of a small signal line (5V analog input)
- Lightning surge protection for a subsequent IC (maximum rated DC7V)

②. Is it possible to protect the subsequent IC against the following surges by using lightning surge protection for a signal line?

- Applied voltage: ±2.0kV, 1.2/50μS
- Discharge interval: 60s
- Applied location: Signal line - GND (TVS mounting location)

③. Is it possible to use two TSD05 (unidirectional) in series in the opposite direction? (Is this a common usage?)

If it is possible, I think the clamp voltage will increase by the forward voltage, is this correct?
Will the internal capacitance be halved?

*For reference, the Toshiba DF2B7PCT,L3F currently under evaluation was broken by a surge, and then the downstream IC was broken.
Diodes D5V0S1B2LP-7B passed the surge test, but was affected by leakage current and capacitance, and the product performance was
not satisfactory. (The product performance is designed with severe leakage current and capacitance.)

④. Sorry, but could you please introduce any other parts you could suggest?

The specifications are roughly as follows.
<Product performance test conditions>

-Leakage current (IR): 1μA or less
-Internal capacitance (Ct): 50pF or less
-Operating voltage (VRWM): 5.5V or more

-Signal line surge resistance: ±2.0kV (lightning surge test: IEC61000-4-5 compliant, 1.2/50μs combination waveform)
-Limit (clamp) voltage (VC): 11Vmax or less
-Peak pulse current (Ipp): 40Amax or more or peak pulse power (PPPM): 400W or more

Best regards,

Hiroshi

5 months ago

0 Josh Prushing 5 months ago

TI__Expert 6165 points

Hi Hiroshi,

Please see the answers to your questions below:

Is it okay to use it for the following purposes?
1. Yes, if Pin 1 is connected to signal line and Pin 2 is connected to GND, this is ideal scenario.
2. Just to confirm, is 7V the maximum DC rating of downstream IC or is 7V the maximum voltage seen on signal line?
Is it possible to protect the subsequent IC against the following surges by using lightning surge protection for a signal line?
1. Please see the table below from our App Note on IEC 61000-4-x tests on the surge ratings required for different voltage/Req combinations. In short, TSD05 will be able to protect ±2.0kV, 1.2/50μS as long as Req is 42 Ohms.
3. To confirm, discharge interval is time between strikes?

Is it possible to use two TSD05 (unidirectional) in series in the opposite direction?

While this is possible, this will increase Breakdown Voltage and Clamping Voltage, while lowering Leakage Current, Capacitance, and Surge Rating. Typically, capacitance is halved, as well as the surge rating.
From the requirements given in question 2, it seems like TSD05 is the only device (of the 4 below) that can support the 2kV surge event, but this device is larger than the DFN1006 options below. Will this be suitable for the application, or is package size an additional concern?

	DF2B7PCT	D5V0S1B2LP	TSD05	TSD05C
Vrwm (V)	5	5	5.5	5.5
Package Type	DFN1006	DFN1006	SOD323	SOD323
Nominal Package Size (L x W) (mm)	1.0 x 0.6	1.0 x 0.6	2.65 x 1.3	2.65 x 1.3
Bi-/uni-directional	Bidi	Bidi	Uni	Bidi
Number of Channels	1	1	1	1
Clamping Voltage (V)	16V (typ) @ 27A	11V (max) @ 40A	9V (typ) @ 60A	11.5V (typ) @ 30A
IO Capacitance (typ) (pF)	45	100	19	4
IEC 61000-4-5 (A)	27	40	60	30
IEC 61000-4-2 Contact (kV)	30	30	30	30
Max Leakage Current (nA)	100	1000	50	10

Sorry, but could you please introduce any other parts you could suggest?
1. Looking at the TI portfolio, it seems like TSD05 will be the best suggestion here, but this will not be p2p with the other devices evaluated for this socket. This device meets all specification requirements, with a small risk on the clamping. The device typically clamps around 9V at 60A, but the maximum is 15V at 60A.
2. There is one other device in the TI portfolio that doesn't meet every specification, but might be desirable: TVS0500. This is part of our Flat Clamp portfolio, which excels at keeping the clamping voltage stable across large surge currents. This device is rated to 43A, and has a max clamping voltage of 9.5V at 43A. The downside will come with the capacitance, as the typical capacitance is 155pF. This device will also be in a 2.0 x 2.0mm package.

Overall, seems like the TSD05 device from TI meets the majority of requirements here. Would this device be of interest?

Please let me know if you have any additional questions!

Best Regards,

Josh Prushing

0 user5163865 5 months ago in reply to Josh Prushing

Genius 4040 points

HI Josh-san,

Thank you for your quick reply.
I will confirm a few points with the customer and report back to them.

The TVS we are currently evaluating does not meet the customer's requirements.
Therefore, it seems likely that we will evaluate TSD05/C.

Best regards,
Hiroshi

0 user5163865 5 months ago in reply to user5163865

Genius 4040 points

Hi Josh-san,

The customer responded promptly.

>>Just to confirm, is 7V the maximum DC rating of downstream IC or is 7V the maximum voltage seen on signal line?

7V is the maximum DC rating of the downstream IC (rating below). (The product is used with VDD = 5V)
The signal line is 5V (the target of the circuit being considered this time is the analog input and reference input circuits).

>>To confirm, discharge interval is time between strikes?

Yes, it is the time between lightning strikes.

>>package size an additional concern?

We are planning to revise the board, so a change in package size will not be a problem.

>>Would this device be of interest?

Thank you for suggesting the TVS0500. As you say, the capacitance may be a bottleneck.
We will verify the TSD05 and TSD05C, and if they are usable, we will adopt them.

Best regards,
Hiroshi

Interface

Interface forum

TSD05: How to Use and Select a TVS