ESD protection of LDC1000 inductance

Gerardo Vanoni

Hello,

since the (PCB-) inductor of the analog front side will be close to ESD-generating sources, I want to improve the ESD tolerance of the circuit. The HBM of 1kV / CDM 250V is too low for my application.

Would it be feasible / adviced to use a bidirectional ultra low capacitance ESD protection diode, e.g. PESD18VF1BL (http://www.nxp.com/documents/data_sheet/PESD18VF1BL.pdf), in parallel with the inductor? What do you think?

Alternatives or other ideas?

Thanks & regards

Gerardo

over 10 years ago

0 Charles Cheung* over 10 years ago

TI__Intellectual 2790 points

Hi Gerardo,

There is an internal 5V clamp and an absolute maximum of 8mA on INA/INB. It is possible to put external clamps on each pin to common. To avoid damaging the internal clamp, we recommend lower voltage clamps/TVS at 4V. Keep in mind that these will have to be fast to avoid affecting the frequency count.

Thanks,

0 Gerardo Vanoni over 10 years ago in reply to Charles Cheung*

Prodigy 220 points

Hi Charles,

what is the internal negative clamp on INA/INB? Are the 4VPP (Asensor_MAX) centered to +2.5V or to GND?
In other words: bidirectional TVS or unidirectional + LowCap-Shottky (i.e. 1PS10SB82, http://www.nxp.com/products/rf/diodes/schottky_diodes_low_capacitance_rf/1PS10SB82.html)? What devices / combination of devices would you recommend?

Shouldn't the TVS better have a Vrwm of 5V, in order to avoid clamping of the normal swinging?

On the other hand, the inputs are (as of datasheet) theirselves ESD protected up to 1kV (HBM) / 250V (CDM), so the external TVS should only "help" to kill higher energies. Or am I misunderstanding a spec?

Thanks & regards
Gerardo

0 Charles Cheung* over 10 years ago in reply to Gerardo Vanoni

TI__Intellectual 2790 points

Negative clamp is 0.6V to GND. 4VPP centered to GND, so differential is 8V.

I would recommend unidirectional TVS on each of the two INA/INB pins to GND.

Again, that is not an issue since these devices are wired to common.

Yes, for higher energies.

Thanks,

0 Gerardo Vanoni over 10 years ago in reply to Charles Cheung*

Prodigy 220 points

Hello,

what do you mean by "that is not an issue since these devices are wired to common"?

Regards

Gerardo

0 Charles Cheung* over 10 years ago in reply to Gerardo Vanoni

TI__Intellectual 2790 points

That is a response to having the TVS rev. standoff be 5V, since the devices proposed are not bi-directional. Having each device at 4V VRWM will be effectively 8V differential. (the clamps mentioned in the initial post are positive uni-directional to GND)

Thanks,

Sensors

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ESD protection of LDC1000 inductance