TLV1702AQ Input voltage

Hamamoto-san,

I am looking for information regarding the TLV1702 ESD cell designs and their electrical characteristics. I'll attempt to answer you questions once I find what I am looking for.

Regards, Thomas

PA - Linear Applications Engineering

Hi Thomas-san

Do you have any information for this?

Regards,

Koji Hamamoto

Hello Hammamoto-san,

I have been making some bench measurements on the TLV1702 input ESD cells and have been in contact with the TLV1702 Design Engineer regarding some questions the measurements raised. I can provide limited information because the ESD cell design is company proprietary, but I will disclose what I can.

Your original questions:

Signal input pins Voltage（2） （Vs-）-0.5V～（Vs+）+0.5V. Note (2) Input pins are diode-clamped to the power-supply rails. Input signals that can swing more than 0.5 V beyond the supply rails must be current limited to 10 mA or less.

1. How much it can be input more than 0.5V beyond the supply rail if the current is limited to 10mA or less? (0.7V? or more?)

The datasheet indicates in Note (2) that there are input ESD diodes to each of the power supply rails. That is true, but there is additional circuitry in series with the ESD diodes in the path that eventually connect to the positive supply rail. Therefore, when the input voltage is raised above Vs+ it doesn't exhibit a typical diode I-V curve. In fact, there is only leakage current level current flow as the voltage begins to exceed (Vs+) + 0.5 V. The current remains in the tens-of-microamps even +1 V above Vs+. The issue is if the voltage is increased further at some point breakdown can occur and the current can increase very rapidly possibly resulting in damage. If the input current is limited to 10 mA, then the input current should be safe. In my bench tests I increased the input voltage several volts above Vs+ and never got up to 10 mA. I think the results could be different if Vs+ is raised to the higher end of the TLV1702 supply range. The designer cautioned that the voltage should be kept to (Vs+) + 0.5 V to assure no issues occur.

2. How about negative rail? Is it possible to input more than -0.5V beyond supply rail if it is limited to 10mA or less?

The ESD cell has a diode response when the input voltage is taken below Vs-. ESD diodes, because of their design, tend to have lower forward current for a given voltage than a conventional signal diode. With (Vs-) - 0.5 V, there was essentially just leakage current levels present. The input current increased to 1.0 mA with the input voltage set to about (Vs-) - 0.8 V. The current reached 10 mA with the input voltage at (Vs-) - 0.97 V.

Since the datasheet specifies a maximum input current of 10 mA is tolerable, that can only be reached if the input voltage is increased beyond (Vs-) - 0.5 V and (Vs+) + 0.5 V specifications. 

Regards, Thomas

PA - Linear Applications Engineering