• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 47 subscribers
  • Views 236 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PGA308: Connection requirement between PGA308 and force (bridge) sensor

user6243139
Prodigy 180 points
Part Number: PGA308

Hi,

We think the force sensor and PGA308 connects with a connector (JST GH connector, gold plate) below.

Sensor (stand alone, in/output resistance: 500ohm) --- connector (gold plate) = board connector (PGA308) *Power supply: 3.3V

Do you have any requirement about connection here ("=" point)? Ex. normal connector, gold connector, direct soldering (difficult our design it...), under some value ohm contact...

And I have one more question. How much minimum current flow about input pin of the PGA308? I think it may high impedance pin. So I'd like to know min. leak current here (a couple of uA?).

If you show a value is difficult, I'd like to know the order about it (mA / about 100uA / about 10uA / about 1uA / ...)

Best regards,

KoT

  • 0
    TI__Guru 52756 points

    Hello KoT,

    The PGA308 input impedance is very high, ~30 GΩ typical as specified on the PGA308EVM datasheet.  The input bias current is ±0.3nA typical and ±1.6nA maximum (Input Bias Current is specified on p.3 of the PGA308 datasheet).  A differential, low-pass R-C-R filter is typically used between the PGA308 inputs and the sensor.  The filter helps reducing extrinsic noise, and the series resistors on the RC filter help provide some level of protection to the inputs limiting current to the inputs in case of a fault or mis-wired condition.  The corner frequency of the filter is set depending on the specific application requirement. For example, the PGA308EVM schematic provides an example of a filter of 39.5kOhm - 0.1uF - 39.5kOhm, offering a corner frequency of about 20-Hz.

    The PGA308 has no specific requirement for connector type or connector material.  This is dependent on your sensor, sensor cable connection and PCB board requirements. 

    Thank you and Regards,

    Luis