SN74CBT1G125: Stray capacitances

Jejomar Ildefonso

Part Number: SN74CBT1G125
Other Parts Discussed in Thread: SN74CBTLV1G125

Hi Team,

We are planning to use this part as a termination resistor switch in an up-to-200Mbps M-LVDS bus. The data sheet only states Cio(OFF) across the open switch

With this we would be needing the details on Con and Coff, from switch terminals to ground, both in ON and OFF state. Can you help us?

Thanks in advance!

Kind Regards,

Jejomar

over 1 year ago

+1 Rami Mooti1 over 1 year ago

TI__Mastermind 25973 points

Hey Jejomar,

We don't have this spec'ed but typically, given the configuration of the device, the C(ON) spec will be just twice C(OFF) spec plus some added stray capacitance when taking into account the added conductor area when the switch is turned on vs turned off. A safe estimation would be 16-18pF for this device.

That being said this device is an NFET device, so the RON will heavily increase when VS approached VDD (Take a look at : [FAQ] What are the Types of Architectures TI Switches and Multiplexers Use and how do I know which one my device has internally?). This may not matter for this application but in case it does the SN74CBTLV1G125 is an upgraded option that has a transmission gate architecture, which will provide a flatter On-resistance region.

Thanks,
Rami

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SN74CBT1G125: Stray capacitances