SN74AXC4T774: Drive Strength

Mitchell Spears

Part Number: SN74AXC4T774

Hi LVT Team,

I have a customer using the SN74AXC4T774, and I wanted to make sure that we were understanding the drive capabilities of the device correctly.

The driving capabilities seemed to be outlined in Section 6.15 of the datasheet with the source and sink charts.

Are the source and sync capabilities of the output independent of the VCC on the input? So for example if they wanted to translate from 1.2 to 3.3V the VCCB in question would be 3.3V and would be the same regardless of VCCA. Am I understanding this correct?

Thanks,

Mitchell

over 4 years ago

0 Rami Mooti1 over 4 years ago

TI__Mastermind 35528 points

Hey Mitchel,

The output current will just be dependent on the output voltage and the load. The input drives the gates while the output current follows ohms low. I = V/R where V is the output voltage or your 3.3V Vccb here.
Here's some more info on this [FAQ] How do I determine the output voltage (VOH, VOL) or output current (IOH, IOL) of a CMOS logic device?

*I'm going to edit your initial question to change 13.3V to 3.3V as the typo may confuse anyone reading it

Thanks,
Rami

0 Mitchell Spears over 4 years ago

TI__Prodigy 575 points

Hey Rami,

Thanks for the information. I did have something I still didn't understand. In the Voltage Translation Buying Guide (Rev. A) it mentions that the SN74AXC4T774 has a drive strength of 12mA. What is this referring to? \

Thanks,

Mitchell

+1 Clemens Ladisch over 4 years ago in reply to Mitchell Spears

Guru 316960 points

12 mA is the highest current for which a V_OL/V_OH is guaranteed.

(The R_DS(on) of the output transistors depends on their gate-to-source voltage, which is the output side's V_CC.)

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SN74AXC4T774: Drive Strength