[SI-LIST] Re: Level Shifter
- From: "Gary Morrell" <gmorrell@xxxxxxxxxxxxxxx>
- To: "'SI LIST'" <si-list@xxxxxxxxxxxxx>
- Date: Mon, 25 Jan 2010 11:22:14 -0700
You didn't mention how many data lines you need to translate, or the
bandwidth is needed, but I've used the 74LVC2T45 from NXP when I need to
translate bi-directional I2C lines over various supply voltages.
It does have a direction control pin that you have to manage, but that may
already exist in your design, or you can create a DIR pin with one of your
uc port pins and a bit of code.
http://www.nxp.com/documents/data_sheet/74LVC_LVCH2T45.pdf
Either side can operate between 1.2 and 5.5V with bandwidth up to 420Mbps
depending on the A-side/B-side supply voltage differences.
Gary Morrell
Solidus Technologies, Inc.
Colorado Springs, CO
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of sunil bharadwaz
> Sent: Monday, January 25, 2010 10:53 AM
> To: SI LIST
> Subject: [SI-LIST] Level Shifter
>
>
> Hi ,
> I'am doing an application where a Microcontroller interacts
> with the rest of the digital
> circuitry working at 3.3 Volts (LVTTL).
>
> The Microcontroller can operate from 2.0 Volts to 3.6 Volts.
>
> The Supply to the Microcontroller can be any thing from 2.0
> Volts to 3.6 Volts , where
> as the rest of the circuitry operates at a fixed 3.3 Volts.
>
> There is a bi-directional data flow between the uc & rest of
> the digital logic.
>
> The max logic high I/P, the uc can tolerate is 2.5 Volts ,
> when operated at 2.0 Volts supply (Supply + 0.5 Volts).The
> logic high O/P of the rest of the circuitry is at almost 3.3
> Volts.We require a level shifter to bring down the level of
> this signal which is I/P to uc.
>
> Similarly , the VIH of the rest of circuitry is 2.0 Volts.The
> VOH of uc at 2.0 Volts supply
> is only about 1.8 Volts or less.This requires a level shifter
> to shift to a higher level.
>
> The problem here is a variable supply to uc , which can be
> any value from 2.0 Volts
> to 3.6 Volts.
>
> Pls suggest a proper level shifter here.Are there any
> bi-directional level shifters for
> these types of applications ?
>
> Thanks in Advance !!
>
> Regards
> Sunil.B
>
>
>
>
>
>
>
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