Forums

compatibility between adsp2181 and bf533

Started by ashr...@rediffmail.com June 8, 2009
Hi friends
ADSP 2181 and BF533 are not compatible. ADSP2181 is a 5V logic(TTL)
while BF533 is a 3.3V logic device.

If i need to connect ADSP2181 sport to BF533 sport is it enough if i use a voltage divider for level shifting?
If not which level shifter IC is ideal in this case?

I need to level shift all 5 signals on ADSP2181 sport i.e DT,DR,TFS,RFS,SCK.
Check out the SN74LVC4245A from TI. NXP and ON semi have similar parts
too.

On Mon, 8 Jun 2009, a...@rediffmail.com wrote:

> Hi friends
> ADSP 2181 and BF533 are not compatible. ADSP2181 is a 5V logic(TTL)
> while BF533 is a 3.3V logic device.
>
> If i need to connect ADSP2181 sport to BF533 sport is it enough if i use a voltage divider for level shifting?
> If not which level shifter IC is ideal in this case?
>
> I need to level shift all 5 signals on ADSP2181 sport i.e DT,DR,TFS,RFS,SCK.
Hi,

For sure you have to protect the BF (3V3)from the 218x (5V), but maybe the 218x(5V) canrecognize a BF signal (3V3) as a high; check the datasheet to be sure.

I also think the voltage divider would work, or use some fast diodes for clipping, or find youself some cheap voltage level translator.I donot which family exactly to recommend you, but alook at Fairchild Semiconductor website can give you some documents which will guide you.

Regards.

Jaime Andr Aranguren Cardona
j...@ieee.org
j...@computer.org

________________________________
From: "a...@rediffmail.com"
To: a...
Sent: Monday, June 8, 2009 10:11:50 AM
Subject: [adsp] compatibility between adsp2181 and bf533

Hi friends
ADSP 2181 and BF533 are not compatible. ADSP2181 is a 5V logic(TTL)
while BF533 is a 3.3V logic device.

If i need to connect ADSP2181 sport to BF533 sport is it enough if i use a voltage divider for level shifting?

If not which level shifter IC is ideal in this case?

I need to level shift all 5 signals on ADSP2181 sport i.e DT,DR,TFS,RFS, SCK.
Jaime Andres Aranguren Cardona wrote:
> Hi,
>
> For sure you have to protect the BF (3V3) from the 218x (5V), but
> maybe the 218x (5V) can recognize a BF signal (3V3) as a high; check
> the datasheet to be sure.
>
> I also think the voltage divider would work, or use some fast diodes
> for clipping, or find youself some cheap voltage level translator. I
> donot which family exactly to recommend you, but a look at Fairchild
> Semiconductor website can give you some documents which will guide you.
>
> Regards.
>
>
> Jaime Andr Aranguren Cardona
> j...@ieee.org
> j...@computer.org
>
> *From:* "a...@rediffmail.com"
>
> *To:* a...
> *Sent:* Monday, June 8, 2009 10:11:50 AM
> *Subject:* [adsp] compatibility between adsp2181 and bf533
>
> Hi friends
> ADSP 2181 and BF533 are not compatible. ADSP2181 is a 5V logic(TTL)
> while BF533 is a 3.3V logic device.
>
> If i need to connect ADSP2181 sport to BF533 sport is it enough if i
> use a voltage divider for level shifting?
>

>
> If not which level shifter IC is ideal in this case?
>
> I need to level shift all 5 signals on ADSP2181 sport i.e
> DT,DR,TFS,RFS, SCK.
>

You can use any of the 74LVC logic parts. If the BF533 is the driver,
just use a pullup (3K3 to 10K) to 3.3V, If the 2181 is the driver buffer
with a 74LVC device. You may find that single versions of these in
SOT-23 are good choices.

I assume that this is an existing design. If not, you can use a 2185M
which has 3.3V I/O

Al Clark
Danville Signal
One more thing,

Make sure to add a small series R (33R2) at the driving side of each
SPORT connection. If you use a 74LVC part place a series R at its output
as well.

Al Clark
Danville Signal

Al Clark wrote:
> Jaime Andres Aranguren Cardona wrote:
>
>> Hi,
>>
>> For sure you have to protect the BF (3V3) from the 218x (5V), but
>> maybe the 218x (5V) can recognize a BF signal (3V3) as a high; check
>> the datasheet to be sure.
>>
>> I also think the voltage divider would work, or use some fast diodes
>> for clipping, or find youself some cheap voltage level translator. I
>> donot which family exactly to recommend you, but a look at Fairchild
>> Semiconductor website can give you some documents which will guide you.
>>
>> Regards.
>>
>>
>> Jaime Andr Aranguren Cardona
>> j...@ieee.org
>> j...@computer.org
>>
>>
>>
>> *From:* "a...@rediffmail.com"
>>
>> *To:* a...
>> *Sent:* Monday, June 8, 2009 10:11:50 AM
>> *Subject:* [adsp] compatibility between adsp2181 and bf533
>>
>> Hi friends
>> ADSP 2181 and BF533 are not compatible. ADSP2181 is a 5V logic(TTL)
>> while BF533 is a 3.3V logic device.
>>
>> If i need to connect ADSP2181 sport to BF533 sport is it enough if i
>> use a voltage divider for level shifting?
>>>
>> If not which level shifter IC is ideal in this case?
>>
>> I need to level shift all 5 signals on ADSP2181 sport i.e
>> DT,DR,TFS,RFS, SCK.
>>
> You can use any of the 74LVC logic parts. If the BF533 is the driver,
> just use a pullup (3K3 to 10K) to 3.3V, If the 2181 is the driver
> buffer with a 74LVC device. You may find that single versions of these
> in SOT-23 are good choices.
>
> I assume that this is an existing design. If not, you can use a 2185M
> which has 3.3V I/O
>
> Al Clark
> Danville Signal