TDA4VM: LVCOMS Drive Strentgth Control

YUTAI LI1

Part Number: TDA4VM

Hi TI Support Team

I want to know the DRV_STR register bit 20-19 for LVCMOS setting from TRM.

Some confuse by me from IBIS model the LVCMOS have nom_3p3_h / slow_3p3_h / fast_1p8_h / utnom_3p3_h / utslow_3p3_h / utfast_3p3_h.

Question:

1. what are differnet about nom with utmom ?

2. How to config the only two bit 20-19 register for totoal 6 different driver strength ? (nom_3p3_h / slow_3p3_h / fast_1p8_h / utnom_3p3_h / utslow_3p3_h / utfast_3p3_h).

3. What are different LVCMOS_H with LVCMOS_V?

4. LVCOMS have 2mA / 4mA/ 6mA driver current from datasheet. Can you let me how to map DRV_STR 00 /01 /10 /11 to 2mA /4mA /6mA ?

******************************************************************************************************************************

[Model Selector] LVCMOS_H
lvcmos1_nom_1p8_h PRWDWUWSWEWCDGLVCMOS_H@_Nom_1p8_comment
lvcmos1_nom_3p3_h PRWDWUWSWEWCDGLVCMOS_H@_Nom_3p3_comment
lvcmos1_slow_1p8_h PRWDWUWSWEWCDGLVCMOS_H@_Slow_1p8_comment
lvcmos1_slow_3p3_h PRWDWUWSWEWCDGLVCMOS_H@_Slow_3p3_comment
lvcmos1_fast_1p8_h PRWDWUWSWEWCDGLVCMOS_H@_Fast_1p8_comment
lvcmos1_fast_3p3_h PRWDWUWSWEWCDGLVCMOS_H@_Fast_3p3_comment
lvcmos1_utnom_1p8_h PRWDWUWSWEWCDGLVCMOS_H@_UT_Nom_1p8_comment
lvcmos1_utnom_3p3_h PRWDWUWSWEWCDGLVCMOS_H@_UT_Nom_3p3_comment
lvcmos1_utslow_1p8_h PRWDWUWSWEWCDGLVCMOS_H@_UT_Slow_1p8_comment
lvcmos1_utslow_3p3_h PRWDWUWSWEWCDGLVCMOS_H@_UT_Slow_3p3_comment
lvcmos1_utfast_1p8_h PRWDWUWSWEWCDGLVCMOS_H@_UT_Fast_1p8_comment
lvcmos1_utfast_3p3_h PRWDWUWSWEWCDGLVCMOS_H@_UT_Fast_3p3_comment
|
|
[Model Selector] LVCMOS_V
lvcmos0_nom_1p8_v PRWDWUWSWEWCDGLVCMOS_V@_Nom_1p8_comment
lvcmos0_nom_3p3_v PRWDWUWSWEWCDGLVCMOS_V@_Nom_3p3_comment
lvcmos0_slow_1p8_v PRWDWUWSWEWCDGLVCMOS_V@_Slow_1p8_comment
lvcmos0_slow_3p3_v PRWDWUWSWEWCDGLVCMOS_V@_Slow_3p3_comment
lvcmos0_fast_1p8_v PRWDWUWSWEWCDGLVCMOS_V@_Fast_1p8_comment
lvcmos0_fast_3p3_v PRWDWUWSWEWCDGLVCMOS_V@_Fast_3p3_comment
lvcmos0_utnom_1p8_v PRWDWUWSWEWCDGLVCMOS_V@_UT_Nom_1p8_comment
lvcmos0_utnom_3p3_v PRWDWUWSWEWCDGLVCMOS_V@_UT_Nom_3p3_comment
lvcmos0_utslow_1p8_v PRWDWUWSWEWCDGLVCMOS_V@_UT_Slow_1p8_comment
lvcmos0_utslow_3p3_v PRWDWUWSWEWCDGLVCMOS_V@_UT_Slow_3p3_comment
lvcmos0_utfast_1p8_v PRWDWUWSWEWCDGLVCMOS_V@_UT_Fast_1p8_comment
lvcmos0_utfast_3p3_v PRWDWUWSWEWCDGLVCMOS_V@_UT_Fast_3p3_comment

Thanks

Yutai

over 6 years ago

0 kcastille over 6 years ago

TI__Guru 57257 points

Yutai,

I'm looking into this and will get back to you asap.

Regards,

Kyle

0 kcastille over 6 years ago in reply to kcastille

TI__Guru 57257 points

Yutai,

1. what are differnet about nom with utmom ?

The UT models are not valid and should be ignored.

2. How to config the only two bit 20-19 register for totoal 6 different driver strength ? (nom_3p3_h / slow_3p3_h / fast_1p8_h / utnom_3p3_h / utslow_3p3_h / utfast_3p3_h)

The DRV_STR settings are as follows:

00 for NOM => Maps to lvcmosN_nom models

01 for FAST => Maps to lvcmosN_fast models

10 for SLOW => Maps to lvcmosN_slow models

11 is reserved

3. What are different LVCMOS_H with LVCMOS_V?

This references the layout orientation of the IO buffer on the die, H=Horizontal and V=Vertical.

4. The DRV_STR setting doesn't directly impact the DC mA capacity. It does have an affect on the transition/edge of the signal.

Regards,

Kyle

0 YUTAI LI1 over 6 years ago in reply to kcastille

Intellectual 400 points

Kyle

Thanks for your comments.

item 1 / 2 / 3 are clear for me.

About item4: Because LVCMOS Buffers have 2mA / 4mA / 6mA output driver current. How to config the output driver current from TDA4VM?

as you mention DRV_STR / IBIS model only used for signal slew rate not impact DC mA capacity.

Some info from Xilinx and Intel about IBIS with current ouput setting.

https://www.xilinx.com/support/answers/38820.html

https://www.intel.cn/content/www/cn/zh/programmable/support/support-resources/download/board-layout-test/ibis/ibs-about_ibis.html

Thanks

Yutai

0 YUTAI LI1 over 6 years ago in reply to YUTAI LI1

Intellectual 400 points

Kyle

Can you please check with your team if the LVCOMS driver current strength is fixed and it can not change from register?

Some confuse by me about the table 5-12 TDA4 use different driver current strength.

Thanks

Yutai

0 kcastille over 6 years ago in reply to YUTAI LI1

TI__Guru 57257 points

Yutai,

I can confirm that the LVCMOS drive strength is fixed and it does not change with any register settings. The Data Manual will be updated to clarify this.

Regards,

Kyle

0 YUTAI LI1 over 6 years ago in reply to kcastille

Intellectual 400 points

Kyle

Which output current 2mA / 4mA or 6mA used from current IBIS model as you mention the LVCMOS drive strength is fixed ?

So I assume only one need used from IBIS LVCMOS model.

Thanks

Yutai

0 YUTAI LI1 over 6 years ago in reply to YUTAI LI1

Intellectual 400 points

Kyle

I double check datasheet, LVCOMS output resistance :0.2V/2mA=100ohm ; 0.3V/4mA=75ohm ; 0.45V/6mA=75ohm .

The different is that lvcmos1_slow_3ps_h V-I curve 4mA => 0.459V not datasheet 0.3V. And the V-I curve is not linear from 3mA to 6mA.

So it is best to use those data from IBIS for more accuracy than datasheet.

Any comments from you?

Thanks

Yutai

0 kcastille over 6 years ago in reply to YUTAI LI1

TI__Guru 57257 points

Yutai,

Yes it does make sense to use the IBIS model to get a more detailed view compared to the data sheet.

Regards,

Kyle

Processors

Processors forum

TDA4VM: LVCOMS Drive Strentgth Control