RM57L843: Default Pull State

Zain Ul Abideen

Part Number: RM57L843

Hello

In datasheet of RM57L843, Pin Description section shows a default pull state which is pull up or down and in nest column it shows the pull type(Programmable 20uA, Fixed 20uA and 20uA).

I need the explanation of these three pull types.

1. Programmable 20uA

My understanding is this pin has programmable pull state with 20uA.

2. Fixed 20uA

My understanding is this pin has fixed pull state with 20uA. But can I externally connect a Pull up/down resistor to these pins?

3. 20uA

This type has no information about programmable or fix. Can any one please enplane me about this, Is it has a fixed or programmable pull state?

Regards,

over 7 years ago

0 Miro over 7 years ago

TI__Mastermind 21425 points

Hello,
Pins with pull type "20uA" are not programmable in stated mode.

Best regards,
Miro

0 Zain Ul Abideen over 7 years ago in reply to Miro

Intellectual 550 points

Hi Miro
What do you mean by "stated mode"?

0 Miro over 7 years ago in reply to Zain Ul Abideen

TI__Mastermind 21425 points

You can put pin in different modes as a part of a different module. For example terminal E3 could be used as one of the following: N2HET1[11]/MIBSPI3NCS[4]/N2HET2[18]/ePWM1SYNCO. If you use it as N2HET[11] then terminal E3 has programmable pull type (page 14, table 4-2 in datasheet). If you use it as ePWM1SYNCO then it is not programmable (page 21, table 4-6 in datasheet).

Best regards,
Miro

0 Zain Ul Abideen over 7 years ago in reply to Miro

Intellectual 550 points

I understand.

But in datasheet at "page 36, pin # K17, EMIF_nCS[3]" is pull down and not programmable but in RM57 evaluation kit TMDXRM57LHDK this pin is externally pull up and in this way it should create a potential divider. What do you think about it?

0 Miro over 7 years ago in reply to Zain Ul Abideen

TI__Mastermind 21425 points

Hi Zain,
If K17 is tri-stated, the voltage on pin will be close to VCC_3V3 (VCC_3V3-Vr33, R33 is much stronger than pull-down).
If K17 is driven high then the voltage on K17 will be VIO.
If K17 is driven low then voltage on K17 will be 0.

Best regards,
Miro

0 Zain Ul Abideen over 7 years ago in reply to Miro

Intellectual 550 points

Hi Miro
Sorry your answer is not clear to me. You means internal pull down does not matters if I externally pull up the pin?
regards

0 Miro over 7 years ago in reply to Zain Ul Abideen

TI__Mastermind 21425 points

Hi Zain,

Speaking for K17, its default function is EMIF_nCS[3]. As this is an output, during power-on reset (nPORRST is low) if there is no external pull-up, then this signal will be "low" thanks to internal pull-down. If external pull-up exists on K17 (EMIF_nCS[3]) this ensures signal stays high during PORRST. NOTE at page 10, Section 4.2 explains how Default Pull State and Pull Type are applied to terminals.

Best regards,

Miro

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RM57L843: Default Pull State