OMAP-L137 GPIO internal pullup

Chikku

Other Parts Discussed in Thread: OMAP-L137, OMAPL138

Hi,

As you know OMAP-L137 has I/O pins with internal pulldown or pullup resistor,
what is the value of these internal resistors,
and what external pull down resistor value would you suggest when opposing internal pull up.

Thankyou and Regards.

over 14 years ago

0 Michael Questo over 10 years ago

TI__Expert 6000 points

Hi,

The OMAPL137's pull-up/downs should be similar to those of the OMAP138. (In the process of double checking this to make sure...)

Please see the following thread for additional discussion.

[OMAPL138] Resistance Specification for Internal Pull-Up and Pull-down Resistors

http://e2e.ti.com/support/dsp/omap_applications_processors/f/42/t/251504.aspx

0 Michael Questo over 10 years ago in reply to Michael Questo

TI__Expert 6000 points

OMAPL137 DS - http://www.ti.com/lit/ds/symlink/omap-l137.pdf

Section "4.2 Recommended Operating Conditions" in Datasheet

Recommended I/O Operating Range (DVDD)

3.3V I/O - 3.0V to 3.45V

1.8V I/O - 1.71V to 1.89V

Section "4.4 Electrical Characteristics Over Recommended Ranges of Supply Voltage and Operating Case Temperature"

LVCMOS Pull-Up Current

Min 30 uA

Max 200 uA

LVCMOS Pull-Down Current

Min -50 uA

Max -300 uA

Resistance Calulations: Pull Down

Resistance Pull Down 3.3V I/O:

Max : 3.00V / 50 uA = 60k

Min : 3.45V / 300 uA = 11k

Typ : 3.30V / 175 uA = 18.85k

Resistance Pull Down 1.8V I/O:

Max : 1.71V / 50 uA = 34.2k

Min : 1.89V / 300 uA = 6.3k

Typ : 1.80V / 175 uA = 10.3k

Resistance Calulations: Pull Up

Resistance Pull Up 3.3V I/O:

Max : 3.00V / 30 uA = 100k

Min : 3.45V / 200 uA = 17.25k

Typ : 3.30V / 115 uA = 28.7k

Resistance Pull Up 1.8V I/O:

Max : 1.71V / 30 uA = 57k

Min : 1.89V / 200 uA = 9.45k

Typ : 1.80V / 115uA = 15.65k

0 EE_MT over 7 years ago in reply to Michael Questo

Intellectual 390 points

How did you get 115 uA for the Resistance Calculations: Pull Up, Typ: 3.30V? I cannot find that value in any of the datasheets.

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OMAP-L137 GPIO internal pullup