LDC1312: Where is the electrical spec for INTB output?

Rick Hille

Part Number: LDC1312

The LDC1312/1314 datasheet seems to be missing the electrical table specification for the INTB output. The I2C specification is there but no mention of INTB. It's not clear whether the output is open drain or totem-pole, and what the Voh Vol are at test currents. The simple diagram Figure 54 shows no pullup resistor on INTB, implying totem-pole, but the I2C are drawn without pullups either so I can't tell what assumptions are made. There is no pullup on the eval board that I can see on schematic, but maybe the MCU internal IO pullup is used. Can you please clarify the electrical parameters of this port?

over 8 years ago

0 Luke LaPointe over 8 years ago

TI__Genius 13335 points

Hello,
This question was previously answered in the following thread: e2e.ti.com/.../1987910
Regards,
Luke

0 Rick Hille over 8 years ago in reply to Luke LaPointe

Intellectual 410 points

I didn't see the answered thread as my search term was LDC1312 INTB; didn't have time to play with permutations. It's a partial answer but not complete. I can at least wire it up on the assumption that it doesn't need a pullup, which solves my immediate requirement. However, the electrical parameters are still missing from the datasheet; I shouldn't have to scrape through a forum to find such info.

0 Varn Khanna over 8 years ago in reply to Rick Hille

TI__Intellectual 2725 points

HI Rick,

Apologies, the DS is missing this important piece of information.We will take your feedback into account in the next revision of the DS.

Here are the voltage level characteristics for digital pins other than I2C:

Input High Voltage	V_IH		0.7xVDD		V
Input Low Voltage	V_IL			0.3xVDD	V
Output Low Voltage	V_OL	sink current 3mA		0.4	V
Hysteresis	HYS		0.1xVDD		V

Let us know if we can provide any additional assistance.

Regards,

Varn.

0 Rick Hille over 8 years ago in reply to Varn Khanna

Intellectual 410 points

Thanks Varn, this is still missing Voh since it looks to be a repeat of the I2C specs which assume open-drain. Can I assume the driven Voh is enough to meet 0.7 VDD plus margin on an LVCMOS input port that receives it?

0 Varn Khanna over 8 years ago in reply to Rick Hille

TI__Intellectual 2725 points

Hi Rick,

Yes, VOH is specd at 0.7*VDD.

Regards,

Varn.

0 Rick Hille over 8 years ago in reply to Varn Khanna

Intellectual 410 points

If Voh is specified as 0.7VDD, there's no margin for driving an LVCMOS input with 0.7VDD Vih. I would interpret your reply as the INTB output is only suitable for driving TTL compatible input thresholds (2.4V). Is that correct? I may need to keep the pullup after all.

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LDC1312: Where is the electrical spec for INTB output?