HD3SS3212: OEn Pin low at startup

SimonF

Part Number: HD3SS3212

Hi Team

in the datasheet page 18 you mention: "TI recommends that OEn is asserted low after device supply V CC is stable and in specification.". While in all TI desgins I could find you pull OEn to low with a resistor or without. Is there any reason to keep OEn floating or high while the device VCC is not there?

Best regards

Simon

over 7 years ago

0 Malik Barton57 over 7 years ago

TI__Guru 64326 points

SimonF,

OEn should be floating or high before Vcc is stable so that the current draw of the device does not adversely impact the VCC supply. Also if OEn is low while VCC is not present the device will be in a non-functional and undefined state.

0 SimonF over 7 years ago in reply to Malik Barton57

TI__Expert 3350 points

Hi Malik

thanks for your reply! Just for my understanding. How will the HD3SS draw current from OEn pin beeing on GND if there is no voltage on VCC?

Best regards
Simon

0 Malik Barton57 over 7 years ago in reply to SimonF

TI__Guru 64326 points

SimonF,

In this case there would be no current draw from OEn pin. You would want to keep OEn high or floating before providing power or while VCC is ramping in order to avoid any current spikes seen by your power supply which could affect your VCC ramp.

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HD3SS3212: OEn Pin low at startup