AFE4490 LED external power supply

Matteo Cardani

Other Parts Discussed in Thread: AFE4490

Hi,

I have a question regarding the external power supply in the Push-Pull LED Drive for common Anode LED configuration:

1 - In this condition the pin LED_DRV_SUP is unconnected?

2 - I need to drive a blu LED with 200mA current, and in that condition the Forward Voltage of about 5V. To guarantee the correct functioning of the LED i would need an external power supply of about 7V. How can i guarantee that the voltage on pin TXN and TXP would not exceed 5.25V?

3 - In this configuration, which use only the lower half of the H-bridge the equation:

Vdd – (VLED + VCABLE) > 1.4 V

is correct? or the supply should be greater only than 0.7V instead of 1.4V?

thank you for your consideration.

Matteo

over 9 years ago

0 Praveen Aroul over 9 years ago

TI__Mastermind 49176 points

Hello Matteo,

We have received your inquiry regarding the AFE4490 and hope to have some answers back to you shortly.

Regards.

0 Praveen Aroul over 9 years ago

TI__Mastermind 49176 points

Hello Matteo,

1. LED_DRV_SUP cannot be left floating for common anode configuration. The LED_DRV_SUP can be connected to the "External supply".

2. Unfortunately you cannot use the Blue LED with 200mA current and 5V forward voltage since this will not satisfy the max LED_DRV_SUP condition mentioned in the datasheet.

3. In common anode configuration, the equation Vdd – (VLED + VCABLE) > 1.4 V still holds.

I apologize for the delay in the response.

I apologize for the delay in my response.

0 Matteo Cardani over 9 years ago in reply to Praveen Aroul

Prodigy 60 points

Hello Praveen,
Thank you for your kind response.
Best regards,
Matteo

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AFE4490 LED external power supply