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# DLP5530Q1EVM: LED DRIVER CIRCUIT CURRENT SENESING RESISTOR

Part Number: DLP5530Q1EVM

Tool/software:

In your LED driver circuit, the resistor that is connected with CSP and CSN power is 1.5W.

Your design current limit is 8A, then the max power consumption at this resistor is 0.64W.

When I design this circuit for my board, do I have to apply 1.5W resistor, too?

In my design, LED current is max 6A, so I think 1W resistor is enough for this resistor.

Is it right my understanding?

• Jin,

Here is what I assume you have done:

• Given: 8A current limit has been set with RSNS= 10 mOhm
• P = I2 * RSNS
• P = (8 A)2 * (10 mOhm)
• P = 0.640 W
• P < 1.0 W < 1.5 W
• Apply to 6A circuit:
• P8W = P
• P6W < P8W < 1.0 W

This is because current flows like so from, the TPS99000-Q1 datasheet:

This looks like the right idea to me.

Chances are that whoever chose these parts filtered for 1.0 W or greater and chose one of the first resistors they trusted.

Given that a 6A-limited circuit only draws 360 mW of power, a 1 W resistor is more than enough headroom for this.

Regards,
Michael Ly