AN2754 datasheet(5/20 Pages) STMICROELECTRONICS

Part #	AN2754

Description	Buck high-brightness LED driver based on the ST1S10

PDF	20 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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5 / 20 page

AN2754

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Figure 2.

Constant current control

Equation 2

Accuracy and efficiency are the two main goals of the current sensing even if they are in

direct conflict. The higher the sense voltage is, the higher the signal-noise ratio, but the

higher the power dissipated on RSENSE.

To reduce the power dissipated in the series resistance, Figure 3 shows a simple method of

amplifying the current sense signal by using a single supply op-amp. This method allows the

user to select the current sense resistor RSENSE according to the desired power dissipation

while setting the average value of IF with the gain of the op-amp.

Figure 3.

Constant current control with VSENSE amplification

Equation 3

Voltage Regulator

VOUT

RSENSE

RFB

RSENSE

RIN

Voltage Regulator

VOUT

OUT

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⋅

SENSE

AN2754 Datasheet(PDF) 5 Page - STMicroelectronics