LED5000 datasheet(28/52 Pages) STMICROELECTRONICS

部件名	LED5000

功能描述	3 A monolithic step-down current source with dimming capability

PDF	52 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

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28 / 52 page

Application notes - buck conversion

LED5000

28/51

Doc ID 023951 Rev 1

higher than this value to compensate for the losses in the overall application. For this

reason, the conduction losses related to the RDSON increase compared to an ideal case.

●

Switching losses due to turning ON and OFF. These are derived using the following

equation:

Equation 38

Where TRISE and TFALL represent the switching times of the power element that cause the

switching losses when driving an inductive load (see

Figure 18). TSW is the equivalent

switching time.

Figure 18.

Switching losses

●

Quiescent current losses.

Equation 39

Example (see

Chapter 5.6):

VIN=42 V, VFW_LED=3.7 V, nLED=8, ILED=1500 mA

The typical output voltage is:

Equation 40

RDSON_HS has a typical value of 200 Ω at 25 °C.

OUT

RISE

FALL

()

-----------------------------------------

OUT

SW_EQ

⋅⋅

⋅

AM13502v1

⋅

OUT

LED

FW_LED

⋅

29.4V

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