UM0670 datasheet(22/43 Pages) STMICROELECTRONICS

Part #	UM0670

Description	80 W offline LED driver with PFC

PDF	43 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

Logo

22 / 43 page

UM0670

Measurement

Doc ID 15327 Rev 2

22/43

Figure 18.

Output LED current for different LED voltage (ILED = 1000 mA)

9.2

Power MOSFET turn ON and OFF time

The power MOSFET turn ON and OFF time is shown in Figure 19. Turn ON time is

approximately 50 ns and turn OFF time is approximately 120 ns (OFF time is used in

Equation 13 in the appendix).

Figure 19.

Power MOSFET turn ON and OFF measurement

9.3

LED current ripple reduction

The output LED current ripple can be reduced by increasing the output capacitor size. For

example, inductor current ripple is 400 mA for the 100 nF / 450 V output capacitor, as shown

in Figure 20. Thanks to the larger 470 nF capacitor used on the STEVAL-ILL013V1, the

VLED v s. ILED for nominal LED current 1 A

200

400

600

800

1000

1200

103

122

LED voltage [V]

LED

current

[mA]

1 A

AM00405

UM0670 Datasheet(PDF) 22 Page - STMicroelectronics