TS19820CS datasheet(7/14 Pages) TSC

Part #	TS19820CS

Description	Single-Stage Power Factor Correction Dimmable LED Driver with 3.3V Voltage Regulator Output

PDF	14 Pages

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Manufacturer	TSC [Taiwan Semiconductor Company, Ltd]

Direct Link	http://www.taiwansemi.com

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7 / 14 page

TS19820CS

Taiwan Semiconductor

Version: A1806

APPLICATION INFORMATION (CONTINUE)

Start-up

After AC supply or DC BUS is powered on, the capacitor CVCC across VCC and GND pin is charged up by DC BUS

voltage through a start-up resistor RS. Once VCC rises up to UVLO(ON), the internal blocks start to work. The whole

start up procedure is divided into two sections shown in Fig.2. Tst1 is the CVCC charged up section, and Tst2, is the

output voltage built-up section. The start-up time Tst composes of Tst1 and Tst2, and usually TST1 is much larger than

Tst2,.

The start-up resistor RS and CVCC are designed by rules below:

(a) Preset start-up resistor RS, make sure that the current through RS is larger than IST

Where IST is the Start-up Current.

(b) Select CVCC to obtain an ideal start up time Tst, and ensure the output voltage is built up.

UVLO(ON) = VDCBUS*

ｅ

- Tst1 / (Rs*CVcc) )

redo such design flow until the ideal start up procedure is obtained.

Constant current control

Figure 2

The switching waveforms are shown in Fig.2. The output current IOUT can be represented by:

TS19820CS Datasheet(PDF) 7 Page - Taiwan Semiconductor Company, Ltd