Continental Device India Pvt. Ltd

An ISO/TS 16949,

ISO 9001 and ISO 14001 Certified Company

TCIL6568

TCIL6568_REV02_22102016

D a t a s h e e t

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which achieve the soft-start.

Soft-start function can help to restrain clash current to reduce LED stress during start up,

which can extend the LED life. On the other hand, soft-start also can restrain clash voltage on

MOSFET’s drain to increase the system reliability.

2.2.3、Power Factor Correction

After the system is stable, the voltage VCAP will be constant. The TCIL6568 achieve high PF

though ensure MOSFET on time stable. The relation between Vin(t), TON, L and inductor peak

current IP(t) can be calculated as fallow:

[

]

LED

()-

()

Vin t V

Ton

L Ip t

×= ×

Vin(t) is a sinusoidal half-wave, and the envelope of inductor current peak value IP(t) fallow

with the input voltage Vin(t), which makes the system achieve high PF.

Inductor Current

VIN(t)

Fig.2 Power Factor Correction Scheme

2.2.4、Constant Current Control

The TCIL6568 employs unique constant current control method and works in boundary

continuous mode, which could control the LED output current accurately.

LED output current can be calculated as:

CS

REF

R

V

Io

=

VREF-feedback loop reference voltage（typically 0.2V）

RCS-The sensing resistor connected between CS pin and GND

2.2.5、Zero Current Detect

When power MOSFET is off, the inductor current fall linearly from peak value to zero, also

make supply power for LED load and charge the output capacitor through freewheeling diode.

When inductor current falls to zero, the inductor voltage will fall to zero quickly. ZCD pin sense

the inductor voltage through divider resistor, and when detected voltage falls below VZCD_FALL,

turn on the MOSFET.