UPSL1630G-S08-R datasheet(5/7 Pages) UTC

5 / 7 page

UPSL1630

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

5 of 7

www.unisonic.com.tw

QW-R502-A010.b



APPLICATION INFORMATION

The UTC UPSL1630 is a primary-side-control AC-DC LED driver which can achieve high power factor and

accurate LED current for an isolate lighting application in a single stage converter. The LED current can be

controlled accurately from the primary side information and integrates power factor correction function and works in

DCM and constant OFF time mode for reducing the harmonic current emission (THD).

Startup Control

A soft-start function is implemented to prevent the transformer from entering into CCM. The VDD pin of UTC

UPSL1630

is charged through a startup resistor. When the VDD voltage reaches VTH(ON), the internal startup circuit is

disabled and the IC turns on. Then, the STP pin is clamped to lower than VDD voltage about 0.2V.

Operating Current

The Operating current of UTC UPSL1630 is as low as 3mA. Good efficiency and very low standby power can be

achieved.

Constant Current Operation

UTC UPSL1630 use the primary side constant current control method to accurately control the LED current. The

LED real current can be approximated as:

LED

≈

Where NP is primary winding, NS is secondary winding; RCS is an external current sensing resistor.

Power Factor Correction

The primary side current increases linearly from zero to peak value, during the external MOSFET on-time. When

the primary current reaches the threshold, UTC UPSL1630 turns off the power MOSFET immediately. After a

constant OFF time, TOFF, UTC UPSL1630 turns on the power MOSFET again. The peak current threshold follows

the rectified sinusoidal-shape of main line voltage. As a result, the envelope of the inductor current is

sinusoidal-shaped, high power factor is therefore achieved in this way.

Over-voltage Protection

UTC UPSL1630 built-in two over-voltage protection schemes:

(1) If DSEN pin’s voltage is detected above 3.2V for three times, UTC UPSL1630 turns off the PWM switching signal,

and VDD voltage gradually drops to UVLO threshold, and the system will be re-started. The threshold voltage of the

output over voltage protection can be easily defined as:

OVP

OUT

)

(

V-VD8

Where NS is the secondary winding, NA is auxiliary winding, VD8 is the forward bias of the secondary side rectifier

diode.

(2) If VDD pin’s voltage exceeds 19.2V three times, UTC UPSL1630 turns off the PWM switching signal, and VDD

gradually drops to UVLO threshold, and then the system will be re-started.

UPSL1630G-S08-R Datasheet(PDF) 5 Page - Unisonic Technologies

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