WS3110S8P Просмотр технического описания (PDF) - Shenzhen Winsemi Microelectronics Co., Ltd

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WS3110S8P

High Performance LED Driver

Shenzhen Winsemi Microelectronics Co., Ltd 

WS3110

Function Description

WS3110 is a primary-side control with single stage PFC

controller targeting at LED lighting applications. The

transition mode control greatly reduces the switch

turn-on loss, improves the conversion efficiency and EMI

performance. It provides very good power factor and low

THD.

Startup Current and Startup Control

The line current charge up the ST capacitor via a start-up

resistor (the internal start up circuit will consume 20 uA

current), the VCC voltage will follow the ST voltage (ST

is clamp to 16V at start-up stage), and quickly over

UVLO threshold, then the startup circuit is shut down,

VCC get power from auxiliary winding, and ST is clamp

at 14V to driver the power MOS, and the VCC over

voltage threshold is set to be 25.8V. At normal operation

condition, when VCC is lower then 7.5V, the startup

circuit will be wake up to hold the VCC voltage until VCC

higher than 8V.

At the secondary ON time, the auxiliary voltage as

follow :

VAUX

=

N AUX

NS

* (Vo

+ ∆V )

Vo is output voltage , ΔV is the forward voltage of the

rectifier diode. So that ZCD can sense the output voltage

via the auxiliary winding divider. When ZCD is higher

than 5.5V, the LED open protection is trigger; the system

will enter automatic self-recovery station.

Programmable output Current

The output current can be programmable by adjust the

resistor between CS and GND. The LED output current

is as follow:

I out

=

Np ×

NS

V REF

2 × R CS

While VREF is the reference voltage of the amplifier of

the CC loop, and Rcs is the current sense resistor from

CS pin to GND, Np/Ns is the The turns ratio of the

primary and secondary of the transformer.

Operating Current

The operating current of WS3110 is low to 0.6mA .Good

efficiency and low standby power is achieved with low

operating current

Transition mode and switching frequency

The WS3110 operates in transition mode, the frequency

varies depending on the line voltage and the load

condition, and the maximum switching frequency is

Demagnetization ， Line-compensation and output

voltage detection

By using a auxiliary winding of the transformer, the

WS3110 can perform zero current detection. When the

stored energy is fully released to the output, the voltage

at ZCD decrease. A negative-going edge triggers

MOSFET’s turn-on

internal limited by the minimum OFF time (4us) to

250KHz.

During start-up or output short circuit, the output voltage

is too low, and the voltage of ZCD is lower than 0.4V

threshold, the demagnetization cannot be detected, then

the switching frequency is set by the maximum OFF time

(150us) to be 7KHz,

At the primary ON time, the ZCD pin can indirectly detect

the line voltage, and be used to Line-compensation, the

compensation rate can be programmable by adjust the

upper resistor of the auxiliary winding divider

Current Sensing and Leading Edge Blanking

The Cycle-by-Cycle current limiting is offered in

WS3110.

6/8

Steady, keep you advance

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