Controller IC for Dimmable LED lighting

Dimming LED lamps can save energy and changes the visual appearance and mood of your space. You can use a dimmable LED lamp in a non-dimmable circuit. You should NOT use a non-dimmable lamp in a dimmable circuit as it may cause damage to the lamp and or circuit. Integral lamps are clearly marked as dimmable or non-dimmable on the packaging and on the lamp.

Some of the issues that may occur when a dimmer is incompatible with an LED lamp are:

• Flickering – Lamps will flicker (can also occur if a non-dimmable lamp is used)
• Drop-out – No light output at the end of the scale
• Dead travel – When the dimmer is adjusted there is no matching change in light output (light may not dim to acceptable level)
• Not smooth – Light output may not go from dim to bright linearly
• Multiple lamps – issues may become apparent when multiple lamps are added
• Damage or failure – LED driver, circuit or LED is damaged or fails.
• Load below minimum – The power load of the LED lamp is below the minimum required by the dimmer
• Mixed models- Different models of LED will likely have different drivers – since drivers behave differently this could result in dimming issues.

ROHM Semiconductor LED Lighting Solutions

ROHM has developed LEDs for lighting utilizing a well-established in-house production system, along with extensive expertise gleaned from fifty years as a market leader in semiconductor products. ROHM has been developing LEDs since 1973 and are actively implementing research and development from the element composition stage. The production volume of 5 billion units annually is among the largest in the industry.

Features of Rohm’s LED Lighting

①For High Power LED

・Built-in PFC Function ⇒Improvement on Power Factor (PF)

・Various Dimming Functions ⇒TRIAC/PWM/Linear Dimming

・Isolation/Non-isolation Type

⇒Buck/Fly-back Circuit Selectable

②For Low Power LED （LED Bulb）

・Built-in bootstrap circuit and MOSFET

⇒Lower cost

・Compact package

⇒Smallest area

・Isolation/Non-isolation Type

⇒Buck/Flyback Circuit Selectable

BD555BKFV AC/DC controller IC for dimmable LED lighting

The BD555BKFV controller AC/DC controller IC can be used in a wide range of dimmable LED lighting driver applications.  The main target application is dimmable retro-fit LED lighting, replacing existing incandescent light bulbs, halogen spot lights, CFL tubes etc.

Key questions for low-power dimmable LED lamps

1. High efficiency:  >85% ‘dimmer detect’
2. Dimmer compatibility: Trailing + leading edge & electronic feature dimmers
3. Accurate dimming: Equally deep dimming of LED lamps on single dimmer
4. Low cost controller: Allows flexible application
5. Non-retro fit lighting: PWM / linear dimming support

BD555BKFV Features

• LED light application

– AC voltage range 80…270VAC

– LED output power 2…10W

– Average and/or peak current regulation in buck / fly-back topology

– Fixed frequency DC/DC 40…400kHz

• Dimming compatibility

– Accurate ‘true phase-cut’ detector allows wide dimming range (<5%)

– Dynamic Load Current Controller (DLCC) function for stable operation with leading/trailing edge dimmers

– False LED activation prevention for mains-powered dimmers that require standby current

– Natural ‘linear’ dimming through logarithmic compensation

– Dimmer detector improves efficiency by turning off DLCC current if dimmer is not present

– Supports PWM and linear dimming (for non retro-fit LED lighting)

• Internal IC supply voltage regulator

– Wide input supply voltage range 15~40V

– Low current consumption <2mA

• Safety & Protection

– Over Current Protection (OCP)

– Thermal Shut Down Protection (TSD)

– Under Voltage Lock Out detection (UVLO)

• Package

Application

For optimal performance with TRIAC / electronic dimmers, the BD555BKFV has three main individual functions:

1) ‘True’ phase-cut detector

2) Dynamic Load Current Controller (DLCC)

3) DC/DC controller for average current and/or peak current feedback

BD555BKFV – ‘True’ phase cut detection (1)

Natural dimming of LED light intensity is achieved by detection of ‘true’ phase-cut (VDET), low-pass averaging and conversion of linear (VDIM) to logarithmic (VREF) reference for LED current.

BD555BKFV – Dynamic load current controller (2)

The dynamic load current controller ‘DLCC’ (or ‘bleeder’) has two functions:

1) Application load current will be matched to the required TRIAC ‘ON’ hold current (stabilizing)

2) For (electronic) dimmers requiring a standby current (<10mA), the DLCC prevents false LED activation

BD555BKFV – Buck controller (3)

Accurate LED current regulation by controlling PWM duty-cycle (VSW) based on average LED current feedback (IFB) & ‘over-current’ protection (Icoil<Isat,coil)

Example 1 – GU10 socket 4W

• Accurate ACC (average current control)

• Efficiency >85%

• Excellent line regulation

• Equal dimming among multiple LED spot lights

• Configurable ‘dynamic load current controller’ supports wide range of dimmers (leading/trailing edge & electronic feature dimmers)

 

Example 2 – E27 socket retrofit 5W

• Low-cost buck or fly-back topology

• Fully configurable dimmer stabilization circuit

• Fits in existing E27 form-factor

• Supports HB-LED and multi-junction (high Vf) LED arrays