NXP公司的UBA2021是高压集成电路,能控制和驱动CFL荧光灯,包括有用来驱动外接半桥电路的驱动电路,振荡器和用来起动,预热, 辉弧和保护等功能.而采用UBA2021的13W CFL电子镇流器采用半桥式逆变器作为灯驱动电路,逆变器的正常输入电压为230 V (RMS) ± 15 %, 50 Hz / 60 Hz.本文介绍了UBA2021的主要特性,方框图和典型应用电路以及采用UBA2021的13W CFL电子镇流器的设计要点,方框图, 镇流器电路图和电子镇流器保护电路以及所用元件清单与火线电压100 V (AC)/120 V (AC)时的倍压电路.
CFL 13 W demo PCB with UBA2021 for integrated lamp-ballast designs
The UBA2021 is a high voltage IC intended to drive and control Compact Fluorescent
Lamps (CFL) or fluorescent TL lamps. It contains a driver circuit for an external
half-bridge, an oscillator and a control circuit for starting up, preheating, ignition, lamp
burning and protection.
UBA2021主要特性:
Adjustable preheat and ignition time.
Adjustable preheat current.
Adjustable lamp power.
Lamp power independent from mains voltage variations.
Overpower protection.
Lamp temperature stress protection at higher mains voltages.
Capacitive mode protection.
Protection against a drive voltage that is too low for the power MOSFETs.
图1.UBA2021方框图
图2.UBA2021应用框图
13W CFL电子镇流器
A small and low cost electronic CFL ballast has been designed, which is able to drive a
13 W NXP PLC lamp or similar 13 W Compact Fluorescent Lamps (CFL). The circuit is
intended for integrated ballast-lamp designs. Therefore no additional protection against
lamp removal is required.
A voltage fed half-bridge inverter has been chosen as lamp driver circuit. The inverter has
been designed for a nominal input voltage of 230 V (RMS) ± 15 %, 50 Hz / 60 Hz. The key
component in this circuit is the UBA2021 Integrated Circuit (IC). This UBA2021 is a high
voltage driver IC, which provides all the necessary functions for a correct preheat, ignition
and burn-state operation of the lamp. Besides these control function the UBA2021 provides the level-shift and drive function (high-side driver and bootstrap circuit included)
for the two discrete power MOSFETS PHU2N60.
The key issues for this design are: compact, low cost and low component count. The
UBA2021 IC has a few peripheral components. Only a minimum amount of components
are required for the optimal balance between maximum design flexibility and low
component count. Furthermore, all components are of compact size.
For a reliable system operation and a long lamp life, the fluorescent lamp is preheated
first, after switch-on. This preheat is controlled by the UBA2021 IC. The electrode currents
and voltages meet the requirements to obtain a proper electrode-emitter temperature.
This results in a smooth ignition of the lamp at a much lower ignition voltage, with less
component stress and/or electrical stress.
In the burn phase, the operation frequency is approximately 43 kHz, so no interference
with infrared communication systems (32 kHz / 36 kHz) will occur. Furthermore, this
frequency is kept below 50 kHz (third harmonic < 150 kHz), which meets a better
RFI performance. During steady state operation, the frequency is determined by a
feed-forward control. The result is a constant level of light output over a large mains
voltage range (approximately 200 V / 250 V).
The 13 W CFL ballast with UBA2021 is available on two versions of printed circuit boards.
Printed-circuit board (PCB) PR38922 is a miniaturized version with SMD components
(referred to as SMD version). PCB PR39001 consists of leaded components only
(referred to as leaded-version). Both PCBs contain the same electrical circuit. Their board
designs (PCB layout) meet the requirements for a good EMC performance.
The AC mains voltage is rectified by four bridge rectifying diodes and the DC supply
voltage for the half bridge inverter is smoothed by a buffer capacitor. An EMC-filter is used
to minimize the disturbance towards the mains. The half-bridge inverter is a voltage fed
type and has been designed to operate a 13 W PLC lamp or similar lamps.
The voltage fed inverter belongs to a group of high frequency resonant inverters, which
are very attractive to drive lamp circuits. They can achieve a high efficiency, due to the
zero-voltage switching principle. This reduces the switching losses of the two power
MOSFETS PHU2N60 to a minimum, so the power loss is MOSFET ON-loss. Therefore
the steady state operation (thermal resistance and ON-loss) determines the choice of
MOSFET type (by RDSon). During ignition and preheat, the total MOSFET current has to
be below the specified maximum rating. All together the PHU2N60 (RDSon < 6 Ω,
Vds-max = 600 V) suits best with this application.
图3.13W CFL电子镇流器方框图
图4.13W CFL电子镇流器电路图
图5.13W CFL电子镇流器保护电路
元件列表PR38922 (SMD 型)
元件列表PR39001 (引线直插型)
图6. 火线电压100 V (AC)/120 V (AC)时的UBA2021和倍压电路
