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36W TLD application with UBA2014
Application Note
Philips Semiconductors
3
CONTENTS
1.
INTRODUCTION. 4
2.
FEATURES 5
3.
APPLICATION PHOTO... 6
4.
BLOCK SCHEMATIC DIAGRAM..
7
5.
CIRCUIT DIAGRAM 9
6.
PARTSLIST 10
7.
LAMP CIRCUIT OPERATION AND DIMENSIONING.. 11
8.
QUICK MEASUREMENTS... 14 36W TLD application with UBA2014
Application Note
Philips Semiconductors
4
1.
INTRODUCTION
The UBA2014 integrated half bridge driver IC has been designed for driving electronically ballasted fluorescent lamps.
The IC provides the drive function for 2 discrete power mosfets. Besides the drive function the IC also includes the
level-shift circuit, the oscillator , a lamp voltage monitor, a current control function a timer function and protections.
This application note will give a description of a typical integrated 36W TLD application. The voltage fed half bridge is
supplied by a constant 400Vdc supply (either an external or a PFC supply). According IEC61000-3-2 (Limits for
harmonic current emission), power factor correction for loads over 25W is required, see figure 1.
Mains voltage
GND
.
PFC
400Vdc
Application
Figure 1. Input circuitry using a PFC.
Rectified mains
Mains voltage
230Vac
Application
GND
Figure 2. Normal input circuitry.
If one doesnt have to comply with IEC61000-3-2, just a normal input circuit like in figure 2, can be used, but keep in
mind that the lamp power is not constant over a big input voltage range (like 190Vac..264Vac). The voltage fed half
bridge topology allows to operate easily in Zero Voltage Switching (ZVS) series resonant mode, thus reducing the
transistor switching losses and the electromagnetic interference. During the preheat time the UBA2014 controls the
current which flows in the filament of the lamp. To provide long life and insure an efficient ignition of the lamp the
preheat timer and control system determine the optimal preheat time and preheat current. After the preheat time the
lamp must be ignited by reducing the switching frequency and thus increasing the voltage across it. The IC controls the
maximum ignition voltage and the ignition timer determines the maximum ignition time. During this phase the capacitive
mode protection ensures a safe operation of the power mosfets. In the burn phase the lamp current is controlled by the
average current system. In this phase the lamp can be dimmed to a low level by frequency dimming.
The UBA2014 has protections for lamp ageing, lamp failures and lamp removal. The power down function can safely
switch off the power inverter. 36W TLD application with UBA2014
Application Note
Philips Semiconductors
5
2.
FEATURES
· Integrated half bridge power IC for fluorescent applications
- integrated high side / low side , including bootstrap circuitry
- based upon BCD 650V power-logic technology
- accurate oscillator and timer
- adjustable frequency range (with fixed fmax/fmin ratio)
- adaptive non-overlap time control
- capacitive mode protection
- adjustable preheat current and time control
- single ignition attempt
- powerdown function
· soft start by frequency sweep down from start frequency
· adjustable ignition voltage control
· lamp current control
· down to 10% dimming
· protection against lamp failures or lamp removal
· SO16, DIP16 package 36W TLD application with UBA2014
Application Note
Philips Semiconductors
6
3.
APPLICATION PHOTO
Figure 3. The Printed Circuit Board of the UBA2014 application. Remark: this controller had no official number. 36W TLD application with UBA2014
Application Note
Philips Semiconductors
7
4.
BLOCK SCHEMATIC DIAGRAM
digital
analog
reset
vddlow
Supply
Driver logic
3V
Bootstrap
FVDD
GH
SH
GL
LS driver
Preheat timer
CS+
CS-
CSW
GND
CT
VDD
VREF
HS driver
Average
reference
Level
shifter
Vpowerdown
UBA2014
voltages
I
V
supply (5V)
Voltage controlled
CF
IREF
counter
logic
Frequency
current sensor
Lamp
Vlampfail
Vlampmax
ANT/CMD
logic
State logic
PCS
PCS
logic
oscillator
voltage
sensor
control
-reset state
-start-up state
-preheat state
-ignition state
-burn state
-hold state
-powerdown state
Reference
current
LVS
ACM
4
3
13
2
16
15
8
12
6
11
10
9
7
14
5
1
Figure 4. Block schematic diagram UBA2014.
In figure 4 the block schematic diagram of the UBA2014 is shown. The block State logic forms the heart of the controller
and controls all other internal functions. Initial start-up is achieved by means of charging an external capacitor (C15 in
figure 5) connected to pin 7. The State logic will be reset and both outputs GL and GH are low (reset state). Reaching a
voltage of 13.6V, the controller enables the blocks Voltage controlled oscillator (VCS), Adaptive non overlap (ANT), Preheat
timer (PRT), Preheat current sensor (PCS) and Lamp voltage sensor (LVS) .
The VCO generates a sawtooth shaped voltage between 2.5V and 0V. The frequency is determined by the value of the
capacitor connected to pin 3 (C14), the resistor connected to pin 4 (R12) and the voltage at pin 2. The minimum
frequency is determined by R12 and C14, see also chapter 7; the maximum frequency, at which the circuit starts
oscillating, is 2.5 times the minimum frequency. The comparator in the VCO changes the sawtooth into a block voltage,
which drives the Driver logic. On its turn the Driver logic drives the HS- and LS-driver, but with a frequency half the VCO-
frequency. The first switching cycle the drive signal for the LS-driver is made extra long to enable the Bootstrap to charge
the externally connected bootstrap capacitor (between pins 9 and 11). The gates of the power mosfets are connected to
GH and GL.
The ANT ensures that both power mosfets have the same on-time independent to the frequency. The voltage at pin 12
is measured across externally connected resistor R16 (see figure 5). 36W TLD application with UBA2014
Application Note
Philips Semiconductors
8
The PRT is included to determine the preheat time and ignition time. The preheat time is defined by the capacitor
connected to pin 1 (C12) and resistor R12 connected to pin 4, and consists of 7 pulses at C12. The maximum ignition
time is 1 pulse at C12. The circuit is operational during start-up and in case of a fault condition, for example when no
lamps are connected. The preheat time begins at the moment when the circuit starts oscillating. Capacitor C13 (at pin 2)
is connected to the input of the VCO and will be discharged, ensuring a defined a frequency sweep which starts at the
maximum frequency. By charging the capacitor with a constant current controlled by the PCS, the frequency will
decrease until the preheat voltage measured at pin 8 exceeds an internally fixed voltage of 0.6V. This voltage is measured
across externally connected resistor R14.
After the preheat time, the State logic disables the PCS and the frequency further sweeps down until the lamp circuit
reaches the resonance frequency of the lamp capacitor and ballast coil. To ensure that the lamp will ignite, two voltage
levels have been defined: V
lampfail
and V
lampmax
, measured at pin 13 (LVS). The ignition level is between them. Passing the
V
lampfail
enables the ignition timer. If the lamp ignites, the lamp voltage will drop and also the voltage measured at pin 13
(LVS) will drop as well. The ignition stops and the increasing voltage at pin 2 will force the controller to the minimum
frequency. At this point the controller enters the burn state and the Averaging current sensor (ACS) circuit will be enabled.
The average current is measured across a resistor (R14) and fed to pin 16 (CS-). Pin 15 (CS+) is externally connected, via
resistors, to the reference voltage of 2.95V. If the CS- voltage reaches the CS+ level, the ACS circuit will take over the
control over the lamp current. The output voltage of the ACS circuit is fed to the VCO and regulates the frequency and,
as a result, the lamp current.
If the lamp does not ignite, the LVS voltage reaches the V
lampmax
level. The Frequency control will keep its frequency. In
this way the lamp voltage can not increase any further. After the adjusted ignition time the State logic will disable all
internal circuits and the controller enters the power down state. The circuit can be start up again by lowering the voltage
at pin 7 below the reset level of 5.5V.
If one disconnects the lamp during normal operation, the lamp voltage will pass the V
lampfail
level and the ignition timer
will start. After a short period, the V
lampmax
level will be reached and after the ignition time the controller enters the
power down state. 36W TLD application with UBA2014
Application Note
Philips Semiconductors
9
5.
CIRCUIT DIAGRAM
C
D
A
B
C
D
1.9mH
PHILIPS
Engineer:
Drawn by:
Changed by:
Date/Time Changed:
Project:
Variant:
Drwg: 130 -
Sheet Name:
Size:
Philips Semiconductors B.V.
Eindhoven The Netherlands
PHILIPS SEMICONDUCTORS
Systems Laboratory Eindhoven
36W-TLD
123456
A4
9:00:46 am
Tuesday, September 25, 2001

pn8026_1x36W
DESIGN
1 / 1
None
PR70574
lkijzers
simons
simons
123456
A
B
100pF
C14
68nF
C20
330nF
C15
R13
150
47
R9
C10
5.6nF
TP12
1nF
C3
TP16
TP13
TP3
TP5
180k
R18
TR2
12nF
C2
TP7
12V
BZD23C
D3
C13
R1
PR01
1M
C6
1.2nF
220nF
5678
9
R12
RC12H
33k
1
10
11
12
13
14
15
16
234
R8
RC01
8.2k
UBA2014/N1A
IC1
R3
RC01
220k
220k
R20
R2
RC12H
8.2k
1
2
3
4
F1
FUSE 1A
12
TP6
R4
1M
C24
100nF
D1
BYD77D
C23
100nF
**
6.8nF
C17
R5
RC11
10k
L1
LAMP_COIL
8.2nF
C22
**
R17
0
RC01
PR01
1M
390pF
C8
C12
330nF
R10
C19
56nF
TP2
R16
MRS25
1.5
100nF
C5
450V
10uF
C7
BYD77D
D4
R14
MRS25
1
400Vdc
TR1
Figure 5. Circuit diagram. 36W TLD application with UBA2014
Application Note
Philips Semiconductors
10
6.
PARTSLIST
REFERENCE PART