ERJ-8GEYJ333V [INFINEON]
IRPLLNR5 Wide Range Input Linear Fluorescent Ballast;
| 型号： | ERJ-8GEYJ333V |
| 厂家： | 
Infineon |
| 描述： | IRPLLNR5 Wide Range Input Linear Fluorescent Ballast |
| 文件： | 总21页 (文件大小：331K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
IRPLLNR5
IRPLLNR5 Wide Range Input Linear Fluorescent Ballast
Reference Design Using the IRS2168D
Table of Contents
Page
1. Features…………………………………………………………………...….2
2. Description.............................................................................................2
3. Electrical Characteristics .......................................................................3
4. Fault Protection Characteristics.............................................................4
5. IRPLLNR5 Schematics…………...……..…………………………………..5
6. PCB Component Placement Diagram and Board Fabrication…………..6
7. Bill of Material and Inductor Specification………………………..………..8
8. Functional Description……….……………………….…………………....11
1
www.irf.com
1. Features
•
•
•
•
•
•
•
•
•
Drives 1 x 54 W TL5 Lamp
Input Voltage: 90-305 VAC
High Power Factor/Low Total Harmonic Distortion
High Frequency Operation
Lamp Filament Preheating
Lamp Fault Protection with Auto-Restart After Lamp Replacement
Low AC Line Protection
Lamp End-of-Life Shutdown
IRS2168D HVIC Ballast Controller
2. Description
The IRPLLNR5 reference design is a high efficiency, high power factor, fixed output, electronic
ballast designed for driving rapid-start fluorescent lamp types. The design contains an EMI filter,
active power factor correction, and a ballast control circuit using the IRS2168D(S)PbF Ballast Control
IC. This reference design is intended to ease the evaluation of the IRS2168D, demonstrate PCB layout
techniques, and serve as an aid in the development of a production-ready ballast using the IRS2168D.
EMI Filter
Rectifier
Boost PFC
Output Stage
Line
Input
Lamp
UVLO
PFC Control
Half-Bridge Driver
Control IC
Lamp Fault
Fig. 1: Ballast Block Diagram
RD-0613
2
www.irf.com
3. Electrical Characteristics
Parameter
Lamp Type
Units
Value
54 W TL5
Input Power
[W]
[Vpp]
[kHz]
[kHz]
[s]
54
400
50
85
1.0
Lamp Running Voltage
Run Mode Frequency
Preheat Mode Frequency
Preheat Time
Lamp Preheat Voltage
Lamp Ignition Voltage
Input AC Voltage Range
[Vpp]
[kVpp]
[VAC]
500
2.0
90-305 VAC
0.995 at 120 VAC
0.98 at 220 VAC
10 at 120 VAC
14 at 220 VAC
Power Factor
Total Harmonic Distortion
[%]
Table 3.1: Ballast Parameters
Vin
Pin (W)
55.5
52.8
51.8
51.1
50.8
50.7
50.6
50.5
50.5
50.5
PF
THD (%) DCBUS (V)
90
0.997
0.996
0.994
0.992
0.99
0.987
0.983
0.978
0.972
0.964
9.15
9.85
11
495
495
495
495
495
495
495
495
495
495
110
130
150
170
190
210
230
250
270
11.25
12.2
12.8
13.9
14.9
16.1
17.7
Table 3.2: PFC Data
RD-0613
3
www.irf.com
1
0.995
0.99
20
18
16
14
12
10
8
0.985
0.98
0.975
0.97
6
PF PM
4
THD PM
0.965
0.96
2
0
90
140
190
VIN
240
Fig. 2: PFC and THD Performances versus Input Voltage
4. Fault Protection Characteristics
Fault
Ballast
Restart Operation
Increase line voltage
Lamp exchange
Line Voltage Low
Upper Filament Broken
Lower Filament Broken
Failure to Ignite
Deactivates
Deactivates
Deactivates
Deactivates
Deactivates
Deactivates
Lamp exchange
Lamp exchange
Lamp exchange
Lamp exchange
Open Circuit (no lamp)
End of Life
RD-0613
4
www.irf.com
5. IRPLLNR5 Schematics
Fig. 3: Schematic Diagram, IRS2168D, Single Lamp, Voltage Mode Heating
RD-0613
5
www.irf.com
6. PCB Component Placement Diagram and Board Fabrication
Fig. 4: PCB Component Placement Diagram
RD-0613
6
www.irf.com
Board Fabrication
1) Board size:
L = 8.59 inch, W = 1.195 inch
2) No. of copper layers:
3) Copper:
1 (bottom layer)
2 oz.
4) Board material:
5) Through hole plating:
6) Solder plating on pads:
7) Solder mask:
8) Silk screen layers:
9) Silk screen ink:
10) Gerber file:
FR-4
No
Yes
Green LP1 (bottom layer only)
Top and bottom
White epoxy, non-conductive
IRPLLNR5.ZIP
11) Gerber file description:
a) IRPLLNR5.apr
b) IRPLLNR5.DRL
c) IRPLLNR5.DRR
d) IRPLLNR5.GBL
e) IRPLLNR5.GBO
f) IRPLLNR5.GBS
g) IRPLLNR5.GD1
h) IRPLLNR5.GG1
i) IRPLLNR5.GM1
j) IRPLLNR5.GTO
Apertures
NC drill
NC drill
Bottom layer
Silk screen bottom
Solder mask bottom
Drill drawing
Drill guide
Mechanical layer
Silk-screen top
RD-0613
7
www.irf.com
7. Bill of Material and Inductor Specification
Item
1
Qty
1
1
1
1
1
1
1
1
1
2
2
2
3
1
1
1
1
1
2
2
1
1
1
3
1
1
1
3
2
5
1
Manufacturer
Part Number
Description
Reference
Diodes Inc.
DF10S
Bridge Rectifier, 1 A, 1000 V
Capacitor, 2.2 nF, 305 VAC Y Cap
Resistor, 0.5 Ω, 1/2 W
BR1
CY
2
Roederstein
Dale
WKP222MCPEJ0K
CW-1/2
3
F1
4
Roederstein
Panasonic
F1772433-2200
ELF-15N007A
Capacitor, 0.33 µF, 275 VAC
EMI Inductor, 10 mH, 0.7 A peak
Capacitor, 0.1 µF, 630 VDC
Capacitor, 0.1 µF, 400 VDC
Transient Suppressor
C1
5
L1
6
Vishay Dale
Wima
MKP1841410634
MKP10-.1/400/10
ERZ-V05D471
IL 060 320 41 02
EEU-EB2V330S
ECJ-3VB1E104K
ECU-V1H102JCH
ECJ-3YB1E105K
ECU-V1H103KBM
ECJ-3VB1E334K
ECE-A1EKG100
102R29W102KV4E
FKP1-3300/2000/5
ECU-V1H471KBM
ECQB1104JFW
ZMM5240B-7
C2
7
CDC
RV1
LPFC
8
Panasonic
9
VOGT
PFC Inductor, 2 mH, 2.5 A peak
Capacitor, 33 µF, 350 VDC, 105 °C
Capacitor, 0.1 µF, SMT 1206
Capacitor, 1 nF, SMT 1206
Capacitor, 1 µF, SMT 1206
Capacitor, 0.01 µF, SMT 1206
Capacitor, 0.33 µF, SMT 1206
Capacitor, 10 µF, 25 VDC, 105 °C
Capacitor, 1 nF, 1 kV, SMT 1808
Capacitor, 3.3 nF, 2 kV
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Panasonic
CBUS1, CBUS2
Panasonic
CBS, CVCC
Panasonic
CSD, CEOL (see Note 2)
Panasonic
CCOMP, CPH, CVCO
Panasonic
CVBUS
Panasonic
CSD1
Panasonic
CVCC1
Johanson Dielectrics
WIMA
CBS
CRES
Panasonic
Capacitor, 470 pF, SMT 1206
Capacitor, 0.1 µF, 100 V
CCS, COC
Panasonic
CH1, CH2
Diodes Inc.
Diodes Inc.
Digi-key
Zener diode, 10 V, Minimelf, 0.5 W
Zener diode, 5.6 V, Minimelf, 0.5 W
Diode, 1 A, 600 V, SMT SMB
Diode, 1N4148, SMT DL35
DIP 16 IC Socket Through-Hole
IC, Ballast Driver / PFC
DEOL1
ZMM5232B-7
DEOL2
MURS160DICT-ND
LL4148DICT-ND
2-641262-1
DPFC
Diodes
DCP1, DCP2, DSD
Tyco Electronics/Amp
International Rectifier
VOGT
IC1
IRS2168D
IC1
IL 060 320 51 01
IRFB9N60A
Resonant Inductor, 2 mH, 2 A peak
Transistor, MOSFET
LRES
International Rectifier
MPFC, MHS, MLS
> = 22 A.W.G
Jumpers
J1, J2
Panasonic
Panasonic
ERJ-8GEYJ120V
ERJ-8GEYJ474V
Resistor, 12 Ω, SMT 1206
Resistor, 470 kΩ, SMT1206
RPFC, RLO, RHO, RLM1, RLM2
RCPH
Phoenix Passive
Components
32
1
5033ED220K0F12AF5
Resistor, 220 kΩ, 1/2 W
RVCC
33
34
35
36
37
38
39
40
41
42
43
44
45
2
1
2
1
1
1
1
4
1
1
1
1
1
Panasonic
Panasonic
Panasonic
Vishay/Dale
Digi-Key
Panasonic
Panasonic
Panasonic
Panasonic
Digi-key
ERJ-8GEYJ684V
ERJ-8GEYJ333V
ERJ-8GEYJ102V
RS01A1R500FS70
P0.62W-1BK-ND
ERJ-8ENF1132V
ERJ-8GEYJ104V
ERJ-8GEYJ224V
ERJ-8GEYJ203V
36.0KFRCT-ND
ERJ-8GEYJ563V
235-203
Resistor, 680 kΩ, SMT 1206
Resistor, 33 kΩ, SMT 1206
Resistor, 1 kΩ, SMT 1206
Resistor, 1.5 Ω, 1%, 1 W
RVBUS1, RVBUS2
RZX
RF1, RF2
RCS
Resistor, 0.62 Ω, 1 W
ROC
Resistor, 11.3 kΩ, 1%, SMT 1206
Resistor, 100 kΩ, SMT 1206
Resistor, 220 kΩ, SMT 1206
Resistor, 20 kΩ, 5%, SMT 1206
Resistor, 36 kΩ, 1%, SMT 1206
Resistor, 56 kΩ, 1%, SMT 1206
Connector, 3 terminal
RVBUS
RSD
REOL1, REOL2, REOL3, RPU
REOL4 (see Note 3)
RFMIN
RPH
X1
Panasonic
WAGO
WAGO
235-207
Connector, 4 terminal
X2
Table 1: Bill of Material
Lamp type: 54 W TL5; Line Input Voltage: 80-305 VAC
RD-0613
8
www.irf.com
Note 1: Different lamp types require different frequency programming components.
Note 2: CEOL and CSD values can be increased up to 470 nF to increase noise immunity.
Note 3: REOL4 value can be increased to 33 kΩ for a more sensitive lamp end-of-life detection
INDUCTOR SPECIFICATION
LPFC
PART NO.: IL 060 320 41 02 REF DES:
EVD25
HORIZONTAL
3.5
8
mm
CORE SIZE
BOBBIN
GAP LENGTH
PINS
Fi 324 or equivalent
CORE MATERIAL
2
NOMINAL INDUCTANCE
MAXIMUM CURRENT
mH
2.5
Apk
ºC
115
MAXIMUM CORE TEMPERATURE
WINDING
MAIN
ZX
START PIN
FINISH PIN
WIRE DIAMETER (mm)
TURNS
TBD
4 strands of AWG 32
1
3
7
5
AWG 32
26
ELECTRICAL
LAYOUT
PHYSICAL LAYOUT
20.05mm
TOP VIEW
5mm
1
2
3
4
8
5mm
7
6
5
25mm
(TEST FREQUENCY = 50kHz)
TEST
MAIN WINDING INDUCTANCE INDUCTANCE TOLERANCES: +/- 5%
MAIN WINDING INDUCTANCE INDUCTANCE RESISTANCE MAX 3.2 OHM
NOTE : Inductor must not saturate at maximum current and maximum core temperature at
given test frequency
Fig. 5: Power Factor Inductor Specification
RD-0613
9
www.irf.com
INDUCTOR SPECIFICATION
PART NO.: IL 060 320 51 01 REF DES: LRES
EVD25
2.82
8
mm
CORE SIZE
BOBBIN
GAP LENGTH
PINS
HORIZONTAL
Fi 324 or equivalent
CORE MATERIAL
2
NOMINAL INDUCTANCE
MAXIMUM CURRENT
mH
2
Apk
ºC
115
MAXIMUM CORE TEMPERATURE
WINDING START PIN FINISH PIN TURNS WIRE DIAMETER (mm)
MAIN
CATHODE (1)
1
8
7
5
185
8
4 strands of AWG 32
4 strands of AWG 32
4 strands of AWG 32
6
CATHODE (2)
4
8
ELECTRICAL
PHYSICAL LAYOUT
20.05mm
TOP VIEW
5mm
1
2
3
4
8
5mm
7
6
5
25mm
(TEST FREQUENCY = 50kHz)
TEST
mH
mH
MAIN WINDING
MIN 1.9
MAX 1.8
MAX 2.1
Ohms
MAIN WINDING
NOTE : Inductor must not saturate at maximum current and maximum core temperature at given
test frequency.
Fig. 6: Resonant Inductor Specification
RD-0613
10
www.irf.com
8. Functional Description
The IRPLLNR5 reference design consists of an EMI filter, an active power factor correction section, a
ballast control section, and a resonant lamp output stage. The active power factor correction section is a
boost converter operating in critical conduction, free-running frequency mode. The ballast control
section provides frequency modulation control of a traditional RCL lamp resonant output circuit and is
easily adaptable to a wide variety of lamp types. The ballast control section also provides the necessary
circuitry to perform lamp fault detection, shutdown, and auto-restart.
Reference Design Overview
This demo-board is designed for a single 54 W TL5 lamp with voltage mode heating. TL5 lamps are
popular due to their low profile and high lumen/watt output. These lamps, however, can be more
difficult to control due to their higher ignition and running voltages. A typical ballast output stage using
current-mode filament heating (filament placed inside L-C tank) will result in excessive filament current
during running. The output stage has therefore been configured for voltage-mode filament heating using
secondary windings off of the resonant inductor LRES. The lamp has been placed outside the under-
damped resonant circuit loop, which consist of LRES and CRES. The filament heating during preheat
can be adjusted with the capacitors CH1 and CH2. The result is a more flexible ballast output stage
necessary for fulfilling the lamp requirements. The DC blocking capacitor, CDC, is also placed outside
the under-damped resonant circuit loop such that it does not influence the natural resonance frequency
of LRES and CRES. The snubber capacitor, CSNUB, serves as EMI reduction and a charge pump for
supplying the IRS2168D.
The IRS2168D ballast control IC is used to program the ballast operating points and protect the ballast
against conditions such as lamp strike failures, low DC bus or lamp failure during normal operations. It
is also used to regulate the DC bus and for power factor correction to give high power factor and low
harmonic distortion of the ballast AC input current.
Power Factor Correction Section
The power factor correction section contained in the IRS2168D controls a boost topology circuit
operating in critical conduction mode. This topology is designed to step-up and regulate the output DC
bus voltage while drawing sinusoidal current from the line (low THD) which is “in phase” with the AC
input line voltage. The power factor correction section also includes over-current protection of the
boost MOSFET to prevent damage that can occur during boost inductor saturation.
Ballast Control Section
The ballast control section of the IRS2168D ballast control IC contains an oscillator, a high-voltage
half-bridge gate driver, and lamp fault protection circuitry. Please refer to the datasheet of this IC for
the block diagram and the state diagram. The following is a breakdown of the different modes of
operation for the ballast.
Startup Mode
When power is initially applied to the ballast, the voltage on the VCC pin of the IRS2168D begins to
increase. The voltage for the IRS2168D is derived from the current supplied from the rectified AC line
through the startup resistor RSUPPLY. During this initial startup when the VCC voltage of the
IRS2168D is below the rising under-voltage lock-out threshold (UVLO+), the IC is in UVLO Mode and
draws micro-power current at VCC. The micro-power current of the IRS2168D allows for the use of a
RD-0613
11
www.irf.com
large value, low-wattage startup resistor (RSUPPLY). When the voltage on the IRS2168D reaches the
rising under-voltage lockout threshold (12.5 V), the gate driver oscillator is enabled (this assumes that
there are no fault conditions) and drives the half-bridge output MOSFETs (MHS and MLS). When the
half-bridge is oscillating, capacitor CSNUB, diodes DCP1 and DCP2 form a snubber/charge pump
circuit which limits the rise and fall time at the half-bridge output and also supplies the current to charge
capacitor CVCC2 to the VCC clamp voltage (approx. 15.6 V). When the rising under-voltage lockout
threshold of the IRS2168D is reached, the power factor control output also starts to oscillate and drives
MOSFET MPFC to boost and regulate the bus voltage to 500 V DC.
Preheat Mode
When the ballast reaches the end of the UVLO mode, the Preheat Mode is entered. At this point, the
ballast control oscillator of the IRS2168D has begun to operate and the half-bridge output is driving
the resonant load (lamp) circuit.
There is an initial startup frequency that is higher than the preheat frequency that lasts for only a short
duration. This is done to ensure that the initial voltage appearing across the lamp at the startup of
oscillation does not exceed the minimum lamp ignition voltage. If, at the initiation of oscillation of the
half-bridge, the voltage across the lamp is large enough, a visible undesired flash of the lamp can occur.
This in effect is a cold strike of the lamp and can shorten the life of the lamp.
The ballast control section oscillator of the IRS2168D consists of an internal timing capacitor and an
external timing resistor (RFMIN). Resistors RFMIN and RPH program a current that determines the
ramp up time of the internal timing capacitor. The preheat frequency is determined by the equivalent
resistance formed by the parallel combination of RFMIN and RPH. The preheat frequency is selected
such that the voltage appearing across the lamp is below the minimum lamp ignition voltage while
supplying enough current to preheat the lamp filaments to their correct emission temperature within the
Preheat Mode time period. The preheating of the lamp filaments is performed using voltage mode
heating that consists of a constant voltage across the lamp filaments. The waveform in Figure 7 shows
the CPH voltage and lamp voltage during normal Preheat, Ignition, and Run Modes. Figure 8 shows the
half-bridge voltage (VS pin) during Preheat Mode.
RD-0613
12
www.irf.com
Fig. 7: CPH Pin Voltage (Black) and Lamp Voltage (Blue) During Normal
Preheat, Ignition and Run Modes
Fig. 8: Half-Bridge Mid-Point Voltage (VS Pin) During Preheat Mode
RD-0613
13
www.irf.com
fosc
fStart
fPreheat
fRun
t
Preheat
Ignition
Run
Fig. 9: Oscillator Frequency versus Time During Normal Operating Conditions
Figure 9 shows a plot of the half-bridge oscillation frequency as a function of time for normal Preheat,
Ignition and Run ballast operating modes. The duration of the Preheat Mode, as well as all ballast
operating modes, are determined by the voltage on the CPH pin of the IRS2168D. At the end of UVLO
Mode, Preheat Mode is entered and the external capacitor at the CPH pin of the IRS2168D begins to
charge through the external resistor (RCPH) from CPH to VCC. The ballast remains in Preheat Mode
until the voltage on the CPH pin exceeds the End-of-Preheat Mode threshold of 0.67(VCC), at which
time the ballast then enters Ignition Mode.
Ignition Mode
When the IC enters Ignition Mode, CPH is discharged quickly to 0.33(VCC) and RPH is disconnected
from COM via an internal MOSFET at the RPH pin. CPH begins to charge up again from 0.33(VCC)
and the frequency begins to ramp down to the run frequency at a rate determined by the time constant
RPH(CVCO). During this ramping downward of the frequency, the voltage across the lamp increases in
magnitude as the frequency approaches the resonant frequency of the LC load circuit until the lamp
ignition voltage is exceeded and the lamp ignites. The maximum ignition voltage that can be generated
is determined from the value of RCS, and the ignition frequency must be higher than the run frequency
so that the frequency sweeps through the resonance frequency to ensure lamp ignition. If the lamp does
not ignite, then the ignition regulation feature of the IRS2168D will regulate the ballast output voltage
to a constant level (programmed by RCS) for the duration of Ignition Mode. Figure 10 shows the lamp
voltage during ignition ramp and ignition regulation during a lamp non-strike condition.
RD-0613
14
www.irf.com
Fig. 10: CPH Pin Voltage (Black) and Lamp Voltage (Blue) During Lamp
Non-Strike Fault Condition
During Ignition Mode, the voltage on the CPH pin of the IRS2168D continues to ramp up until the
voltage at the CPH pin exceeds 0.67(VCC) a second time and the IC enters Run Mode. The over-current
fault counter is disabled during Ignition Mode due to the ignition regulation feature and enabled again
at the start of Run Mode. During a lamp non-strike condition, the ignition voltage will be regulated for
the duration of Ignition Mode and then unregulated during Run Mode. This means that the ignition
voltage will increase slightly after Ignition Mode (as the frequency decreases towards the run
frequency) until the fault counter times out, after 65 cycles above the over-current threshold, and the
ballast shuts off. The amount of frequency shift and resulting voltage increase is determined by the
value of CVCO. The 5 V shutdown threshold at the SD pin is also disabled during Ignition Mode and
enabled again at the start of Run Mode. A full explanation of the functionality of the over-current
sensing and shutdown functions are in the Fault Mode section.
Run Mode
During Run Mode and after a successful lamp ignition, the frequency is at the final run frequency and
is determined by RFMIN. The 1 V and 3 V end-of-life (EOL) window comparator at the SD/EOL pin,
the 5 V unlatched shutdown threshold at the SD/EOL pin, and the fault counter at the CS pin, are all
enabled in Run Mode. A functional description of the over-current sensing and end-of-life sensing is
given in the Fault Mode section.
RD-0613
15
www.irf.com
The Run Mode frequency (Figure 11) is that at which the lamp is driven to the lamp manufacturer’s
recommended lamp power rating. The running frequency of the lamp resonant output stage for selected
component values is defined as,
2
2VDCbus
⎛
⎜
⎝
⎞
⎟
⎠
2
1−
2
2
⎡
⎢
⎤
⎥
1
1
P
Lamp
1
P
Lamp
VLampπ
⎛
⎝
⎞
⎟
⎠
⎛
⎝
⎞
⎟
⎠
frun
=
− 2
+
− 2
− 4
⎜
⎜
L2 C2
2
2
2π LC
LC
CV Lamp
CV Lamp
⎢
⎥
⎣
⎦
where,
L
C
P
= Lamp resonant circuit inductor (LRES) (H)
= Lamp resonant circuit capacitor (CRES) (F)
Lamp = Lamp running power
(W)
VLamp = Lamp running voltage amplitude
(V)
Fig. 11: Half-Bridge Mid-Point Voltage (VS Pin) During Run Mode
Normal Power Down
A normal power down occurs when the AC line voltage is disconnected from the ballast. When this
occurs, the voltage on the VBUS pin of the IRS2168D drops below the VBUS pin under-voltage reset
threshold of 3 V. This will cause VCC to be discharged internally to UVLO- (10.5 V). The IC enters
RD-0613
16
www.irf.com
UVLO Mode and the PFC and ballast oscillators are disabled, the PFC and half-bridge driver outputs
(PFC, LO, and HO) are turned off, and the IRS2168D consumes micro-power current at VCC.
Lamp Removal and Auto-Restart
Resistors RPU, RSD and capacitor CSD1 form a divider/filter network used to detect an open lower
lamp filament and/or lamp replacement. Under normal conditions, the voltage across CSD1 is close to
zero. If the lower filament becomes open or the lamp is removed, however, the voltage at the SD pin
increases above the 5 V threshold and causes the IC to shutdown (Figure 12). The ballast remains
shutdown until a lamp replacement is performed. If the lamp is replaced with a lamp with a good lower
filament, the voltage on the SD pin of the IRS2168D drops back below the 3 V threshold and the
ballast will restart in Preheat Mode. The ballast will go through the Preheat, Ignition, and Run Mode
sequences each time a restart is performed. Note that the SD pin of the IRS2168D is active during
Preheat and Run Modes and is disabled during Ignition Mode.
Fig. 12: SD Pin Voltage (Black) and Lamp Voltage (Blue) during
Lamp Removal/Auto-Restart Condition
Fault Mode
When a fault is detected at the CS pin or SD/EOL pin, the IC will enter Fault Mode. During Fault
Mode, the ballast section and PFC section are both shutdown. The DC bus voltage will drop to the
non-boosted peak AC line voltage level. There are several lamp fault conditions that can cause the IC
to enter into Fault Mode. These include: hard-switching at the half-bridge mid-point (open load), over-
current (non-strike), lamp voltage shift (end-of-life), and lamp removal (SD/EOL pin). Resistor RCS in
the source lead of the low-side MOSFET (MLS) serves as the current-sensing point for the half-bridge,
and is used to detect hard-switching or over-current. During normal operation when the half-bridge is
oscillating, a voltage appears across RCS when the low-side MOSFET, MLS, is turned on. The
magnitude of this voltage directly relates to the current in the lamp resonant circuit.
RD-0613
17
www.irf.com
If at any time during Preheat Mode or Run Mode the voltage across resistor RCS rises above the over-
current threshold (1.25 V) for 65 events, the PFC and half-bridge MOSFETs, (MPFC, MHS and MLS)
are turned off and the ballast goes into Fault Mode. During the Ignition Mode, the over-current is
disabled and the ignition regulation feature limits the maximum current flowing in the resonant tank
and half-bridge. An over-current condition can occur if the lamp fails to ignite or the lamp is broken
(an open circuit cathode or broken lamp). If a cathode is broken (open circuit), the half-bridge output
hard-switches. Each time the low-side MOSFET (MLS) is turned on, a large current pulse occurs and
thus a large voltage pulse occurs across resistor RCS signaling a fault. The ballast will remain in Fault
Mode until the AC line voltage is reset or a lamp replacement is performed.
During an end-of-life lamp fault condition, the lamp voltage can increase or decrease asymmetrically.
The resulting excessive voltage across the lamp filaments can cause the lamp ends to reach temperatures
high enough to melt the tube glass. The lamp can then fall out of the fixture and cause harm or damage.
To protect against this condition, resistors REOL1, REOL2, REOL3, REOL4, and zener diodes DEOL1
and DEOL2, are used for end-of-life protection. The end-of-life window comparator at the SD/EOL pin
is enabled in Run Mode. If the voltage on SD/EOL pin falls outside the range of the internal 1 V – 3 V
window comparator, the IC will enter Fault Mode. The SD/EOL pin is internally biased at 2 V with an
internal +/-10 µA OTA. The value of REOL4, DEOL1 and DEOL2 are selected such that the SD/EOL
pin remains at 2 V during normal operation, but increases above 3 V or decreases below 1 V during an
end-of-life fault condition. The lamp voltage end-of-life threshold can be adjusted by changing the value
of resistor REOL4 and/or zener diodes DEOL1 and DEOL2. A threshold of 30% higher than the
nominal running lamp voltage is typical.
PFC Control Section
The IRS2168D contains control circuitry for driving a boost-type power factor correction (PFC) circuit.
This is necessary for producing sinusoidal input current at the mains input that is “in phase” with the
mains voltage and contains minimal total harmonic distortion (THD). It is also convenient to use the
boost converter to regulate the DC bus voltage to a constant DC level. The PFC control is achieved
using five control pins. The DC bus voltage is sensed with a resistor divider at the VBUS pin. The loop
compensation speed is programmed with an external capacitor at the COMP pin. The cycle-by-cycle
zero-crossing of the boost inductor current is detected at the ZX pin. The gate drive for the boost
MOSFET is provided by the PFC pin. The cycle-by-cycle over-current protection is performed by the
OC pin. The following waveforms show the operation of the PFC at 120 VAC (Figure 13) and 290 V
AC (Figure 14) input line conditions.
RD-0613
18
www.irf.com
Fig. 13: AC Input Current (Green) and AC Input Voltage (Blue) at 120 VAC
Fig. 14: AC Input Current (Green) and AC Input Voltage (Blue) at 290 VAC
PFC Over-Current Protection
The PFC section includes cycle-by-cycle over-current protection. The OC pin senses the current in the
PFC MOSFET via an external sense resistor (ROC). Should the voltage across this resistor exceed the
internal threshold (1.25 V typical), the PFC MOSFET will turn off to limit the instantaneous current
RD-0613
19
www.irf.com
and will turn on again at the next zero-crossing of the inductor current as detected by the ZX pin. This
over-current condition can occur, for example, during a low-line condition (Figure 15). As the AC line
decreases, the PFC inductor and MOSFET current will increase to keep the DC bus constant for a
given power level. When the peak current reaches the over-current threshold, the cycle-by-cycle
current limit will cause the peak of the MOSFET current to flatten and the DC bus to start to drop. This
current limit is necessary to prevent saturation of the PFC inductor current and to protect the PFC
MOSFET from being damaged.
Fig. 15: OC Pin Voltage (Black) and DC Bus Voltage (Green) During Low-Line Condition
Brown-Out Protection
The IRS2168D includes an under-voltage reset (UVR) function at the VBUS pin. Should the DC bus
decrease too far during a momentary interrupt of the mains input voltage, the ballast should be properly
shutdown and restarted. This will prevent the lamp from extinguishing and will properly preheat and
restart the lamp when the mains voltage returns. If the VBUS pin voltage decreases below 3 V, the
PFC and half-bridge gate drivers will be turned off and VCC will be discharged to UVLO-. The ballast
will then be restarted via the RSUPPLY resistor when the mains voltage reaches a high enough level
again (Figure 16).
RD-0613
20
www.irf.com
Fig. 16: VBUS Pin (Black), Lamp Voltage (Blue) and DC Bus Voltage (Green) During
Momentary Interruption of the Mains
02/15/2007
RD-0613
21
www.irf.com
相关型号：
©2020 ICPDF网 联系我们和版权申明