IRPLLNR3
International Rectifier • 233 Kansas Street, El Segundo, CA 90245 USA
Universal Input Linear Fluorescent Ballast
using the IR2167
Cecilia Contenti, Dana Wilhelm and Tom Ribarich
Features
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Drives 1 x 35W TL5 Lamp (or 1X28WTL5 Lamp)
Input Voltage: 80-260Vac
High Power Factor/Low THD
High Frequency Operation (42kHz)
Lamp Filament Preheating
Lamp Fault Protection with Auto-Restart
Brownout Protection
End of Lamp Life Shutdown
IR2167 HVIC Ballast Controller
Description
The IR2167 Demo Board 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 IR2167. This demo board is intended to ease
the evaluation of the IR2167 Ballast Control IC, demonstrate PCB layout techniques and serve as an
aid in the development of production ballast’s using the International Rectifier IR2167.
Ballast Block Diagram
EMI Filter
Input Bridge
PFC
Line
Output Stage
L
C
UVLO
PFC Control
Half - Bridge Driver
Preheat Feedback
Lamp Fault
Lamp
IRPLLNR3
Parameter
Lamp Type
Input Power
Lamp running voltage
Run Mode Frequency
Preheat Mode Frequency
Preheat Time
Lamp Preheat Voltage
Ignition Ramp Mode Frequency
Ignition Voltage
Input AC Voltage Range
Power Factor
Total Harmonic Distortion
Units
[W]
[Vpp]
[kHz]
[kHz]
[s]
[Vpp]
[kHz]
[Vpp]
[VACrms]
[%]
Value
35W TL5
35
750
42
56
1
400Vpp
36
2000
80-260VAC
0.99 at 120VAC
10 at 120VAC
Note: Measurements performed with input AC line voltage = 220Vrms
Fault Protection Characteristics
Fault
Line voltage low
Upper filament broken
Lower filament broken
Failure to ignite
Open circuit (no lamp)
End of life
Ballast
Deactivates
Deactivates
Deactivates
Deactivates
Deactivates
Deactivates
Restart Operation
Increase line voltage
Lamp exchange
Lamp exchange
Lamp exchange
Lamp exchange
Lamp exchange
Functional Description
Overview
The IR2167 Demo Board 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 mode, 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. All
functional descriptions refer to the IR2167 Demo Board schematic diagram.
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RPLLNR3
IR2167 Demo Board
L
N
GND
F1
L1
CY
RV1
C1
BR1
C2
RVBUS
RVBUS2
RVBUS1
RVDC
CVDC
RT
CPH
RDT
RRUN
RPH
CRAMP
CT
COC
ROC
CCOMP
RZX
RVAC
VDC
CPH
RT
RPH
RUN
CT
DT
OC
1
2
3
4
5
6
20
19
18
17
16
15
14
IR2167
13
7
8
12
11
HO
VS
CBOOT
VB
DBOOT
VCC
RLO
RLIM2
RHO
RSUPPLY
CVCC1
COM
RLIM1
CVCC2
CSD1
CSD2
DSD
LO
CCS
CS
SD
PFC
VBUS
9
10
COMP
ZX
IC BALLAST
CVBUS
RLIM3
RCS
DEOL1
RSD
MLS
MHS
JC1 and JC2 no mounted, JV1 and JV2 mounted
DPFC
CBUS
RPFC
DEOL2
RPU
DCP2
CSNUB
2167 Single Lamp, Voltage mode heating
LPFC
MPFC
Note: Thick traces represent high-frequency, high-current paths. Lead
lengths should be minimized to avoid high-frequency noise problems
DCP1
CEOL
1
LRES:A
REOL1
REOL2
REOL3
REOL4
5
6
CDC
X21
CRES
X23
4
8
LRES:B
X24
X22
CH1
CH2
LRES:C
7
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IRPLLNR3
Bill Of Materials
Lamp type: TL5/35W, Line Input Voltage: 80-260 VAC
Note: Different lamp types require different frequency programming components.
4
Item #
1
2
3
4
5
6
7
8
9
Qt
1
1
1
1
2
1
1
1
1
Manufacturer
International Rectifier
Roederstein
Dale
Roederstein
Wima
Panasonic
Panasonic
B.I. technologies
Part Number
DF10S
WY
CW-1/2
F1772433-2200
MKP10
ERZ-V05D471
EEU-EB2W100
ELF-15N007A
HM00-01762
Description
Bridge Rectifier, 1A 1000V
Capacitor, 2.2nF 275 VAC Y Cap
Resistor, 0.5Ohm, 1/.2W
Capacitor, 0.33uF 275 VAC
Capacitor, 0.1uF 400 VDC
Transient Suppressor
Capacitor, 10uF 450VDC 105C
EMI Inductor, 1X10mH 0.7Apk
PFC Inductor, 1.0mH 2.0Apk/
secondary 10 turns
BR1
CY
F1
C1
C2, CDC
RV1
CBUS
L1
LPFC
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
3
1
3
1
1
3
1
1
1
2
3
1
1
3
3
1
1
1
1
3
2
1
1
2
1
1
1
Panasonic
Panasonic
ECJ-2VB1HC104K
ECJ-2YB1C474K
Panasonic
Panasonic
Digi-key
WIMA
Panasonic
Digi-key
Diodes
International Rectifier
B.I. technologies
International Rectifier
Panasonic
Panasonic
Panasonic
Panasonic
Yageo
Panasonic
Panasonic
Panasonic
ECE-A1HGE02R2
Capacitor, 0.1uF SMT 0805
Capacitor, 0.47uF SMT 0805
Capacitor, 0.47uF SMT 1206
Capacitor, 0.01uF SMT 0805
Capacitor, 2.2uF 50VDC 105C
Capacitor, 0.68uF SMT 1206
Capacitor, 1nF 1KV SMT 1812
Capacitor, 3.3nF 2KV
Capacitor, 470pF SMT 0805
Diode, 1A 600V, SMT SMB
Diode, 1N4148 SMT DL35
IC, Ballast Driver /PFC
Inductor, 4.0mH 1.5Apk/ 10
1
Transistor, MOSFET
Resistor, 22 ohm SMT 1206
Resistor, 110K ohm SMT 1206
Resistor,16Kohm 1%SMT1206
Resistor,43Kohm 1%SMT 1206
Resistor, 270K ohm ¼ watt
Resistor, 680K ohm SMT 1206
Resistor, 20K ohm SMT 1206
Resistor, 10K ohm SMT 1206
Resistor, 1 megohm SMT1206
Resistor, 10 ohm SMT 1206
Resistor, 1K ohm SMT 1206
Resistor, 1.2 ohm SMT 2010
Resistor, 2.2 megohm 1/4W
CBOOT, CVCC1, COC
CSD1
CVDC, CSD2, CEOL
CVBUS
CVCC2
CCOMP, CRAMP, CPH
CSNUB
CRES
CT
DBOOT, DPFC
DCP2, DCP1, DSD
IC BALLAST
LRES
MPFC, MHS, MLS
RPFC, RLO, RHO
RVDC
RPH
RRUN
RSUPPLY
RVBUS1, RVBUS2, RSD
RT, ROC
RDT
RPU
RLIM2, RLIM3
RLIM1
RCS
RVAC
37
38
39
40
1
1
1
1
4
Resistor, 22K ohm SMT 1206
5.1V Zener 0.5W SMT
7.5V Zener 0.5W SMT
Resistor, 12.5Kohm 5% SMT805
Jumper
RZX
DEOL2
DEOL1
RVBUS
JV1, JV2, J1, J2
311-1183-1-ND
FKP1
ECU-V1H471KBN
MURS160DICT-ND
LL4148DICT-ND
IR2167
HM00-01761
IRF830
ERJ-8GEYJ22
270KQBK-ND
ERJ-8GEYJ680K
Panasonic
Panasonic
Panasonic
ERJ-8GEYJ1K
Digi-Key
Digi-Key
ZMM5231BDICTND
ZMM5236BDICTND
Reference
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RPLLNR3
Item #
Qt
41
42
2
3
43
1
44
45
46
1
1
1
Total
1
Manufacturer
Part Number
Description
RG Allen
Reference
Capacitor, 0.1uF, 50V
Resistor, 220K ohm SMT 1206
WAGO
WAGO
235-203
235-204
CH1, CH2
REOL1, 2, 3
Resistor, 160K ohm SMT 1206
REOL4
Connector, 3 terminal
Connector, 4 terminal
Capacitor, 100pF SMT 1206
Not needed
X1
X2
CCS
RDC
67 without Jumpers
A smaller number of turns: 6-8, could give better performance
Inductor Specs
INDUCTOR SPECIFICATION
TYPE : LPFC
CORE SIZE
E25/13/7 (EF25)
GAP LENGTH
1
HORIZONTAL
PINS
8
BOBBIN
mm
Philips 3C85, Siemens N27 or equivalent
CORE MATERIAL
NOMINAL INDUCTANCE
1
mH
MAXIMUM CURRENT
2
Apk
MAXIMUM CORE TEMPERATURE
100
ºC
WINDING START PIN FINISH PIN TURNS WIRE DIAMETER (mm)
MAIN
1
6
125
4 strands of AWG 32
ZX
3
8
10
4 strands of AWG 32
ELECTRICAL LAYOUT
PHYSICAL LAYOUT
20.05mm
TOP VIEW
5mm
25mm
TEST
1
8
2
7 5mm
6
5
3
4
(TEST FREQUENCY = 50kHz)
MAIN WINDING INDUCTANCE MIN 0.9
mH
MAIN WINDING RESISTANCE
Ohms
MAX 1.5
MAX 1.1
mH
NOTE : Inductor must not saturate at maximum current and maximum core temperature at given
test frequency.
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IRPLLNR3
INDUCTOR SPECIFICATION
TYPE : LRES(VOLTAGE MODE)
CORE SIZE
E25/13/7 (EF25)
GAP LENGTH
1
HORIZONTAL
PINS
8
BOBBIN
mm
Philips 3C85, Siemens N27 or equivalent
CORE MATERIAL
NOMINAL INDUCTANCE
4
MAXIMUM CURRENT
2
mH
Apk
100
MAXIMUM CORE TEMPERATURE
ºC
WINDING START PIN FINISH PIN TURNS WIRE DIAMETER (mm)
MAIN
1
8
250
4 strands of AWG 32
CATHODE (1)
6
7
10
4 strands of AWG 32
CATHODE (2)
4
5
10
4 strands of AWG 32
ELECTRICAL LAYOUT
PHYSICAL LAYOUT
20.05mm
TOP VIEW
5mm
25mm
TEST
1
8
2
3
4
7 5mm
6
5
(TEST FREQUENCY = 50kHz)
MAIN WINDING INDUCTANCE MIN 3.9
mH
MAIN WINDING RESISTANCE
Ohms
MAX 2
MAX 4.1
mH
NOTE : Inductor must not saturate at maximum current and maximum core temperature at given
test frequency.
Demo board Overview
This demo-board is designed for single TL5/35W Lamp, voltage mode heating (JV1, JV2 mounted).
TL5 lamps are becoming more popular due to their lower profile and higher 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,
CSNUBB, serves as charge pump for supplying the IR2167.
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RPLLNR3
The IR2167 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, thermal overload or lamp failure during
normal operations. It is also used to regulate the DC bus and for power factor control allowing high
power factor and low harmonic distortion.
Power Factor Correction Section
The power factor correction section contained in the IR2167 forms the control for 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 (HPF).
Ballast Control Section
The ballast control section of the IR2167 Ballast Control IC contains an oscillator, a high voltage halfbridge gate driver and lamp fault protection circuitry. Please, refer to the datasheet of this IC for the
block diagram and the state diagram. Following is a breakdown of the operation of the ballast in all of
the different modes of operation. Please, refer to the AN: IRPLLNR2 for the ballast section design
(www.irf.com/Lighting).
Startup Mode
When power is initially applied to the ballast, the voltage on the VCC pin of the IR2167 begins to
charge up. The voltage for the IR2167 is derived from the current supplied from the rectified AC line
through startup resistor RSUPPLY. During this initial startup when the VCC voltage of the IR2167 is
below its rising under-voltage lock-out threshold (11.4V), it is in its UVLO and also its micro-power
mode. The micro-power mode of the IR2167 allows the use of a large value, low wattage startup
resistor (RSUPPLY). When the voltage on the IR2167 reaches the rising under-voltage lockout threshold,
the 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 halfbridge output and also supplies the current to charge capacitor CVCC2 to the VCC clamp voltage
(approx. 15.6V) of IR2167. When the rising under-voltage lockout threshold of the IR2167 is reached,
the PFC oscillator starts to oscillate and drive MOSFET MPFC to boost and regulate the bus voltage to
400 VDC. Oscillagraph of the start up of the VCC of the IR2167 DC is shown in figure 1.
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IRPLLNR3
I
Figure 1:
Top trace: Half-bridge output voltage
Middle trace: Bus Voltage
Bottom trace: VCC of the IR2167
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 IR2167 has begun to operate and the half-bridge output is driving the
resonant load (lamp) circuit. The ballast control section oscillator of the IR2167 is similar to oscillators
found in many popular PWM voltage regulator ICs and consists of a timing capacitor and resistor
connected to ground. Resistors RT and RPH program a current which determines the ramp up time
of capacitor CT and resistor RDT determines the ramp down time. The downward ramping time of CT
is the dead time between the switching off of the LO (HO) and the switching on of the HO (LO) pins on
the IR2167. The Preheat mode frequency of oscillation 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 the correct emission temperature within the Preheat mode period. The preheating of the lamp filaments is performed with a constant voltage during the Preheat mode. The waveform in Figure 2 shows the lamp filament current while Figure 3 shows lamp filament voltage during
the normal Startup, Preheat and Ignition Ramp modes of the ballast.
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RPLLNR3
Figure 2:
Lamp filament current during
Preheat and Ignition Ramp
(500mA / div)
(Crossed lamps)
Figure 3:
Lamp filament voltage
during preheat and
Ignition Ramp
(Crossed lamps)
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IRPLLNR3
Figure 4 shows a plot of the half-bridge oscillation frequency as a function of time for all of the normal
modes of operation: Preheat mode, Ignition Ramp mode and Run mode. As shown in Figure 4 there
is an initial startup frequency that is much higher than the steady state Preheat mode 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 flash of the lamp
occurs which should be avoided. This in effect is a cold strike of the lamp, which could shorten the
life of the lamp. Figure 5 shows the lamp voltage without the high initial startup frequency while Figure
6 shows the lamp voltage with the high initial frequency startup.
fosc
fPreheat
fRun
fIgnition
t
preheat
ignition
run
Figure 4: Oscillator frequency versus time, Normal operating conditions
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RPLLNR3
Figure 5: Typical lamp voltage at startup:
fStartup = fPreheat
Figure 6: Improved lamp voltage at startup:
fStartup > fPreheat
The duration of the Preheat mode as well as the mode of operation of the ballast are determined by
the voltage on the CPH pin of the IR2167. At the completion of the UVLO mode, Preheat mode is
entered and an internal current source is activated at the CPH pin of the IR2167, which begins to
charge up capacitor CPH. The ballast remains in the Preheat mode until the voltage on the CPH pin
exceeds the Ignition Ramp mode threshold (4V).
Ignition Ramp Mode
At the completion of the Preheat mode (4V < CPH pin < 5.1V) the ballast switches to the Ignition
Ramp mode and the frequency ramps down to the ignition frequency. The frequency ramping is
accomplished by turning off the internal open drain MOSFET on the RPH pin of the IR2167 (see
IR2167 block diagram). Resistor RPH is no longer connected directly in parallel with resistor RT. The
shift in frequency does not occur in a step function but rather with an exponential decay because of
capacitor CRAMP in series with resistor RPH to COM. The duration of this frequency ramp is
determined by the time constant of the RC combination of capacitor CRAMP and resistor RPH. The
minimum frequency of oscillation occurs at the end of this ramp and is determined by resistor RT and
capacitor CT. 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. Figure 7 shows the ramping of voltage appearing across the lamp. Note that the sudden drop in lamp voltage indicates that the lamp has ignited.
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IRPLLNR3
Also note that the voltage on capacitor CRAMP is still increasing at the point when the lamp has
already ignited meaning the frequency is still ramping down to the final minimum ignition frequency.
This minimum frequency corresponds to the absolute maximum ignition voltage required by the lamp
under all conditions. Figure 8 shows the ignition ramp and the maximum ignition voltage with crossed
lamp (in this case the oscillator ramps down to the final minimum ignition frequency).
Figure 7:
Upper trace: voltage on capacitor
CRAMP during Ignition Ramp mode
Lower trace: Lamp voltage during
Ignition Ramp mode
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RPLLNR3
Figure 8: Ignition ramp (crossed lamps)
During the Ignition Ramp mode the voltage on the CPH pin of the IR2167 continues to ramp up until
the voltage at the CPH pin of the IR2167 exceeds the Run mode threshold (5.1V). Over-current
sensing is also enabled at the beginning of the Ignition Ramp mode. A full explanation of the functionality of the over-current sensing is in the section on Fault Mode.
Run Mode
At the end of the Ignition Ramp mode (CPH pin > 5.1V) the ballast switches to the Run mode at which
point the frequency is shifted to the run frequency. The run frequency is determined by the parallel
combination of resistors RT and RRUN and capacitor CT. Resistor RRUN is connected in parallel by
turning on the internal open drain MOSFET connected to the RUN pin of the IR2167 (see IR2167
block diagram). The sensing of under-current conditions and the 1-3V window comparator in the SD
pin are also enabled at the beginning of the Run mode. The full explanation of the functionality of the
under-current sensing and end-of-life sensing is in the section on Fault Mode. Figure 9 shows the
functionality of the CPH, RPH and RUN pins of the IR2167 during Startup, Preheat, Ignition Ramp
and Run modes.
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IRPLLNR3
Figure 9:
Top trace: CPH pin
Middle trace: RPH pin
Bottom trace: RUN pin
The Run mode frequency 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
frun =
1
2π
2
2
1
1
PLamp
PLamp
2
− 2
+
−
−4
CV 2 Lamp
CV 2 Lamp
LC
LC
L
C
PLamp
VLamp
14
2VDCbus
1−
VLampπ
2
L2 C 2
= Lamp resonant circuit inductor (L3)
= Lamp resonant circuit capacitor (C14)
(H)
(F)
= Lamp running power
(W)
= Lamp running voltage amplitude
(V)
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RPLLNR3
Figure 10 shows the voltage appearing across the lamp during Startup, Preheat, Ignition Ramp and
Run modes.
Fig. 10: Preheat, Ignition Ramp and Run Voltage in the lamp
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 VDC pin of the IR2167 drops below the line fault threshold (3V)
and the IR2167 shuts down in a controlled fashion. The ballast control oscillator is stopped, the halfbridge driver outputs (LO and HO) are turned off and capacitors CPH, CRAMP, CSTART and CT are
discharged. IR2167 also goes into its UVLO/micro-power mode and the bus voltage begins to collapse.
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IRPLLNR3
Resistors RVAC, RVDC and capacitor CVDC form a voltage divider/filter network, which is connected to the VDC pin of the IR2167 and is used to determine if the line voltage falls below permissible levels. This happens when the line voltage is cycled or possibly a brownout condition occurs.
The VDC pin of the IR2167 senses a fault if the voltage at the pin falls below 3 volts and shutdown of
the ballast occurs. The ballast remains shutdown until the voltage at the VDC pin rises above 5.1 volts.
At this time if there are no other fault conditions the ballast will go through a full Preheat, Ignition
Ramp and Run mode. As in the case of the SD pin of the IR2167, the VDC pin of the IR2167 is active
during all modes of operation of the ballast.
Lamp removal and autorestart
Resistors RPU, RSD and capacitor CSD1 form a divider/filter network which is used to detect an
open lower lamp filament and/or lamp replacement. Under normal conditions, the voltage across
CSD2 is close to zero. However, if the lower filament becomes open or the lamp is removed, the
voltage across CSD2 increases above the 5.1V threshold for the SD pin of the IR2167 and signals a
lamp removal condition, which in turn puts the ballast into UVLO mode. The ballast remains in the
UVLO mode until the 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 IR2167 drops back below the threshold and the ballast
will go through a restart. Line voltage cycling is also used to restart the ballast for all lamp fault
conditions. The ballast will go through a full Preheat, Ignition Ramp and Run modes any time a restart
is performed. Note that the SD pin of the IR2167 is active during all modes of operation.
Fault Mode
Fault mode is when the ballast driver is shutdown due to the detection of a lamp fault. Note that when
the ballast is in this Fault mode the power factor correction section of the ballast is also shutdown and
the bus voltage will drop to the non-boosted/unregulated level. There are several lamp fault conditions
that can put the ballast into the Fault mode. The lamp fault conditions detected include: near/below
resonance (under-current) detection, hard-switching detection, over-current detection (CS pin) and
end of life or no load detection (SD pin). Resistor RCS in the source lead of the low side MOSFET
(MHS) serves as the current sensing point for the half-bridge, which is used to detect these lamp fault
conditions. In operation when the half-bridge is oscillating, a voltage appears across RCS whenever
the low side MOSFET, MHS, is turned on or the high side MOSFET, MLS, is turned off. The magnitude of this voltage directly relates to the current in the lamp resonant circuit. Figure 11 shows the
voltage which appears across resistor RCS during normal Run mode conditions. Also shown in
Figure 11 are the gate drive signals for the low side MOSFET (LO pin) and the high side MOSFET
(HO-VS pin).
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RPLLNR3
Figure 11: Normal Run
mode; Upper trace: voltage
across RCS, Middle trace:
LO pin voltage, Lower trace:
HO-VS pin voltage
During the Preheat mode the voltage across resistor RCS is not measured. However, at the end of
Preheat mode (the beginning of the Ignition Ramp mode) the hard-switching and over-current detection are enabled. If at any time thereafter the voltage magnitude across resistor RCS rises above the
over-current (CS+) threshold of the CS pin of the IR2167, a lamp fault condition is signaled and the
half-bridge output MOSFETs’, (MHS and MLS) are turned off and the ballast goes into Fault mode.
This can happen if the lamp fails to ignite or if the upper cathode is open circuit (or upper filament
open in current mode configuration). For failure to ignite the lamp, the current in the half-bridge
increases and thus the voltage across resistor RCS increases above the over-current threshold
signaling a fault. Figure 12 shows the voltage across resistor RCS and the voltage appearing across
the lamp when the ballast detects a failure to ignite the lamp and goes into Fault mode. The CS+
threshold is determined by resistor ROC. An internal current source of 50uA is connected to the OC
pin of the IR2167 which when applied to resistor ROC sets a voltage at the OC pin. This voltage is the
CS+ threshold of the IR2167. Figure 13 shows the voltage appearing across the lamp during the tail
end of the Preheat mode and the Ignition Ramp mode for a failure of the lamp to ignite condition. If
the upper cathode is open circuit (or upper filament open in current mode configuration), the halfbridge output hard-switches and each time the low side MOSFET (MHS) is turned on a large current
pulse occurs and thus a large voltage pulse occurs across resistor RCS signaling a fault, Figure 14
shows this hard-switching condition. Figure 15 shows the lamp voltage during the Preheat mode and
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IRPLLNR3
beginning of Ignition Ramp mode for this hard-switching condition when the lamp fault condition is
detected. The ballast will remain in Fault mode until either the line voltage is cycled or a lamp replacement is performed.
Figure 12: Failure of lamp to ignite condition
(lamp filaments good): Upper trace: voltage
across RCS, Lower trace: lamp voltage
Figure 14: Hard-switching condition (upper
filament open): Upper trace: voltage across
RCS, Middle trace: LO pin voltage, Lower trace:
IC2 HO-VS pin voltage
18
Figure 13: Failure of lamp to ignite
condition (lamp filaments good): Lamp
voltage during end of Preheat and Ignition
Ramp modes
Figure 15: Hard-switching condition
(upper filament open): Lamp voltage during
Preheat mode and beginning of Ignition
Ramp mode when lamp fault is detected
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RPLLNR3
At the completion of the Ignition Ramp mode (beginning of the Run mode) the near/below resonance
(under-current) detection is also enabled. Near/below resonance detection is performed by synchronously sensing the voltage across resistor RCS, which relates to the current flowing in the low side
MOSFET (MLS), just prior to the turn off of MHS. If this voltage is lower than the near/below resonance threshold (CS- = 0.2V) of the CS pin of the IR2167, a lamp fault condition is signaled and the
ballast goes into Fault mode. This could occur if the frequency of oscillation becomes too close to the
resonant frequency of the load circuit and the current in the load circuit commutates to close to zero.
Figure 16 shows a near/below resonance condition where the voltage on resistor RCS falls below the
0.2V threshold on the CS pin of the IR2167.
Figure 16:
Near/Below Resonance conditions
Upper trace: voltage across RCS
Lower trace: half-bridge output voltage
The components REOL1 REOL2, REOL3, REOL4, CEOL, DEOL1 and DEOL2 are used for end of
life protection. The end-of-life window comparator is enabled at the beginning of the Run mode. If
the voltage on the lamp change +-20%, one of the zener diodes DEOL1 or DEOL2 will conduct and
the voltage on pin SD of the IR2167 will fall outside the range of the internal window comparator 13V causing the IR2167 to go into Fault mode.
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19
IRPLLNR3
Improved End of Life solution
The same PCB can be used with a different end of life configuration. It is needed to put a capacitor
in the place of DEOL1 diode (100nF), to short DEOL2 (0 Ohm resistor) and to reduce the capacitor
in the SD pin CSD1 (100pF). The resultant circuit is shown in fig. 17.
2V
in A
REOL
0V
CRES
CEOL
A
SD
CSD1
in the SD pin
REOL4
2V
Inside the
IR2167
Fig. 17: Improved End-of-life circuit
The value of REOL4 is changed so that the lamp voltage during normal running produces a signal with
1.5 Vppk at the point (A) were the capacitor CEOL connects it to the SD pin. For a T5/35W lamp
1.2Kohm at REOL4 provides the correct voltage.
The SD pin is internally biased at 2V with 1Mohm impedance and therefore at the SD pin a signal
varying between 1.25V and 2.75V will normally be present due to the AC coupling of the 100nF
capacitor (CEOL).
During end of life the lamp voltage may increase either symmetrically (AC end of life, due to a similar
deterioration in both cathode) or asymmetrically (DC end of life, due to a deterioration only in one
cathode). This circuit is simpler and cheaper than the previous version and it has the advantage of
detecting both failure modes.
The peak to peak voltage at the SD pin will increase (with 2V DC offset) in either case until the
positive peak exceeds 3V and/or the negative peak drops below 1V, therefore triggering the window
comparator shutdown. The threshold of end of life can be adjusted by changing the value of REOL4
(usually 30% Vlamp is required).
20
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RPLLNR3
Figure 18 shows the voltage in the SD pin and the voltage on the lamp in these 4 cases: no end of life,
DC end of life (upper cathode deteriorated and lower cathode deteriorated) and AC end of life (both
filaments deteriorated in the same way).
SD pin Voltage
3V
3V
3V
3V
2V
2V
2V
2V
1V
1V
1V
1V
Lamp Voltage
Vspec
0V
Vspec + 30%
0V
-Vspec - 30%
Vspec + 30%
0V
0V
-Vspec - 30%
Vspec = VpK in the spec of the
lamp
Figure 18: Voltage in the SD pin and voltage on the lamp in these 4 cases:
no end of life, DC end of life and AC end of life.
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21
IRPLLNR3
L
N
GND
F1
L1
CY
RV1
C1
LPFC
RVBUS1
RVBUS2
RVBUS
RVDC
CVDC
RT
CPH
RDT
RRUN
RPH
CRAMP
CT
COC
ROC
CCOMP
RZX
RVAC
VDC
CPH
RPH
RT
RUN
CT
DT
OC
1
2
3
4
5
6
7
20
19
18
17
16
15
14
IR2167
12
13
11
8
9
HO
CBOOT
VS
VB
DBOOT
VCC
CVCC2
RLIM3
RLO
RLIM2
RHO
RSUPPLY
CVCC1
COM
RLIM1
CSD1
CSD2
DSD
LO
CCS
CS
SD
PFC
VBUS
10
COMP
ZX
IC BALLAST
CVBUS
MHS
MLS
RSD
RCS
CSNUB
DCP2
RPU
CEOL
DCP1
JC1 and JC2 not mounted, JV1 and JV2 mounted
DPFC
CBUS
RPFC
REOL4
REOL3
REOL2
REOL1
LRES:A
CRES
CDC
CH2
LRES:C
CH1
LRES:B
2167 Single Lamp, Voltage mode heating improved End of Life Cicuit
BR1
C2
MPFC
Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid highfrequency noise problems
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22
RPLLNR3
Voltage mode Configuration Protection
Open cathode (one cathode disconnected completely) conditions are detected using the CS pin.
Open filament condition is detected in the lower cathode using the pin SD. In the case of open
filament in the upper cathode, the lamp preheats and ignites without causing over-current in the CS
pin, this is usually not a problem. However, we propose a circuit that has shutdown for open filament
as well using the SD pin (schematics of the whole circuit in the following page).
When the upper filament is connected, the transistor base is supplied with current via the 220K
resistor from the DC bus. This keeps it switched on at all times while the upper filament provides a DC
path. When the transistor is on the diode anode is held close to 0V so the SD pin is not affected by
this circuit and stays at 2V.
When the upper filament is open circuit, the transistor looses its base current and switches off so the
diode conducts and pulls the SD pin above the 5V threshold causing the system to shutdown. When
the lamp fails in this way and is replaced, the transistor will switch on and so the ballast will restart
without resetting the AC line.
Current mode configuration
The same PCB can be configured for current mode heating. It is needed to remove the Jumpers JV1
and JV2 and to introduce the Jumpers JC1 and JC2. It could be also usefull to add a resistor RDC in
parallel to CDC because in this configuration After initial start-up you could have some striations
(visible dark rings) on the lamps for a short period (a few minutes) particularly when the lamp has
been off for some time and is cold. The value should in the order of 100kOhm 0.5W.
We suggest the use of the Ballast Designer software to determine the values of the components to
use in this configuration.
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23
IRPLLNR3
L
N
GND
F1
L1
CY
RV1
C1
LPFC
DPFC
CBUS
RPFC
RVBUS1
RVBUS2
RVBUS
RVDC
CVDC
RT
CPH
RDT
RRUN
RPH
CRAMP
CT
COC
ROC
CCOMP
RZX
RVAC
VDC
CPH
RPH
RT
RUN
CT
DT
OC
1
2
3
4
5
6
7
20
19
18
17
16
15
14
IR2167
12
13
11
8
9
HO
CBOOT
VS
VB
DBOOT
VCC
RSUPPLY
RLIM3
CVCC2
CSD1
CSD2
DSD
RLIM1
RLO
RLIM2
RHO
CCS
CVCC1
COM
LO
CS
SD
PFC
VBUS
10
COMP
ZX
IC BALLAST
CVBUS
MHS
MLS
RSD
RCS
DCP2
RPU
CEOL
REOL4
CSNUB
REOL1
REOL2
REOL3
DCP1
100K
PN2222A
1N4148
100nF
LRES:A
100K
100nF
220K
220K
CDC
CRES
CH2
LRES:C
CH1
LRES:B
2167 Single Lamp, Voltage mode heating plus open upper filaments
protectionJC1 and JC2 not mounted, JV1 and JV2 mounted
BR1
C2
MPFC
Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid high-frequency
noise problems
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24
RPLLNR3
L
N
GND
F1
L1
CY
RV1
C1
BR1
C2
2167 Single Lamp, Current mode heating
DPFC
CBUS
RPFC
RVBUS
RVBUS2
RVBUS1
RVDC
CVDC
RT
CPH
RDT
RRUN
RPH
CRAMP
CT
COC
ROC
CCOMP
RZX
RVAC
VDC
CPH
RPH
RT
RUN
CT
DT
OC
19
20
IR2167
1
15
16
17
18
2
3
4
5
6
13
14
8
12
7
9
11
VS
HO
VB
CVCC2
CSD1
CSD2
DSD
RLIM1
RLO
RLIM2
RHO
RSUPPLY
CBOOT
DBOOT
VCC
CCS
CVCC1
COM
LO
CS
SD
PFC
VBUS
10
COMP
ZX
IC BALLAST
CVBUS
RLIM3
JV1 and JV2 not mounted, JC1 and JC2 mounted
LPFC
MPFC
MHS
MLS
RSD
RCS
DCP2
CSNUB
RPU
CEOL
LRES:A
DCP1
RDC
CDC
REOL1
REOL2
REOL3
REOL4
CRES
Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid high-frequency
noise problems
25
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IRPLLNR3
Design Procedure to adapt the design to different lamp types
To adapt the design to different types of lamps you need to adjust the values of: LPFC, MPFC, MLO,
MHO, CPH, RT, RPH, RRUN, RCS, ROC, CT, RDT, CRAMP, REOL4, CRES and LRES. Do not
change any others values!
1) Use the Ballast Designer Software to set the values of LRES, CRES, MPFC, MLO and
MHO, RDT, CT, CRAMP, CS and to set the starting values of LPFC, CPH, RT, RPH, RRUN
and ROC.
Cross both lamps (i.e. connect a filament or resistor to each lamp cathode position but not a good
lamp) and measure the lamp voltage at ignition using a storage oscilloscope.
1) Set ROC to get the right ignition voltage (decrease ROC to decrease the ignition voltage or
decrease RCS to increase the ignition voltage)
2) Set RT to set the minimum frequency of the oscillator (increase RT to decrease the
minimum frequency). Increase RT up to when the over-current protection is working in the
worst case (i.e. the ballast shuts down at ignition):
3) Select CPH to set the preheat time (increase CPH to increase the preheat time)
4) Set RPH to set the right preheat current (increase RPH to increase the preheat current)
In case of voltage mode heating, increase CH1 and CH2 to increase the preheat voltage (use
6-7 turns in the secondary of LRES).
Connect both lamps correctly and measure the input power
5) Select RRUN to set the correct power, RRUN is required only if the run frequency is above
the ignition frequency (increase RRUN to increase the power on the lamp)
6) Verify the value of LPFC at each limit of the line/load range:
Minimum load and maximum input voltage:
If the COMP pin becomes less than 400mV the PF will not operate in a stable manner and it is
necessary to increase LPFC.
Maximum load and minimum input voltage:
If the PF does not operate in a stable manner and audible noise can be heard from LPFC, it is
necessary to decrease LPFC.
26
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RPLLNR3
7) Set ROL4 to set the End of life protection to a percentage of the lamp voltage. For example,
to set the protection threshold to 20% of the lamp voltage:
With the first method: {(Vpklamp) x 20/100} x REOL4 / (REOL4 + REOL1 + REOL2 + REOL3)
should give approximately 7V.
With the second method: The value of REOL4 is chosen to have the SD pin varying between 2-0.7V
and 2+0.7 during normal operations and exceeding the window comparator limits (less than 1V
or more than 3V) with 30% change in the voltage of the lamp.
(Fine tuning of this threshold can be done by trying different REOL4 values on the test bench)
IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105
Data and specifications subject to change without notice. 3/29/2002
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27