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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
! ! ! ! ! ! ! ! !
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 Line Input Bridge PFC Output Stage
L C PFC Control Half - Bridge Driver
Lamp
UVLO
Preheat Feedback Lamp Fault
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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2167 Single Lamp, Voltage mode heating
JC1 and JC2 no mounted, JV1 and JV2 mounted
LPFC
DPFC
RVAC
RSUPPLY
L
L1 C1
F1
RV1
RVDC CVDC RHO VDC HO
IR2167 Demo Board
N
BR1 CBUS CPH CPH
1 2
CRAMP CY RVBUS1 RUN C2 CT RRUN CT RPH RT RPH
20
VS
MHS 1 LRES:A
CDC
19 3 18
RT
5 CBOOT VB DBOOT VCC CSNUB
LRES:B
GND
6
7
RLIM2
RLIM3
CH1
4 5 6
RVBUS2 COC RDT DT
17
CVCC1 COM CVCC2
X21
X22
16
LO RLO
DCP2
REOL1
15
CS RLIM1
MLS REOL2
CRES
7
ROC OC
14
SD DSD RSD
RPU DCP1
8
CCOMP COMP
13
PFC CCS
REOL3
9
RZX ZX
12
CSD2 VBUS
10
IC BALLAST
11
X23
X24
4 DEOL1 RVBUS CVBUS CSD1 RCS DEOL2
LRES:C CEOL REOL4
CH2
8
RPFC 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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Bill Of Materials
Lamp type: TL5/35W, Line Input Voltage: 80-260 VAC Note: Different lamp types require different frequency programming components.
Item # 1 2 3 4 5 6 7 8 9 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 37 38 39 40 Qt 1 1 1 1 2 1 1 1 1 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 1 1 1 1 4 Manufacturer International Rectifier Roederstein Dale Roederstein Wima Panasonic Panasonic B.I. technologies Panasonic Panasonic Part Number DF10S WY CW-1/2 F1772433-2200 MKP10 ERZ-V05D471 EEU-EB2W100 ELF-15N007A HM00-01762 ECJ-2VB1HC104K ECJ-2YB1C474K 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 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 1/4 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 Resistor, 22K ohm SMT 1206 5.1V Zener 0.5W SMT 7.5V Zener 0.5W SMT Resistor, 12.5Kohm 5% SMT805 Jumper Reference BR1 CY F1 C1 C2, CDC RV1 CBUS L1 LPFC 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 RZX DEOL2 DEOL1 RVBUS JV1, JV2, J1, J2
Panasonic Panasonic Digi-key WIMA Panasonic Digi-key Diodes International Rectifier B.I. technologies International Rectifier Panasonic Panasonic Panasonic Panasonic Yageo Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic
ECE-A1HGE02R2 311-1183-1-ND FKP1 ECU-V1H471KBN MURS160DICT-ND LL4148DICT-ND IR2167 HM00-01761 IRF830 ERJ-8GEYJ22
270KQBK-ND ERJ-8GEYJ680K
ERJ-8GEYJ1K
Digi-Key Digi-Key
ZMM5231BDICTND ZMM5236BDICTND
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Item #
Qt
Manufacturer
Part Number
Description
Reference
41 42 43 44 45 46 Total
2 3 1 1 1 1
RG Allen
Capacitor, 0.1uF, 50V Resistor, 220K ohm SMT 1206 Resistor, 160K ohm SMT 1206 235-203 235-204 Connector, 3 terminal Connector, 4 terminal Capacitor, 100pF SMT 1206 Not needed
CH1, CH2 REOL1, 2, 3 REOL4 X1 X2 CCS RDC
WAGO WAGO
67 without Jumpers
1
A smaller number of turns: 6-8, could give better performance
Inductor Specs
INDUCTOR SPECIFICATION TYPE : LPFC CORE SIZE BOBBIN CORE MATERIAL
E25/13/7 (EF25) HORIZONTAL
GAP LENGTH PINS
1 8
mm
Philips 3C85, Siemens N27 or equivalent
1 2
NOMINAL INDUCTANCE MAXIMUM CURRENT MAXIMUM CORE TEMPERATURE
mH Apk C
100
WINDING START PIN FINISH PIN TURNS WIRE DIAMETER (mm) MAIN ZX
1 3 6 8 125 10 4 strands of AWG 32 4 strands of AWG 32
ELECTRICAL LAYOUT
PHYSICAL LAYOUT
20.05mm TOP VIEW 5mm 1 2 25mm 3 4 8 7 5mm 6 5
TEST
(TEST FREQUENCY = 50kHz)
MAIN WINDING INDUCTANCE MIN 0.9 MAIN WINDING RESISTANCE MAX 1.5
mH
MAX 1.1
mH
Ohms
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 BOBBIN CORE MATERIAL
E25/13/7 (EF25) HORIZONTAL
GAP LENGTH PINS
1 8
mm
Philips 3C85, Siemens N27 or equivalent
4 2
NOMINAL INDUCTANCE MAXIMUM CURRENT MAXIMUM CORE TEMPERATURE
mH Apk C
100
WINDING START PIN FINISH PIN TURNS WIRE DIAMETER (mm) MAIN
CATHODE (1) CATHODE (2)
1 6 4
8 7 5 PHYSICAL LAYOUT
250 10 10
4 strands of AWG 32 4 strands of AWG 32 4 strands of AWG 32
ELECTRICAL LAYOUT
20.05mm
TOP VIEW 5mm 1 8 7 5mm 6 5
25mm
2 3 4
TEST
(TEST FREQUENCY = 50kHz)
MAIN WINDING INDUCTANCE MIN 3.9 MAIN WINDING RESISTANCE MAX 2
mH
MAX 4.1
mH
Ohms
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. 6 www.irf.com
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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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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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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. www.irf.com 11
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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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. www.irf.com 13
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,
frun =
1 2
2 2 1 1 PLamp PLamp - 2 - 2 + -4 CV 2 Lamp CV 2 Lamp LC LC
2
2VDCbus 1- VLamp L2 C 2
2
L C PLamp VLamp
= Lamp resonant circuit inductor (L3) = Lamp resonant circuit capacitor (C14) = Lamp running power = Lamp running voltage amplitude
(H) (F) (W) (V)
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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). 16 www.irf.com
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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 www.irf.com 17
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 13: Failure of lamp to ignite condition (lamp filaments good): Lamp voltage during end of Preheat and Ignition Ramp modes
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
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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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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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
CRES
0V
CEOL SD
A
REOL4
in the SD pin 2V
CSD1
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 www.irf.com
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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 2V 1V 3V 2V 1V 3V 2V 1V 3V 2V 1V
Lamp Voltage
Vspec Vspec + 30% Vspec + 30% 0V
0V
0V
0V
-Vspec - 30% Vspec = VpK in the spec of the lamp
-Vspec - 30%
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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IRPLLNR3
2167 Single Lamp, Voltage mode heating improved End of Life Cicuit
JC1 and JC2 not mounted, JV1 and JV2 mounted
LPFC DPFC
RVAC
RSUPPLY
L
L1 C1
F1
RV1
RVDC CVDC RHO VDC HO
N
BR1 CBUS CPH CPH
1 2
CRAMP CY RVBUS1 RUN C2 CT RRUN CT RPH RT RPH
20
VS
MHS LRES:A
CDC
19 3 18
RT
CBOOT VB DBOOT VCC CSNUB
LRES:B
GND
RLIM2
RLIM3
CH1
4 5 6
RVBUS2 COC RDT DT
17
CVCC1 COM CVCC2
16
LO RLO
DCP2
REOL1
15
CS RLIM1
MLS REOL2
CRES
7
ROC OC
14
SD DSD RSD
RPU DCP1
8
CCOMP COMP
13
PFC CCS
REOL3
9
RZX ZX
12
CSD2 VBUS
10
IC BALLAST
11
LRES:C CEOL RVBUS CVBUS CSD1 RCS REOL4
CH2
RPFC MPFC
Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid highfrequency noise problems
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IR2167
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
2167 Single Lamp, Voltage mode heating plus open upper filaments protectionJC1 and JC2 not mounted, JV1 and JV2 mounted
LPFC DPFC
RVAC
RSUPPLY
220K
L
L1 C1
F1
RV1
RVDC
CVDC
VDC
HO
RHO
N
BR1 CBUS CPH CPH
1 2
CRAMP RPH
20
VS
MHS LRES:A CDC
19 3 18
RT RVBUS1 RUN RPH RT
CBOOT VB CSNUB DBOOT VCC RLIM2 RLIM3 DCP2
LRES:B
GND
CY
CH1
4 5
RRUN CT CT
17
CVCC1 COM CVCC2
C2
16
LO RLO
REOL1
6
RVBUS2 COC RDT DT
15
CS RLIM1
MLS REOL2 CRES
7
ROC OC
14
SD DSD RSD
RPU DCP1
8
CCOMP COMP
13
REOL3 PFC CCS
9
RZX ZX
12
CSD2 VBUS
10
IC BALLAST
11
100K CEOL RVBUS CVBUS CSD1 RCS REOL4 PN2222A 1N4148 RPFC MPFC 100nF 100K 100nF 220K
LRES:C
CH2
Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid high-frequency noise problems
24
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IR2167
RPLLNR3
2167 Single Lamp, Current mode heating
JV1 and JV2 not mounted, JC1 and JC2 mounted
LPFC DPFC
RVAC
RSUPPLY
L
L1 C1 CVDC
F1 RVDC
RV1
VDC
HO
RHO
RDC
N
BR1 CBUS CPH CPH
1 2
CRAMP RPH
20
VS
MHS LRES:A CDC
19
CBOOT VB CSNUB
GND
CY RT
3
18
RPH RT DBOOT VCC RLIM2 RLIM3 DCP2
4
RVBUS1 C2 CT RVBUS2 COC RDT DT RRUN CT RUN
17
CVCC1 COM CVCC2
5 6 7
ROC OC
16
REOL1 LO RLO
15
CS RLIM1
MLS REOL2
CRES
14
RPU SD DSD RSD
8
CCOMP COMP
13
PFC CCS
DCP1 REOL3
9
RZX ZX
12
VBUS
CSD2
10
IC BALLAST
11
CEOL
CSD1 RVBUS CVBUS RCS
REOL4
RPFC 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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25
IR2167
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.
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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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