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Preliminary Data Sheet No. PD60184-B
IR2167(S)
Features
* PFC, Ballast Control and Half Bridge Driver in * * * * * * *
One IC Critical Conduction Mode Boost Type PFC No PFC Current Sense Resistor Required Programmable Preheat Time & Frequency Programmable Ignition Ramp Programmable Over-Current Internal Fault Counter End-of-Life Protection
PFC BALLAST CONTROL IC
* * * * * * * * * *
Lamp Filament Sensing & Protection Capacitive Mode Protection Brown-Out Protection Dynamic Restart Automatic Restart for Lamp Exchange Thermal Overload Protection Programmable Deadtime Internal 15.6V Zener Clamp Diode on VCC Micropower Startup (150A) Latch Immunity and ESD Protection
Description
The IR2167 is a fully integrated, fully protected 600V ballast control IC designed to drive all types of fluorescent lamps. PFC circuitry provides for high PF, low THD and DC Bus regulation. Externally programmable features such as preheat time & frequency, ignition ramp characteristics, and running mode operating frequency provide a high degree of flexibility for the ballast design engineer. Comprehensive protection features such as protection from failure of a lamp to strike, filament failures, low AC line conditions, thermal overload, or lamp failure during normal operation, as well as an automatic restart function, have been included in the design. The heart of the ballast control section is a variable frequency oscillator with externally programmmable deadtime. Precise control of a 50% duty cycle is accomplished using a T-flip-flop. The IR2167 is available in both 20-pin DIP and 20-pin wide body SOIC packages.
Packages
20-Lead SOIC (wide body)
20-Lead PDIP
Typical Application Diagram
L1 D1
+ Rectified AC Line
R5 R4 C1 VDC HO R7 M2 VS C5 L2 RSUPPLY
1
CBUS CPH CPH
20 19
VB CBS
2
RPH
CRAMP RPH RRUN
3
18
VCC DBS
IR2167
RT R2
RT
4
RUN
17
COM CVCC CSNUBBER
5
CT CT
16
LO R8 M3 D3 CS R9 R11 SD D2 R10 D4 C7 R12
6
COC RDT DT
15 14 13
PFC
7
ROC CCOMP OC
8
COMP
9
R6 ZX
12
C3 VBUS
10
11
D5 C4 RCS D6 C6 R13
R3
C2
R1 M1
- Rectified AC Line
Please note that this datasheet contains advance information that could change before the product is released to production.
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IR2167(S)
Absolute Maximum Ratings
Absolute maximum ratings indicate sustained limits beyond which damage to the device may occur. All voltage parameters are absolute voltages referenced to COM, all currents are defined positive into any lead. The thermal resistance and power dissipation ratings are measured under board mounted and still air conditions.
Symbol
VB VS VHO VLO VPFC IOMAX IRT VCT VDC ICPH IRPH IRUN IDT VCS ICS IOC ISD VBUS IZX ICOMP ICC dV/dt PD RthJA TJ TS TL
Definition
High side floating supply voltage High side floating supply offset voltage High side floating output voltage Low side output voltage PFC gate driver output voltage Max. allowable output current (HO,LO,PFC) due to external power transistor miller effect RT pin current CT pin voltage VDC pin voltage CPH pin current RPH pin current RUN pin current Deadtime pin current Current sense pin voltage Current sense pin current Over-current threshold pin current Shutdown pin current DC bus sensing input voltage PFC inductor current, zero crossing detection input PFC error amplifier compensation current Supply current (note 1) Allowable offset supply voltage slew ratet Package power dissipation @ TA +25C Thermal resistance, junction to ambient Junction temperature Storage temperature Lead temperature (soldering, 10 seconds) (20 lead PDIP) (20 lead SOIC) (20 lead PDIP) (20 lead SOIC)
Min.
-0.3 VB - 25 VS - 0.3 -0.3 -0.3 -500 -5 -0.3 -0.3 -5 -5 -5 -5 -0.3 -5 -5 -5 -0.3 -5 -5 -20 -50 -- -- -- -- -55 -55 --
Max.
625 VB + 0.3 VB + 0.3 VCC + 0.3 VCC + 0.3 500 5 6.5 VCC + 0.3 5 5 5 5 6.5 5 5 5 VCC 5 5 20 50 1.50 1.25 85 90 150 150 300
Units
V
mA
V
mA
V
mA
V
mA
V/ns W C/W
C
2
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IR2167(S)
Recommended Operating Conditions
For proper operation the device should be used within the recommended conditions. All voltage parameters are absolute voltages referenced to COM, all currents are defined positive into any lead
Symbol
VBS VS VCC ICC VDC ISD ICS CT RDT IRT IRPH IRUN IZX TJ
Definition
High side floating supply voltage Steady state high side floating supply offset voltage Supply voltage Supply current VDC lead voltage Shutdown lead current Current sense lead current CT lead capacitance Deadtime resistance RT lead current (Note 3) RPH lead current (Note 3) RUN lead current (Note 3) Zero crossing detection lead current Junction temperature
Min.
VCC - 0.7 -3.0 VCCUV+ Note 2 0 -1 -1 220 1.0 -500 0 0 -1 -40
Max.
VCLAMP 600 VCLAMP 10 VCC 1 1 --
Units
V
mA V mA pF k uA mA
o
--
-50 450 450 1 125
C
Electrical Characteristics
VCC = VBS = V BIAS = 14V +/- 0.25V, RT = 16.9k, CT = 470 pF, RPH and RUN leads no connection, VCPH = 0.0V, RDT = 6.1k, R OC = 20.0k, VCS = 0.5V, VSD = 2.0V, CL = 1000pF, TA = 25 oC unless otherwise specified.
Supply Characteristics
Symbol Definition
VCCUV+ VUVHYS IQCCUV IQCCFLT IQCC ICC50K VCLAMP Note 2: Note 3: VCC supply undervoltage positive going threshold VCC supply undervoltage lockout hysteresis UVLO mode quiescent current Fault-mode quiescent current Quiescent VCC supply current VCC supply current, f = 48kHz VCC zener clamp voltage
Min.
-- -- -- -- -- -- --
Typ.
11.4 1.8 150 200 3.8 4.5 15.6
Max.
-- -- -- -- --
Units
Test Conditions
VCC rising from 0V
A
mA -- -- V
VCC < VCCUVSD = 5V, CS = 2V or Tj > TSD RT no connection, CT connected to COM ICC = 10mA
Sufficient current should be supplied to the VCC pin to keep the internal 15.6V zener clamp diode on this pin regulating its voltage. Due to the fact that the RT pin is a voltage-controlled current source, the total RT pin current is the sum of all of the parallel current sources connected to that pin. During the preheat mode, the total current flowing out of the RT pin consists of the RPH pin current plus the current due to the RT resistor. During the run mode, the total RT pin current consists of the RUN pin current plus the the current due to the RT resistor.
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IR2167(S)
Electrical Characteristics (cont.)
VCC = VBS = V BIAS = 14V +/- 0.25V, RT = 16.9k, CT = 470 pF, RPH and RUN leads no connection, V CPH = 0.0V, RDT = 6.1k, R OC = 20.0k, V CS = 0.5V, VSD = 2.0V, CL = 1000pF, T A = 25o C unless otherwise specified.
Floating Supply Characteristics
Symbol Definition
IQBS0 IQBS1 VBSMIN ILK Quiescent VBS supply current Quiescent VBS supply current Min. req'd VBS voltage for proper HO functionality Offset supply leakage current
Min.
-- -- -- --
Typ.
0 30 4 --
Max.
-- -- 5 50
Units
A V A
Test Conditions
VHO = VS VHO = VB VB = VS = 600V
PFC Error Amplifier Characteristics
Symbol Definition
VBUS IVBUS gm ISOURCE ISINK VOH(EA) V0L(EA) VBUS sense input threshold VBUS sense input bias current Error amplifier transconductance Error amplifier output current sourcing Error amplifier output current sinking Error amplifier output voltage swing (Hi state) Error amplifier output voltage swing (Lo state)
Min.
-- -- -- -- -- -- --
Typ.
4.0 -- 100 30 30 13.5 0.5
Max.
-- 0.1 -- -- -- -- --
Units
V A mho A V
Test Conditions
RUN mode operation VBUS = 3V VBUS = 5V VBUS = 3V VBUS = 5V
PFC Over Voltage Comparator
Symbol Definition
V0V Over voltage comparator threshold
Min.
--
Typ.
4.3
Max.
--
Units
V
Test Conditions
PFC Overvoltage Comparator
VZX ZX lead comparator threshold voltage VZXhys ZX lead comparator hysterisis VZXclamp+ ZX lead clamp voltage (high state) -- -- -- 2.0 200 7.5 -- -- -- V mV V IZX = 1mA
Oscillator, Ballast Control, I/O Characteristics
Symbol Definition
fosc Oscillator frequency
Min.
-- --
Typ.
48 100 0.5 0.02 50 4.0 2.0 0 2.0 0 2.0 2.0
Max.
-- -- -- -- -- -- -- -- -- -- -- --
Units
kHz %/V %/C % V mV V mV sec
Test Conditions
RT = 16.9k, RDT = 6.1k, CT=470pF RT = 6.1k, RDT = 6.1k, CT=470pF VCCUV+ < VCC < 15V -40oC < Tj < 125oC
df/dV df/dT d VCT+ VCTVCTFLT VRT VRTFLT tDLO tDHO
Oscillator frequency voltage stability Oscillator frequency temperature stability Oscillator duty cycle Upper CT ramp voltage threshold Lower CT ramp voltage threshold Fault-mode CT lead voltage RT lead voltage Fault-mode RT lead voltage LO output deadtime HO output deadtime
-- -- -- -- -- -- -- -- -- --
SD = 5.5V, CS = 2V, or Tj > TSD SD = 5.5V, CS = 2V, or Tj > TSD
4
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IR2167(S)
Electrical Characteristics (cont.)
VCC = VBS = V BIAS = 14V +/- 0.25V, RT = 16.9k, CT = 470 pF, RPH and RUN leads no connection, V CPH = 0.0V, RDT = 6.1k, R OC = 20.0k, VCS = 0.5V, VSD = 2.0V, CL = 1000pF, T A = 25oC unless otherwise specified.
Preheat Characteristics
Symbol Definition
ICPH+ CPH lead charging current ICPHCPH lead discharge current VCPHIGN CPH lead lgnition mode threshold voltage VCPHRUN CPH lead run mode threshold voltage VCPHCLMP CPH lead clamp voltage VCPHFLT Fault-mode CPH lead voltage
Min.
-- -- -- -- -- --
Typ.
3.0 300 4.0 5.15 10 0
Max.
-- -- -- -- -- --
Units
A nA V mV
Test Conditions
VCPH = 0V VCPH = 0V
ICPH = 1A SD = 5.5V, CS = 2V, or Tj > TSD
RPH Characteristics Symbol Definition
IRPHLK Open circuit RPH lead leakage current VRPHFLT Fault-mode RPH lead voltage
Min.
-- --
Typ.
0.1 0
Max.
-- --
Units
A mV
Test Conditions
VRPH =5V,VRPH =6V SD = 5.5V, CS = 2V, or Tj > TSD
RUN Characteristics Symbol Definition
IRUNLK Open circuit RUN lead leakage current VRUNFLT Fault-mode RUN lead voltage
Min.
-- --
Typ.
0.1 0
Max.
-- --
Units
A mV
Test Conditions
VRUN = 5V SD = 5.5V, CS = 2V, or Tj > TSD
Protection Circuitry Characteristics
Symbol Definition
VSDTH+ Rising shutdown lead threshold voltage VSDHYS Shutdown lead threshold hysteresis VSDEOL+ Rising shutdown lead end-of-life threshold voltage VSDEOL- Falling shutdown lead end-of-life threshold voltage VCSTH+ Over-current sense threshold voltage VCSTHUnder-current sense threshold voltage TCS Over-current sense propogation delay VVDC+ Low VBUS/rectified line input upper threshold VVDCLow VBUS/rectified line input lower threshold TSD Thermal shutdown junction temperature Note 4:
Min.
-- -- -- -- -- -- -- -- -- --
Typ.
5.15 150 3.0 1.0 1.1 0.2 160 5.15 3.0 160
Max.
-- -- -- -- -- -- -- -- -- --
Units
V mV
Test Conditions
V
nsec V
oC
Delay from CS to LO
Note 4
When the IC senses an overtemperature condition (Tj > 160C), the IC is latched off. In order to reset this Fault Latch, the SD lead must be cycled high and then low, or the VCC supply to the IC must be cycled below the falling undervoltage lockout threshold (VCCUV-).
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IR2167(S)
Gate Driver Output Characteristics
Symbol Definition
VOL VOH tr tf Low level output voltage (PFC, LO or HO) High level output voltage (PFC, LO or HO) Turn-on rise time (PFC, LO or HO) Turn-off fall time (PFC, LO or HO)
Min.
-- -- -- --
Typ.
0 0 85 45
Max.
100 100 150 100
Units
mV nsec
Test Conditions
Io = 0 VBIAS - VO, Io = 0
Lead Assignments
Pin Assignments
VDC CPH RPH RT RUN CT DT OC
1 2 20 19
Pin # Symbol
HO VS VB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 VDC CPH RPH RT RUN CT DT OC COMP ZX VBUS PFC SD CS LO COM VCC VB VS HO
Description
DC Bus Sensing Input Preheat Timing Capacitor Preheat Frequency Resistor & Ignition Capacitor Oscillator Timing Resistor Run Frequency Resistor Oscillator Timing Capacitor Deadtime Programming Over-current (CS+) Threshold Programming Error Amplifier Compensation Zero-Crossing, PFC Inductor Bus Voltage Sense Input PFC Gate Driver Output Shutdown Input Current Sensing Input Low-Side Gate Driver Output IC Power & Signal Ground Logic & Low-Side Gate Driver Supply High-Side Gate Driver Floating Supply High Voltage Floating Return High-Side Gate Driver Output
IR2167
3 4 5 6 7 8
18
17 VCC 16 COM 15 14 13
LO CS SD
COMP 9 ZX
10
12 PFC 11 VBUS
6
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IR2167(S)
State Diagram
Power Turned On
UVLO Mode
1/2-Bridge Off PFC Off COMP=0V IQCC 150A CPH = 0V VCC > 11.4V (UV+) and VDC > 5.1V (Bus OK) and SD < 4.9V (Lamp OK) and TJ < 160C (Tjmax) VCC < 9.5V (VCC Fault or Power Down) or VDC < 3.0V (dc Bus/ac Line Fault or Power Down) or SD > 5.1V (Lamp Fault or Lamp Removal)
SD > 5.1V (Lamp Removal) or VCC < 9.5V (Power Turned Off)
FAULT Mode
Fault Latch Set 1/ -Bridge Off 2 PFC Off COMP=0V IQCC 150A CPH = 0V VCC = 15.6V
TJ > 160C (Over-Temperature)
PREHEAT Mode
-Bridge @ fPH 2 PFC Enabled CPH Charging @ IPH = 1A RPH = 0V RUN = Open Circuit CS Disabled CPH > 4.0V (End of PREHEAT Mode)
1/
CS > OC Threshold (Failure to Strike Lamp or Hard Switching) or TJ > 160C (Over-Temperature)
IGNITION RAMP Mode
fPH ramps to fMIN CPH Charging @ IPH = 1A RPH = Open Circuit RUN = Open Circuit CS OC Threshold Enabled CPH > 5.1V (End of IGNITION RAMP)
CS > OC Threshold (Over-Current or Hard Switching) or CS < 0.2V (No-Load or Below Resonance) or TJ > 160C (Over-Temperature) or SD < 1V or SD > 3V (End-of-Life)
RUN Mode
fMIN Ramps to fRUN CPH Charges to 10V Clamp RPH = Open Circuit RUN = 0V CS 0.2V Threshold Enabled SD 1.0V and 3.0V Thresholds Enabled
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IR2167(S)
Functional Block Diagram
3.0V
VDC 1
S R
5.1V 3.0uA
18 VB
Q Q
LEVEL SHIFT
PULSE FILTER & LATCH
20 HO 19 VS
CPH 2
9.5V 5.1V
QUICK RESTART LOGIC
17 VCC
4.0V
S R1
Q
T R
Q Q
15.6V
15 LO 16 COM
4.0V
2.0V
R2 Q
RPH 3
IRT
RT 4
2.0V
RUN 5
ICT = IRT
Q Q Q S R Q
D CLK R
0.2V
14 CS
CT 6 DT 7
7.6V
FAULT COUNTER OVERTEMP DETECT
50uA
OC 8
7.6V
UNDERVOLTAGE DETECT
2V 3V 1meg
13 SD
1V 7.6V
VBUS 11
5.1V 7.6V 4.0V 4.3V GMhi VCC
12 PFC
S R Q Q
COMP 9
S
4.0V
Q
R1 R2 Q S Q Q S R1 R2 Q Q
4.0V
WATCHDOG TIMER
R
ZX 10
2.0V 7.6V
8
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IR2167(S)
BALLAST CONTROL SECTION TIMING DIAGRAMS
NORMAL OPERATION
15.6V UVLO+ UVLO-
VCC
7.6V 5.1V 4.0V VCPH
2.0V
VRPH
2.0V
VRUN
FREQ
fSTART fPREHEAT fRUN fMIN
HO LO CS
Over-Current Threshold
IGN
UVLO
PH
RUN
UVLO
CT HO LO
CT CT HO LO LO HO
CS
CS
CS
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IR2167(S)
BALLAST CONTROL SECTION TIMING DIAGRAMS
FAULT CONDITION
15.6V UVLO+ UVLO-
VCC
7.6V 5.1V 4.0V
VCPH
2.0V
VRPH
2.0V
VRUN
fSTART fPH fRUN fIGN
FREQ SD
5.2V 2V
HO LO CS
SD > 5.1V
FAULT
IGN
IGN
UVLO
PH
PH
RUN
UVLO
CT HO LO
CT CT HO HO LO LO
CS
CS
CS
10
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IR2167(S)
Functional Description Under-voltage Lock-Out Mode (UVLO)
The under-voltage lock-out mode is defined as the state the IC is in when VCC is below the turn-on threshold of the IC. (To identify the different modes of the IC, refer to the State Diagram shown on page 2 of this document). During undervoltage lock-out mode, the HO, LO and PFC driver outputs are low and the CT pin is connected to COM through resistor RDT to disable the oscillator. Also, the internal supply to the RT pin circuitry is shut off and pins CPH, RUN, DT and COMP are internally pulled to COM. The IR2167 undervoltage lock-out mode is designed to maintain a very low supply current of less than 200A, and to guarantee the IC is fully functional before the high side, low side and PFC drivers are activated. Figure 1 shows an efficient supply using the start-up current of the IR2167 together with a charge pump from the ballast stage (RSUPPLY, CVCC, DCP1 and DCP2).
by the IC. The value of (RSUPPLY) is chosen to provide 2X the maximum start-up current to guarantee ballast start-up at low line input voltage. Once the capacitor voltage on the VCC pin reaches the start-up threshold, the SD lead is below 5.1 volts and VVDC is greater than 5.1V, the IC turns on and LO and HO begin to oscillate. PFC does not begin to oscillate until the IC reaches Preheat Mode.
Preheat Mode Startup Mode
The IR2167 enters Preheat mode when VCC exceeds the UVLO positive-going threshold. Before Preheat mode begins, the CPH and RPH pins are connected to COM. (See Figure 3). As Preheat begins, the external capacitor CPH is charged up by an internal 3?A current source. C PH determines the preheat time which continues until the voltage on the CPH pin charges to 4.0V. Preheat mode is defined as the state the IC is in when the lamp filaments are being heated to their correct emission temperature. This is necessary for maximizing lamp life and reducing the required ignition voltage. At the onset of Preheat Mode, CVCC begins to discharge due to the increase in IC operating current (Figure 2) above the available current through resistor RSUPPLY. However, the half-bridge output also begins to oscillate and the charge pump, consisting of CSNUBBER, DCP1 and DCP2, supply the current to charge capacitor CVCC and thus the voltage to the IC. The VCC voltage supplied to the IC is
+ VBUS
+ rectified AC Line
R1 RSupply R3
VDC
HO
1
CPH
20
VS
Half-bridge output
VC1
CVCC DISCHARGE VUVLO+
DCP2
R2
C1
RPH
2 3
19
VB
CBS CSNUBBER DBS CVCC R4 DCP1
18
INTERNAL VCC ZENER CLAMP VOLTAGE
IR2167
RT
VCC
4
RUN
17
COM
5
CT
16
LO
VHYST
6
DT
15
CS
VUVLO-
7
OC
14
SD
DISCHARGE TIME
8
COMP
13
PFC
RCS
9
ZX
12
VBUS
CHARGE PUMP OUTPUT RSUPPLY & CVCC TIME CONSTANT
10
11
t
VBUS return
Figure 2: Supply Capacitor (CVCC) voltage limited by the internal 15.6V zener clamp. C VCC and CSNUBBER must be selected such that enough supply current
Figure 1: Start-up and supply circuitry The VCC capacitor (CVCC) is charged by current through supply resistor (RSUPPLY) minus the start-up current drawn
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IR2167(S)
is available over all ballast operating conditions. Bootstrap diode (DBS) and supply capacitor (CBS) comprise the supply voltage for the high-side driver circuitry. To guarantee that the high-side supply is charged up before the first pulse on HO, the first pulse from the output drivers comes from the LO pin. The Preheat mode oscillation frequency of the half-bridge output is determined by the parallel combination of RPH and RT with the values of CT, RDT and an internal circuit as
M1 turns off and CRAMP begins to charge. CRAMP determines the time it takes for the oscillator to ramp down from the Preheat frequency to the Ignition Mode frequency. Once the voltage on the RPH lead reaches 2.0V, external resistor RPH has no effect on the frequency that is now determined by external components RT, CT and RDT. This is the minimum frequency. By this time, the oscillator will have ramped down toward the resonance of the load circuit causing the lamp to ignite.
CPH
CPH
2
3.0uA
COMP1
9.5V 5.1V
QUICK RESTART LOGIC
4.0V
COMP2
CRAMP
S R1
Q
RPH
3
RPH
4.0V
2.0V
R2 Q
M1
IRT
RT
RT
4
2.0V RRUN
RUN
5
M2
CT
CT
6
RDT
ICT = IRT
DT
7
Fault signal
Figure 3: Oscillator section block diagram with external component connection
shown in Figure 3. Note that at the onset of Preheat mode the initial startup frequency is much higher than the preheat frequency. The half-bridge output frequency then ramps down from this initial start-up frequency to the Preheat mode frequency. This is to ensure that the instantaneous voltage across the lamp during the first few cycles of operation does not exceed the strike potential of the lamp
Run Mode
When the voltage on the CPH pin reaches 5.1V, the IC enters Run mode. At this time, the output of COMP1 (figure 3) goes high which turns M2 on and pulls the RUN pin to COM. The frequency is now controlled by external components RT, RRUN, CT and RDT. In certain cases it is necessary to have the run frequency higher than the ignition frequency to control the power used by the load. Figure 4 shows the ballast control sequence explained in the previous paragraphs
Ignition Mode
When the CPH pin charges up to 4.0V, ignition mode begins. At this time, the output of COMP2 (figure 3) goes low,
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IR2167(S)
fStart frequency
fPH fRun fmin t
5V
VCPH
2V
VRPH
Figure 5: Oscillator Waveforms This falling portion of the sawtooth waveform is referred to as deadtime, during which both HO and LO outputs are low. The deadtime can be programmed by means of the external RDT resistor.
Preheat mode Ignition Run mode Ramp mode
2V
VRUN
Figure 4: IR2167 Ballast Control Sequence The control sequence used in the IR2167 allows the Run mode operating frequency of the ballast to be higher than the ignition frequency (i.e., fstart > fph > frun > fign). This control sequence is recommended for lamp types where the ignition frequency is too close to the run frequency to ensure proper lamp striking for all production resonant LC component tolerances (please note that it is possible to use the IR2167 in systems where fstart > fph > fign > frun, simply by leaving the RUN pin open). The heart of this controller is an oscillator that resembles those found in many popular PWM voltage regulator ICs. In its simplest form, this oscillator consists of a timing resistor and capacitor connected to ground. The voltage across the timing capacitor CT is a sawtooth, where the rising portion of the ramp is determined by the current in the RT lead, and the falling portion of the ramp is determined by an external deadtime resistor RDT. The oscillograph in Figure 5 illustrates the relationship between the oscillator capacitor waveform and the gate driver outputs
The RT input is a voltage-controlled current source, where the voltage is regulated to be approximately 2.0V. In order to maintain proper linearity between the RT pin current and the CT capacitor charging current, the value of the RT pin current should be kept between 50A and 500A. The RT pin can also be used as a feedback point for closed loop control.
PFC Section
In most AC to DC power converters it is necessary to have the circuit act as a pure resistive load to the AC input line voltage. To achieve this, active power factor correction (PFC) can be implimented which, for an AC input line voltage, produces an AC input line current. It is also important to produce a sinusoidal input current which has a low total harmonic distortion (THD) and a high power factor (PF) (See Figure 6). .
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IR2167(S)
Figure 7: Inductor Current
Figure 6: Input Voltage & Current PF=0.96, THD=22% The approach used in the IR2167 is classified as running in critical conduction mode, in which the inductor current discharges to zero with each switching cycle. There is no need to sense the rectified AC line input voltage because it is already sinusoidal. Therefore, the inductor current will naturally follow the sinusoidal voltage envelope as the PFC MOSFET is turned on and off at a much higher frequency (>10KHz) than the line input frequency (50 to 60Hz). The circuit compares the DC Bus voltage to a fixed reference voltage to determine the on-time of the PFC MOSFET. The off-time is determined by the time it takes the LPFC current to drop to zero. This zero current level is detected by a secondary winding in LPFC that is connected to the ZX pin. The result is a system where the switching frequency is freerunning and constantly changing from a high frequency near the zero crossing of the AC input line voltage, to a lower frequency at the peaks. (See Figures 7, 8 & 9).
Figure 8: Boost Inductor Envelope & Line Voltage
ILPFC
0
PFC pin
0
ZX pin
0
near peak region of rectified AC line
near zero crossing region of rectified AC line
Figure 9: Boost FET On Time vs Line Input
14
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IR2167(S)
As the external capacitor on the COMP pin begins to charge, the PFC MOSFET on time duration increases. The gain of OTA1 is at its maximum value (See Figures 10 & 11). Maximum gain is desireable to raise the Bus voltage to its nominal value as quickly as possible. When the voltage at the VBUS pin reaches 3V, the gain of OTA1 decreases to its
MOSFET is turned on with minimum on time and LPFC is shorted to ground and begins charging. The PFC MOSFET then turns off and LPFC begins to discharge into the DC BUS capacitor. COMP4 has a 4.3V threshold with hysteresis so that if the voltage at the VBUS pin overshoots the 4.0V threshold,
Run Mode Signal
From Fault Detection Circuitry
VBUS 11
OTA1
4.0V 4.3V GMhi
COMP4
VCC
COMP 9
COMP1 RS2
4.0V
COMP5
RS3 S Q Q WATCHDOG TIMER RS4 SQ R1 R2 Q
12
PFC
M1
R
COMP2 RS1 S
4.0V
SQ R1 R2 Q
C1 M2
Q Q
R
ZX 10
1.0V 7.6V
COMP3
Figure 10: PFC Section nominal value. The BUS voltage continues to increase to its nominal value at which time the voltage measured at the VBUS pin equals 4V. The gain of OTA1 now increases to its maximum value and remains there until the Run mode. This is necessary because if VBUS overshoots its nominal value, the circuit can react quickly to correct he error. Also, during ignition, there is a sudden increase in load current which can cause the Bus voltage to sag. With maximum gain, OTA1 can quickly restore the DC Bus voltage to its nominal value. When the AC line voltage is applied to the ballast, VCC rises to 15V. The PFC section is not enabled until the beginning of the Preheat mode of operation. By not enabling the PFC section until the beginning of the Preheat mode, the DC Bus voltage in the ballast is not yet boosted to its nominal running value. This helps alleviate the initial flash of the lamp when the half-bridge driver section first begins to switch. When the PFC circuit is first enabled, (See Figure 10), the voltage at the VBUS and COMP pins is low. The PFC the PFC MOSFET will not turn on again until the voltage at the VBUS pin drops to approximately 4.0V. This effectively limits ths maximum bus voltage to approximately 8% greater than the regulated level. In some instances, the line voltage may be too high. This causes the AC rectified line current to directly charge the DC Bus capacitor without being boosted. Since the current never drops to zero, the ZX pin never goes high and the PFC MOSFET never turns on. The Watch Dog Timer circuit provides a pulse to turn on the PFC MOSFET if no pulse is detected at the ZX pin for 500mS. This enables the PFC circuitry to regulate the DC Bus voltage at its nominal value
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t
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IR2167(S)
VVBUS
4.3 4.0 3.0
0 6.0 5.1 5.0 4.0
DRIVE SIGNALS
VCPH
2.0 0
6.0 4.0
VCOMP
2.0 0
Note 1
ICOMP
0
Note 1
Note 1 Note 1
RESULTANT SIGNALS
1000
gm (max)
200 0
QUICK START MODE
POWER UP MODE
POWER BOOST MODE
RUN MODE
Note 1: ICOMP in these regions is the output saturation current of the OTA Error amplifier
Figure 11: PFC Timing Sequence
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IR2167(S)
Lamp Protection & Automatic Restart Circuitry Operation
+VBUS
R1
VDC
1
3.0V
S R
Q Q from oscillator section
R2
C1 2
5.1V 1.0uA
CPH
9.5V 5.1V
QUICK RESTART LOGIC
T R
4.0V
Q Q
Q2 R3
Q Q Q S R Q D CLK R
0.2V
CS
14
RCS
R4
DT 7
OVERTEMP DETECT
FAULT COUNTER
7.6V
C3
2V 3V 1meg
R5
50uA
OC
8 ROC COC
7.6V
UNDERVOLTAGE DETECT
VCC SD
13 C2 R6 R7 C4
from upper lamp cathode
1V
7.6V
5.1V
from lower lamp cathode
Figure 12: Lamp Protection & Automatic Restart circuitry block diagram with external component connection
Sensing the AC Line Voltage
The first of these protection pins senses the voltage on the AC line by means of an external resistor divider (R1, R2 and capacitor C1) and an internal comparator with hysterisis. When power is first supplied to the IC at system startup, three conditions are required before oscillation is initiated: 1.) the voltage on the VCC pin must exceed the rising undervoltage lockout threshold (11.5V), 2.) the voltage at the VDC pin must exceed 5.1V, and 3.) the voltage on the SD pin must be below approximately 4.85V. If a low ac line condition occurs during normal operation, or if power to the ballast is shut off, the ac line will collapse prior to the VCC of the chip (assuming theVCC is derived from a charge pump off of the output of the half-bridge). In this case, the voltage on the VDC pin will shut the oscillator off, thereby protecting the power transistors from potentially hazardous hard switching. Approximately 2V of hysterisis has been designed into the internal comparator sensing the VDC pin, in order to account for variations in the ac line voltage under varying load conditions. When the ac line recovers, the chip restarts from the beginning of the control sequence, as shown in timing diagram (See Figure 13).
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IR2167(S)
5
VDC
3
4
CT
automatically restarts the lamp in the proper manner. In the Run mode there are two additional thresholds enabled on the SD pin: 1V and 3V. These thresholds form a window and during normal lamp running the voltage appearing at the SD pin is maintained within these two levels. As a lamp nears its end-of-life, its running voltage will increase and the signal applied to the SD pin detects this by exceeding the window threshold width. The oscillator is disabled, both gate driver outputs are pulled low, and the chip is put into the micropower mode.
8
CPH
VDC HO
+ rectified AC Line
1
CPH
+ VBUS
20
VS
RGHS CBS RSupply
CBLOCK
LRES
15
RPH
2 3
19
VB
LO
18
VCC
CSNUBBER D1
RT
DBOOT CVCC
IR2167
4
RUN
17
COM
5
CT
16 D2
LO
CRES
6
15
CS
15
DT
R3
RGLS R5 D3 R4
7
OC
14
SD
R6
HO-VS
8
COMP
13
PFC
9
ZX
12
VBUS
C2 RCS C3
C4 R7
10
11
RUN mode
Low VDC
Restart
VBUS return
Figure 13: VDC lead fault and auto restart
Figure 14: Lamp presence detection circuit connection (shaded area)
Lamp Presence and End-of-Life Detection
The second protection pin, SD, is used for both shutdown and end-of-life detection. The SD pin would normally be connected to an external circuit that senses the presence of the lamp(s) and the voltage appearing across the lamp(s). An example circuit for a single lamp is shown in Figure 14. During all modes of operation if the SD pin exceeds 5.1V (approximately 150mV of hysterisis is included to increase noise immunity), signaling either a lamp fault or lamp removal, the oscillator is disabled, both gate driver outputs are pulled low, and the chip is put into the micropower mode. Since a lamp fault would normally lead to a lamp exchange, when a new lamp is inserted in the fixture, the SD pin would be pulled back to near ground potential. Under these conditions a reset signal would restart the chip from the beginning of the control sequence, as shown in the timing diagram in Figure 15. Thus, for a lamp removal and replacement, the ballast
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IR2167(S)
5
R OC = VCS+ , 55E - 6
or
SD
VCS + = 55E - 6 ROC
4
CT
rectifie AC d line
8
VDC
+ V
BUS
CPH
CPH RPH
1 2 3
15
R T RUN
2 0 1 9 1 8
H O VS
Q1 R GHS
1
/2
VB
C BOOT D BOOT
Bridge output
R SUPPLY D 1 CVCC Q2
C SNUBBE
R
IR2167
LO
4 5
1 7 1 6 1 5 1 4 13 1 2 1 1
VCC
COM L O CS
C T D T O C COMP
6 7 8 9
R GLS R3
D 2
15
HO-VS
SD
PFC
ZX
VBUS
RUN mode
SD mode
Restart
ROC 10
R CS
VBUS
return
Figure 15: SD lead fault and auto restart
Half-Bridge Current Sensing and Protection
The third pin used for protection is the CS pin, which is normally connected to a resistor in the source of the lower power MOSFET, as shown in Figure 16. The CS pin is used to sense fault conditions such as failure of a lamp to strike, over-current during normal operation, hard switching, no load, and operation below resonance. If any one of these conditions is sensed, the fault latch is set, the oscillator is disabled, the gate driver outputs go low, and the chip is put into the micropower mode. The CS lead performs its sensing functions on a cycle-by-cycle basis in order to maximize ballast reliability. For the over-current, failure-to-strike, and hard switching fault conditions, an externally programmable, positive-going CS+ threshold is enabled at the end of the preheat time. The level of this positive-going threshold is determined by the value of the resistor ROC. The value of the resistor ROC is determined by the following formula:
Figure 16: Half-bridge current sensing circuit connection (shaded area) For the under-current and under-resonance conditions, there is a negative-going CS- threshold of 0.2V which is enabled at the onset of the run mode. The sensing of this CSthreshold is synchronized with the falling edge of the LO output. Figures 17, 18 and 19 are oscillographs of fault conditions. Figure 17 shows a failure of the lamp to strike, Figure 18 shows a hard switching condition and Figure 19 shows an under-current condition.
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IR2167(S)
Figure 17: Failure of lamp to strike Figure 19: Operation below resonance
Figure 18: Hard switching condition Figure 20: Auto restart for lamp replacement
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IR2167(S)
Recovery from such a fault condition is accomplished by cycling either the SD pin or the VCC pin. (See Figure 20). When a lamp is removed, the SD pin goes high, the fault latch is reset, and the chip is held off in an unlatched state. Lamp replacement causes the SD pin to go low again, reinitiating the startup sequence. The fault latch can also be reset by the undervoltage lockout signal, if VCC falls below the lower undervoltage threshold.
this CMOS circuitry is very low (typically 45A in the onstate), the majority of the drop in the VBS voltage when Q1 is on occurs due to the transfer of charge from the bootstrap capacitor to the gate of the power MOSFET.
Design Equations
Note: The results from the following design equations can differ slightly from experimental measurements due to IC tolerances, component tolerances, and oscillator over- and under-shoot due to internal comparator response time. Step 1: Program Maximum Ignition Voltage
Bootstrap Supply Considerations
Power is normally supplied to the high-side circuitry by means of a simple charge pump from VCC, as shown in Figure 21.
rectifie AC d line
VDC
+ V
BUS
1
CPH
2 0 1 9 1 8
H O VS
Q1 RGHS
1/ 2
2
RPH
VB
CBOOT D BOOT
Bridge output
3
R T RUN
RSUPPLY D 1 CVCC Q2
CSNUBBE
R
4 5
1 7 1 6 1 5 1 4 13 1 2 1 1
VCC
COM L O CS
Maximum lamp voltage is required during ignition. This will vary depending on the type of lamp, but 1600V is typical for a T8 lamp. As the frequency decreases from the preheat frequency to the resonant frequency, the voltage across the lamp increases. During ignition, only RT along with CT and DT determine the frequency. R PH and R RUN are not connected to COM at this time. The value of RT should be chosen so that the desired ignition voltage is reached. The RT pin current and timing capacitor charging current are both approximately:
IR2167
C T D T O C COMP
6 7 8 9
RGLS R3
D 2
I CT = I RT =
SD
2.0V RT
PFC
RCS
ZX
VBUS
10
The value of this current should be kept between 50 A and 500 A. The value for CT is computed as follows:
VBUS
return
Figure 21 : Typical bootstrap supply connection with VCC charge pump from half-bridge output (shaded area) A high voltage, fast recovery diode DBOOT (the so-called bootstrap diode) is connected between VCC (anode) and VB (cathode), and a capacitor CBOOT (the so-called bootstrap capacitor) is connected between the VB and VS leads. During half-bridge switching, when MOSFET Q2 is on and Q1 is off, the bootstrap capacitor CBOOT is charged from the VCC decoupling capacitor, through the bootstrap diode DBOOT, and through Q2. Alternately, when Q2 is off and Q1 is on, the bootstrap diode is reverse-biased, and the bootstrap capacitor (which `floats' on the source of the upper power MOSFET) serves as the power supply to the upper gate driver CMOS circuitry. Since the quiescent current in
CT =
1 RT
1 - td 2 fign
And the ignition mode frequency is:
f IGN =
1 2(RT CT + td ) 1 - td 2 fign
21
RT =
1 CT
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IR2167(S)
Deadtime is equal to:
td = 0.69 RDT CT
The following graphs, figures 22 and 23, illustrate the relationship between the effective resistance (i.e. the parallel combination of resistors which programs the CT capacitor charging current) and the operating frequency.
FREQ (KHz)
250
200 CT=220pF, RDT=5.6K CT=470pF, RDT=2.7K CT=1nF, RDT=1.2K 150
100 150
FREQ (KHz)
50 CT=220pF,RDT=11K CT=470pF,RDT=6.2K CT=1nF,RDT=3K 0 0 5 10 15 20 25 30 35 40
100
RT (K)
50
Figure 23: fOSC vs effective RT (tDEAD=1.0sec) Figure 24 illustrates the relationship between deadtime vs RDT.
0 0 5 10 15 20 25 30 35 40
10
RT (K)
Figure 22: fOSC vs effective RT (tDEAD=2.0sec)
tDEAD (usec)
CT = 220 pF CT = 470 pF CT = 1 nF
1
0.1 1 10 100
RDT (K)
Figure 24: Deadtime vs RDT
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IR2167(S)
Step 2: Program Maximum Ignition Current The ignition current should be limited to the rating of the lamp resonant inductor and the half-bridge MOSFETS. The saturation current of the lamp resonant inductor should be much lower than the current rating of the MOSFETS. Under worst case conditions, the lamp resonant inductor should not be allowed to saturate. This current is controlled by the CS pin and the OC pin. The OC lead has an internal 50A current source. This current through external resistor ROC determines the threshold on the CS pin.
Step 4: Program preheat time The preheat time is determined by external capacitor CPH. The preheat time required for a 4:1 hot to cold ratio can be observed by measuring the voltage across the filaments. The preheat time is calculated as follows:
tPH = 4.0 E 6 CPH
The IR2167 is held in preheat until CPH is charged to 4.0V. Step 5: Program the ignition mode time The difference in time between the preheat mode and the run mode is the ignition mode. The rate at which the frequency changes from preheat to run is determined by external resistor RRAMP.
ROC =
VCS + or 55E - 6
VCS + = 55E - 6 - ROC
If the current through external resistor RCS exceeds a predetermined value, the IC shuts off.
Step 6. Program the run frequency Step 3: Program Preheat Frequency The preheat frequency is determined by the parallel combination of RPH and RT along with CT and RDT. The frequency should be chosen so that the voltage across the lamp is much lower than the ignition voltage but still provides adequate heating of the filaments. During preheat, the current through the filaments is constant. However, as the filaments heat up, their resistance increases. This results in an increase in the voltage measured across the filaments, which indicates the hot to cold ratio. The run mode begins when external resistor RPH is charged to 5.1V. At this time, the run frequency is determined by the parallel combination of RT and RRUN along with RDT and CT. The run frequency can be programmed above or below the ignition frequency. fRUN is determined by the following equation:
f RUN =
1 R R 2 T RUN CT + td R +R RUN T 1 CT
f PH =
1 R R 2 T PH CT + td R +R PH T 1 CT RRUN
RPH
1 2 f - td ph = 1 1 1- - td RT CT 2 f ph
1 - td 2f RUN = 1 1 1- - td RT CT 2 f RUN
4:1 is an acceptable ratio for proper heating
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23
IR2167(S)
Component Selection Tips
Supply Bypassing and pc Board Layout Rules
Component selection and placement on the pc board is extremely important when using power control ICs. VCC should be bypassed to COM as close to the IC terminals as possible with a low ESR/ESL capacitor, as shown in Figure 25.
(surface mount) CBOOT
Connecting the IC Ground (COM) to the Power Ground
Both the low power control circuitry and low side gate driver output stage grounds return to this lead within the IC. The COM lead should be connected to the bottom terminal of the current sense resistor in the source of the low side power MOSFET using an individual pc board trace, as shown in Figure 26. In addition, the ground return path of the timing components and VCC decoupling capacitor should be connected directly to the IC COM lead, and not via separate traces or jumpers to other ground traces on the board.
IR2167 pin 1
(surface mount)
CVCC IR2167 pin 1
(surface mount) (surface DBoot mount)
CVCC
CVCC (through hole)
CVCC (through hole)
timing component s
RCS (through hole)
VBUS return
Figure 25: Supply bypassing PCB layout example Figure 26: COM lead connection PCB layout example A rule of thumb for the value of this bypass capacitor is to keep its minimum value at least 2500 times the value of the total input capacitance (Ciss) of the power transistors being driven. This decoupling capacitor can be split between a higher valued electrolytic type and a lower valued ceramic type connected in parallel, although a good quality electrolytic (e.g., 10F) placed immediately adjacent to the VCC and COM terminals will work well. In a typical application circuit, the supply voltage to the IC is normally derived by means of a high value startup resistor (1/4W) from the rectified line voltage, in combination with a charge pump from the output of the half-bridge. With this type of supply arrangement, the internal 15.6V zener clamp diode from VCC to COM will determine the steady state IC supply voltage. These connection techniques prevent high current ground loops from interfering with sensitive timing component operation, and allows the entire control circuit to reject common-mode noise due to output switching.
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IR2167(S)
Caseoutline
20 Lead SOIC (wide body)
(MS-013AC) 01-3080 00
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25
IR2167(S)
Caseoutline
20 Lead PDIP
(MS-001AD) 01-3079 00
IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105 Data and specifications subject to change without notice. 2/28/2002
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