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Data Sheet No. PD60182-I
IR2156(S) & (PbF)
BALLAST CONTROL IC
Features
* * * * * *
Ballast control and half-bridge driver in one IC Programmable preheat frequency Programmable preheat time Internal ignition ramp Programmable over-current threshold Programmable run frequency
* Programmable dead time * DC bus under-voltage reset * Shutdown pin with hysteresis * Internal 15.6V zener clamp diode on Vcc * Micropower startup (150A) * Latch immunity and ESD protection * Also available LEAD-FREE (PbF)
Description
The IR2156 incorporates a high voltage half-bridge gate driver with a programmable oscillator and state diagram to form a complete ballast control IC. The IR2156 features include programmable preheat and run frequencies, programmable preheat time, programmable dead-time, and programmable over-current protection. Comprehensive protection features such as protection from failure of a lamp to strike,filament failures, as well as an automatic restart function, have been included in the design. The IR2156 is available in both 14 lead PDIP and 14 lead SOIC packages.
Packages
14 Lead PDIP
14 Lead SOIC (narrow body)
CFL Application Diagram
R BUS R SUPPLY D BOOT D RECT1
L FILTE
R
L F1
NC VCC
1 2
14 13
VB
D CP2 M1
LRES
C ELCAP1
C FILTE
R
HO
IR2156
CVCC2 CVCC1
VDC
3
RT
12 11 10 9
VS
N M2 CCP R1 CCS RCS C SNUB
CRES
4 RT RPH
RPH
LO
C BOOT
5
CT
CS SD
6
CPH
C ELCAP1 D CP1 D RECT2
COM
7 CT C VDC C CPH
8
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IR2156(S) & (PbF)
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 IOMAX VVDC VCT ICPH IRPH VRPH IRT VRT VCS ICS ISD ICC dV/dt PD RthJA TJ TS TL Note 1:
Definition
High side floating supply voltage High side floating supply offset voltage High side floating output voltage Low side output voltage Maximum allowable output current (HO, LO) due to external power transistor miller effect VDC pin voltage CT pin voltage CPH pin current RPH pin current RPH pin voltage RT pin current RT pin voltage Current sense pin voltage Current sense pin current Shutdown pin current Supply current (note 1) Allowable offset voltage slew rate Package power dissipation @ TA +25C PD = (TJMAX-TA)/RthJA Thermal resistance, junction to ambient Junction temperature Storage temperature Lead temperature (soldering, 10 seconds) (14 pin PDIP) (14 pin SOIC) (14 pin PDIP) (14 pin SOIC)
Min.
-0.3 VB - 25 VS - 0.3 -0.3 -500 -0.3 -0.3 -5 -5 -0.3 -5 -0.3 -0.3 -5 -5 -20 -50 -- -- -- -- -55 -55 --
Max.
625 VB + 0.3 VB + 0.3 VCC + 0.3 500 VCC + 0.3 VCC + 0.3 5 5 VCC + 0.3 5 VCC + 0.3 5.5 5 5 20 50 1.70 1.00 70 120 150 150 300
Units
V
mA V VCC + 0.3 mA V mA V
mA V/ns W
o
C/W
o
C
This IC contains a zener clamp structure between the chip VCC and COM which has a nominal breakdown voltage of 15.6V. Please note that this supply pin should not be driven by a DC, low impedance power source greater than the VCLAMP specified in the Electrical Characteristics section.
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IR2156(S)&(PbF)
Recommended Operating Conditions
For proper operation the device should be used within the recommended conditions.
Symbol
VBs VBSMIN VS VCC ICC CT ISD ICS TJ ISDLK ICSLK Note 2:
Definition
High side floating supply voltage Minimum required VBS voltage for proper HO functionality Steady state high side floating supply offset voltage Supply voltage Supply current CT lead capacitance Shutdown lead current Current sense lead current Junction temperature SD pin leakage current (@VSD=6V) CS pin leakage current (@VCS=3V)
Min.
VCC - 0.7 5 -1 VCCUV+ note 2 220 -1 -1 -40 -- --
Max.
VCLAMP VCC 600 VCLAMP 10
Units
V
mA
--
1 1 125 125 25
pF
mA
o
C
A
Enough current should be supplied into the VCC lead to keep the internal 15.6V zener clamp diode on this lead regulating its voltage, VCLAMP.
Electrical Characteristics
VCC = VBS = VBIAS = 14V +/- 0.25V, VVDC = Open, RT = 39.0k, RPH = 100.0k, CT = 470 pF, VCPH = 0.0V, VCS = 0.0V, VSD = 0.0V, CLO, HO = 1000pF, TA = 25oC unless otherwise specified.
Symbol Definition
Min.
10.5 8.5 1.5 50 -- -- -- 14.5
Typ.
11.5 9.5 2.0 120 200 1.0 1.0 15.6
Max.
12.5 10.5
Units Test Conditions
V CC rising from 0V VCC falling from 14V
Supply Characteristics
VCCUV+ VCCUVVUVHYS IQCCUV IQCCFLT IQCC IQCC50K VCLAMP VCC supply undervoltage positive going threshold VCC supply undervoltage negative going threshold VCC supply undervoltage lockout hysteresis UVLO mode quiescent current Fault-mode quiescent current Quiescent VCC supply current VCC supply current, f = 50kHz VCC zener clamp voltage
V 3.0 200 470 1.5 1.5 16.5 mA
A
VCC = 11V SD = 5.1V, or CS > 1.3V CT connected toCOM VCC =14V,RT=15k RT = 15k CT = 470 pF ICC = 5mA
V
Floating Supply Characteristics
IQBS0 IQBS1 ILK Quiescent VBS supply current Quiescent VBS supply current Offset supply leakage current -5 -- -- 0 30 -- 5 50 50 A A VHO = VS (CT = 0V) VHO = VB (CT = 14V) VB = VS = 600V
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IR2156(S) & (PbF)
Electrical Characteristics
VCC = VBS = VBIAS = 14V +/- 0.25V, VVDC = Open, RT = 39.0k, RPH = 100.0k, CT = 470 pF, VCPH = 0.0V, VCS = 0.0V, VSD = 0.0V, CLO, HO = 1000pF, TA = 25oC unless otherwise specified.
Symbol Definition
f osc Oscillator frequency
Min.
28
Typ.
30
Max.
32
Units
Test Conditions
RT=33.0k, VVDC= 5V VCPH = Open (Guaranteed by design) RT=40k, RPH = 100K CT = 470pF VCC = 14V SD > 5.1V or CS >1.3V only CT CAP should beconnected to CT
Oscillator, Ballast Control, I/O Characteristics
kHz
f osc d VCT+ VCTVCTFLT
Oscillator frequency Oscillator duty cycle Upper CT ramp voltage threshold Lower CT ramp voltage threshold Fault-mode CT pin voltage
37.6 -- -- -- --
40 50 8.3 4.8 0
43.9 -- -- -- --
KHz % V mV
tDLO tDHO RDT ICPH VCPHFLT IRPHLK VRPHFLT IRTLK VRTFLT VSDTH+ VSDHYS VCSTH tCS VCSPW RVDC
LO output deadtime HO output deadtime Internal deadtime resistor CPH pin charging current Fault-mode CPH pin voltage Open circuit RPH pin leakage current Fault-mode RPH pin voltage Open circuit RT pin leakage current Fault-mode RT pin voltage Rising shutdown pin threshold voltage Shutdown pin threshold hysteresis Over-current sense threshold voltage Over-current sense propogation delay Over-current sense minimum pulse width DC bus sensing resistor
-- -- -- 3.6 --
2.0 2.0 3 4.3 0
-- -- -- 5.2 --
usec usec K A mV A mV A mV V mV V nsec nsec k V
VCPH=10V,CT=10V, VDC=5V
Preheat Characteristics
SD > 5.1V or CS >1.3V
RPH Characteristics
-- -- -- -- -- -- 1.1 -- -- 7.5 10.3 -- -- -- -- 0.1 0 0.1 0 5.1 450 1.25 160 135 10 10.9 0 0 110 55 -- -- -- -- -- -- 1.44 -- -- 14 11.4 105 100 150 100 CT = 10V SD > 5.1V or CS >1.3V CT = 10V SD > 5.1V or CS >1.3V
RT Characteristics Protection Characteristics
VCPH-VDC CPH to VDC offset voltage
Delay from CS to LO VCS pulse amplitude = VCSTH+100mV VCPH>12V, VCT=0V VDC= 7V VCPH=open,VVDC=0V Io = 0 VBIAS - Vo, Io = 0 CLO = CHO =1nF
Gate Driver Output Characteristics
VOL VOH tr tf Low-level output voltage High-level output voltage Turn-on rise time Turn-off fall time mV ns
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IR2156(S)&(PbF)
Block Diagram
Vcc
S1 RT S2 40K CT RDT 2.5K S3 S4 R RPH ICPH CPH 5.1V 5.1V VDC RVDC 10K R Schmitt 1 Fault Logic S R1 R2 Q CS 1.3V SD 5.1V Comp 2 COM UnderVoltage Detect Comp 3 Q LowSide Driver LO S6 VTH R Soft Start R Comp 1 T R Q Q VS R Driver Logic VB
HighSide Driver
HO
Lead Assignments & Definitions
Pin Assignments
NC VCC VDC RT RPH CT 1 2 14 VB 13 HO
Pin # Symbol
1 2 3 4 5 6 7 8 9 10 11 12 13 14 NC VCC VDC RT RPH CT CPH COM SD CS LO VS HO VB
Description
No connect Logic & low-side gate driver supply IC start-up and DC bus sensing Input Minimum frequency timing resistor Preheat frequency timing resistor Oscillator timing capacitor Preheat timing capacitor IC power & signal ground Shutdown input Current sensing input Low-side gate driver output High-side floating return High-side gate driver output High-side gate driver floating supply
IR2156
3 4 5 6
12 VS 11 LO 10 CS 9 SD 8 COM
CPH 7
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IR2156(S) & (PbF)
State Diagram
Power Turned On
UVLO Mode
/2-Bridge Off IQCC 120A CPH = 0V CT = 0V (Oscillator Off) CS > 1.3V (Lamp Removal) or SD > 5.1V or VCC < 9.5V (UV-) (Power Turned Off) VCC < 9.5V (VCC Fault or Power Down) or SD > 5.1V (Lamp Fault or Lamp Removal)
1
VCC > 11.5V (UV+) and SD < 5.1V
FAULT Mode
Fault Latch Set 1 /2-Bridge Off IQCC 180A CPH = 0V VCC = 15.6V CT = 0V (Oscillator Off)
1
PREHEAT Mode
/2-Bridge oscillating @ f PH RPH // RT CPH Charging @ I CPH = 5 A CS Enabled @ CPH > 7.5V RVDC to COM = 12.6k @ CPH > 7.5V CPH > 10V (End of PREHEAT Mode)
CS > 1.3V (Failure to Strike Lamp)
Ignition Ramp Mode
RPH Open fPH ramps to f RUN CPH charging
CPH > 13V
CS > 1.3V (Lamp Fault)
RUN Mode
RPH = Open 1/2-Bridge Oscillating @ fRUN
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IR2156(S)&(PbF)
Timing Diagrams
Normal operation
VCC
15.6V UVLO+ UVLO-
VDC
VCC 7.5V
CPH
frun
FREQ
fph
HO LO CS
1.3V Over-Current Threshold
IGN
UVLO
PH
RUN
UVLO
RT
RT
RT
RPH CT
RPH CT
RPH CT
HO LO
HO LO
HO LO
CS
CS
CS
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IR2156(S) & (PbF)
Timing Diagrams
Fault condition
VCC
15.6V UVLO+ UVLO-
VDC
VCC 7.5V
CPH f run FREQ f ph
SD
HO LO CS
1.3V
SD > 5.1V
FAULT
IGN
IGN
UVLO
PH
PH
RUN
UVLO
RT
RT
RT
RPH CT
RPH
RPH CT
CT
HO
HO LO
CSTH
HO
LO
LO
CS
CS
CS
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IR2156(S)&(PbF)
1600 1400 1200 1000 CT (pF) 800 600 400 200 0 0 0.5 1 1.5 DT (S) 2 2.5 3 1 0 40 80 120 Frequency (KHz) 160 200 ICC (mA) 4 3 2 6 5
Graph 1. CT vs Dead Time (IR2156)
Graph 2. ICC vs Frequency (IR2156)
120 110 100 Frequency (KHz) Frequency (KHz) 90 80 70 60 50 40 9 10 11 VCPH (V) 12 13 RPH=30K RPH=15K
90 80 70 60 50 40 30 0 1 VDC (V) 2 3
RPH=15K RPH=30K RPH=100K
Graph 3. Frequency vs VCPH (IR2156)
Graph 4. Frequency vs VDC (IR2156)
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IR2156(S) & (PbF)
6 5 4 ICPH (A) 3 2 1 0 0 5 VCPH (V)
Graph 5. ICPH vs VCPH (IR2156)
2
1000000
Frequency (Hz)
100000
CT=220pF CT=470pF CT=1000pF CT=2200pF CT=3300pF CT=4800pF CT=6800pF
10000
1000
10
15
4
13
22 RT (k)
31
40
Graph 6. Frequency vs RT (IR2156)
70 60 125oC
1.5
50 40
75oC 25oC
IQCC (mA)
IQBS ( A)
1
30 20 -25oC
0.5
10 0
0 8 9 10 11 12 13
-10 0 3 6 V BS (V) 9 12 15
V CC (V)
Graph 7. IQCC vs VCC (IR2156) UVLO Hysteresis
Graph 8. IQBS vs VCC vs Temp(IR2156)
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IR2156(S)&(PbF)
1.5
5 4.5 4 RDT (K )
1.4
CS+ (V)
1.3
3.5 3
1.2
1.1
2.5 2 -25 0 25 50 75 100 125 -25 0 25 50 75 100 125 Temperature C
1
Temperature C
Graph 10. RDT vs Temperature (IR2156)
Graph 9. VCSTH+ vs Temperature (IR2156)
15
14 13 12 11 10 9 8
0 25 50 75 100 125
14
UV+, UV- (V)
RVDC (K )
13
UV+
12
UV-
11
10 -25
-25
0
25
50
75
100
125
Temperature C
Graph 11. RVDC+ vs Temperature (IR2156)
Temperature C
Graph 12. UV+, UV- vs Temperature (IR2156)
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IR2156(S) & (PbF)
6 5.75 5.5 SD+ SD+, SD- (V) 5.25 5 4.75 4.5 4.25 4 -25 0 25 50 75 100 125 SDILK ( A)
35 30 25 20 15 10 5 0 -25 0 25 50 75 100 125
Temperature C
Graph 13. SD+, SD- vs Temperature (IR2156)
20 -25 16 25 75 125 IQCC (mA) IQCC (mA) 12 12 16 20 -25 25 75 125
Temperature C
Graph 14. ILK vs Temperature (IR2156)
8
8
4
4
0 0 5 10 VCC (V) 15 20
0 15 15.5 VCC (V) 16 16.5
Graph 15. IQCC vs VCC vs Temperature (IR2156)
Graph 16. IQCC vs VCC vs Temperature (IR2156) Internal Zener Diode Curve
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IR2156(S)&(PbF)
2 1.8 1.6 1.4 IQCC (mA) 1.2 1 0.8 0.6 0.4 0.2 0 10 10.5 11 11.5 VCC (V) 12 12.5 13
1.6
-25 25 75 125
IQCC ( A) 1.4 1.2 1 0.8 0.6 0.4 0.2 0 8.5 9
-25 25 75 125
9.5 VCC (V)
10
10.5
Graph 17. IQCC vs VCC vs Temperature (IR2156) VCCUV +
Graph 18. IQCC vs VCC vs Temperature (IR2156) VCCUV-
58.5 58 57.5
Frequency (kHz)
-25oC
70 65
Frequency (kHz)
57 56.5 56 55.5 55 54.5 54 11 12
VCC (V)
75oC
60 55 50 45 40
125oC
25 C
o
13
14
-25
0
25
50
Temp(C)
75
100
125
Graph 19. FOSC vs VCC vs Temperature (IR2156) VCPH = 0V
Graph 20. FOSC vs Temperature (IR2156) VCPH = 0V
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IR2156(S) & (PbF)
3.5 3 2.5 ICPH ( A) 2 1.5 1 0.5 0 11 12 13 VCC (V) 14 15 -25 25 75 125 ICPH ( A)
6 125oC 5.5 75oC 25oC 5 -25oC 4.5
4 11 12 13 VCC (V) 14 15
Graph 21. ICPH vs VCC vs Temperature (IR2156) VCPH = VCC
Graph 22. ICPH vs VCC vs Temperature (IR2156) VCPH = 0V
2.25 2.2 2.15 tDEAD (LO) ( Sec) 2.1 2.05 2 1.95 1.9 1.85 1.8 11 12 13 VCC (V) 14 15 -25oC 25oC 75oC 125oC
200 180 160 140 tRISE(HO) (nSec) 120 100 80 60 40 20 0 11 12 13 V CC (V) 14 15 -25oC 125oC 75oC 25oC
Graph 23. tDEAD vs VCC vs Temperature (IR2156) CT = 1nF
Graph 24. tRISE(HO) vs VCC vs Temperature (IR2156)
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IR2156(S)&(PbF)
120 100 80 60 -25oC 40 20 0 11 12 13 VCC (V) 14 15 125oC
250 125oC 75oC tRISE(LO)(nSec) 150 25oC -25 C
o
200 75 C 25oC
o
tFALL(HO)(nSec)
100
50
0 11 12 13 VCC (V) 14 15
Graph 25. tFALL(HO) vs VCC vs Temperature (IR2156)
Graph 26. tRISE(LO) vs VCC vs Temperature (IR2156)
120
125oC
100
75oC
tFALL(LO)(nSec) 80
25oC
60
-25oC
40 20 0 11 12 13 V CC (V) 14 15
Graph 27. tFALL(LO) vs VCC vs Temperature (IR2156)
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IR2156(S) & (PbF)
Functional Description
Under-voltage Lock-Out Mode (UVLO)
VUVLO+
VC1
CVCC DISCHARGE
INTERNAL VCC ZENER CLAMP VOLTAGE
The under-voltage lock-out mode (UVLO) 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 6 of this document. The IR2156 undervoltage lock-out is designed to maintain an ultra low supply current of less than 200uA, and to guarantee the IC is fully functional before the high and low side output drivers are activated. Figure 1 shows an efficient supply voltage using the start-up current of the IR2156 together with a charge pump from the ballast output stage (RSUPPLY, CVCC, DCP1 and DCP2).
VBUS(+) RSUPPLY DBOOT VB 14 VCC 2 13 12 CVCC HO VS LO M2 CSNUB CBOOT M1 Half-Bridge Output
VHYST
VUVLO-
DISCHARGE TIME
CHARGE PUMP OUTPUT RSUPPLY & CVCC TIME CONSTANT
t
Figure 2, Supply capacitor (CVCC) voltage.
IR2156
11
DCP1 8 COM RCS DCP2
VBUS(-)
Figure 1, Start-up and supply circuitry.
The start-up capacitor (CVCC) is charged by current through supply resistor (RSUPPLY) minus the start-up current drawn by the IC. This resistor 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 VCC reaches the start-up threshold, and the SD pin is below 4.5 volts, the IC turns on and HO and LO begin to oscillate. The capacitor begins to discharge due to the increase in IC operating current (Figure 2).
16
During the discharge cycle, the rectified current from the charge pump charges the capacitor above the IC turn-off threshold. The charge pump and the internal 15.6V zener clamp of the IC take over as the supply voltage. The start-up capacitor and snubber capacitor must be selected such that enough supply current is available over all ballast operating conditions. A bootstrap diode (DBOOT) and supply capacitor (CBOOT) 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 pin HO, the first pulse from the output drivers comes from the LO pin. During undervoltage lock-out mode, the high- and low-side driver outputs HO and LO are both low, pin CT is connected internally to COM to disable the oscillator, and pin CPH is connected internally to COM for resetting the preheat time. Preheat Mode (PH) The 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. The IR2156 enters preheat mode when VCC exceeds the UVLO positive-going threshold. HO and LO begin to
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IR2156(S)&(PbF)
oscillate at the preheat frequency with 50% duty cycle and with a dead-time which is set by the value of the external timing capacitor, CT, and internal deadtime resistor, RDT. Pin CPH is disconnected from COM and an internal 4A current source (Figure 3)
V BUS(+)
RT
RT
4 S4 5
OSC.
13
HO
M1
Half HalfBridge Driver Bridge
12
RPH
R PH
VS
Output I LOAD
off) of the output gate drivers, HO and LO. The selected value of CT together with RDT therefore program the desired dead-time (see Design Equations, page 19, Equations 1 and 2). Once CT discharges below 1/3 VCC, MOSFET S3 is turned off, disconnecting RDT from COM, and MOSFET S1 is turned on, connecting RT and RPH again to VCC. The frequency remains at the preheat frequency until the voltage on pin CPH exceeds 13V and the IC enters Ignition Mode. During the preheat mode, both the over-current protection and the DC bus under-voltage reset are enabled when pin CPH exceeds 7.5V. Ignition Mode (IGN) The ignition mode is defined as the state the IC is in when a high voltage is being established across the lamp necessary for igniting the lamp. The IR2156 enters ignition mode when the voltage on pin CPH exceeds 13V.
V BUS(+) VCC
2 S1
CT
6 11
LO
M2
CT
4uA
CPH
CCPH
7 8
RCS
COM Load Return
IR2156
V BUS (-)
Figure 3, Preheat circuitry.
charges the external preheat timing capacitor on CPH linearly. The over-current protection on pin CS is disabled during preheat. The preheat frequency is determined by the parallel combination of resistors RT and RPH, together with timing capacitor CT. CT charges and discharges between 1/3 and 3/5 of VCC (see Timing Diagram, page 7). CT is charged exponentially through the parallel combination of RT and RPH connected internally to VCC through MOSFET S1. The charge time of CT from 1/3 to 3/5 VCC is the on-time of the respective output gate driver, HO or LO. Once CT exceeds 3/5 VCC, MOSFET S1 is turned off, disconnecting RT and RPH from VCC. CT is then discharged exponentially through an internal resistor, RDT, through MOSFET S3 to COM. The discharge time of CT from 3/5 to 1/3 VCC is the dead-time (both
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RT
RT
4 S4 5
OSC.
13
HO
M1
RPH
R PH
CT
6
Fault Logic
HalfBridge Driver
Half Bridge
12
VS
Output I LOAD
11 CT S3
1.3V
LO
M2
CS
10
R1 CCS RCS
4uA
Comp 4
CPH
CCPH
7 8
COM Load Return
IR2156
V BUS(-)
Figure 4, Ignition circuitry.
Pin CPH is connected internally to the gate of a p-channel MOSFET (S4) (see Figure 4) that connects pin RPH with pin RT. As pin CPH
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IR2156(S) & (PbF)
exceeds 13V, the gate-to-source voltage of MOSFET S4 begins to fall below the turn-on threshold of S4. As pin CPH continues to ramp towards VCC, switch S4 turns off slowly. This results in resistor RPH being disconnected smoothly from resistor RT, which causes the operating frequency to ramp smoothly from the preheat frequency, through the ignition frequency, to the final run frequency. The over-current threshold on pin CS will protect the ballast against a non-strike or open-filament lamp fault condition. The voltage on pin CS is defined by the lower half-bridge MOSFET current flowing through the external current sensing resistor RCS. The resistor RCS therefore programs the maximum allowable peak ignition current (and therefore peak ignition voltage) of the ballast output stage. The peak ignition current must not exceed the maximum allowable current ratings of the output stage MOSFETs. Should this voltage exceed the internal threshold of 1.3V, the IC will enter FAULT mode and both gate driver outputs HO and LO will be latched low. Run Mode (RUN) Once the lamp has successfully ignited, the ballast enters run mode. The run mode is defined as the state the IC is in when the lamp arc is established and the lamp is being driven to a given power level. The run mode oscillating frequency is determined by the timing resistor RT and timing capacitor CT (see Design Equations, page 19, Equations 3 and 4). Should hard-switching occur at the half-bridge at any time due to an openfilament or lamp removal, the voltage across the current sensing resistor, RCS, will exceed the internal threshold of 1.3 volts and the IC will enter FAULT mode. Both gate driver outputs, HO and LO, will be latched low. DC Bus Under-voltage Reset Should the DC bus decrease too low during a brown-out line condition or over-load condition, the resonant output stage to the lamp can shift near or below resonance. This can produce hardswitching at the half-bridge which can damage the half-bridge switches. To protect against this, pin VDC measures the DC bus voltage and pulls down on pin CPH linearly as the voltage on pin VDC decreases 10.9V below VCC. This causes the p-channel MOSFET S4 (Figure 4) to close as the DC bus decreases and the frequency to shift higher to a safe operating point above resonance. The DC bus level at which the frequency shifting occurs is set by the external RBUS resistor and internal RVDC resistor. By pulling down on pin CPH, the ignition ramp is also reset. Therefore, should the lamp extinguish due to very low DC bus levels, the lamp will be automatically ignited as the DC bus increases again. The internal RVDC resistor is connected between pin VDC and COM when CPH exceeds 7.5V (during preheat mode). Fault Mode (FAULT) Should the voltage at the current sensing pin, CS, exceed 1.3 volts at any time after the preheat mode, the IC enters fault mode and both gate driver outputs, HO and LO, are latched in the 'low' state. CPH is discharged to COM for resetting the preheat time, and CT is discharged to COM for disabling the oscillator. To exit fault mode, VCC must be recycled back below the UVLO negativegoing turn-off threshold, or, the shutdown pin, SD, must be pulled above 5.1 volts. Either of these will force the IC to enter UVLO mode (see State Diagram, page 6). Once VCC is above the turnon threshold and SD is below 4.5 volts, the IC will begin oscillating again in the preheat mode.
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IR2156(S)&(PbF)
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 Dead-time The dead-time between the gate driver outputs HO and LO is programmed with timing capacitor CT and an internal dead-time resistor RDT. The dead-time is the discharge time of capacitor CT from 3/5VCC to 1/3VCC and is given as: Step 3: Program Preheat Frequency The preheat frequency is programmed with timing resistors RT and RPH, and timing capacitor CT. The timing resistors are connected in parallel internally for the duration of the preheat time. The preheat frequency is therefore given as:
f PH = 1 0 .6 RT R PH 2 CT + 2000 [Hertz] (5) R +R T PH
or
1 1.12 C f - 3333 RT T PH = 1 RT - 1.12 C f - 3333 T PH
t DT = CT 2000 [Seconds]
or
(1)
RPH
[Ohms] (6)
CT =
tDT 2000
[Farads]
(2)
Step 4: Program Preheat Time The preheat time is defined by the time it takes for the capacitor on pin CPH to charge up to 13 volts (assuming Vcc = 15 volts). An internal current source of 4.3A flows out of pin CPH. The preheat time is therefore given as:
t PH = C PH 3.02e6
Step 2: Program Run Frequency The final run frequency is programmed with timing resistor RT and timing capacitor CT. The charge time of capacitor CT from 1/3VCC to 3/5VCC determines the on-time of HO and LO gate driver outputs. The run frequency is therefore given as:
[Seconds] (7)
f RUN =
or
1 2 C T ( 0 .6 RT + 2000 )
or [Hertz] (3)
C PH = t PH 0.331e - 6
[Farads] (8)
Step 5: Program Maximum Ignition Current
RT =
1 - 3333 1 .12 C T f RUN
[Ohms] (4)
The maximum ignition current is programmed with the external resistor RCS and an internal threshold of 1.25 volts. This threshold determines the overcurrent limit of the ballast, which can be exceeded when the frequency ramps down towards resonance during ignition and the lamp does not
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IR2156(S) & (PbF)
ignite. The maximum ignition current is given as: Step 3: Program Preheat Frequency The preheat frequency is chosen such that the lamp filaments are adequately heated within the preheat time. A preheat frequency of 70kHz was chosen. Using Equation (6) gives the following result:
1 1.12 C f - 3333 RT T PH = 1 - 3333 RT - 1.12 CT f PH
I IGN =
or
1.25 RCS
[Amps Peak] (9)
RCS =
1.25 I IGN
[Ohms] (10)
RPH
Design Example: 42W-QUAD BIAX CFL
Note: The results from the following design example can differ slightly from experimental results due to IC tolerances, component tolerances, and oscillator over- and under-shoot due to internal comparator response time. Step 1: Program Dead-time The dead-time is chosen to be 0.8s. Using Equation (2) gives the following result:
CT = t DT 0.8e - 6 = = 400 pF 470 pF 2000 2000
R PH
1 1 . 12 470 pF 70000 - 3333 43000 = 1 43000 - 1 . 02 470 pF 70000 - 3333
RPH = 53,330 51k
Step 4: Program Preheat Time The preheat time of 500ms seconds was chosen. Using Equation (8) gives the following result:
C PH = t PH 0.331e - 6 C PH = (500e - 3) (0.331e - 6) C PH = 0.166uF - > 0.22uF
Step 5: Program Ignition Current The maximum ignition current is given by the maximum ignition voltage and is chosen as 2.0Apk. Using Equation (10) gives the following result:
Step 2: Program Run Frequency The run frequency is chosen to be 43kHz. Using Equation (4) gives the following result:
RT = RT = 1 - 3333 1 .12 C T f RUN 1 - 3333 1 .12 470 pF 43000
RT = 40 ,846 43 k
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IR2156(S)&(PbF)
1.25 I IGN 1.3 = 0.625Ohms 0.61Ohms 2.0
RCS =
RCS =
Results
A fully-functional ballast was designed, built and tested using the calculated values. The values were then adjusted slightly in order to fulfill various ballast parameters (Table 1). The ballast was designed using the 'Typical Application Schematic' given on page 1.
Parameter fph Vph tph Rw:Rc Vign tign frun Vrun Pin Description Preheat Frequency Lamp Preheat Voltage Preheat Time Filament Preheat Ratio Maximum Ignition Voltage Ignition Ramp Time Running Frequency Running Lamp Voltage Running Ballast Input Power Value 68kHz 460Vpp 700ms 4:1 1500Vpp 50ms 47.5kHz 180Vpk 42W
Waveform 3, Half-bridge and current sense voltage during run mode
Waveform 2. Lamp voltage during preheat, ignition and run modes
Table 1, 42W-Quad Biax Ballast Measured Results
Waveforms
Waveform 1. Lamp filament voltage during preheat
Waveform 4, Lamp voltage and current sense pin during a failure-to-strike lamp fault condition.
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IR2156(S) & (PbF)
Case outline
14-Lead PDIP
01-6010 01-3002 03 (MS-001AC)
14-Lead SOIC (narrow body)
22
01-6019 01-3063 00 (MS-012AB)
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IR2156(S)&(PbF)
Bill Of Materials
Schematic: Typical Application Diagram, Page 1 Lamp Type: 42W-Quad Biax Line Input Voltage: 120VAC
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 TOTAL
Qty
1 1 1 2 2 1 1 2 1 1 2 1 1 1 2 1 1 1 2 1 1 1 1 1 30
Description
Fuse Filter Capacitor Filter Inductor Rectifier Diode Electrolytic Capacitor Resonant Inductor Charge Pump Capacitor Charge Pump Diodes Resonant Capacitor Snubber Capacitor Half-Bridge MOSFET Current Sense Resistor Limit Resistor Filter Capacitor Supply Capacitor Supply Capacitor Bootstrap Diode Ballast Control IC Resistor Timing Resistor Timing Capacitor Preheat Resistor Preheat Capacitor Capacitor
Designator
F1 CFILTER LFILTER DRECT1, DRECT2 CELCAP1, CELCAP2 LRES CCP DCP1, DCP2 CRES CSNUB M1, M2 RCS R1 CCS CBOOT, CVCC1 CVCC2 DBOOT IC1 RSUPPLY, RBUS RT CT RPH CPH CVDC
Value
0.1F/400V 330H/0.5A 1N4007 47F/250V 1.25mH/1.5A 470pF/1kV 1N4148 6.8nF/1kV 470pF/1kV IRF730 0.75R/0.5W 1k/0.25W 470pF/16V 0.1F/25V 2.2F/25V 10DF6 IR2156 1M/0.25W 39k/0.25W 470pF/25V 75k/0.25W 0.22F/25V 0.01F/25V
Manufacturer
Part No.
Device qualified to Industrial Level
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23
IR2156(S) & (PbF)
LEADFREE PART MARKING INFORMATION
Part number
IRxxxxxx YWW? ?XXXX
Lot Code (Prod mode - 4 digit SPN code) IR logo
Date code
Pin 1 Identifier ? P MARKING CODE Lead Free Released Non-Lead Free Released
Assembly site code Per SCOP 200-002
ORDER INFORMATION
Basic Part (Non-Lead Free) 14-Lead PDIP IR2156 order IR2156 14-Lead SOIC IR2156S order IR2156S Leadfree Part 14-Lead PDIP IR2156 order IR2156PbF 14-Lead SOIC IR2156S order IR2156SPbF
Thisproduct has been designed and qualified for the industrial market. Qualification Standards can be found on IR's Web Site http://www.irf.com Data and specifications subject to change without notice. IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105 10/25/2004
24
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