1/15
L6567
March 2001
This is preliminary information on a new product now in development. Details are subject to change without notice.
■BCD-OFF LINE TECHNOLOGY
■FLOATING SUPPLY VOLTAGE UP TO 570V
■GND REFERRED SUPPLY VOLTAGE UP TO
18V
■UNDER VOLTAGE LOCK OUT
■CLAMPING ON Vs
■DRIVER CURRENT CAPABILITY:
30mA SOURCE
70mA SINK
■PREHEAT AND FREQUENCY SHIFT TIMING
DESCRIPTION
The device is amonolithic high voltage integrated cir-
cuit designed to drive CFL and small TL lamps with a
minimum part count.
It provides all the necessary functions for proper pre-
heat, ignition andsteady state operation of the lamp:
♦ variable frequency oscillator;
♦ settable preheating and ignition time;
♦ capacitive mode protection;
♦ lamp power independent from mains voltage variation.
Besides the control functions, the IC provides the lev-
el shift and drive function for two external power MOS
FETs in a half-bridge topology.
SO14 DIP14
ORDERING NUMBERS:
L6567D L6567
HIGH VOLTAGE DRIVER FOR CFL
BLOCK DIAGRAM
L
FEED FORWARD
VCO +
FREQ. SHIFTING
VOLTAGE
REFERENCE
BIAS
CURRENT
GENERATOR
CSCfCi
CI
CF
VS
to
comp.
14
12
5
13
PREHEATING
TIMING
LOGIC
RHV
Rhv
Vhv
Cp/Cav
C
10
11
8
CP
LEVEL
SHIFTING
HIGH
SIDE
DRIVER
VS
Cboot
FS
G1
S1
1
2
3
LOW
SIDE
DRIVER
T1
6
7
9
Vhv
Chv
Chv MAINS
T2
Rshunt
G2
PGND
RS
RREF
Ref
D96IN441B
Lamp
CL
SGND
MULTIPOWER BCD TECHNOLOGY
L6567
2/15
PIN FUNCTION
PIN CONNECTION (Top view)
N°Pin Description
1F
S
Floating Supply of high side driver
2 G1 Gate of high side switch
3 S1 Source of high side switch
4 NC High Voltage Spacer. (Should be not connected)
5V
S
Supply Voltage for GND level control and drive
6 G2 Gate of low side switch
7 PGND Power Ground
8 CP First timing (TPRE TIGN), then averaging the ripple in the representation of the HVB (derived
through RHV).
9R
S
R
SHUNT: current monitoring input
10 RREF Reference resistor for current setting
11 SGND Signal Ground. Internally Connected to PGND
12 CF Frequency setting capacitor
13 RHV Start-up supply resistor,then supply voltage sensing.
14 CI Timing capacitor for frequency shift
FS
G1
S1
N.C.
VS
PGND
G2
CP
RREF
RS
SGND
CF
RHV
CI1
3
2
4
5
6
7
12
11
10
9
8
13
14
D96IN440
3/15
L6567
ABSOLUTE MAXIMUM RATINGS
NOTES: (1) Do not exceed package thermal dissipation limits
(2)For VS ≤VShigh 1
(3) For VS > VS high 1
(4) Internally Limited
Note: ESD immunity for pins 1, 2 and 3 is guaranteed up to 900 V (Human Body Model)
Symbol Parameter Value Unit
VSLow Voltage Supply 18 (1) V
VRHV Mains Voltage Sensing VS +2VBE (2)
VCP Preheat/Averaging 5 V
VCF Oscillator Capacitor Voltage 5 V
VCI Frequency Shift Capacitor Voltage 5 V
VRREF Reference Resistor Voltage 5 V
VRS Current Sense Input Voltage -5 to 5 V
transient 50ns -15 V
VG2 Low Side Switch Gate Output 18 V
VS1 High Side Switch Source Output: normal operation -1 to 373 V
0.5sec mains transient -1 to 550 V
VG1 High Side Switch Gate Output: normal operation -1 to 391 V
0.5sec mains transient -1 to 568 V
with respect to pin S1 Vbe to VSV
VFS Floating Supply Voltage: normal operation 391 V
0.5sec mains transient 568 V
VFS/S1 Floating Supply vs S1 Voltage 18 V
∆VFS/∆TVFS Slew Rate (Repetitive) -4 to 4 V/ns
∆VS1/∆TVS1 Slew Rate (Repetitive) -4 to 4 V/ns
IRHV Current Into RHV 3 (3) mA
IVs Clamped Current into VS200 (4) mA
Tstg Storage Temperature -40 to 150 °C
TjJunction Temperature -40 to 150 °C
L6567
4/15
ELECTRICAL CHARACTERISTCS
(VS=12V;R
REF =30KΩ;C
F= 100pF; Tj=25°C; unless otherwise specified.)
Symbol Parameter Test Condition Min. Typ. Max. Unit
VS- SUPPLY VOLTAGE SECTION
VS high 1 VSTurn On Threshold 10.7 11.7 12.7 V
VS high2 VSClamping Voltage VS = 20mA 12 13 14 V
VS low 2 VSTurn Off Threshold 9 10 11 V
VS HYST Supply Voltage Hysteresis 1.5 1.65 1.8 V
VS low 1 VSVoltage to Guarantee
VG1 =”0”and VG2 =”1 16V
I
SSP VSSupply Current at Start Up VS= 10.6V Before turn on 50 250 µA
ISOP VSSupply Operative Current VS= VShigh 1 1.2 mA
OSCILLATOR SECTION
fosc min Minimum Oscillator frequency IRHV = 0mA; CI = 5V 41.7 43 44.29 kHz
fosc 600
m
Feed Forward Frequency IRHV = 600mA 47.88 50.4 52.92 kHz
fosc 1mA Feed Forward Frequency IRHV = 1mA 79.8 84 88.2 kHz
fosc max Maximum Oscillator Frequency CI = 0V 96.75 107.5 118.25 KHz
∆ICF/∆VCI Oscillator Transconductance 9 17.5 µA/V
PREHEAT/IGNITION SECTION
P.H.T. Preheat Time Cp = 150nF 0.88 1 1.12 sec
P.H.clocks Number of Preheat Clocks 16
IGN.clocks Number of Ignition Clocks 15
RATE OF FREQUENCY CHANGE SECTION
ICIP charge CI Charging Current During
Preheat 106 118 130 mA
ICII charge CI Charging Current During
Ignition 1 1.2 1.4 mA
ICI disch CI Discharge Current -52 -47 -42 mA
VTH CI CI Low Voltage Threshold 10 100 mV
RS - THRESHOLD SECTION
VCMTH Capacitive Mode Voltage
Threshold 02040mV
V
PH Preheat Voltage Threshold -0.64 -0.6 -0.56 V
G1 - G2 DELAY TIMES SECTION
G1DON On Delay of G1 Output 1.05 1.4 1.75 µs
5/15
L6567
(*) Before startingthe first commutation; when switching 6V is guaranteed.
General operation
The L6567 uses a small amount of current from a supply resistor(s) to start the operation of the IC. Once start
up condition is achieved, the IC turns on the lower MOS transistor of the half bridge which allows the bootstrap
capacitor to charge. Once this is achieved, the oscillator begins toturn on the upper and lower MOS transistors
at high frequency, and immediately ramps down to a preheat frequency. During this stage, the IC preheats the
lamp and after a predetermined time ramps down again until it reaches the final operating frequency. The IC
monitors thecurrent to determine if the circuitis operating in capacitive mode. If capacitive switching is detected,
the IC increases the output frequency until zero-voltage switching is resumed.
Startup and supply in normal operation
At start up the L6567 is powered via a resistor connected to the RHV pin (pin 13) from the rectified mains. The
current charges the CScapacitor connected to the VSpin (pin 5). When the VSvoltage reaches the threshold
VSLOW1(max 6V), the low side MOS transistor is turned on while the high side one is kept off. This condition
assures that the bootstrap capacitor is charged. When VSHIGH1 threshold is reached the oscillator starts, and
the RHV pin does not provide anymore the supply current for the IC (see fig.1).
G2DON On Delay of G2 Output 1.05 1.4 1.75 µs
Ratio between Delay Time +
Conduction Time of G1 and G2 IRHV = 1mA; Cl = 5V
Cl = 0V 0.87
0.77 1.15
1.30
LOW SIDE DRIVER SECTION
Ron G2 so G2 Source Output Resistance VS= 12V, V = 3V 80 190 Ω
Ron G2 si G2 Sink Output Resistance VS= 12V, V = 3V 65 125 Ω
Ron G1 so G1 Source Output Resistance VS= 10V, V = 3V 80 190 Ω
Ron G1 si G1 Sink Output Resistance VS= 10V, V = 3V 65 125 Ω
HIGH SIDE DRIVER SECTION
IFSLK Leakage Current of FS PIN to
GND VFS = 568V; G1 = L
VFS = 568V; G1 = H 5
5µA
µA
IS1 LK Leakage Current of S1 PIN to
GND VS1 = 568V;G1 = L
VS1 = 568V;G1 = H 5
5µA
µA
BOOTSTRAP SECTION
Boot Th BOOTSTRAP Threshold VS= 10.6V before turn on 5 (*) V
AVERAGE RESISTOR
RAVERAGE Average Resistor 27 38.5 50 kΩ
Symbol Parameter Test Condition Min. Typ. Max. Unit
G1DON G1ON
+
G2DON G2ON
+
-------------------------------------------
ELECTRICAL CHARACTERISTCS (Continued)
L6567
6/15
Figure 1. Start up
Oscillator
The circuit starts oscillating when the voltage supply VShas reached the VS HIGH1 threshold. In steady state
condition the oscillator capacitor CF(at pin 12)is charged anddischarged symmetrically with a current setmain-
ly by the external resistor RREF connected to pin 10. The value of the frequency is determined by capacitor CF
and resistor RREF. This fixed value is called FMIN. A dead time TDT between the ON phases of the transistors
is provided for avoiding cross conduction, so the duty cycle for each is less than 50%. The dead time depends
on RREF value (fig. 7).
The IC oscillating frequency is between FMIN and FMAX = 2.5 · FMIN in all conditions.
Preheatingmode
The oscillator starts switching at the maximum frequency FMAX. Then the frequency decreases at once to reach
the programmed preheating frequency (fig.2). The rate of decreasing (df/dt) is determined by the external ca-
pacitor CI(pin 14). The preheat time TPRE is adjustable with external components (RREF and CP). The preheat
current is adjusted by sense resistance RSHUNT. During the preheating time the load current is sensed with the
sense resistor RSHUNT (connected between pin 9-RS- and pin 7-PGND-). At pin 9 the voltage drop on RSHUNT
is sensed at themoment the low side MOS FET is turnedoff. There is an internal comparator with afixed thresh-
old VPH:ifV
RS>V
PHthe frequency isdecreased and if VRS<VPHthefrequency is increased. If the VPHthresh-
old is reached, the frequency is held constant for the programmed preheating time TPRE.
TPREis determined by the external capacitor CP(pin8) and by the resistor RREF:C
Pis charged 16 times with a
current that depends on RREF, and these 16 cycles determine the TPRE.
So the preheat mode is programmable with external components as far as TPRE is concerned (RREF &CP) and
as far as the preheating current is concerned (choosing properly RSHUNTand the resonant load components:
LandC
L
).
The circuit is held in the preheating mode when pin 8 (CP) is grounded.
In case FMIN is reached during preheat, the IC assumes an open load. Consequently the oscillation stops with
the low side MOS transistor gate on and the high side gate off. This condition is kept until V
Sundershoots VSLOW1
.
VSLOW1
VSHIGH1
VG
lowside mosfet
VG-VS
high side mosfet
CF
VSTDT
TIME
0
0
0
0
7/15
L6567
Figure 2. Preheating and ignition state.
Ignitionmode
At the end of the preheat phase the frequency decreses to the minimum frequency (FMIN), causing anincreased
coil current and a high voltage appearing across the lamp. That is because the circuit works near resonance.
This high voltage normally ignites the lamp. There is no protection to avoid high ignition currents through the
MOS transistors when the lamp doesn’t ignite. Thisonly occurs in an end of lamp life situation in which the circuit
may break. Now the lowest frequency is the resonance frequency of L and CL(the capacitor across the lamp).
The ignition phase finishes when the frequency reaches FMIN or (at maximum) when the ignition time has
elapsed. The ignition time is related to TPRE:T
IGN= (15/16) · TPRE. The CPcapacitor is charged 15 times with
the same current used to charge it during TPRE.
The frequency shifting slope is determined by CI.
During the ignition time the VRS monitoring function changes in the capacitive mode protection.
Steady state operation: feed forwardfrequency
The lamp starts operating at FMIN, determined by RREF and CFdirectly after the ignition phase. To prevent too
high lamp power at high mains voltages, a feed forward correction is implemented. At the end of the preheat
phase the RHV pinisconnected to an internal resistor to sense the HighVoltage Bus.If the current in this resistor
increases and overcomes a value set by RREF , the current that charges the oscillator capacitor CFincreases
too. The effect is an increase in frequency limiting the power in the lamp. In order to prevent feed forward of the
ripple of the VHV voltage, the ripple is filtered with capacitor CPon pin 8 and an integrated resistor RAVERAGE.
Figure 3. Burn state
TIME
FREQUENCY
FMAX
FMIN
preheating
state ignition
state burning state
FMIN feed forward mode
FREQUENCY
Irhv
L6567
8/15
Capacitive mode protection
During ignition and steady state the operating frequency is higher than the resonance frequency of the load
(L,CL,RLAMP and RFILAMENT), so the transistors are turned on during the conduction time of the body diode in
order to maintain Zero Voltage Switching.
If the operating frequency undershoots the resonance frequency ZVS doesn’t occur and causes hard switching
of the MOStransistors. The L6567 detects this situation bymeasuring VRSwhen the lowsideMOS FET is turned
on. At pin 9 there is an internal comparatorwith thresholdV
CMTH (typ~20mV): if VRS <V
CMTH capacitive mode is
assumed and the frequency is increased as long as this situation is present. The shift is determined by CI.
Steady state frequency
At any time during steady state the frequency isdetermined by the maximum on the following three frequencies:
fSTEADY STATE=MAX{F
MIN,f
FEEDFORWARD
,f
CAPACITIVEMODEPROTECTION}.
IC supply
At start up the IC is supplied with a current that flows through RHV and an internal diode to the VSpin which-
charges the external capacitor CS. In steady state condition RHVis used as a mains voltage sensor, so it doesn’t
provide anymore the supply current. The easiest way to charge the CScapacitor (and tosupply the IC) is to use
a charge pump from the middle point of the half bridge.
To guarantee a minimum gate power MOS drive, the IC stops oscillating when VSis lower than VSHIGH2
. It will
restart once the VSwillbecome higher than VSHIGH1
. A minimum voltage hysteresis is guaranteed. The IC re-
starts operating at f = FMAX,then the frequency shifts towards FMIN. The timingof this frequency shifting is TIGN
(that is: CPcapacitor is charged and discharged 15 times).Now the oscillator frequency is controlled as in stan-
dard burning condition (feed forward and capacitive mode control). Excess charge on CSis drained by an inter-
nal clamp that turns on at voltage VSCL.
Groundpins
Pin 7(PGND) is the ground reference of the IC with respect to the application. Pin 11( SGND) provides a local
signal ground reference for the components connected to the pins CP,C
I
,R
REF and CF.
Relationship between external components and sistem working condition
L6567 is designed to drive CFL and TL lamps with a minimum part count topology. This feature implies that each
external component is related to one or more circuit operating state.
This table is a short summary of these relationships:
FMIN ---> RREF &C
F
F
FEEDFORWARD--->CF&I
RHV
TPRE &T
IGN ---> CP&R
REF
FPRE ---> RSHUNT,L,C
L
, LAMP
TDT ---> RREF
df/dt ---> CI
Some useful formulas can well approximate the values:
If IRHV is greater than: , the feed forward frequency is settledand the frequency value is fitted by the
following expression:
FMIN 1
8R
REF CF
⋅⋅
---------------------------------
≅
IRHV 15
RREF
--------------
≥
FFEEDFORWARD IRHV
121 CF
⋅
---------------------≅
9/15
L6567
Other easy formulas fit rather well:
TDT
≅
46.75 · 10^-12 ·R
REF
TPRE≅224 · CP·R
REF
As faras df/dt is concerned, there are no easy formulas that fitthe relation between CF,R
F
, and CI.C
Iis charged
and discharged by three different currents that are derived from different mirroring ratios by the current flowing
on RREF. The voltage variations on CIare proportional to the current that charges CF, that is to say they are
proportional to df/dt.
The values obtained in the testing conditions (CI= 100nF) are:
during preheating and working conditions the typical frequency increase is ~ 20KHz/ms, the typical decrease is
~-10Khz/ms;
During ignition the frequency variation is ~ -200Hz/ms.
If slower variations are needed, CI has to be increased.
Due to these tight relationships, it is recommended to follow a precise procedure: first RHV has to be chosen
looking at startup current needs and dissipation problems. Then the feed forward frequency range has to be
determined, and so CFis set.
Given a certain CF,R
REF is set in order to fix FMIN. Now CPcan be chosed to set the desired TPRE and TIGN.
The other external parameters (RSHUNT and CI) can be chosen at the end because they are just related to a
single circuit parameters.
L6567
10/15
Figure 4. IC Operation
START
VS>VSLOW1
RESTARTWITH
F=FMAX
FREQUENCYSHIFTSIN T=TIGN
TOWARDSBURNINGSTATECONDITION
(F=MAX{FMAX,FFEEDFORWARD,FCAPACITIVEMODE})
NO OSCILLATION
LOW SIDE MOS ON
HIGH SIDE MOS OFF
VS>VSHIGH1
Y
Y
N
N
START OSCILLATION
F=FMAX
T=T0
N
T=T0+TPRE
Y
VRS>VPH
N
F>FMIN
DECREASE
FREQUENCY
OPEN LOAD DETECTION:STOP
LOW SIDE MOSON
AND HIGH SIDEMOS OFF
INCREASE
FREQUENCY
NY
Y
N
V
S
>VSHIGH2
VS>VSHIGH2
T>T0+TPRE+TIGN
Y
N
F>FMIN
DECREASE
FREQUENCY
INCREASE
FREQUENCY
Y
NY
N
Y
FEED FORWARD MODE
ACTIVATED
VS>VSHIGH2
VRS<VCMTH
VRS<VCMTH
F>FFEEDFORWARD
F>FMIN
DECREASE
FREQUENCY
INCREASE
FREQUENCY
Y
N
N
Y
Y
N
Y
N
STOP OSCILLATION
LOW SIDE MOS ON
HIGH SIDE MOS OFF
VS>VSHIGH1
Y
N
Y
PREHEATING MODE IGNITION MODE
BURNING MODE
11/15
L6567
Figure 5. Working frequency vs I
RHV
@R
REF = 30Kohm
Figure 6. Frequency vs C
F@R
REF=30Kohm
Figure 7. TDT vs RREF @C
F= 100pF
Figure 8. Frequency vs IRHV @C
F= 82pF
Figure 9. Frequency vs IRHV @C
F
=100pF
Figure 10. Frequency vs IRHV @C
F
=120pF
0.20 0.40 0.60 0.80 1.00 1.20
Irhv [mA]
10.00
20.00
30.00
50.00
60.00
70.00
90.00
100.00
110.00
130.00
140.00
150.00
0.00
40.00
80.00
120.00
160.00
frequency [kHz]
Cf=47pF
Rref=30Kohm
Cf=56pF
Cf=68pF
Cf=82pF
Cf=100pF
Cf=120pF
Cf=150pF
Cf=180pF
Cf=220pF
60.00 100.00 140.00 180.00 220.0040.00 80.00 120.00 160.00 200.00 240.00
Cf[pF]
10.00
20.00
30.00
50.00
60.00
70.00
90.00
100.00
110.00
130.00
140.00
150.00
0.00
40.00
80.00
120.00
160.00
frequency[kHz]
I=0.5mA
I=0 .75 mA)
I=1mA
Rref=30Kohm
20.00 30.00 40.00 50.00 60.00
Rref[Kohm]
0.80
1.20
1.60
2.00
2.40
Tdt[us]
Tdt[measured data]
Tdt [calculated data]
0.20 0.40 0.60 0.80 1.00 1.20
Irhv [mA]
40.00
60.00
80.00
100.00
120.00
frequency [kHz]
Rref=20K
Rref=22K
Rref=24K
Rref=27K
Rref=30K
Rref=33K
Rref=36K
Rref=39K,43K, 47K, 51K
0.20 0.40 0.60 0.80 1.00 1.20
Irhv [m A]
20.00
40.00
60.00
80.00
100.00
frequency [kHz]
Rref=20K
Rref=22K
Rref=24K
Rref=27K
Rref=30K
Rref=33K
Rref=36K
Rref=39K,43K
0.20 0.40 0.60 0.80 1.00 1.20
Irhv [mA]
20.00
40.00
60.00
80.00
frequency [kHz]
Rref=20K
Rref=22K
Rref=24K
Rref=27K
Rref=30K
Rref=33K
Rref=36K
Rref=39K
Rref=43K, 47K, 51K
L6567
12/15
Figure 11. Frequency vs IRHV @C
F
= 150pF
Figure 12. FMIN: measurementsand calculations
Figure 13. FFEED FORWARD: measurements and
calculations
0.20 0.40 0.60 0.80 1.00 1.20
Irhv [mA]
20.00
40.00
60.00
80.00
frequency [kHz]
Rref=20K
Rref=22K
Rref=24K
Rref=27K
Rref=30K
Rref=33K
Rref=36K
Rref=39K
Rref=43K, 47K, 51K
20.00 30.00 40.00 50.00
Rref[Kohm]
0.00
20.00
40.00
60.00
80.00
100.00
Fmin [KHz]
Cf=82pF
Cf=100pF
Cf=120pF
Cf=150pF
measuraments
Fmin=1/(8*Cf*Rref)
0.40 0.60 0.80 1.00 1.20
Irhv [mA]
0.00
10000.00
20000.00
30000.00
40000.00
50000.00
60000.00
70000.00
80000.00
90000.00
100000.00
110000.00
120000.00
Freq. feed forward [Hz]
measurements
calculations (1/121)*Irhv/Cf Cf=82pF
Cf=100pF
Cf=120pF
Cf=150pF
13/15
L6567
DIP14
DIM. mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
a1 0.51 0.020
B 1.39 1.65 0.055 0.065
b 0.5 0.020
b1 0.25 0.010
D 20 0.787
E 8.5 0.335
e 2.54 0.100
e3 15.24 0.600
F 7.1 0.280
I 5.1 0.201
L 3.3 0.130
Z 1.27 2.54 0.050 0.100
OUTLINE AND
MECHANICAL DATA
L6567
14/15
SO14
DIM. mm inch
MIN.. TYP. MAX.. MIN.. TYP.. MAX..
A 1.75 0.069
a1 0.1 0.25 0.004 0.009
a2 1.6 0.063
b 0.35 0.46 0.014 0.018
b1 0.19 0.25 0.007 0.010
C 0.5 0.020
c1 45°(typ.)
D (1) 8.55 8.75 0.336 0.344
E 5.8 6.2 0.228 0.244
e 1.27 0.050
e3 7.62 0.300
F (1) 3.8 4 0.150 0.157
G 4.6 5.3 0.181 0.209
L 0.4 1.27 0.016 0.050
M 0.68 0.027
S8°
(1) D andF do not includemold flashor protrusions. Moldflash or
potrusions shallnot exceed0.15mm (.006inch).
OUTLINE AND
MECHANICAL DATA
(max.)
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences
of use of such information nor for any infringement of patents or other rights ofthird partieswhich may resultfrom its use.No license isgranted
by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject
to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not
authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
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15/15
L6567
