L6567D013TR - STMicroelectronics, Inc.

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

FEED FORWARD

VCO +

FREQ. SHIFTING

VOLTAGE

REFERENCE

BIAS

CURRENT

GENERATOR

CSCfCi

comp.

PREHEATING

TIMING

LOGIC

RHV

Rhv

Vhv

Cp/Cav

LEVEL

SHIFTING

HIGH

SIDE

DRIVER

Cboot

LOW

SIDE

DRIVER

Vhv

Chv

Chv MAINS

Rshunt

PGND

RREF

Ref

D96IN441B

Lamp

SGND

MULTIPOWER BCD TECHNOLOGY

L6567

2/15

PIN FUNCTION

PIN CONNECTION (Top view)

N°Pin Description

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)

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).

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

N.C.

PGND

RREF

SGND

RHV

CI1

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

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

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

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

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

lowside mosfet

VG-VS

high side mosfet

VSTDT

TIME

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

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

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

FEEDFORWARD--->CF&I

RHV

TPRE &T

IGN ---> CP&R

REF

FPRE ---> RSHUNT,L,C

, 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

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

, 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

START OSCILLATION

F=FMAX

T=T0

T=T0+TPRE

VRS>VPH

F>FMIN

DECREASE

FREQUENCY

OPEN LOAD DETECTION:STOP

LOW SIDE MOSON

AND HIGH SIDEMOS OFF

INCREASE

FREQUENCY

>VSHIGH2

VS>VSHIGH2

T>T0+TPRE+TIGN

F>FMIN

DECREASE

FREQUENCY

INCREASE

FREQUENCY

FEED FORWARD MODE

ACTIVATED

VS>VSHIGH2

VRS<VCMTH

F>FFEEDFORWARD

F>FMIN

DECREASE

FREQUENCY

INCREASE

FREQUENCY

STOP OSCILLATION

LOW SIDE MOS ON

HIGH SIDE MOS OFF

VS>VSHIGH1

PREHEATING MODE IGNITION MODE

BURNING MODE

11/15

L6567

Figure 5. Working frequency vs I

RHV

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

=100pF

Figure 10. Frequency vs IRHV @C

=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

= 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.

The ST logo is a registered trademark of STMicroelectronics

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L6567