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February 2012

FAN7710V

Ballast Control IC for Compact Fluorescent Lamps

Features

Description

FAN7710V developed using Fairchild’s high-voltage

process and system-in-package (SiP) concept, are

ballast-control integrated circuits (ICs) for compact

fluorescent lamps (CFL). FAN7710V incorporates a

preheating / ignition function, controlled by a user-

selected external capacitor, to increase lamp life. The

FAN7710V detects switch operation after ignition mode

through an internal active Zero-Voltage Switching (ZVS)

control circuit. This control scheme enables the

FAN7710V to detect an open-lamp condition, without the

expense of external circuitry, and prevents stress on the

MOSFETs. The high-side driver in the FAN7710V has a

common-mode noise cancellation circuit that provides

robust operation against high-dv/dt noise intrusion.

.

Integrated Half-Bridge MOSFET

Floating Channel FAN7710V for Bootstrap Operation

to +440V

.

Low Startup and Operating Current: 120μA, 2.6mA

Under-Voltage Lockout with 1.8V of Hysteresis

Adjustable Run Frequency and Preheat Time

Internal Active ZVS Control

Internal Protection Function (No Lamp)

Internal Clamping Zener Diode

High Accuracy Oscillator

Soft-Start Functionality

8-DIP

Applications

.

Compact Fluorescent Lamp Ballast

Ordering Information

Operating

Temperature

Part Number

Package

Packing Method

FAN7710VN

-40 to +125°C

8-Lead Dual Inline Package (DIP)

Tube

FAN7710V • 1.0.4

www.fairchildsemi.com

Typical Applications Diagrams

Figure 1. Typical Application Circuit for Compact Fluorescent Lamp

Internal Block Diagram

Figure 2. Functional Block Diagram

FAN7710V • 1.0.4

www.fairchildsemi.com

2

Pin Configuration

Figure 3. Pin Configuration (Top View)

Pin Definitions

Pin #

Name

VDC

VB

Description

1

2

3

4

5

6

7

8

High-Voltage Supply

High-Side Floating Supply

Supply Voltage

VDD

RT

Oscillator Frequency Set Resistor

Preheating Time Set Capacitor

Signal Ground

CPH

SGND

PGND

OUT

Power Ground

High-Side Floating Supply Return

FAN7710V • 1.0.4

www.fairchildsemi.com

3

Absolute Maximum Ratings

Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be

operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In

addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The

absolute maximum ratings are stress ratings only. T_A=25°C unless otherwise specified.

Symbol

VB

Parameter

High-Side Floating Supply Voltage

High-Side Floating Supply Return

RT, CPH Pins Input Voltage

Min.

-0.3

Typ.

Max.

465.0

440.0

8.0

Unit

V

V_OUT

V_IN

V

I_CL

Clamping Current Level⁽¹⁾

25

mA

V/ns

°C

dV_OUT/dt

T_A

Allowable Offset Voltage Slew Rate

Operating Temperature Range

Storage Temperature Range

50

-40

-65

+125

+150

T_STG

°C

P_D

Power Dissipation

2.1

70

W

Thermal Resistance, Junction-to-Air

°C/W

Θ_JA

Note:

1. Do not supply a low-impedance voltage source to the internal clamping Zener diode between the GND and the

VDD pin of this device.

FAN7710V • 1.0.4

www.fairchildsemi.com

4

Electrical Characteristics

V_BIAS(V_DD, V_B-V_OUT)=14.0V and T_A=25°C, unless otherwise specified.

Symbol

Parameter

Conditions

Min. Typ. Max. Unit

High-Voltage Supply Section

V_DC

High-Voltage Supply Voltage

440

V

Low-Side Supply Section (V_DD

)

V_DDTH(ST+)V_DDUVLO Positive-Going Threshold

V_DDTH(ST-)V_DDUVLO Negative-Going Threshold

V_DDHY(ST)V_DD-Side UVLO Hysteresis

V_DDIncreasing

12.4

10.8

13.4

11.6

1.8

14.4

12.4

V_DDDecreasing

V

V_CL

I_ST

Supply Camping Voltage

I_DD=10mA

14.8

15.2

120

2.6

Startup Supply Current

V_DD=10V

µA

I_DD

Dynamic Operating Supply Current

50kHz, C_L=1nF

mA

High-Side Supply Characteristics (V_B-V_OUT

)

V_HSTH(ST+)High-Side UVLO Positive-Going Threshold

V_HSTH(ST-)High-Side UVLO Negative-Going Threshold

V_HSHY(ST)High-Side UVLO Hysteresis

V_B-V_OUTIncreasing

V_B-V_OUTDecreasing

8.5

7.9

9.2

8.6

0.6

50

10.0

9.5

V

I_HST

I_HD

High-Side Quiescent Supply Current

V_B-V_OUT=14V

µA

High-Side Dynamic Operating Supply Current

50kHz, C_L=1nF

250

Oscillator Section

V_MPHCPH Pin Preheating Voltage Range

I_PH

2.5

1.25

8

3.0

2.00

12

3.5

2.85

16

V

CPH Pin Charging Current During Preheating

CPH Pin Charging Current During Ignition

CPH Pin Voltage Level at Running Mode

Preheating Frequency

V_CPH=1V

V_CPH=4V

µA

I_IG

V_MO

f_PRE

f_OSC

7.0

85

V

72

98

kHz

R_T=80kΩ, V_CPH=2V

R_T=80kΩ

Running Frequency

48.7

53.0

57.3

V_CPH=1V, V_OUT=SGND

During Preheat Mode

DT_MAX

DT_MIN

Maximum Dead Time

Minimum Dead Time

3.1

1.0

µs

V_CPH=6V, V_OUT=SGND

During Run Mode

Protection Section

V_CPHSDShutdown Voltage

2.6

V

V_RT=0 After Run Mode

I_SD

Shutdown Current

250

450

µA

°C

TSD

Thermal Shutdown⁽²⁾

+165

Internal MOSFET Section

I_LKMOS

R_ON

I_S

Internal MOSFET Leakage Current

Static Drain-Source On-Resistance

V_DS=400V

50

6.0

µA

V_GS=10V, I_D=190mA

4.6

Ω

Maximum Continuous Drain-Source Diode Forward Current

0.38

3.04

1.4

A

V

I_SM

Maximum Pulsed Continuous Drain-Source Diode Forward Current

V_SD

Drain-Source Diode Forward Voltage

V_GS=0V, I_S=0.38A

Note:

2. These parameters, although guaranteed, is not 100% tested in production.

www.fairchildsemi.com

FAN7710V • 1.0.4

5

Typical Performance Characteristics

Figure 4. Startup Current vs. Temperature

Figure 5. Preheating Current vs. Temperature

Figure 6. Ignition Current vs. Temperature

Figure 7. Operating Current vs. Temperature

Figure 8. High-Side Quiescent Current

vs. Temperature

Figure 9. Shutdown Current vs. Temperature

FAN7710V • 1.0.4

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6

Typical Performance Characteristics (Continued)

Figure 10. V_DDUVLO vs. Temperature

Figure 11. V_BSUVLO vs. Temperature

Figure 12. V_DDClamp Voltage vs. Temperature

Figure 13. Shutdown Voltage vs. Temperature

Figure 14. Running Frequency vs. Temperature

Figure 15. Preheating Frequency vs. Temperature

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FAN7710V • 1.0.4

7

Typical Performance Characteristics (Continued)

Figure 16. Minimum Dead Time vs. Temperature

Figure 17. Maximum Dead Time vs. Temperature

Figure 19. On-Resistance Variation vs.

Drain Current and Gate Voltage

Figure 18. On-Region Characteristics

Figure 20. Body Diode Forward Voltage Variation

vs. Source Current and Temperature

Figure 21. Breakdown Voltage Variation

vs. Temperature

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FAN7710V • 1.0.4

8

Typical Performance Characteristics (Continued)

Figure 22. On-Resistance Variation vs. Temperature

Figure 23. Maximum Safe Operating Area

Figure 24. Maximum Drain-Current

vs. Case Temperature

www.fairchildsemi.com

FAN7710V • 1.0.4

9

Typical Application Information

result, the current warms up the filament for easy

ignition. The amount of the current can be adjusted by

controlling the oscillation frequency or changing the

capacitance of C_P. The driving frequency, f_PRE, is called

preheating frequency and is derived by:

1. Under-Voltage Lockout (UVLO) Function

The FAN7710V has UVLO circuits for both high-side and

low-side circuits. When V_DDreaches V_DDTH(ST+), UVLO is

released and the FAN7710V operates normally. At UVLO

condition, FAN7710V consumes little current, noted as

I_ST. Once UVLO is released, FAN7710V operates

normally until V_DDgoes below V_DDTH(ST-), the UVLO

hysteresis. At UVLO condition, all latches that determine

the status of the IC are reset. When the IC is in the

shutdown mode, the IC can restart by lowering V_DD

f_PRE= 1.6 × f_OSC

(1)

After the warm-up, the FAN7710V decreases the

frequency, shown as (B) of Figure 26. This action

increases the voltage of the lamp and helps the

fluorescent lamp ignite. The ignition frequency is

described as a function of CPH voltage, as follows:

voltage below V_DDTH(ST-)

.

FAN7710V has a high-side gate driver circuit. The supply

for the high-side driver is applied between V_Band V_OUT

.





+1 × f

CPH OSC

f_IG

=

0.3 × 5-V

(2)

(

)





To protect from malfunction of the driver at low supply

voltage between V_Band V_OUT, there is an additional

UVLO circuit between the supply rails. If V_B-V_OUTis under

V_HSTH(ST+), the driver holds LOW state to turn off the high-

side switch, as shown in Figure 25. As long as V_B-V_OUTis

where V_CPHis the voltage of CPH capacitor.

Equation 2 is valid only when V_CPHis between 3V and 5V

before entering running mode. Once V_CPHreaches 5V,

the internal latch records the exit from ignition mode.

Unless V_DDis below V_DDTH(ST-), the preheating and

ignition modes appear only during lamp-start transition.

higher than V_HSTH(ST-)after V_B-V_OUTexceeds V_HSTH(ST+)

operation of the driver continues.

,

2. Oscillator

Finally, the lamp is driven at a fixed frequency by an

external resistor, R_T, shown as (C) in Figure 26. If V_DDis

higher than V_DDTH(ST+)and UVLO is released, the voltage

of the RT pin is regulated to 4V. This voltage adjusts the

oscillator's control current according to the resistance of

R_T. Because this current and an internal capacitor set the

oscillation frequency, the FAN7710V does not need any

external capacitors.

The ballast circuit for a fluorescent lamp is based on the

LCC resonant tank and a half-bridge inverter circuit, as

shown in Figure 25. To accomplish Zero-Voltage

Switching (ZVS) of the half-bridge inverter circuit, the

LCC is driven at a higher frequency than its resonant

frequency, which is determined by L, C_S, C_P, and R_L;

where R_Lis the equivalent lamp's impedance.

V_DC

The proposed oscillation characteristic is given by:

FAN7710

V_DD

RT

V_DC

4 ×10⁹

RT

Inverter

(3)

f_OSC

=

Oscillator

V_B

V_DD

High-side

LCC resonant tank

driver

Even in the active ZVS mode, shown as (D) in Figure 26,

the oscillation frequency is not changed. The dead time

is varied according to the resonant tank characteristic.

Filament

L

C_S

RT

Dead-time

controller

CPH

OUT

PGND

Low-side

driver

CPH

SGND

R_L

C_P

40dB

equivalent lamp impedance

FAN7710 Rev. 1.00

Figure 25. Typical Connection Method

R_L=100k

The transfer function of LCC resonant tank is heavily

dependent on the lamp impedance, R_L, as illustrated in

Figure 26. The oscillator in FAN7710V generates

effective driving frequencies to assist lamp ignition and

improve lamp life longevity. Accordingly, the oscillation

frequency is changed in following sequence:

20dB

R_L=10k

Preheating

frequency

(B)

0dB

Preheating Frequency → Ignition Frequency → Normal

Running Frequency

(A)

(C)

R_L=1k

Running frequency

R_L=500

Before the lamp is ignited, the lamp impedance is very

high. Once the lamp is turned on, the lamp impedance

significantly decreases. Since the resonant peak is very

high due to the high-resistance of the lamp at the instant

of turning on the lamp, the lamp must be driven at higher

frequency than the resonant frequency, shown as (A) in

Figure 26. In this mode, the current supplied by the

inverter mainly flows through C_P. C_Pconnects both

filaments and makes the current path to ground. As a

(D) Dead-time control mode

at fixed frequency

FAN7710 Rev. 1.00

Figure 26. LCC Transfer Function in Terms

of Lamp Impedance

FAN7710V • 1.0.4

www.fairchildsemi.com

10

3.2 Ignition Mode (t1~t2)

3. Operation Modes

FAN7710V has four operation modes: (A) preheating

mode, (B) ignition mode, (C) active ZVS mode and (D)

shutdown mode; all depicted in Figure 27. The modes

are automatically selected by the voltage of CPH

capacitor shown in Figure 27. In modes (A) and (B), the

CPH acts as a timer to determine the preheating and

ignition times. After preheating and ignition modes, the

role of the CPH is changed to stabilize the active ZVS

control circuit. In this mode, the dead time of the inverter

is selected by the voltage of CPH. Only when in active

ZVS mode is it possible to shut off the whole system

using the CPH pin. Pulling the CPH pin below 2V in

active ZVS mode causes the FAN7710V series to enter

shutdown mode. In shutdown mode, all active operation

is stopped except UVLO and some bias circuitry. The

shutdown mode is triggered by the external CPH control

or the active ZVS circuit. The active ZVS circuit

automatically detects lamp removal (open-lamp

condition) and decreases CPH voltage below 2V to

protect the inverter switches from damage.

When the CPH voltage exceeds 3V, the internal

current source charging CPH is increased about six

times larger than I_PH, noted as I_IG, causing rapid

increase in CPH voltage. The internal oscillator

decreases the oscillation frequency from f_PREto f_OSCas

CPH voltage increases. As depicted in Figure 27,

lowering the frequency increases the voltage across

the lamp. Finally, the lamp ignites. Ignition mode is

when CPH voltage is between 3V and 5V. Once CPH

voltage reaches 5V, the FAN7710V does not return to

ignition mode, even if the CPH voltage is in that range,

until the FAN7710V restarts from below V_DDTH(ST-)

.

Since the ignition mode continues when CPH is from

3V to 5V, the ignition time is given by:

2×CPH

I_IG

t_ignition

=

[seconds]

(5)

In this mode, dead time varies according to the CPH

voltage.

CPH voltage [V]

(C) Active ZVS mode

3.3 Running Mode and Active Zero-Voltage Switching

(AZVS) Mode (t2~)

8

(B) Ignition Mode

7

6

5

When CPH voltage exceeds 5V, the operating

frequency is fixed to f_OSCby R_T. However, active ZVS

operation is not activated until CPH reaches ~6V. Only

the FAN7710V prepares for active ZVS operation from

the instant CPH exceeds 5V during t2 to t3. When

CPH becomes higher than ~6V at t3, the active ZVS

operation is activated. To determine the switching

condition, FAN7710V detects the transition time of the

output (VS pin) of the inverter by using the VB pin.

From the output-transition information, FAN7710V

controls the dead time to meet the ZVS condition. If

ZVS is satisfied, the FAN7710V slightly increases the

CPH voltage to reduce the dead time and to find

optimal dead time, which increases the efficiency and

decreases the thermal dissipation and EMI of the

inverter switches. If ZVS fails, the FAN7710V

decreases CPH voltage to increase the dead time.

CPH voltage is adjusted to meet optimal ZVS

operation. During the active ZVS mode, the amount of

(A) Preheating Mode

4

3

2

(D) Shutdown

mode

1

0

3

2

1

time

0

Dead-Time[μs]

Oscillation

frequency

Preheating Frquency:f_PRE

Preheating

Mode

Running frequency:

f_OSC

Running

Mode

Ignition

Mode

time

t0

FAN7710 Rev. 1.00

t1 t2 t3

Figure 27. Operation Modes

3.1 Preheating Mode (t0~t1)

the charging / discharging current is the same as I_PH

.

When V_DDexceeds V_DDTH(ST+), the FAN7710V series

starts operation. At this time, an internal current source

(I_PH) charges CPH. CPH voltage increases from 0V to

3V in preheating mode. Accordingly, the oscillation

frequency follows Equation 4. In this mode, the lamp is

not ignited, but warmed up for easy ignition. The

preheating time depends on the size of CPH:

Figure 28 depicts normal operation waveforms.

3×CPH

I_PH

t_preheat

=

[seconds]

(4)

According to the preheating process, the voltage

across the lamp to ignite is reduced and the lifetime of

the lamp is increased. In this mode, the dead time is

fixed at its maximum value.

FAN7710V • 1.0.4

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11

4. Automatic Open-Lamp Detection

The FAN7710V can automatically detect an open-lamp

condition. When the lamp is opened, the resonant tank

fails to make a closed-loop to the ground, as shown in

Figure 30. The supplied current from the OUT pin is used

to charge and discharge the charge pump capacitor, C_P.

Since the open-lamp condition means resonant tank

absence, it is impossible to meet ZVS condition. In this

condition, the power dissipation of the FAN7710V, due to

capacitive load drive, is estimated as:

1

2

P_dissipation

=

×C_P×V_DC× f [W ]

(6)

2

where f is driving frequency and V_DCis DC-link voltage.

Figure 28. LCC Transfer Function in Terms

of Lamp Impedance

Figure 30. Current Flow When the Lamp is Open

Assuming that C_P, V_DC, and f are 1nF, 311V, and 50kHz,

respectively; the power dissipation reaches about 2.4W

and the temperature of is increased rapidly. If no

protection is provided, the IC can be damaged by the

thermal attack. Note that a hard-switching condition

during the capacitive-load drive causes EMI.

3.4 Shutdown Mode

If the voltage of capacitor CPH is decreased below

~2.1V by an external application circuit or internal

protection circuit, the IC enters shutdown mode. Once

the IC enters shutdown mode, this status continues

until an internal latch is reset by decreasing V_DDbelow

Figure 31 illustrates the waveforms during the open-lamp

condition. In this condition, the charging and discharging

current of C_Pis directly determined by FAN7710V and

considered hard-switching condition. The FAN7710V

tries to meet ZVS condition by decreasing CPH voltage

to increase dead time. If ZVS fails and CPH goes below

2V, even though the dead time reaches its maximum

value, FAN7710V shuts off the IC to protect against

damage. To restart FAN7710V, V_DDmust be below

V_DDTH(ST-)to reset an internal latch circuit, which

remembers the status of the IC.

V

_DDTH(ST-). Figure 29 shows an example of external

shutdown control circuit.

Figure 29. External Shutdown Circuit

Shutdown

Release Restart

The amount of the CPH charging current is the same

as I_PH, making it possible to shut off the IC using a

small signal transistor. Only the FAN7710V provides

active ZVS operation by controlling the dead time

according to the voltage of CPH. If ZVS fails, even at

the maximum dead time, FAN7710V stops driving

the inverter.

V_DD

V_DDTH(ST+)

V_DDTH(ST-)

time

Active ZVS activated

CPH

6V

5V

Automatic

Shutdown

3V

2V

The FAN7710V thermal shutdown circuit senses the

junction temperature of the IC. If the temperature

exceeds ~160°C, the thermal shutdown circuit stops

operation of the FAN7710V.

time

Running mode

Active ZVS mode

OUT

0V

time

The current usages of shutdown mode and under-

voltage lockout status are different. In shutdown mode,

some circuit blocks, such as bias circuits, are kept

alive. Therefore, the current consumption is slightly

higher than during under-voltage lockout.

Shutdown

mode

Preheating period

(Filament warm-up)

Ignition period

FAN7710 Rev. 1.00

Figure 31. CPH Voltage Variation During Open-Lamp

FAN7710V • 1.0.4

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12

This current flows along path 1 in Figure 32. It charges

C_VDD, which is a bypass capacitor to reduce the noise on

the supply rail. If C_VDDis charged over the threshold

voltage of the internal shunt regulator, the shunt

regulator turns on and regulates V_DDwith the trigger

voltage.

5. Power Supply

When V_DDis lower than V_DDTH(ST+), it consumes very little

current, I_ST, making it possible to supply current to the

V_DDpin using a resistor with high resistance (R_startin

Figure 32). Once UVLO is released, the current

consumption is increased and whole circuit is operated,

which requires additional power supply for stable

operation. The supply must deliver at least several mA. A

charge pump circuit is a cost-effective method to create

an additional power supply and allows C_Pto be used to

reduce the EMI.

When OUT is changing from HIGH to LOW state, C_CPis

discharged through Dp2, shown as path 2 in Figure 32.

These charging/discharging operations are continued

until FAN7710V is halted by shutdown operation. The

charging current, I, must be large enough to supply the

operating current of FAN7710V.

V_DC

The supply for the high-side gate driver is provided by

the boot-strap technique, as illustrated in Figure 33.

When the low-side MOSFET connected between OUT

and PGND pins is turned on, the charging current for V_B

flows through D_B. Every low OUT gives the chance to

charge the C_B. Therefore, C_Bvoltage builds up only when

FAN7710V operates normally.

R_start

FAN7710

dv/dt

V_DD

RT

V_DC

V_B

Shunt

regulator

C_S

(2)

L

C_VDD

CPH

SGND

OUT

PGND

R_L

C_P

When OUT goes HIGH, the diode D_Bis reverse-biased

and C_Bsupplies the current to the high-side driver. At this

time, since C_Bdischarges, V_B-V_OUTvoltage decreases. If

V_B-V_OUTgoes below V_HSTH(ST-), the high-side driver

cannot operate due to the high-side UVLO protection

circuit. C_Bmust be chosen to be large enough not to fall

into UVLO range, due to the discharge during a half of

the oscillation period, especially when the high-side

MOSFET is turned on.

(1)

C_CP

Dp1

Dp2

FAN7710 Rev. 1.00

Charge pump

Figure 32. Local Power Supply for V_DDUsing a

Charge-Pump Circuit

V_DC

D_B

As presented in Figure 32; when OUT is HIGH, the

inductor current and C_CPcreate an output transition with

FAN7710

R_start

Bootstrap circuit

the slope of dv/dt. The rising edge of OUT charges C_CP

.

V_DD

RT

V_DC

V_B

At that time, the current that flows through C_CPis:

dv

CB

I ≅ C_CP

×

(7)

L

C_S

C_VDD

dt

CPH

SGND

OUT

PGND

R_L

C_P

Chraging path

Cp

Dp1

Dp2

FAN7710 Rev. 1.00

Figure 33. Implementation of Floating Power Supply

Using the Bootstrap Method

FAN7710V • 1.0.4

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13

Design Guide

If R_startmeets Equation 14, restart operation is possible.

However, it is not recommended to choose R_startat that

range since V_DDrising time could be long and increase

the lamp's turn-on delay time, as depicted in Figure 34.

1. Startup Circuit

The startup current (I_ST) has to be supplied to the IC

through the startup resistor, R_start. Once operation starts,

the power is supplied by the charge pump circuit. To

reduce the power dissipation in R_start, select R_startas high

as possible, considering the current requirements at

startup. For 220V_ACpower, the rectified voltage by the

full-wave rectifier makes DC voltage, as shown in

Equation 8. The voltage contains lots of AC component,

due to poor regulation characteristic of the simple full-

wave rectifier:

V_DD

V_CL

V_DDTH(ST+)

V_DDTH(ST-)

t_start

(8)

V_DC

= 2 ×220[V] ≅ 311[V]

Considering the selected parameters, R_startmust satisfy

the following equation:

0

time

FAN7710 Rev. 1.00

V_DC−V_{DDTH(ST +)}

> I_ST

(9)

Figure 34. V_DDBuild-up

R_start

Figure 35 shows the equivalent circuit for estimating t_start

From the circuit analysis, V_DDvariation versus time is

given by:

.

From Equation 9, R_startis selected as:

V_DC−V_{DDTH(ST +)}

> R _start

(10)

I_ST

_start⋅C_VDD

)

V_DD(t) = V − R_start⋅I_ST1 − e^{−t /(R}

(

)

(15)

(

)

DC

Note that if choosing the maximum R_start, it takes a long

time for V_DDto reach V_DDTH(st+). Considering V_DDrising

time, R_startmust be selected as shown in Figure 34.

Another important concern for choosing R_startis the

available power rating of R_start. To use a commercially

available, low-cost 1/4Ω resistor, R_startmust obey the

following rule:

where C_VDDis the total capacitance of the bypass

capacitors connected between V_DDand GND.

From Equation 15, it is possible to calculate t_startby

substituting V_DD(t)with V_DDTH(ST+)

:

V_DC− R_start⋅I_ST−V_{DDTH(ST +)}

V_DD− R_start⋅I_ST

t_start= −R_start⋅C_VDD⋅ln

(16)

(17)

2

V

−V_CL

(

)

1

4

DC

(11)

<

[W ]

In general, Equation 16 can be simplified as:

R_start

R_start⋅C_VDD⋅V_{DDTH(ST +)}

Assuming V_DC=311V and V_CL=15V, the minimum

resistance of R_startis about 350kΩ.

t_start

≈

V_DC− R_start⋅I_ST−V_{DDTH(ST +)}

When the IC operates in shutdown mode due to thermal

protection, open-lamp protection, or hard-switching

protection; the IC consumes shutdown current, I_SD, which

is larger than I_ST. To prevent restart during this mode,

R_startmust be selected to cover I_SDcurrent consumption.

The following equation must be satisfied:

Accordingly, t_startcan be controlled by adjusting the value

of R_startand C_VDDFor example, if V_DC=311V,

.

R_start=560kΩ, C_VDD=10µF, I_st=120µA, and V_DDTH(ST+)

=

13.5V; t_startis about 0.33s.

V_DC−V_{DDTH(ST +)}

> R _start

(12)

I_SD

R_START

From Equations 10 - 12; it is possible to select R_start

:

I_ST

(1) For safe startup without restart in shutdown mode:

VDD

V_DC−V_{DDTH(ST +)}

2

4 V −V_CL< R_start

<

(

)

(13)

DC

I_SD

(2) For safe startup with restart from shutdown mode:

C_VDD

V_DC−V_{DDTH(ST +)}

SGND

< R_start

<

(14)

I_SD

I_ST

Figure 35. Equivalent Circuit During Startup

FAN7710V • 1.0.4

www.fairchildsemi.com

14

2. Current Supplied by Charge Pump

3. Lamp Turn-On Time

For the IC supply, the charge pump method is used in

Figure 36. Since C_CPis connected to the half-bridge

output, the supplied current by C_CPto the IC is

determined by the output voltage of the half-bridge.

The turn-on time of the lamp is determined by supply

build-up time t_start, preheating time, and ignition time;

where t_starthas been obtained by Equation 17. When the

IC's supply voltage exceeds V_DDTH(ST+)after turn-on or

restart, the IC operates in preheating mode. This

operation continues until CPH pin's voltage reaches ~3V.

In this mode, CPH capacitor is charged by I_PHcurrent, as

depicted in Figure 37. The preheating time is achieved

by calculating:

When the half-bridge output shows rising slope, C_CPis

charged and the charging current is supplied to the IC.

The current can be estimated as:

V_DC

DT

dV

dt

I = C_CP

≈ C_CP

(18)

3 × CPH

I_PH

t_preheat

=

[seconds]

(21)

where DT is the dead time and dV/dt is the voltage

variation of the half-bridge output.

The preheating time is related to lamp life (especially

filament). Therefore, the characteristics of a given lamp

should be considered when choosing the time.

When the half-bridge shows falling slope, C_CPis

discharged through Dp2. Total supplied current, I_total, to

the IC during switching period, t, is:

I_total= I ⋅DT = C_CP⋅V_DC

I_PH

(19)

From Equation 19, the average current, I_avg, supplied to

the IC is obtained by:

CPH

I_totalC_CP⋅V_DC

CPH

I_avg

=

= C_CP⋅V_DC⋅f

(20)

t

SGND

For stable operation, I_avgmust be higher than the

required current. If I_avgexceeds the required current, the

residual current flows through the shunt regulator

implemented on the chip, which can cause unwanted

heat generation. Therefore, C_CPmust be selected

considering stable operation and thermal generation.

Figure 37. Preheating Timer

Compared to the preheating time, it is almost impossible

to exactly predict the ignition time, whose definition is the

time from the end of the preheating time to ignition. In

general, the lamp ignites during the ignition mode.

Therefore, assume that the maximum ignition time is the

same as the duration of ignition mode, from 3V until CPH

reaches 5V. Thus, ignition time can be defined as:

For example, if C_CP=0.5nF, V_DC=311V, and f=50kHz, I_avg

is ~7.8mA; it is enough current for stable operation.

Discharging mode

Charging mode

C_CP

Dp1

To V_DD

Dp1

To V_DD

I_dp1=0

I_dp1

C_VDD

CPH

I_IG

CPH

I_IG

Dp2

t_ignition= (5 − 3)

= 2

(22)

f=1/t

Note that in ignition mode, CPH is charged by IIG, which

is six times larger than IPH. Consequently, total turn-on

time is approximately V_DDBuild-Time + Preheating Time

+ Ignition Time, or:

V_DC

DT:dead time

Half-bridge output

CPH

I_IG

CPH

I_IG

t_ignition

=

(5 − 3

)

= 2

[seconds]

(23)

I_dp1

FAN7710 Rev. 1.00

Figure 36. Charge Pump Operation

FAN7710V • 1.0.4

www.fairchildsemi.com

15

Component List for 20W CFL Application ⁽³⁾

Part

Value

Note

Part

Value

Diode

Note

Resistor

R1⁽⁴⁾

R2

470kΩ

90kΩ

0.25W

D1

D2

D3

D4

D5

1N4007

UF4007

1kV, 1A

0.25W, 1%

Capacitor

C1

10μF/400V

10μF/50V

Electrolytic Capacitor, 105°C

C2⁽⁵⁾

Electrolytic Capacitor, 105°C

Miller Capacitor

C3

C4

100nF/25V

470pF/500V

680nF/25V

2.7nF/1kV

33nF/630V

D6

D7

UF4007

IC

1kV, 1A

Ceramic Capacitor

Miller Capacitor, 5%

Miller Capacitor

C5⁽⁶⁾

C6⁽⁷⁾

C7⁽⁷⁾

IC

FAN7710V

Ballast IC

Miller Capacitor

Inductor

L2⁽⁷⁾

2.5mH

EE1916S,280T

Notes:

3. Refer to the Typical Application Circuit for 3U type CFL lamp provided in Figure 1.

4. Refer to the Design Guide startup circuit in Figure 35. Due to reducing power loss on the startup resistor (R1) for

high-efficiency systems, it is possible to use a higher resistor value than recommended. In this case, the IC doesn’t

reliably keep SD (shutdown) state for protection. Carefully select the startup resistor (R1) or use the recommended

value (470k) to sufficiently supply shutdown current (I_SD) and startup current (I_ST).

5. Normally, this component could be changed to a normal miller capacitor to increase system reliability instead of

the electrolytic capacitor with high temperature characteristics.

6. Temperature dependency of the capacitance is important to prevent destruction of the IC. Some capacitors show

capacitance degradation in high temperatures and cannot guarantee enough preheating time to safely ignite the

lamp during the ignition period at high temperatures. If the lamp does not ignite during the ignition period, the IC

cannot guarantee ZVS operation, Thus, the peak current of the switching devices can be increased above

allowable peak current level of the switching devices. Especially in high temperatures, the switching device can be

easily destroyed. Consequently, CPH capacitor (C5) must be large enough to warm the filaments of the lamp up

over the concerning temperature range.

7. Consider the components (L2, C6, C7) of resonant tank variation over the concerning temperature range. Normally,

these components would be changed toward increasing inductance and capacitance in high temperature. That

means that the resonant frequency is decreased. In the lower resonant frequency condition, the preheating current

reduces, so the resonant tank cannot supply enough to preheat the filaments before lamp turn on. If the preheating

current is insufficient, the ignition voltage / current is increased. Check the ignition current in high temperature: the

current capacity of internal MOSFETs on IC must be larger than ignition current.

FAN7710V • 1.0.4

www.fairchildsemi.com

16

Physical Dimensions

9.83

9.00

6.67

6.096

8.255

7.61

3.683

3.20

7.62

5.08 MAX

0.33 MIN

3.60

3.00

(0.56)

2.54

0.356

0.20

0.56

0.355

9.957

7.87

1.65

1.27

7.62

NOTES: UNLESS OTHERWISE SPECIFIED

A) THIS PACKAGE CONFORMS TO

JEDEC MS-001 VARIATION BA

B) ALL DIMENSIONS ARE IN MILLIMETERS.

C) DIMENSIONS ARE EXCLUSIVE OF BURRS,

MOLD FLASH, AND TIE BAR EXTRUSIONS.

D) DIMENSIONS AND TOLERANC

ASME Y14.5M-1994

ES PER

E) DRAWING FILENAME AND REVSION: MKT-N08FREV2.

Figure 38. 8-Lead, Dual Inline Package (DIP)

Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner

without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or

obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions,

specifically the warranty therein, which covers Fairchild products.

Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:

http://www.fairchildsemi.com/packaging/.

FAN7710V • 1.0.4

www.fairchildsemi.com

17

FAN7710V • 1.0.4

www.fairchildsemi.com

18

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1


型号：	FAN7710VN
厂家：	ONSEMI
描述：	用于紧凑型荧光灯的镇流器控制器控制器
文件：	总20页 (文件大小：1543K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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