KA7540DTF [FAIRCHILD]
Fluorescent Light Controller, Voltage-mode, 0.3A, 56kHz Switching Freq-Max, BIPolar, PDSO8, SOIC-8;
| 型号： | KA7540DTF |
| 厂家： | 
FAIRCHILD SEMICONDUCTOR |
| 描述： | Fluorescent Light Controller, Voltage-mode, 0.3A, 56kHz Switching Freq-Max, BIPolar, PDSO8, SOIC-8 光电二极管 |
| 文件： | 总16页 (文件大小：135K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
www.fairchildsemi.com
KA7540
Simple Dimming Ballast Control IC
Features
Descriptions
• Internal soft start
• No lamp protection
• Voltage controlled dimming
• Trimmed 1.5% internal bandgap reference
• Under voltage lock out with 1.8V of hysteresis
• Totem pole output with high state clamp
• Low start-up and operating current
• 8-pin DIP & 8-pin SOP
The KA7540 provides simple and high performance
electronic ballast control functions. KA7540 is optimized for
electronic ballast requiring a minimum board area, reduced
component count and low power dissipation. Internal soft
start circuitry eliminates the need for an external soft start
PTC resistor. Voltage controlled dimming circuit is built into
the IC to control the lighting output in a wide range.
Protection circuitry has also been added to prevent switches
from burning out in no lamp condition. Output gate drive
circuit clamps power MOSFET gate voltage irrespective of
supply voltage.
Applications
• Electronic Ballast
• Lighting Control System
• Half-bridge Drive Control System
8-DIP
1
8-SOP
1
Rev. 1.0.1
©2001 Fairchild Semiconductor Corporation
KA7540
Internal Block Diagram
UVLO
2V Ref
−
1.8V
+
8
1
V
CC
C
S
Internal
bias
+
6.8µF
−
17µA
25µA
I
S
Vref
12.5V
V
Z
V
Z
UVLO
Oscillator
Ict
I
C
+
OUT 1
7
2
Ct
+
+
latch
Q
180pF
F.D
8Ict
from V
CS
OUT 2
Id
Vdim
V
CC
3
6
+
100µA
80kΩ
Frequency
divider
−
Vd
3pF
kVref
20kΩ
V
Z
25µA
40kΩ
I
= 17µA × (Vref − V ) / Vref
SS
S
Ldet
−
GND
5
4
Id = 25µA × (Vref − Vd) / Vref
5pF
Shut down signal
+
2V
IC Characteristics
Parameter
KA7540
Initial soft start frequency
Voltage controlled dimming
1.33 × normal operating frequency
1 ~ 10V
2
KA7540
Pin Assignments
V
CC
1
2
C
8
7
6
5
S
OUT1
OUT2
GND
Ct
Vdim
Ldet
3
4
(Top View)
Pin Definitions
Pin Number
Pin Name
Pin Function Description
Soft start capacitor connection pin. The pin voltage determines the phase of soft
start, normal and dimming mode.
1
C
S
Timing capacitor connection pin. The timing capacitor is charged and discharged
to generate the sawtooth waveform that determines the oscillation frequency in
the internal oscillator block.
2
3
C
T
Input to the dimming stage. The pin voltage sets the switching frequency in
dimming mode.
Vdim
Input to the protection circuit. If the pin voltage is lower than 2V, the output of the
gate driver is inhibited.
4
5
6
Ldet
GND
The ground potential of all the pins.
The output of a high current power driver capable of driving the gate of a power
MOSFET.
OUT 2
OUT 1
The output of a high current power driver capable of driving the gate of a power
MOSFET.
7
8
V
CC
The logic and control power supply connection.
3
KA7540
Absolute Maximum Ratings
Parameter
Symbol
Value
30
Unit
V
Supply voltage
V
CC
Peak drive output current
Drive output clamping diodes
I
, I
±300
mA
OH OL
Iclamp
±10
mA
V >V , or V <−0.3
CC
O
O
Dimming, soft start, and no lamp detection input voltage
Operating temperature range
V
−0.3 to 6
-25 to 125
−65 to 150
0.8
V
IN
Topr
Tstg
°C
°C
Storage temperature range
8-DIP
Power dissipation
8-SOP
Pd
W
0.5
8-DIP
Thermal resistance (Junction-to-air)
8-SOP
100
θja
°C/W
165
Absolute Maximum Ratings (-25°C≤Ta≤125°C)
Parameter
Symbol
Value
15
Unit
mV
Temperature stability for reference voltage (Vref)
Temperature stability for operating frequency (fos)
∆Vref (Typ)
∆fos (Typ)
5
kHz
4
KA7540
Electrical Characteristics
Unless otherwise specified, for typical values Vcc=14V, Ta=25°C, For Min/Max values Ta is the operating ambient
temperature range with -25°C ≤ Ta ≤ 125°C and 14V≤ Vcc≤ 30V
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
UNDER VOLTAGE LOCK OUT SECTION
Start threshold voltage
UVLO hysteresis
V
(st)
V
V
increasing
-
11.5
1.3
12.5
1.8
13.5
2.3
V
V
TH
CC
HY(st)
SUPPLY CURRENT SECTION
<V (st),
CC TH
Start up supply current
I
-
0.2
0.3
mA
ST
Vcc=14V
Operating supply current
Dynamic operating supply current
REFERENCE SECTION
Reference voltage(Note1)
Line regulation(Note1)
I
Output not switching
50kHz, CI=1nF
-
-
6
7
10
14
mA
mA
CC
I
DCC
Vref
Iref=0mA, Vcc=14V
1.95
-
2
2.05
10
V
∆Vref 1
14V≤V ≤25V
0.1
mV
CC
-25≤Ta≤125°C,
Vcc=14V
Temperature stability of Vref(Note1)
∆Vref 2
-
15
-
mV
OSCILLATOR SECTION
Operating frequency
fos
tod
fss
V
V
V
V
V
=3V, C =470pF
T
44
2.4
56
50
2.9
65
56
3.4
74
kHz
µs
SS
SS
SS
SS
SS
Operating dead time
=3V, Vcc=14V
Soft start frequency
=0V, C =470pF
T
kHz
µA
Soft start time current
Soft start dead time
I
=0V
17
25
33
SS
tsd
fd
=0V, Vcc=14V
1.8
58
2.3
72
2.8
86
µs
Dimming frequency
Vss=5V, Vdim=1V
kHz
OUTPUT SECTION
Rising time (Note2)
Falling time (Note2)
tr
CI=1nF
CI=1nF
-
-
120
50
15
-
200
100
18
ns
ns
V
tf
Maximum output voltage
Output voltage with UVLO activated
NO LAMP PROTECTION SECTION
No lamp detect voltage
Vomax(o)
Vomin(o)
V
V
=20V
12
-
CC
CC
=5V, I =100µA
1
V
O
Vnd
-
1.9
2
2.1
V
Notes :
1. This parameter is not tested in production but tested in wafer.
2. This parameter, although guaranteed, is not 100% tested in production.
5
KA7540
Start-up Circuit
Start-up current is supplied to the IC through the start-up resistor (Rst). In order to reduce the power dissipation in Rst, the Rst
is connected to the full-wave rectified AC line voltage.
The following equation can be used to calculate the value of Rst.
2
(Vin(ac_max) 2 – V
)
Vin(ac) × 2 – Vth(st), max
CC
---------------------------------------------------------------------------
≤ 1W
---------------------------------------------------------------------------
≤
R
P
=
st
lst, max
Rst
Rst
130KΩ ≤ Rst ≤ 356KΩ
2
85 × 2 – 13.5
= ------------------------------------- = 356KΩ
Rst ≥ (Vin(ac_max) 2 – V
Rst ≥ 130KΩ
)
CC
–3
0.3 × 10
The value of start-up capacitor (Cst) is normally determined in terms of the start-up time and operating current build up time
with the auxiliary operating current source.
The turn-off snubber capacitor (Cq2) and two diodes (D1, D2) constitute the auxiliary operating current source for the IC. The
charging current through the Cq2 flows into the IC and also charges the start-up capacitor. If the value of Cq2 is increased, the
V
CC
voltage of the Cst is also increased.
Q1
Q2
Rectifier
Output
Cq2
Rst
D1
To V
CC
(Pin 8)
+
D2
Cst
−
Figure 1. Start-up circuit
Oscillator
The frequency of the gate drive output is as half as that of the triangular waveform in timing capacitor (Ct) at pin #2. In normal
operating mode, the timing capacitor charging current is 50µA. The discharging current is seven times of the charging current
(7 × 50µA). During the charging period, one of the two MOSFETs remains ON state. On the contrary both of MOSFETs are
OFF during the discharging period.
The rising slope and falling slope of the triangular waveform are as following.
Rising slope: dv / dt = i / C = 50µA / Ct
Falling slope: dv / dt = i / C = 7 × 50µA / Ct
For example, when the timing capacitor is 470pF, ∆V(Vhigh - Vlow) = (2.86V - 1.0V) = 1.86V,
∆Tch = 17.5µs, ∆Tdis = 2.5µs
6
KA7540
Vct
Vhigh
(Pin #2)
Vlow
14V
Voutput
(Pin #6, 7)
0V
Charging
Period( Tch)
Discharging
Period( Tdis)
∆
∆
Figure 2. Oscillator sawtooth & Output gate drive waveform
As a result, the switching frequency is as following
Ts = 2 × (∆Tch + ∆Tdis) = 40µs
fsw = 1 / T = 25kHz
S
The explicit equation calculating the value of the timing capacitor for a certain switching frequency is written below.
11.76 × 10–6
Ct = --------------------------------
fsw
Soft Start
The switching frequency is decreasing linearly from the pre-heating frequency to the normal switching frequency. In KA7540,
the normal timing capacitor charging current is increased by 25µA during the pre-heating mode. This addition of the charging
current sets the pre-heating frequency to be 1.33 times the switching frequency at the normal mode.
fsw, V
CS
fsw (pre)
fsw (dim)
fsw (nor)
3.5V
2.7V
2V
0.95
ts/s
td1
td2
Figure 3. Frequency & Soft start capacitor voltage variation during soft start and dimming mode
7
KA7540
No Lamp Protection
When the voltage at pin #4 is lower than 2V, the gate drive output is off-state, so the external power MOSFETsstop
switching. In no lamp protection circuit the dc link voltage is divided by a couple of resistors including both lamp filaments,
and the divided voltage is applied to the pin #4 before the MOSFETs start switching.
When 2 Lamp
R19
--------------------------------------------------------------------------------------
= Vdd ×
V
R4
R15 + R18 + 2 × Rf
R14 + -------------------------------------------------- + R19
2
15kΩ
----------------------------------------------------------------------------------------
≡ 400 ×
330kΩ + 680kΩ
180kΩ + ------------------------------------------ + 15kΩ
2
R18
R15 + R18
----------------------------
V3 = V2 ×
≡ 200V
V
> 2V
R4
When 1 Lamp
R19
--------------------------------------------------------------------------------
= Vdd ×
V
R4
R14 + R15 + R18 + 2Rf + R19
15kΩ
----------------------------------------------------------------------------------------
≡ 400 ×
> 2V
180kΩ + 330kΩ + 680kΩ + 15kΩ
V
R4
When No Lamp
V
= 0V( <2V)
Stop switching
R4
In normal mode, the average voltage of the V3 is the half of the dc link voltage (Vdd, PFC_OUT). So, in order to make the
start condition stable, the resistors are designed to make the voltage of V3 be the half of the dc link voltage.
DC Link Voltage (Vdd), PFC_OUT
R14
V2
Rfilament
Rfilament
R15
R16
Rfilament
V3
Rfilament
R18
R17
C13
VR4
R19
To pin #4
Figure 4. Lamp detection resistor network
8
KA7540
Dimming Control
The lighting output of the lamp can be controlled by varying the switching frequency of the ballast circuit. In voltage source
series resonant type converter, the output power is inversely proportional to the switching frequency. As a result, in order to
make the lamp lighting output less bright (so called “dimming”), the switching frequency should be increased compared to that
of the normal full lighting output frequency.
With KA7540, the switching frequency can be controlled by the voltage level at the pin #3 (Vdim). Since the IC starts to
operate, the voltage level at the dimming pin doesn’t affect the oscillator frequency until the time of td1 in figure 3. At the time
td1, the switching frequency starts to ramp up to the dimming switching frequency level that is determined by the voltage level
at the pin #3 (Vdim). In dimming mode, the timing capacitor charging current is increased by the following amount of the
dimming current (Id).
Id = 25uA × (Vref - Vd) / Vref
Vd = Vdim / 5
So, the equations for the dimming frequency are as following.
dV
50uA + Id
------- = -------------------------
dt Ct
dV × Ct
dTch(dim) = -----------------------------------------------------------------------
25uA(Vref – Vd)
---------------------------------------------
50uA +
Vref
dV × Ct
dTdis(dim) = ---------------------------------------------------------------------------------
25uA(Vref – Vd)
---------------------------------------------
7 × 50uA +
Vref
Ts(dim) = 2 × (Tch(dim) + Tdis(dim))
1
f
= ---------------------
SW(dim)
Ts(dim)
If the dimming pin is open, the dimming pin voltage becomes 10V due to the internal 100µA current source, which is
equivalent to the normal full lighting output case.
Dimming Control can be reallized by simple voltage source and current source of variable resistor at pin #3.
9
KA7540
Application Circuit
[85 ~ 265Vac Input, 400V Vdd, 32W × 2 Lamps Ballast,Group Dimming Control]
Full-wave Rectified Output
L2
PFC Output
D5
C5
D3
D1
D4
D2
R3
R6
D6
R4
R8
R5
Q1
NTC
R1
C9
C3 C4
C6
C2
FAN7527
L1
F1
C1
TNR
R9
R7
C8
C7
R2
AC INPUT
To PFC Output
R15
C15
Q2
Q3
C17
C19
C20
T1
R14
C14
L3
L4
R10
C21
R11
C18
C16
D7
To full-wave
rectified voltage
R16
R12
C10
D8
Z1
KA7540
R17
R18
R19
C11 C12
C13
1~10V
10
KA7540
Component List
Part number
R1
Value
2.7MΩ
Note
1/4W
Manufacturer
-
R2
18kΩ
1/4W
-
R3, 12
R4
150kΩ
1W
-
22kΩ
1/4W
-
R5, 10, 11
R6
47Ω
1/4W
-
3.3Ω
1/4W
-
R7
0.2Ω
1W
-
R8
1.2MΩ
1/4W
-
R9
103
Variable resistor
1/4W
-
R14
180kΩ
-
R15, 16
R17, 18
R19
330kΩ
1/4W
-
680kΩ
1/4W
-
15kΩ
1/4W
-
C1, 2
C3, 4
C5
150nF, 275vac
2200pF, 3000V
0.22µF, 630V
47µF, 35V
0.33µF
Box-Cap
Y-Cap
-
-
Miller-Cap
Electrolytic
MLCC
-
C6, 10
C7
-
-
C8
1nF, 25V
47µF, 450V
6.8µF, 35V
180pF, 25V
0.1µF, 25V
1nF, 630V
4700pF, 1000V
6800pF, 630V
0.22µF, 25V
500V, 3.6A
1000V, 1A
1000V, 1A
75V, 150mA
600V, 1A
15V, 1W
Ceramic
Electrolytic
Electrolytic
Ceramic
Ceramic
Miller-Cap
Miller-Cap
Miller-Cap
Ceramic
FQPF6N50
1N4007
UF4007
1N4148
1N4937
1N4744
Line Filter
EI3026
EI2820
EE1614
Fuse
-
C9
-
C11
-
C12
-
C13
-
C14
-
C15, 16
C17, 18, 19, 20
C21
-
-
-
Q1, 2, 3
D1, 2, 3, 4
D5
FairChild
-
-
-
-
-
-
D6
D7, 8
ZD1
L1
45mH
L2
590µH (62T:5T)
3.1mH (120T)
1.2mH(30T:60T)
250V, 3A
470V
L3, 4
T1
-
F1
-
-
-
TNR
NTC
471
10Ω
10D09
11
KA7540
Mechanical Dimensions
Package
Dimensions in millimeters
8-DIP
6.40 ±0.20
0.252 ±0.008
#1
#4
#8
#5
3.30 ±0.30
0.130 ±0.012
5.08
MAX
0.200
7.62
0.300
3.40 ±0.20
0.134 ±0.008
0.33
MIN
0.013
12
KA7540
Mechanical Dimensions (Continued)
Package
Dimensions in millimeters
8-SOP
0.1~0.25
MIN
0.004~0.001
1.55 ±0.20
0.061 ±0.008
#8
#5
#1
#4
6.00 ±0.30
0.236 ±0.012
1.80
0.071
MAX
3.95 ±0.20
0.156 ±0.008
5.72
0.225
0.50 ±0.20
0.020 ±0.008
13
KA7540
Ordering Information
Product Number
KA7540
Package
Operating Temperature
8-DIP
-25°C ~ +125°C
KA7540D
8-SOP
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
10/29/01 0.0m 001
Stock#DSxxxxxxxx
2001 Fairchild Semiconductor Corporation
Product Folder - Fairchild P/N KA7540 - Dimming Ballast Controller
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The KA7540 provides simple, yet high
performance electronic ballast control
Quality and reliability
This pagePrint version
functions. KA7540 is optimized for electronic
ballast requiring a minimum board area,
reduced component count and low power
dissipation. Internal soft start circuitry
eliminates the need for an external soft start
PTC resistor. Voltage controlled dimming
circuit is built into the IC to control the lighting
output in a wide range. Protection circuitry has
also been added to prevent burning out of
switches in no lamp condition. Output gate
drive circuit clamps power MOSFET gate
voltage irrespective of supply voltage
Design tools
technical information
buy products
technical support
my Fairchild
company
back to top
Features
●
●
●
●
Internal soft start
No lamp protection
Voltage controlled dimming
Trimmed 1.5% internal bandgap
reference
●
●
Under voltage lock out with 1.8V of
hysteresis
Totem pole output with high state
clamp
●
●
Low start-up and operating current
8-pin DIP & 8-pin SOP
back to top
Product Folder - Fairchild P/N KA7540 - Dimming Ballast Controller
Applications
●
●
●
Electronic Ballast
Lighting Control System
Half bridge Drive Control System
back to top
Product status/pricing/packaging
Product
KA7540DTF
KA7540D
Product status
Package type
SOIC
Leads
Packing method
TAPE REEL
RAIL
Full Production
Full Production
Full Production
8
8
8
SOIC
KA7540
DIP
RAIL
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© Copyright 2002 Fairchild Semiconductor
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