NE5565 Philipss, NE5565 Datasheet - Page 2

• Manufacturer Part Number: NE5565
• Description: Electronic ballast controller circuit
• Manufacturer: Philipss

Philips Semiconductors
Voltage Regulator
The V
V
supply of the control logic. It is based on a trimmed band gap
voltage reference circuit. The nominal V
chip is 12.7V. The V
can produce regulated output. The V
absolute accuracy of 3.5% over the temperature range of 0 C to
85 C.
Lamp Voltage Regulator
Limits the maximum open circuit voltage across the lamp load during
the pre-heat, ignition and lamp removal conditions. During steady
state operation, the lamp voltage is governed by the arc voltage of
the lamps, not by the control circuit. The lamp voltage comparator is
used to sense when the voltage at the V
the time this occurs, the lamp voltage has reached its maximum
allowed open circuit value and the circuit responds by producing a
rapid frequency increase which reduces the voltage at the Vlamp
pin. The RxCx time constant sets the frequency sweep time of the
start up circuit. The frequency sweep range has a rate of 2:1.
Low Supply Lock-out Protection
Senses the DC power supply voltage at the V
when the PFC and half-bridge control circuits should turn on or off.
This protection circuit uses a Schmitt trigger with a voltage reference
to determine the upper and lower trip points of the power supply
voltage. As the power supply voltage rises from 0V to a value just
below the upper trip point of 11V, both the PFC and the half-bridge
control circuits are held in the off state. Once the V
1996 May 21
REF
Electronic ballast controller circuit
pin. This voltage is used as a reference as well as the power
REF
FILTER
LINE
AC
AC
output provides a regulated output voltage of 7.42V at the
REF
circuit requires a minimum of 9.3V before it
SUPPLY
V
RXCX
DC
CC
13
5
C
R
X
REF
X
LAMP
V
CC
PF
REF
output voltage has an
Figure 3. Typical Application: 2-Lamps Dimming Ballast
16
17
voltage for the control
CC
pin exceeds V
OUT
12
R
pin to determine
T
4
P
R
POWER FACTOR
CC
T
CORRECTION
CSI
CIRCUIT
R
10
voltage rises
C
1
1
D
GND
MAX
REF
3
11
. At
R
2
DC
C
19
P
2
C
P
2
OV
C
18
T
1
C
above the upper trip point, both PFC and half-bridge oscillator
circuits become operational. When the V
trip point of 10V, both PFC and half-bridge circuits are disabled.
Once the half-bridge oscillator turns off, it is not allowed to turn back
on until V
set by external components at the D
Start up Ckt
The Low Half-bridge Voltage Lock-out Circuit senses the DC output
voltage of the PFC SMPS clrcuit. It is used to inhibit the lamp
ignition sequence or frequency sweep of the half-bridge oscillator
until the PFC output voltage has reached a pre-determined value.
This value is set by external components. The PFC voltage is
sensed by the over voltage input pin, OV. When this input exceeds
5/7 of V
the lamp ignition sequence.
The Over Voltage Protection Circuit prevents the PFC DC output
voltage from exceeding a pre-determined value. When the voltage
at the OV pin is greater than V
OUT
output voltage. The over voltage circuit only protects against an
over voltage or over shoot generated by the PFC itself. This may
occur during turn on when the SMPS is not loaded and the circuit is
under damped. Transient voltages from the AC line are not
suppressed by this circuit.
Capacitive Load Protection
Prevents failure of the half-bridge power transistors during lamp
removal. It does this by limiting the operation of the half-bridge
oscillator to frequencies above the resonant frequency of an
T
DC
OUT
P
20
C
2
OUT
is turned off. This prevents any further increase in PFC DC
REF
CC
SQUARE WAVE
H
C
HALF-BRIDGE
OSCILLATOR
7
RECT
C
14
the frequency sweep is allowed to occur, thus beginning
3
exceeds the upper trip point and a minimum time delay,
V
LAMP
6
R
3
15
I
LI
PRIM
9
DIMMING
INPUT
LI2
8
REF
the PFC buffer gate drive output
R
R
MAX
5
4
FLUORESCENT LAMPS
pin, has passed.
CC
falls below the lower
Product specification
NE5565
SL00526