NE5565 Philipss, NE5565 Datasheet - Page 3

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

Philips Semiconductors
external LC network driven by the bridge. At frequencies above
resonance the primary voltage of the half-bridge LC load network
leads the primary current in phase. The protection logic senses the
LC network current phase relative to the half-bridge gate drive
voltage to determine if a resonant condition exists. The Iprim input
voltage represents the primary current signal from the external LC
network. If the voltage at Iprim is more positive than -100mV when
the gate drive signal is high, then a fault condition exists and the
half-bridge oscillator frequency is swept high.
Half-Bridge Oscillator
Is a triangle wave generator used to produce a square wave signal
for driving the half-bridge buffer circuit. The triangle wave appears
on the C
by the value of the resistor connected to the R
of the C
Output Buffer Drive
Convert the low level logic signals from the half-bridge oscillator and
pulse width modulator into a 10V drive signal for the power switches.
The OUT
shift scheme which will then be used to operate the half-bridge
power switches. The OUT
MOSFET switch or an external level shift/power MOSFET
combination.
Pulse Width Modulator
Generates a ramp voltage used to control the duty cycle of the PFC
SMPS. The frequency of the pulse width modulator is set by the
half-bridge oscillator. The ramp voltage appears at the C
is synchronized to the half-bridge oscillator so that the beginning of
the ramp occurs at the valley of the C
ramp voltage at C
amplifier, the capacitor connected to C
of the PFC gate drive pulse correspond to the C
maximum duty cycle, soft start function, and half-bridge off time are
all controlled by the external capacitor and resistors connected to
the D
Over Current Protection
An over current is sensed by an external resistor connected to the
current sense input pin, CSl. A voltage of minus 500mV at CSl
1996 May 21
Electronic ballast controller circuit
MAX
t
t
capacitor.
H
capacitor output pin. The oscillator frequency is governed
pin.
half-bridge buffer/drive circuit will drive an external level
P
exceeds the voltage at the DC out pin in the DC
P
output may directly drive a power
t
P
triangle waveform. When the
is discharged. The period
t
input and the value
P
ramp time. The
P
output. It
3
triggers the over current protection circuit this turns off the OUT
output and forces the external capacitor connected to D
discharge when an over current condition occurs in the PFC input
circuit. An over current condition is usually produced during the turn
on transient of the SMPS or when the AC line voltage has a power
interruption.
Power Factor Amplifier
Senses the phase and amplitude of a peak rectified AC line voltage
in order to modulate the duty cycle of the PFC power switch. This is
done to improve the sinusoidal wave shape of the AC line current.
The power factor input is provided by the PF input pin. The voltage
at this pin is 1V when the AC line voltage reaches its peak and 0V
when the AC voltage is at its 0V crossing.
DC Error Amplifier
Provides negative feedback control of the PFC DC output voltage.
The DC pin senses the DC output voltage of the PFC through an
external resistor voltage divider and filter network. The reference
voltage for the DC error amplifier is V
amplifier is available at the DC out pin and an external capacitor is
connected to this pin in order to remove switching frequency noise
before its signal is applied to the pulse width modulator in the PWM
oscillator circuit.
Lamp Current Rectifier
Is used to provide negative feedback control of the average lamp
current. An external lamp current transformer and load resistor are
used to convert the lamp current signal into a voltage. This voltage
is applied to the lamp current input pins, Li1 and Li2. The full wave
rectified output is provided at C
capacitor determine the gain and time constant of the circuit. A
differential error amplifier compares the voltage of C
internal reference of 2/7 V
frequency so that the error voltage is minimized. This forces the
average lamp current to be a constant.
Dimming
Dimming input should be an extra current put into charging C
addition to the current from Pin 7. This creates the same condition
as higher voltage differential across Pins 8 and 9, hence, the IC
reacts as if there is too much power applied to the lamps.
REF
and adjusts the half-bridge oscillator
RECT
pin. External resistors and a
REF
. The output of the
Product specification
NE5565
RECT
MAX
to an
to
3
in
P