NE5565 데이터 시트보기 (PDF) - Philips Electronics

부품명

상세내역

일치하는 목록

NE5565

Electronic ballast controller circuit

Philips Electronics 

Philips Semiconductors

Electronic ballast controller circuit

Product specification

NE5565

AC

LINE

AC

FILTER

DC

SUPPLY

POWER FACTOR

CORRECTION

CIRCUIT

HALF-BRIDGE

SQUARE WAVE

OSCILLATOR

FLUORESCENT LAMPS

13

VCC

17 12 10

11

19

18

PF OUTP CSI GND DC OV

14 6 15

OUTH VLAMP IPRIM

RXCX

5

VREF RT

16

4

DMAX CP CT DCOUT CRECT

LI LI2

3

2

1

20 7

98

R5

RT

R4

RX

R1

CX

C1

R2

CP CT C2

C3

R3

DIMMING

INPUT

SL00526

Figure 3. Typical Application: 2-Lamps Dimming Ballast

Voltage Regulator

The VREF output provides a regulated output voltage of 7.42V at the

VREF pin. This voltage is used as a reference as well as the power

supply of the control logic. It is based on a trimmed band gap

voltage reference circuit. The nominal VCC voltage for the control

chip is 12.7V. The VREF circuit requires a minimum of 9.3V before it

can produce regulated output. The VREF output voltage has an

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 VLAMP pin exceeds VREF. At

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 VCC pin to determine

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 VCC voltage rises

above the upper trip point, both PFC and half-bridge oscillator

circuits become operational. When the VCC falls below the lower

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 VCC exceeds the upper trip point and a minimum time delay,

set by external components at the DMAX pin, has passed.

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 VREF the frequency sweep is allowed to occur, thus beginning

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 VREF the PFC buffer gate drive output

OUTP is turned off. This prevents any further increase in PFC DC

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

1996 May 21

2

Share Link: