1996 Jan 03

4

Philips Semiconductors

Product specification

Electronic TL-lamp starter

UBA2000T

PINNING

SYMBOL

PIN

DESCRIPTION

1

sense voltage

GND

2

ground (0 V)

3

output voltage

4

input voltage

n.c.

5

not connected

6

supply voltage

n.c.

7

not connected

TEST

8

test pin

Fig.2 Pin configuration.

handbook, halfpage

1

2

3

4

8

7

6

5

MGE001

UBA2000T

TEST

n.c.

GND

VCC

n.c.

Vin

Vout

Vsense

FUNCTIONAL DESCRIPTION

The UBA2000T is an Integrated Circuit that performs all

functions necessary to ignite a TL-lamp. The circuit is

connected to the lamp circuit according to Figs. 7 or 8.

The mains voltage is rectified and divided over resistors

R1 and R2 to a lower level. When the mains power is

switched on, the buffer capacitor C1 is charged through

the resistive divider and internal switch S1. As long as the

the UBA2000T initializes its internal circuitry.

near its peak value), the external switching device TH1 will

be turned on. This results in a current through the

electrodes of the TL-lamp, the switching device and an

integrated sense resistor. Because the current starts to

flow when the mains voltage is near its peak value,

transient currents are limited.

When the switching device is turned on, the circuit draws

its supply current from buffer capacitor C1. A typical wave

the preheat periods the buffer capacitor is discharged.

The rectified current through the sense resistor is detected

and the output signal of the detector is used as a clock

signal for the counter. The preheat time is defined to 1.52 s

(at 50 Hz mains supply) using this counter. The preheat

time is very accurate, since it only depends on the

frequency of the mains supply.

After preheating, the switching device is turned off when

the current through the internal sense resistor equals at

least 285 mA. As a result of the current interruption and the

presence of an inductive load, a voltage peak is generated

that will normally ignite the TL-lamp. After ignition, the

lamp voltage is lower than the mains voltage. An ignited

level. In Fig.3 the TL-lamp is ignited after two ignition

attempts.

Fig.3 Typical wave shape of supply voltage.

handbook, full pagewidth

MGE006

VCC(sl)

VCC

tprf

tini

tprn

first preheat

second

preheat

time

first

ignition

second

ignition