Philips UBA2000T-N2 Datasheet

DATA SH EET

Product speciﬁcation File under Integrated Circuits, IC11

1996 Jan 03

INTEGRATED CIRCUITS

UBA2000T

Electronic TL-lamp starter

1996 Jan 03 2

Philips Semiconductors Product speciﬁcation

Electronic TL-lamp starter UBA2000T

FEATURES

• Electronic starter, fully compatible with conventional glow-switch starters

• Reliable and instant ignition

• Accurate defined preheat time derived from the mains

frequency

• Increased starter life since no mechanical parts are used

• No radio-interference (according to

“IEC926 10.5”

)

• Automatic reset after interruption of supply voltage

• Large operating temperature range: −40 to +85 °C

• Maximum current protection of the preheat current

• Ignition shut-off at end of lamp life; no overheating of

load.

GENERAL DESCRIPTION

The UBA2000T is an integrated circuit for electronic TL-lamp starters and is fully compatible with conventional glow switch starters. The circuit controls the preheating and ignition of the lamp. The preheat time is well defined without spread, since it is derived from the mains frequency. When the lamp fails, ignition is shut-off after 7 ignition attempts. The circuit has an automatic reset when the supply voltage is interrupted.

ORDERING INFORMATION

TYPE NUMBER

PACKAGE

NAME DESCRIPTION VERSION

UBA2000T SO8 plastic small outline package; 8 leads; body width 3.9 mm SOT96-1

1996 Jan 03 3

Philips Semiconductors Product speciﬁcation

Electronic TL-lamp starter UBA2000T

BLOCK DIAGRAM

Fig.1 Block diagram.

handbook, full pagewidth

MGE002

1 kΩ

IC-SUPPLY

TIME

SELECT

EDGE

DETECTOR

CURRENT

DETECTOR

CURRENT

PROTECTION

OUTPUT

DRIVER

LATCH

DECODER 1 DECODER 2

NUMBER

OF STARTS

COUNTER

ign

sense

TEST

GND

CC(rst)

out

supply

COUNTER

RES

THS

UBA2000T

VOLTAGE

DETECTORS

1996 Jan 03 4

Philips Semiconductors Product speciﬁcation

Electronic TL-lamp starter UBA2000T

PINNING

SYMBOL PIN DESCRIPTION

sense

1 sense voltage GND 2 ground (0 V) V

out

3 output voltage V

4 input voltage n.c. 5 not connected V

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 V

n.c.

out

sense

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 supply voltage at the buffer capacitor (VCC, see “Characteristics”) is below the reset level (V

CC(rst)

the UBA2000T initializes its internal circuitry. When V

has reached the start level (V

CC(sl)

) and the

peak value of Vin>V

ign

(indicating that the mains supply is 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 shape of the voltage at pin 6 (V

) is given in Fig.3. During 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 TL-lamp prevents the voltage at pin 6 (VCC) to exceed start 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

CC(sl)

prf

ini

prn

first preheat

second preheat

time

first ignition

second ignition

1996 Jan 03 5

Philips Semiconductors Product speciﬁcation

Electronic TL-lamp starter UBA2000T

During preheating, the integrated circuit draws its supply current from the buffer capacitor. As a result, the voltage over the buffer capacitor decreases. When the ignition has failed after the ignition pulse, the voltage on the buffer capacitor increases to start level and the external switching device will be turned on again. This time the preheat time is reduced to 0.64 seconds because the lamp electrodes are still warm. An internal counter limits the number of ignitions attempts to 7. This prevents the lamp from flickering at end of lamp life.

The UBA2000T has an integrated current protection. When the current through the sense resistor exceeds the protection level (I

prot

), the switching device is turned off and the circuit will enter a standby state. Switching the mains voltage off and on again will reset the circuit.

The flow chart of the starting process is given in Fig.5. In the following subsections the several blocks of the block diagram are described in more detail.

IC supply

When the mains power is switched on, the buffer capacitor is charged and the internal current source is started. The internal voltage is stabilized, making it independent of the voltage at the buffer capacitor. An internal zener diode limits the voltage at pin 6 (V

) to start level (V

CC(sl)

Voltage detectors

The voltage detectors measure the voltage on the buffer capacitor and activate the switching device when the start value (V

CC(sl)

) is reached. The time required to charge the

capacitor is the initial time (t

ini

, see also Fig.3).

This time depends on the value of C1, the IC current and the source resistance at pin V

(R1//R2). When the mains voltage is near its peak value, the switching device is actually turned on. When the voltage decreases to a value indicating that the mains supply is interrupted, the starter is ready to start preheating and igniting the TL-lamp at the moment the mains supply returns.

Latch

The internal state of the latch represents the state of the switching device. The setting of the latch depends on the outputs of the voltage detectors, the number of starts counter and the standby state. Resetting the latch is controlled by the timer, the current detector and the current protection circuit.

Current detector

The current detector detects when the switching device must be turned off. The current detector also generates the clock pulses to activate the counter (see Fig.4). For proper functioning, the preheat current should be within the range indicated by I

. By including an hysteresis, unwanted current peaks on the preheat current have no effect on the counter. Because the current detector has a low-pass transfer function, it is not influenced by spikes. This circuitry eliminates the effect of spikes on the preheat time.

Edge detector

The edge detector ensures that the switching device will be turned off when the rectified preheat current is on the negative-going edge.

Fig.4 Current detection.

handbook, full pagewidth

MGE007

hysteresis

level

current through

sense resistor

clock signal

(fed to counter)

switch off level at end of preheat

clock generation during preheat

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