UBA2014 NXP Semiconductors, UBA2014 Datasheet - Page 6

• Manufacturer Part Number: UBA2014
• Description: 600 V Driver Ic For Hf Fluorescent Lamps
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 11428
Product data sheet
8.8.1 During ignition state
8.8.2 During burn state
8.5 Preheat state
8.6 Ignition state
8.7 Burn state
8.8 Lamp failure mode
After starting at f
across sense resistor R14 reaches the internally fixed preheat voltage level (pin PCS). At
crossing the preheat voltage level, the output current of the Preheat Current Sensor (PCS)
circuit discharges the capacitor C
at the moment that the circuit starts oscillating. During the preheat time the Average
Current Sensor (ACS) circuit is disabled. An internal filter of 30 ns is included at pin PCS
to increase the noise immunity.
After the preheat time the ignition state is entered and the frequency will sweep down due
to charging of the capacitor at pin CSW with an internally fixed current; see
During this continuous decrease in frequency, the circuit approaches the resonant
frequency of the load. This will cause a high voltage across the load, which normally
ignites the lamp. The ignition voltage of a lamp is designed above the V
lamp voltage exceeds the V
If the lamp voltage does not exceed the V
continue to increase until the clamp level at pin CSW is reached; see
consequence the frequency will decrease until the minimum frequency is reached.
When the frequency reaches its minimum level it is assumed that the lamp has ignited and
the circuit will enter the burn state. The Average Current Sensor (ACS) circuit will be
enabled. As soon as the averaged voltage across sense resistor R14, measured at pin
CSN, reaches the reference level at pin CSP, the average current sensor circuit will take
over the control of the lamp current. The average current through R14 is transferred to a
voltage at the voltage controlled oscillator and regulates the frequency and, as a result,
the lamp current.
If the lamp does not ignite, the voltage level increases. When the lamp voltage exceeds
the V
When the V
pin LVS is above the V
oscillating and is forced into the Power-down mode. The circuit will be reset only when the
supply voltage is powered down.
If the lamp fails during normal operation, the voltage across the lamp will increase and the
lamp voltage will exceed the V
is started. If the lamp voltage increases further it will reach the V
the circuit to re-enter the ignition state and results in an attempt to re-ignite the lamp. If
during restart the lamp still fails, the voltage remains high until the end of the ignition time.
At the end of the ignition time the circuit stops oscillating and the circuit will enter the
Power-down mode.
lamp(max)
lamp(fail)
level, the voltage will be regulated at the V
max
level is crossed the ignition timer has already started. If the voltage at
, the frequency decreases until the momentary value of the voltage
Rev. 02 — 12 September 2005
lamp(fail)
lamp(fail)
lamp(fail)
level at the end of the ignition time the circuit stops
CSW
level the ignition timer is started.
, thus raising the frequency. The preheat time begins
level; see
lamp(max)
600 V driver IC for HF fluorescent lamps
Figure
level the voltage at pin CSW will
7. At that moment the ignition timer
lamp(max)
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
lamp(max)
level; see
Figure
UBA2014
lamp(fail)
level. This forces
Figure
Figure
5. As a
level. If the
6.
5.
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