datasheetbank_Logo
Integrated circuits, Transistor, Semiconductors Search and Datasheet PDF Download Site

UBA2014P View Datasheet(PDF) - NXP Semiconductors.

Part Name
Description
View to exact match
UBA2014P
NXP
NXP Semiconductors. NXP
UBA2014P Datasheet PDF : 19 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
NXP Semiconductors
UBA2014
600 V driver IV for HF fluorescent lamps
8.5 Preheat state
After starting at fmax, the frequency decreases until the momentary value of the voltage
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 CCSW, thus raising the
frequency. The preheat time begins 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.
8.6 Ignition state
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 Figure 5.
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 Vlamp(fail) level. If the
lamp voltage exceeds the Vlamp(fail) level the ignition timer is started.
8.7 Burn state
If the lamp voltage does not exceed the Vlamp(max) level the voltage at pin CSW will
continue to increase until the clamp level at pin CSW is reached; see Figure 5. As a
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 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.
8.8 Lamp failure mode
8.8.1 During ignition state
If the lamp does not ignite, the voltage level increases. When the lamp voltage exceeds
the Vlamp(max) level, the voltage will be regulated at the Vlamp(max) level; see Figure 6.
When the Vlamp(fail) level is crossed the ignition timer has already started. If the voltage at
pin LVS is above the Vlamp(fail) level at the end of the ignition time the circuit stops
oscillating and is forced into the Power-down mode. The circuit will be reset only when the
supply voltage is powered down.
8.8.2 During burn state
If the lamp fails during normal operation, the voltage across the lamp will increase and the
lamp voltage will exceed the Vlamp(fail) level; see Figure 7. At that moment the ignition timer
is started. If the lamp voltage increases further it will reach the Vlamp(max) level. This forces
the circuit to reenter 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.
UBA2014_4
Product data sheet
Rev. 04 — 16 October 2008
© NXP B.V. 2008. All rights reserved.
6 of 19
 

Share Link: 

datasheetbank.com [ Privacy Policy ] [ Request Datasheet ] [ Contact Us ]