Electronic Components Datasheet Search |
|
UBA2021P Datasheet(PDF) 5 Page - NXP Semiconductors |
|
UBA2021P Datasheet(HTML) 5 Page - NXP Semiconductors |
5 / 16 page UBA2021_4 © NXP B.V. 2008. All rights reserved. Product data sheet Rev. 04 — 25 July 2008 5 of 16 NXP Semiconductors UBA2021 630 V driver IC for CFL and TL lamps 7.5 Ignition state The RS monitoring function changes from VRS(ctrl) regulation to capacitive mode protection at the end of the preheat time. Normally this results in a further frequency decrease down to the bottom frequency fB (approximately 43 kHz). The rate of change of frequency in the ignition state is less than that in the preheat mode. During the downward frequency sweep the circuit sweeps through the resonant frequency of the load. A high voltage then appears across the lamp. This voltage normally ignites the lamp. 7.6 Failure to ignite Excessive current levels may occur if the lamp fails to ignite. The IC does not limit these currents in any way. 7.7 Transition to the burn state Assuming that the lamp has ignited during the downward frequency sweep, the frequency normally decreases to the bottom frequency. The IC can transit to the burn state in two ways: 1. In the event that the bottom frequency is not reached, transition is made after reaching the ignition time tign. 2. As soon as the bottom frequency is reached. The bottom frequency is determined by RRREF and CCF. 7.8 Feed-forward frequency During burn state a feed-forward mechanism ensures that the lamp power will not increase above the maximum allowed value due to an increased mains voltage. In the feed-forward range the UBA2021 driver IC can be configured in such a way that the application is optimized for close to constant lamp power. Above a defined voltage level the oscillation frequency also depends on the supply voltage of the half-bridge (see Figure 6). The current for the current controlled oscillator is derived from the current through RRHV in the feed-forward range. The feed-forward frequency is proportional to the average value of the current through RRHV within the operating range of Ii(RHV), given the lower limit set by fB. For currents beyond the operating range (i.e. between 1.0 mA and 1.6 mA) the feed-forward frequency is clamped. In order to prevent feed-forward of ripple on Fig 5. Operation in the preheat mode mgs992 time burn state ignition state preheat state fstart fB |
Similar Part No. - UBA2021P |
|
Similar Description - UBA2021P |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |