TEA1716T 데이터 시트보기 (PDF) - NXP Semiconductors.

부품명

상세내역

제조사

TEA1716T

Resonant power supply control IC with PFC

NXP Semiconductors. 

NXP Semiconductors

UBA2071; UBA2071A

Half bridge control IC for CCFL backlighting

Vlamp

(V)

Vign

Vburn

(1)

(2)

fsw(min) freg fign

fsw(max)

f (kHz)

014aaa103

(1) Indicates lamp-OFF.

(2) Indicates lamp-ON.

Fig 8. Initial ignition of cold cathode fluorescent lamp via frequency sweep and load

resonance

Advantage of the sweep rather than a fixed ignition frequency is that sensitivity for spread

in resonance frequency is much lower.

Once the lamps are ignited the frequency sweep-down continues, gradually increasing the

lamp current (the resonance circuit should now still be inductive, so current increases as

frequency drops) until the current regulation level is reached (at fsw = freg). The frequency

will not reach fsw(min) if the lamp current comes into regulation. Once it has been detected

that the lamps are on (if the average absolute voltage at the current feedback input (pin

IFB) is above Vth(lod)(IFB)) PWM dimming is enabled. See Figure 9.

The initial ignition frequency sweep and the PWM generator are not synchronized. Once

the regulation frequency is reached, PWM dimming can start anywhere in its cycle. A

small internal PWM dimming enable delay time, td(en)PWM, allows the lamps to settle

before PWM dimming starts.

At the start of the lamps-off period of the PWM dimming, the switching frequency is swept

up to fsw(max). This reduces the lamp voltage so the lamps go out. If fsw(max) is reached,

both GL and GH are made low, so both half bridge powers will be non-conducting. This is

indicated by the dotted part of the switching frequency (fsw) line in Figure 9.

UBA2071_A_1

Product data sheet

Rev. 01 — 23 June 2008

© NXP B.V. 2008. All rights reserved.

12 of 35

Share Link: