UBA2016AP datasheet(22/42 Pages) PHILIPS

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UBA2016A_15_15A

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Objective data sheet

Rev. 1 — 20 May 2011

22 of 42

NXP Semiconductors

UBA2016A/15/15A

600 V fluorescent lamp driver

7.6.6 Coil saturation protection

When the peak voltage on pin SLHB exceeds saturation threshold voltage Vth(sat)SLHB, an

additional current Iadd(CF) is sourced to pin CF to shorten the running oscillator cycle. In

Ignition state the fault timer is started and a discharge current Idch(CIFB) is drawn from pin

CIFB during the next cycle to increase the switching frequency.

In Burn state the IC will go to Stop state if coil saturation is detected longer than the

saturation detection delay time td(det)sat.

Current Ibias(SLHB) is sourced to pin SLHB which will force the controller into coil saturation

protection if pin SLHB is left open.

7.6.7 Lamp overcurrent protection

If voltage on pin IFB exceeds the overcurrent detection threshold voltage Vth(ocd)(IFB), and

the oscillator is running at fsw(high), an overcurrent is detected and the IC will immediately

enter the Stop state.

7.6.8 Lamp overvoltage protection

When the peak voltage on pin VFB exceeds Vth(ov)(VFB), the fault timer is started and a

discharge current Idch(CIFB) is drawn from pin CIFB during the next cycle to increase the

switching frequency.

When VVFB >Vth(ovextra)(VFB) for longer than the fault activation delay time tdet(fault) then the

IC will enter the Stop state.

7.6.9 Lamp removal detection

Removing the lamp from applications that have the resonant capacitor connected via the

lamp filaments, will result in hard switching because current cannot flow through the

ballast inductor.

If hard switching is detected during Ignition or Burn state the fault timer will be started.

For applications with the resonant capacitor connected directly to the ballast inductor,

capacitive mode, coil saturation or over voltage will be detected. Capacitive mode is

activated if the switching frequency ends up below the resonance frequency due to

removal of the lamp. If the switching frequency is near or above the resonance frequency,

the lamp (or rather the lamp socket) voltage and half-bridge current will be very high due

to the unloaded resonant circuit (lamp inductor and lamp capacitor) which activates the

coil saturation protection or the overvoltage protection.

7.6.10 Temperature protection

When the temperature is above Tth(act)otp and GLHB is high, the IC enters Standby state.

The IC cannot exit the Standby state until the temperature drops below Tth(rel)otp.

7.6.11 Fault timer

Any fault that starts the fault timer must be detected for longer than the fault activation

delay time td(act)fault to actually start the timer. When the timer is started, the capacitor at

pin CPT is alternately being charged and discharged. After 8 charging and 7 discharging

cycles the fault time-out period tto(fault) is reached and the IC enters either the Stop state or

the Auto-restart state, depending on the fault detected, the current state of the timer and

the number of ignition attempts; see Figure 9 “State diagram”. If the fault that started the

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