UBA2016AP datasheet(23/42 Pages) PHILIPS

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UBA2016A_15_15A

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Objective data sheet

Rev. 1 — 20 May 2011

23 of 42

NXP Semiconductors

UBA2016A/15/15A

600 V fluorescent lamp driver

timer is no longer detected for a period longer than the fault release delay time td(rel)fault,

the fault timer will be reset and at any new occurance of the fault, the timer will start from

zero.

Faults which activate the fault timer are shown as SlowFault in Figure 9 “State diagram”.

The fault timer uses the same pin (CPT) to set the time with an external capacitor Cext(CPT)

as the preheat timer. The ratio between the preheat time-out time tto(ph) and the fault

time-out time tto(fault) can be changed by adding an external series resistor Rs(ext)(CPT) or

an external parallel resistor Rp(ext)(CPT) to the external capacitor Cext(CPT); see Figure 15

“CPT connections”.

The fault timer incorporates a protection that ensures safe operation conditions if the CPT

pin voltage is below Vth(scp)(CPT) (shorted to GND) by holding the oscillation frequency at

fsw(high).

7.6.12 Brownout protection

Brownout protection is designed to maintain stable and safe lamp operation during dips in

mains supply. Without this protection the current demand from the bus voltage to maintain

constant lamp power would increase upon a drop in bus voltage. This creates an unstable

situation with the mains input voltage dropping and the PFC reaching its regulation range

limit.

Brownout protection reduces the lamp power when the PFC is out of regulation. This

situation is only allowed for a limited time to prevent excessive component stress.

When the PFC is outside its regulation range and the bus voltage is still too low

(VCOMPPFC =Vclamp(COMPPFC) and VFBPFC <Vreg(FBPFC)), a brownout current Ibo(CF) is

added to the charge current at pin CF, thus increasing the fsw(low). A discharge brownout

current Idch(bo)(CIFB) is also drawn from pin CIFB. Both Ibo(CF) and Idch(bo)(CIFB) are

proportional to the difference between VFBPFC and Vreg(FBPFC). If VFBPFC <Vth(bo)(FBPFC)

the fault timer will start.

The start-up bleeder resistor and the regulation range of the PFC should be dimensioned

in such a way that if the fault timer times out on brownout protection and the IC enters

Stop state, the input mains voltage is too low to support the standby current of the IC via

the bleeder resistor. The IC will then automatically reset and start-up in normal mode (and

reignite the lamps) when the mains voltage has returned to normal.

Fig 15. CPT connections

001aan210

Cext(CPT)

Rp(ext)(CPT)

Rs(ext)(CPT)

CPT

Cext(CPT)

CPT

Cext(CPT)

CPT

smaller ratio

default ratio

larger ratio

tto(ph)/tto(fault)

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