UBA2211AP PHILIPS [NXP Semiconductors], UBA2211AP Datasheet - Page 9

• Manufacturer Part Number: UBA2211AP
• Description: Half-bridge power IC family for CFL lamps
• Manufacturer: PHILIPS [NXP Semiconductors]

NXP Semiconductors
UBA2211
Product data sheet
7.12 Capacitive Mode Protection (CMP)
7.11 Saturation Current Protection (SCP)
Remark: The glow time control is active as t
A critical parameter in the design of the lamp inductor is its saturation current. When the
momentary inductor exceeds its saturation current, the inductance drops significantly. If
the inductance drops significantly, the inductor current and the current flowing through the
high-side and low-side power switches increases rapidly. This increase can cause the
current to exceed the half-bridge power transistors maximum ratings.
Saturation of the lamp inductor is likely to occur in cost-effective and miniaturized CFLs.
The UBA2211 family internally monitors the power transistor current. When this current
exceeds the momentary rating of the internal power transistors, the conduction time is
reduced and the frequency is slowly increased (by discharging C
the system to balance at the edge of the current rating of the power switches.
When capacitive mode is detected, capacitor C
increase. The system sets itself to the operating point where capacitive mode switching is
minimized. CMP is active during the ignition state and in the steady state.
If capacitive mode is sensed during the preheat time, the oscillator restarts at f
is 2.5  f
electrode is broken.
Fig 6.
2.5 × f
0.6 × V
V
min
SW
f
V
osc(nom)
osc(nom)
V
SW(ph)
lamp
). CMP could be triggered by an end of lamp life condition when a lamp
HIGH
H(RC)
, f
0
All information provided in this document is subject to legal disclaimers.
osc(int)
, V
Rev. 3 — 26 August 2011
SW
and V
preheat time
V
SW(ph)
SW(ph)
plotted against time
ph
Half-bridge power IC family for CFL lamps
is too short to preheat the electrodes.
SW
V
SW
is discharged causing the frequency to
ignition
glow
SW
). This action causes
UBA2211
© NXP B.V. 2011. All rights reserved.
RMS control
001aal991
max
time (s)
f
osc(int)
V
V
lamp
SW
(which
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