UBA2211APN1 NXP [NXP Semiconductors], UBA2211APN1 Datasheet - Page 9

• Manufacturer Part Number: UBA2211APN1
• Description: Half-bridge power IC family for CFL lamps
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
UBA2211
Objective data sheet
7.12 Capacitive Mode Protection (CMP)
7.11 Saturation Current Protection (SCP)
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
this happens, the inductor current and the current flowing through the LSPT and HSPT
power switches increases rapidly. This 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 half-bridge 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
could be triggered by an end of lamp life condition when a lamp electrode is broken.
Fig 6.
2.5 × f
0.6 × V
V
SW
f
f
active as t
osc(nom)
osc(nom)
V
osc(nom)
SW(ph)
HIGH
H(RC)
0
All information provided in this document is subject to legal disclaimers.
, V
ph
SW
is too short to preheat the electrodes
, V
Rev. 2 — 3 January 2011
SW(ph)
and V
preheat time
V
SW(ph)
lamp
plotted against time. The glow time control is
Half-bridge power IC family for CFL lamps
SW
is discharged causing the frequency to
ignition
glow
UBA2211
© NXP B.V. 2011. All rights reserved.
RMS control
SW
). This causes
001aal991
max
time (s)
f
osc(int)
V
V
lamp
. CMP
SW
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