uba20261 NXP Semiconductors, uba20261 Datasheet - Page 11

• Manufacturer Part Number: uba20261
• Description: 600 V And 350 V Power Ic For Step Dimmable Cfls
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UBA20261_UBA20262
Preliminary data sheet
7.2.1 Oscillator control
7.2.2 Combined timing circuit
7.2 Oscillation and timing
the supply voltage V
is 2 mA when V
fall in V
function enables the comparators to monitor the voltage on the CP pin and if the supply
voltage V
The internal oscillator is a VCO which generates a saw-tooth waveform between the
V
determine the saw-tooth frequency. R
maximum switching frequencies. Their ratio is internally fixed. Two ratios are available,
the ratio between f
f
Transistors HS (Q1) and LS (Q2) are switched to conducting at a duty cycle of
approximately 50 %. An overview of the oscillator signal and driver signals is shown in
Figure
gate driver signals V
A combined timing circuit is used to determine the preheat time, ignition enabling time and
overcurrent time (see
generator circuit. When the timer is not running, C
bridge(bst)min
Fig 8.
th(CF)max
8. The oscillator starts oscillating at f
DD
DD
Saw-tooth, gate driver and half-bridge output signals
level and 0 V. Capacitor C
because the internal analog supply is turned on when V
is 4.6. The saw-tooth frequency is twice the half-bridge frequency.
falls below V
All information provided in this document is subject to legal disclaimers.
DD
V
(GHS-HBO)
bridge(max)
falls between V
V
DD
V
GLS
HBO
V
GLS
Rev. 1 — 9 September 2011
Figure
CF
voltage
0
0
0
0
rises between V
and V
(V)
DD(stop)
and f
9). C
GHS
.
t
no
bridge(min)
CP
DD(start)
is t
600 V and 350 V power IC for step dimmable CFLs
CF
, R
ext(RREF)
no
, resistor R
ext(RREF)
t
DD(stop)
.
dch
and V
is 2.5 and the ratio between f
bridge(max)
and C
and V
DD(stop)
and the counter comprise the clock
ext(RREF)
t
CP
no
CF
. The non-overlap time between the
DD(start)
is charged to 5 V. The timing circuit
. More current is drawn during the
determine the minimum and
and the voltage on the CI pin
. Typically, the supply current
UBA20261/2
DD
001aam766
time (s)
> V
© NXP B.V. 2011. All rights reserved.
bridge(max)
DD(start)
. This
and
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