UBA2021T/N2 NXP Semiconductors, UBA2021T/N2 Datasheet - Page 4

• Manufacturer Part Number: UBA2021T/N2
• Description: CFL Lamp DRVR 14-Pin SO Tube
• Manufacturer: NXP Semiconductors

Specifications of UBA2021T/N2

• Package: 14SO
• Driver Type: CFL Lamp
• Module Configuration: Half Bridge
• Supply Current: 1mA
• Meter Display Type: Fluorescent Lamp
• Supply Voltage Range: 9.55V To 10.75V, 11.35V To 12.55V
• Driver Case Style: SOIC
• No. Of Pins: 14
• Operating: RoHS Compliant
• Operating Supply Voltage: 630 V
• Maximum Operating Temperature: + 150 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-14
• Minimum Operating Temperature: - 40 C
• Lead Free Status / Rohs Status: Details

NXP Semiconductors
UBA2021_4
Product data sheet
7.2 Initial start-up
7.3 Oscillation
7.4 Operation in the preheat mode
Initial start-up is achieved by charging capacitor CS9 with the current applied to the
RHV-pin. At start-up, MOSFET T2 conducts and T1 does not conduct. This ensures C
becomes charged. This start-up state is reached for a supply voltage of V
the voltage level on the VS-pin at which the circuit will be reset to its initial state and
maintained until the low voltage supply (V
reset to the start-up state.
When the low voltage supply (V
oscillating in the preheat state. The internal oscillator is a current-controlled circuit which
generates a sawtooth waveform. The frequency of the sawtooth is determined by the
capacitor C
frequency is twice the frequency of the signal across the load. The IC brings MOSFETs
T1 and T2 alternately into conduction with a duty factor of approximately 50 %.
represents the timing of the IC. The circuit block 'non-overlap' generates a non-overlap
time t
the reference current I
The circuit starts oscillating at approximately 2.5
decreases until a defined value of current I
decrease in frequency is determined by capacitor C
approximately 90 kHz. This frequency is well above the resonant frequency of the load,
which means that the lamp is off, the load only consists of L2, C5 and the electrode
resistance. The preheat time is determined by capacitor C
the preheat state by connecting the CP-pin to ground. During preheating, the circuit
monitors the load current by measuring the voltage drop over external resistor R
the end of
conduction of T2 with decision level V
V
Fig 4.
RS
> V
no
that ensures conduction periods of exclusively T1 or T2. Time t
RS(ctrl)
Oscillator timing
CF
. The frequency is increased for V
and the current out of the CF-pin, mainly set by R
V
RREF
internal
(G1-S1)
V
clock
V
Rev. 04 — 25 July 2008
(G2)
CF
.
0
0
0
0
VS
start-up
) has reached the value of V
RS(ctrl)
VS
shunt
. The frequency is decreased as long as
t
) reaches a value of V
no
is reached (see
RS
630 V driver IC for CFL and TL lamps
< V
f
B
CI
(108 kHz). The frequency gradually
. The frequency during preheating is
RS(ctrl)
t
no
CP
.
. The circuit can be locked in
time
VS(start)
mgs991
Figure
RREF
VS(start)
. The sawtooth
the circuit starts
UBA2021
5). The slope of the
no
© NXP B.V. 2008. All rights reserved.
. The circuit is
is dependent on
VS(reset)
Figure 4
shunt
. This is
4 of 16
at
boot