UBA2024T View Datasheet(PDF) - NXP Semiconductors.
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UBA2024T Datasheet PDF : 14 Pages
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NXP Semiconductors
UBA2024
Half-bridge power IC for CFL lamps
6.2 Pin description
Table 2.
Symbol
SW
SGND
FS
PGND
OUT
HV
VDD
RC
Pin description
Pin SOT97-1 Pin SOT108-1 Description
1
8
sweep timing input
2
1, 2, 3, 5, 9, signal ground
10, 13
3
11
high-side floating supply output
4
12
power ground
5
14
half-bridge output
6
4
high-voltage supply
7
6
internal low-voltage supply output
8
7
internal oscillator input
7. Functional description
7.1 Supply voltage
The UBA2024 does not require an external low-voltage supply as the mains supply
voltage applied to pin HV powers it. The IC derives its own low supply voltage from this for
its internal circuitry.
7.2 Start-up state
With an increase of the supply voltage on pin HV, the IC enters the start-up state. In the
start-up state the high-side power transistor is not conducting and the low-side power
transistor is switched on. The internal circuit is reset and the capacitors on the bootstrap
pin FS and low-voltage supply pin VDD are charged. Pins RC and SW are switched to
ground. The start-up state is defined until VDD = VDD(startup).
7.3 Sweep mode
The IC enters the sweep mode when the voltage on pin VDD > VDD(startup). The capacitor
on pin SW is charged by ISW and the half-bridge circuit starts oscillating. The circuit enters
the start-up state again when the voltage on pin VDD < VDD(stop).
The sweep time (tsweep) is determined by the charge current (Ich(sw)) and the external
capacitor (CSW). Typical the total sweep time set by CSW is:
tsweep = CSW (nF ) × 10.3ms
(1)
During the sweep time the current flowing through the lamp electrodes performs some
preheating of the filaments. See Figure 5.
7.4 Reset
A DC reset circuit is incorporated in the high-side driver. The high-side transistor is
switched off when the voltage on pin FS is below the high-side lockout voltage Vfloat(UVLO).
UBA2024_4
Product data sheet
Rev. 04 — 17 September 2009
© NXP B.V. 2009. All rights reserved.
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