UBA2028(2009) Просмотр технического описания (PDF) - NXP Semiconductors.

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производитель

UBA2028
(Rev.:2009)

600 V dimmable power IC for compact fluorescent lamps

NXP Semiconductors. 

NXP Semiconductors

UBA2028

600 V dimmable power IC for compact fluorescent lamps

during restart the lamp still fails, the voltage remains high until the end of the ignition time.

At the end of the ignition time the circuit stops oscillating and the circuit will enter the

Power-down mode.

8.9 Power-down mode

The Power-down mode will be entered if, at the end of the ignition time, the voltage at pin

LVS is above Vlamp(fail). In the Power-down mode the oscillator will be stopped and both

TR1 and TR2 will be non-conductive. The VDD supply is internally clamped. The circuit is

released from the Power-down mode by lowering the low-voltage supply below VDD(rst).

8.10 Capacitive mode protection

The signal across R15 see Figure 8 (R6 in Figure 9) also gives information about the

switching behavior of the half bridge. If, after the preheat state, the voltage across the

ACM resistor (R15 or R6) does not exceed the Vdet(capm) level during the non-overlap time,

the Capacitive Mode Detection circuit (CMD) assumes that the circuit is in the capacitive

mode of operation. As a consequence the frequency will directly be increased to fmax. The

frequency behavior is de coupled from the voltage at pin CSW until CCSW has been

discharged to zero.

8.11 Charge coupling

Due to parasitic capacitive coupling to the high voltage circuitry all pins are burdened with

a repetitive charge injection. Given the typical application the pins IREF and CF are

sensitive to this charge injection. For charge coupling of approximately 8 pC, a safe

functional operation of the IC is guaranteed, independent of the current level.

Charge coupling at current levels below 50 µA will not interfere with the accuracy of the

VCS, Vi(PCS) and Vi(ACM) levels.

Charge coupling at current levels below 20 µA will not interfere with the accuracy of any

parameter.

8.12 Design equations

The following design equations are used to calculate the desired preheat time, the

maximum ignition time, and the minimum and the maximum switching frequency.

t ph = 1.8 × 3----3---0-C---×--C---1T---0---–---9 × 3---R-3---I-×-R---E-1---F0---3-

(1)

tign = 0.26 × 3----3---0-C---×--C---1T---0---–---9 × 3---R-3---I-×-R---E-1---F0---3-

(2)

f min

=

40.5

×

103

×

1----0---0----×-----1---0---–---1--2

CCF

×

3----3----×-----1---0---3-

RIREF

(3)

f max = 2.5 × f min

(4)

Start of ignition is defined as the moment at which the measured lamp voltage crosses the

Vlamp(fail) level; see Section 8.8.

UBA2028_1

Product data sheet

Rev. 01 — 9 October 2009

© NXP B.V. 2009. All rights reserved.

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