SSL4120 datasheet(30/48 Pages) NXP

30 / 48 page

SSL4120

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 2 — 1 November 2012

30 of 48

NXP Semiconductors

SSL4120

Resonant power supply controller IC with PFC for LED lighting

7.8.10.2

Overcurrent regulation, OCR-HBC

The lowest comparator levels at the SNSCURHBC pin (Vocr(HBC) = 0.5 V and +0.5 V),

relate to the overcurrent regulation voltage. There are comparators for both the positive

and negative polarities. The positive comparator is active during the high-side on-time and

the following high-side to low-side non-overlap time. The negative comparator is active

during the remaining time. If either level is exceeded, the frequency is slowly increased.

Discharging the soft-start capacitor achieves this decrease.

Each time the OCR level is exceeded, the event is latched until the next stroke and the

soft-start discharge current is enabled. When both the positive and negative OCR levels

are exceeded, the soft-start discharge current flows continuously.

Overcurrent regulation is very effective at limiting the output current during start-up. A

smaller soft-start capacitor is used to achieve a faster start-up. Using a smaller capacitor

can result in an output current that is too high at times. However, the OCR function slows

down the frequency sweep when required to keep the output current within the specified

limits. Figure 18 shows the operation of the OCR during output voltage start-up.

Fig 17. Boost voltage compensation

VCur(HBC) = Rcur(HBC) × ICur(HBC)

Iocr(high)

Iocp(high)

Iocp(nom)

Iocr(nom)

-Iocr(nom)

-Iocp(nom)

-Iocr(high)

-Iocp(high)

ICur(HBC)

ISNSCURHBC

Vreg

Vuvp

Vboost

GATELS

GATEHS

sink current only with positive VSNSCURHBC

sink

source

low Vboost

strong compensation

high OCP

low Vboost

strong compensation

high OCR

nominal Vboost

no compensation

nominal OCP

nominal Vboost

no compensation

nominal OCR

VSNSCURHBC

014aaa865

VSNSCURHBC

Vocr(HBC)

-Vocr(HBC)

Vocp(HBC)

-Vocp(HBC)

SSL4120 датащи(PDF) 30 Page - NXP Semiconductors

SSL4120 датащи(HTML) 30 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

датащи скачать

ссылки URL