SSL21084T(2013) 데이터 시트보기 (PDF) - NXP Semiconductors.

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SSL21084T
(Rev.:2013)

Mains driver LED driver IC

NXP Semiconductors. 

NXP Semiconductors

SSL21084T

Mains dimmable LED driver IC

8.4 Protective features

The IC has the following protective features:

• UnderVoltage LockOut (UVLO)

• Leading-Edge Blanking (LEB)

• OverCurrent Protection (OCP)

• Internal OverTemperature Protection (OTP)

• Brownout protection

• Short-winding protection (SWP)

• LED overtemperature control and protection

• An optional output OverVoltage Protection circuit is implemented using external

components and the NTC pin.

• Output Short Protection (OSP)

The internal OTP and LED overtemperature protections are safe-restart protections. The

IC halts, causing VCC to drop to below VCC(stop) and triggers a start-up. When VCC drops to

below VCC(rst), the IC resets the latch protection mode. If VCC drops to below VCC(stop), the

IC halts. Switching starts only when no fault condition exists.

8.4.1 UnderVoltage LockOut (UVLO)

When the voltage on the VCC pin < VCC(stop), the IC stops switching. An attempt is then

made to restart by supplying VCC from the HV pin voltage.

8.4.2 Leading-Edge Blanking (LEB)

To prevent false detection of the short-winding or overcurrent, a blanking time following

switch-on is implemented. When the MOSFET switch switches on there can be a short

current spike due to capacitive discharge of voltage over the drain and source and the

charging of the gate to source capacitance. During the LEB time (tleb), the spike is

disregarded.

8.4.3 OverCurrent Protection (OCP)

The SSL21084T contains a highly accurate peak current detector. It triggers when the

voltage on the SOURCE pin reaches the peak level Vth(ocp)SOURCE. The current through

the switch is sensed using a resistor connected to the SOURCE pin. The sense circuit is

activated following LEB time tleb. As the LED current is half the peak current (by design), it

automatically provides protection for maximum LED current during operation. There is a

propagation delay (td(ocp-swoff)) between the overcurrent detection and the actual switching

off of the switch. Due to the delay, the actual peak current is slightly higher than the OCP

level set by the resistor in series to the SOURCE pin.

8.4.4

OverTemperature Protection (OTP)

When the internal OTP function is triggered at a certain IC temperature (Tth(act)otp), the

converter stops operating. The OTP safe-restart protection and the IC restart with

switching resuming when the IC temperature drops below Tth(rel)otp.

SSL21084T

Product data sheet

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

Rev. 6 — 3 October 2013

© NXP B.V. 2013. All rights reserved.

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