SSL5021BTS datasheet(7/20 Pages) NXP

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SSL5021BTS

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Product data sheet

Rev. 2 — 11 March 2015

7 of 20

NXP Semiconductors

SSL5021BTS

Compact low-ripple buck LED driver IC

8.5 Leading-Edge Blanking (LEB)

To prevent false detection of overcurrent, a blanking time following switch-on is

implemented. When the internal switch turns on, a short current spike can occur because

of the discharge capacitance of the MOSFET/bipolar (Q1) drain/collector node.

8.6 Protections

The IC incorporates the following protections:

• UnderVoltage LockOut (UVLO)

• Cycle-by-cycle OverCurrent Protection (OCP)

• Internal OverTemperature Protection (OTP)

• Cycle-by-cycle maximum on-time protection

• Output OverVoltage Protection

• Output Short Protection (OSP)

8.6.1 UnderVoltage LockOut (UVLO)

When voltage on VCC pin drops to below Vth(UVLO), the IC stops switching. An attempt is

made to restart IC when the voltage on the VCC pin > Vstartup.

8.6.2 Cycle-by-cycle OverCurrent Protection (OCP)

The SSL5021BTS incorporates a built-in peak current detector. It triggers when the

voltage at the ISNS pin reaches the peak level VI(max)ISNS. A resistor connected to ISNS

pin senses the current through inductor IL. The maximum current in inductor, IL(max)

equals:

(2)

Fig 6.

Start-up current waveform

Lmax



max

ISNS

0.09

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