SSL152X_2

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 02 — 10 March 2009

8 of 17

NXP Semiconductors

SSL152x

SMPS ICs for low power systems

8.9 OverTemperature Protection (OTP)

An accurate temperature protection is provided in the device. When the junction

temperature exceeds the thermal shutdown temperature, the IC stops switching. During

thermal protection, the IC current is lowered to the start-up current. The IC continues

normal operation as soon as the overtemperature situation has disappeared.

8.10 OverVoltage Protection (OVP)

Overvoltage protection can be achieved in the application by pulling pin REG above its

normal operation level. The current primary stroke is terminated immediately. No new

primary stroke is started until the voltage on pin REG drops to its normal operation level.

Pin REG has an internal clamp. The current feed into this pin must be limited.

8.11 Characteristics of complete LED power supply

8.11.1 Input

The input voltage range comprises the universal AC mains from 80 V to 276 V.

8.11.2 Accuracy

The accuracy of the complete converter, functioning as a voltage source with primary

sensing, is approximately 8 % (mainly dependent on the transformer coupling). The

accuracy with secondary sensing is defined by the accuracy of the external components.

For safety requirements in case of opto coupler feedback loss, the primary sensing

remains active when an overvoltage circuit is connected.

8.11.3 Efficiency

An efficiency over 80 % at maximum output power can be achieved for a complete

converter designed for universal mains.

8.11.4 Ripple

A minimum ripple is obtained in a system designed for a maximum duty factor of 50 %

under normal operating conditions and a minimized dead time. The magnitude of the

ripple in the output voltage is determined by the frequency and duty factor of the

converter, the output current level, and the value and ESR of the output capacitor.

8.11.5 Output

The SSL152x family can handle a wide range of output power levels up to 15 W through

the selection of RDson.