SSL3401HN Datasheet, PDF (12/29 Pages) NXP Semiconductors – Low voltage dimmable controller for LED lighting

NXP Semiconductors
SSL3401HN
Low voltage dimmable controller for LED lighting
8.8.3 Overtemperature protection
During normal operation, at an ambient temperature up to 100 C, the die temperature
must not exceed 105 C. SSL3401HN features a temperature roll-back protection to
maintain the maximum temperature to a predefined set point by adjusting the LED
current.
Internally, the IC senses the junction temperature of the die every 10 ms for a 50 Hz
supply and 8.3 ms for a 60 Hz supply. A feedback loop decreases the LED current by
adjusting the LED PWM control signal to maintain the junction temperature at a maximum
value of 20 °C below the OTP threshold. The maximum LED current reduction is 80 % of
its maximum value during normal operation.
If the chip temperature exceeds the predefined OTP threshold, the protection is triggered.
The boost converter is disabled and the LED PWM signal is set HIGH to shut down the
LED current immediately. Once the OTP is triggered, normal operation resumes only
when the chip temperature drops 30 °C below the OTP threshold.
The OTP, fallback, and recovery thresholds can be set via external resistors. Table 5 gives
the OTP threshold value as a function of the output voltage of the OTP setting resistor
divider: V_set(otp) = (V_DD  RSET2/(RSET2 + RSET1)).


3$5$06(7






56(7
56(7
Fig 6. OTP threshold setting
56(7
273VHWWLQJ
UHVLVWRUGLYLGHU
DDD
SSL3401HN
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 28 January 2014
© NXP B.V. 2014. All rights reserved.
12 of 29