UM10468
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 1 — 30 August 2011
15 of 27
NXP Semiconductors
UM10468
SSL2108X buck evaluation board
8. Negative Temperature Coefficient (NTC) function
The NTC pin can act as a control for thermal protection, an input for disabling/enabling the
light output using PWM dimming and a soft-start function.
When using the NTC pin as a control for thermal protection, the pre-soldered NTC RT1
can be used. Alternatively, a user-defined NTC resistor can be directly connected to this
pin through connector K4. Remove the pre-soldered NTC RT1 in this case. If necessary, a
resistor R6 can be mounted to fine-tune the NTC protection. As the default, a 0
resistance is mounted.
In addition, a PWM signal can be connected to connector K4, making PWM dimming
possible. Capacitor C7 is used as the soft-start capacitor. When using the soft-start
capacitor, the NTC protection function changes from auto-restart protection to a latched
protection.
Remark:
Detailed information on the NTC function can be found in the
SSL2108X
data sheet
).
