CS1611A-FSZ View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CS1611A-FSZ

TRIAC Dimmable LED Driver IC

Cirrus Logic 

CS1610A/11A

CS1612A/13A

When exiting reset, the chip enters startup and the ADC

quickly (<5ms) tracks the external temperature to check if it is

below the 110°C reference code before the boost and second

stages are powered up. If this check fails, the rest of the

system will not be initialized until the external temperature is

below 110C.

For external overtemperature protection, a second low-pass

filter with a time constant of two minutes filters the ADC output

and uses it to scale down the internal dim level of the system

(and hence LED current ILED) if the temperature exceeds

95 °C (see Figure 18). The large time constant for this filter

ensures that the dim scaling does not happen spontaneously

and is not noticeable (suppress spurious glitches). LED

current ILED starts reducing when resistor RNTC is

approximately 6.3k (assuming a 14k 1% tolerance,

series resistor), which corresponds to a temperature of 95°C

for a 100k NTC (100k at 25°C). LED current ILED is scaled

until the NTC thermistor value reaches 2.5k (125°C). The

CS1610A/11A/12A/13A uses this calculated value to scale

output LED current ILED, as shown in Figure 18.

100%

50%

0

25

95

125

Temperature (°C)

Figure 18. LED Current vs. eOTP Temperature

Beyond this temperature, the IC shuts down using the

mechanism discussed above. If the external overtemperature

protection feature is not required, connect the eOTP pin to GND

using a 50k-to-500k resistor to disable the eOTP feature.

14

DS976PP4

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