AS3649

Datasheet - Application In form atio n

www.ams.com/AS3649

1.0-2

34 - 39

The fast switching frequency (4MHz) of the AS3649 allows for the use of small SMDs for the external inductor. The saturation current

the I

9.1.4 Thermistor (NTC)

The NTC is used to protect the LED against overheating (hardware protection inside the AS3649, which works without any software - see NTC -

Flash LED Overtemperature Protection on page 14).

The thermistor has to be thermally coupled to the LED (and therefore as close as possible to the LED) and it shall not share the same ground

connection as the LED return ground (if they share the same ground connection the high current through the LED will offset the measurement of

the NTC).

It is recommended to use 220k

 resistance for a detection threshold of 125ºC, 100k for 110ºC and 68k for 80ºC LED temperature detection

threshold.

Table 26. Recommended Inductor

Part Number

L

DCR

Size

Manufacturer

LQM32PN1R0MG0

1.0µH

>0.6µH @ 3.0A

60m



3.0A

1

1. Flash pattern: 200ms/3A, 200ms pause, 200ms/3A, 2s then repeat again (no limit on the number of total cycles)

Alternative pattern with 1000ms/1.6A, 200ms pause, 200ms/3A, 200ms pause, 200ms/3A, 2s then repeat again. (no limit on the number

of total cycles). Use only up to coil_peak=2.9A setting

3.2x2.5x0.9mm

max 1.0mm

height

Murata

www.murata.com

SPM4012T-1R0M

1.0µH +/-20%

38m



4.57A

4.4x4.1x1.2

mm

height is max

TDK

www.tdk.com

SPM3012T-1R0M

1.0µH +/-20%

57m



+/-10%

3.4A

2

2. Inductance changes by -30%, use only up to coil_peak=3.3A setting

3.2x3x1.2

mm

height is max

CIG32W1R0MNE

1.0µH

>0.7µH @ 2.7A

>0.6µH @ 3.0A

60m



+/-25%

3.0A

4

3.2x2.5mm

max 1.0mm

height

Samsung Electro-Mechancs

www.sem.samsung.co.kr

CKP3225N1R0M

1.0µH

>0.6µH @ 3.0A

<60m



3.0A

4

3.2x2.5x0.9mm

max 1.0mm

height

Taiyo Yuden

www.t-yuden.com

NRH2412T1R0N

1.0µH

>0.6µH @ 2.5A

77m



2.5A

3

3. Use only for coil_peak=2.5A setting.

2.4x2.4x1.2mm

(height is max.)

MAMK2520T1R0M

1.0µH

>0.6µH @ 2.75A

45m



3.1A

4

4. Use only up to coil_peak=2.9A setting.

2.5x2.0x1.2mm

height is max

Table 27. Recommended Thermistors

Part Number

Resistance @ 25ºC

B-constant 25/50ºC

Size

Manufacturer

NCP03WL224E05RL

220k

 +/-3%

4485K +/-1%

0201

Murata

www.murata.com

NCP03WL104E05RL

100k

 +/-3%

4485K +/-1%

NCP15WF104F03RC

100k



0402

NCP15WL683J03RC

68k

