Nexperia

NCR420Z / NCR421Z

150 mA LED driver in SOT223

6. Thermal characteristics

Table 7. Thermal characteristics

Symbol Parameter

Conditions

Min

Typ

Max

Unit

[1] -

-

164

K/W

[2] -

-

108

K/W

[3] -

-

100

K/W

Rth(j-a)

thermal resistance from

junction to ambient

in free air

[4] -

-

70

K/W

Rth(j-sp)

thermal resistance from

junction to solder point

-

-

27

K/W

[1] Device mounted on an FR4 PCB, single-sided copper (70 µm), tin-plated and standard footprint.

[2] Device mounted on an FR4 PCB, single-sided copper (70 µm), tin-plated; mounting pad

for collector 1 cm2.

[3] Device mounted on an FR4 PCB, 4-layer copper, tin-plated and standard footprint.

[4] Device mounted on an FR4 PCB, 4-layer copper, tin-plated; mounting pad for collector 1 cm2.

aaa-029432

10-5

10

10-2

10-4

102

10-1

tp (s)

10-3

103

1

102

10

103

Zth(j-a)

(K/W)

1

0

0.02

0.05

0.33

0.75

duty cycle = 1

0.01

0.10

0.20

0.50

FR4 PCB; single-sided copper; tin-plated and standard footprint

Fig. 2. Transient thermal impedance from junction to ambient as a function of pulse duration; typical values

aaa-029433

10-5

10

10-2

10-4

102

10-1

tp (s)

10-3

103

1

102

10

103

Zth(j-a)

(K/W)

1

0

0.02

0.05

0.33

0.75

duty cycle = 1

0.10

0.20

0.50

0.01

FR4 PCB; single-sided copper, tin-plated; mounting pad for collector 1 cm 2

Fig. 3. Transient thermal impedance from junction to ambient as a function of pulse duration; typical values

NCR420Z_NCR421Z

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Product data sheet

Rev. 1 — 4 February 2019

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