LM39100 데이터 시트보기 (PDF) - HTC Korea

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LM39100

1A Low-Voltage Low-Dropout Regulator

HTC Korea 

1A Low-Voltage Low-Dropout Regulator LM39100/39101/39102

heat sink may be required depending on the maximum power dissipation and maximum ambient temperature

of application. With respect to the applied package, the maximum output current of 1A may be still

undeliverable due to the restriction of the power dissipation of LM39100/1/2. Under all possible conditions, the

junction temperature must be within the range specified under operating conditions. The temperatures over

the device are given by:

TC = TA + PD X θCA / TJ = TC + PD X θJC / TJ = TA + PD X θJA

Where TJ is the junction temperature, TC is the case temperature, TA is the ambient temperature, PD is the total

power dissipation of the device, θCA is the thermal resistance of case-to-ambient, θJC is the thermal resistance

of junction-to-case, and θJA is the thermal resistance of junction to ambient. The total power dissipation of the

device is given by:

PD = PIN – POUT = (VIN X IIN)–(VOUT X IOUT)

= (VIN X (IOUT+IGND)) – (VOUT X IOUT) = (VIN - VOUT) X IOUT + VIN X IGND

Where IGND is the operating ground current of the device which is specified at the Electrical Characteristics.

The maximum allowable temperature rise (TRmax) depends on the maximum ambient temperature (TAmax) of

the application, and the maximum allowable junction temperature (TJmax):

TRmax = TJmax – TAmax

The maximum allowable value for junction-to-ambient thermal resistance, θJA, can be calculated using the

formula:

θJA = TRmax / PD = (TJmax – TAmax) / PD

LM39100/1/2 is available in SOT-223, TO-252, and SOP-8 package. The thermal resistance depends on

amount of copper area or heat sink, and on air flow. If the maximum allowable value of θJA calculated above is

over 115°C/W for SOT-223 package, 95°C/W for TO-252 package, 130°C/W for SOP-8 package, no heat sink

is needed since the package can dissipate enough heat to satisfy these requirements. If the value for

allowable θJA falls near or below these limits, a heat sink or proper area of copper plane is required. In

summary, the absolute maximum ratings of thermal resistances are as follow:

Absolute Maximum Ratings of Thermal Resistance

Characteristic

Symbol

Rating

Thermal Resistance Junction-To-Ambient / SOT-223

θJA-SOT-223

115

Thermal Resistance Junction-To-Ambient / TO-252

θJA-TO-252

95

Thermal Resistance Junction-To-Ambient / SOP-8

θJA-SOP-8

130

No heat sink / No air flow / No adjacent heat source / 20 mm2 copper area. (TA=25°C)

Unit

°C/W

°C/W

°C/W

Nov. 2010 - Rev. 1.5.1

- 12 -

HTC

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