tk64829amf Toko Inc., tk64829amf Datasheet - Page 27

• Manufacturer Part Number: tk64829amf
• Description: Auto Discharge Function, Ultra Small Package, High Rr, Fast Response, Low Noise, 300ma Cmos Ldo Regulator Ic Tk648xxamf
• Manufacturer: Toko Inc.

12-2. Layout
Please do derating with 3.2mW/°C(PCB size: 7mm×
8mm×0.8mm), 7.2mW/°C(PCB size: 30mm×30mm×
1mm), at P
900mW(PCB size: 30mm×30mm×1mm), and 25°C or
more.
D
=400mW(PCB size: 7mm×8mm×0.8m),
PCB Material: Glass epoxy
PCB Material: Glass epoxy
Size: 30mm×30mm×1mm
Size: 7mm×8mm×0.8mm
図12-4: Layout example
V
V
V
Out
In
V
Out
In
(Top View)
(Top View)
GND
V
Cont
V
GND
Cont
GC3-O005
internal temperature sensor works (about 150°C).
Therefore, the package loss is assumed to be an internal
limitation. There is no heat radiation characteristic of the
package unit assumed because of its small size. Heat is
carried away from the device by being mounted on the
PCB. This value is directly effected by the material and
the copper pattern etc. of the PCB. The losses are
approximately 400mW. Enduring these losses becomes
possible in a lot of applications operating at 25°C.
junction temperature reaches 150°C (this happens when
the regulator is dissipating excessive power, outside
temperature is high, or heat radiation is bad). The output
current and the output voltage will drop when the
protection circuit operates. However, operation begins
again as soon as the output voltage drops and the
temperature of the chip decreases.
How to determine the thermal resistance when
mounted on PCB
follows:
T
thermal sensor is activated.
If the ambient temperature is 25°C, then:
The package loss is limited at the temperature that the
The overheating protection circuit operates when the
The thermal resistance when mounted is expressed as
j
of IC is set around 150°C. P
900
400
P
T
150=θ
θ
D
ja
j
=θ
(mW)
=125/P
ja
-3.2mW/°C
PCB size
(7mm×8mm×0.8mm)
×P
ja
×P
D
25
D
+T
D
Fig12-5: Derating Curve
+25
(°C /mW)
a
-7.2mW/°C
PCB size
(30mm×30mm×1mm)
50
(85°C)
D
100
is the value when the
TK648xxAMF
150°C
Page 27