bd00c0awfp ROHM Co. Ltd., bd00c0awfp Datasheet - Page 7

• Manufacturer Part Number: bd00c0awfp
• Description: 1a Standard Variable Output Ldo Regulators
• Manufacturer: ROHM Co. Ltd.

● Thermal Design
www.rohm.com
BD00C0AWFP,BD00C0AWCP-V5
© 2011 ROHM Co., Ltd. All rights reserved.
When using at temperatures over Ta=25 ℃ , please refer to the heat reducing characteristics shown in Fig.15 and Fig.16.
The IC characteristics are closely related to the temperature at which the IC is used, so it is necessary to operate the IC at
temperatures less than the maximum junction temperature Tjmax.
Fig.15 and Fig.16 shows the acceptable loss and heat reducing characteristics of the TO252-5 package. Even when the
ambient temperature Ta is a normal temperature (25 ℃ ), the chip (junction) temperature Tj may be quite high so please
operate the IC at temperatures less than the acceptable loss Pd.
The calculation method for power consumption Pc(W) is as follows :(Fig.16 ③ and Fig.17)
Solving this for load current Io in order to operate within the acceptable loss,
It is then possible to find the maximum load current Io
design.
Calculation Example) When TO252-5,Ta=85 ℃ ,Vcc=10V,Vo=5V
Calculation Example) When TO220CP-V5,Ta=85 ℃ ,Vcc=25V,Vo=5V
Please refer to the above information and keep thermal designs within the scope of acceptable loss for all operating
temperature ranges. The power consumption Pc of the IC when there is a short circuit (short between Vo and GND) is :
5
4
3
2
1
0
0
1.30
Pc=Vcc × (Ib+Ishort)
Io ≦
Io ≦
Io ≦ 498.2mA (Ib:0.5mA)
Io ≦
Io ≦ 519.4mA (Ib:0.5mA)
25
Pc=(Vcc-Vo) × Io+Vcc × Ib
Acceptable loss Pd ≧ Pc
Temperature atmosphere Ta(℃)
Mounted on a Rohm standard board
Board size : 70 ㎜×70 ㎜×1.6 ㎜
Copper foil area :7 ㎜×7 ㎜
TO252-5θja=96.2(℃/W)
50
10.4 － 25 × Ib
2.496 － 10 × Ib
TO252-5
Pd － Vcc × Ib
Fig.15
Vcc － Vo
75
20
5
100
125
150
(Please refer to Fig.9 for Ib.)
(Please refer to Fig.5 for Ishort.)
5
4
3
2
1
0
0
③ 4.80
② 3.50
① 1.85
Fig.16(Reference data)
Fig.17(Aluminium heat dissipation board) θ ja=6.3 ℃ /W → -160mW/ ℃
25 ℃ =20W → 85 ℃ =10.4W
Fig.16 ③ : θ ja=26.0 ℃ /W → -38.4mW/ ℃
25 ℃ =4.80W → 85 ℃ =2.496W
25
Temperature atmosphere Ta(℃)
50
TO252-5
Max
7/11
Mounted on a Rohm standard board
Board size : 70 ㎜×70 ㎜×1.6 ㎜
Copper foil area :7 ㎜×7 ㎜
75
with respect to the applied voltage Vcc at the time of thermal
① 2-layer board
② 2-layer board
③ 4-layer board
(back surface copper foil area :15 ㎜× 15 ㎜ )
(back surface copper foil area :70 ㎜× 70 ㎜ )
(back surface copper foil area :70 ㎜× 70 ㎜ )
100
125
① : θ ja=67.6 ℃ /W
② : θ ja=35.7 ℃ /W
③ : θ ja=26.0 ℃ /W
150
25
20
15
10
5
0
0
② 20.0 (Ref erence data)
① 1.85
25
Temperature atmosphere Ta(℃)
IC Only
θja=67.6℃/W
TO220CP-V5
Ishort:
50
Vcc:
Fig.17
Vo:
Io:
Ib:
Aluminum heat
dissipation board
θja=6.3℃/W
75
Technical Note
2011.08 - Rev.B
Input voltage
Output voltage
Load current
Circuit current
Short current
(Reference Data)
100
125
150