BD12KA5W(2009) 查看數據表（PDF） - ROHM Semiconductor
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BD12KA5W Datasheet PDF : 10 Pages
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BD□□KA5,BD□□KA5W Series,BD00KA5W Series
Technical Note
●Input / Output Equivalent Circuit Diagrams
Vcc
Vcc Vcc
31.25kΩ 2kΩ
CTL
25kΩ
Fig.18
●Thermal Design
2.0
1.6
1.30
1.2
TO252-5
Rohm standard board mounting
Board size：70×70×1.6ｍｍ
Copper foil area：7×7ｍｍ2
θja=96.2(℃/W)
0.8
0.4
2.0
1.6
1.20
1.2
0.8
0.4
Vcc
R2
R1
※ With BD00KA5WFP/WF,R1and R2 are connected
OUT
outside the IC between ADJ and GND and
between OUT and ADJ.
ADJ
(BD00KA5WFP/WF)
Fig.19
TO252-3
Rohm standard board mounting
Board size：70×70×1.6ｍｍ
Copper foil area：7×7ｍｍ2
θja=104.2(℃/W)
SOP8
1000
(1)When using a standard board:
θj-c=181.8(℃/W)
800
(2) When using an IC alone
687.6mW
θj-a=222.2(℃/W)
600
(1)
562.6mW
400
(2)
200
0.0
0
25
50
75
100
125
150
Ambient temperature：Ta(℃)
Fig.20 Power Dissipation heat
reducing characteristics
0.0
0
25
50
75
100
125
150
Amb周ien囲t te温mp度era：tuTrea：(℃Ta()℃)
Fig.21 Power Dissipation heat
reducing characteristics
0
0
25
50
75
100 125 150
Am周bi囲ent温tem度pe：raTtuare(℃：T)a(℃)
Fig.22 Power Dissipation heat
reducing characteristics
When using at temperatures over Ta=25℃, please refer to the power dissipation shown in Fig.20 through 22.
The IC characteristics are closely related to the temperature at which the IC is used, so if the temperature exceeds the
maximum junction temperature TjMAX, the device may malfunction or be destroyed. The heat of the IC requires sufficient
consideration regarding instantaneous destruction and long-term operation reliability. In order to protect the IC from thermal
damage, it is necessary to operate it at temperatures less than the maximum junction temperature TjMAX.
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 :
Pc = (Vcc-Vo)×Io+Vcc×Icca
Acceptable loss Pd≧Pc
Solving for the load current IO in order to operate within the acceptable loss,
Vcc：Input voltage
Vo：Output voltage
Io：Load current
Icca：Circuit current
Io≦
Pd – Vcc×Icca
Vcc－Vo
It is then possible to find the maximum load current IoMAX with respect to the applied voltage Vcc at the time of thermal design.
Calculation Example
Example 1) When Ta=85℃, Vcc=2.5V, Vo=1.0V
Io≦
0.676－2.5×Icca
2.5-1.0
Io≦440mA (Icca : 2mA)
BA10KA5WFP（TO252-5 packaging）
θja=96.2℃/W → -10.4mW/℃
25℃=1300mW → 85℃=676mW
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 :
Pc=Vcc×(Icca+Ishort)
*Ishort : Short circuit current
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5/9
2009.04 - Rev.A
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