BD3021HFP-M_10 ROHM [Rohm], BD3021HFP-M_10 Datasheet - Page 10

• Manufacturer Part Number: BD3021HFP-M_10
• Description: Regulator with Voltage Detector and Watchdog Timer
• Manufacturer: ROHM [Rohm]

●Thermal Design
© 2010 ROHM Co., Ltd. All rights reserved.
BD3021HFP-M
www.rohm.com
Refer to Fig.14 and Fig.15 thermal dissipation characteristics for usage above Ta=25℃. The IC’s characteristics are affected
heavily by the temperature, and if is exceeds its max junction temperature (Tjmax), the chip may degrade or destruct.
Thermal design is critical in terms of avoiding Instantaneous destruction and reliability in long term usage. The IC needs to
be operated below its max junction temperature (Tjmax) to avoid thermal destruction. Refer to Fig.14 and Fig.15 for HRP7
package thermal dissipation characteristics. Operate the IC within power dissipation (Pd) when using this IC.
Power consumption Pc(W) calculation will be as below (for Fig.15③)
If load current Io is calculated to operate within power dissipation, it will be as below, where you can find the max load current
Io
Example) at Ta=125℃,Vcc=12V,VOUT=5V
Refer to above and adjust the thermal design so it will be within power dissipation within the entire operation temperature
range. Below is the power consumption Pc calculation when (VOUT-GND short)
Max
Io ≦
Io ≦
Io ≦ 208mA (Icc2=150µA)
Pc=Vcc×(Icc2+Ishort)
Pc=(Vcc－VOUT)×Io+Vcc×Icc2
Power dissipation Pd≧Pc
for the applied voltage Vcc of the thermal design.
10
8
6
4
2
0
(Refer to Fig.4 for I short)
0
Pd－Vcc×Icc2
1.60W
1.46－12×Icc2
Vcc－VOUT
25
12－5
AMBIENT TEMPERATURE:Ta[ ℃ ]
Mounted on a Rohm standard board
Board size : 70 ㎜×70 ㎜×1.6 ㎜
50
Fig.14
θja=78.1(℃/W)
75
100
Ishort: short current
(Refer to Fig2 for Icc2)
125
Fig.15③ : θja=17.1℃/W → -58.4mW/℃
25℃=7.3W → 125℃=1.46W
150
10/14
VOUT
10
8
6
4
2
0
Icc2
Vcc
0
③7.3W
②5.5W
①2.3W
Io
: Input Voltage
: Output Voltage
: Load Current
: Circuit Current
25
AMBIENT TEMPERATURE:Ta[ ℃ ]
Mounted on a Rohm standard board
Board size : 70 ㎜×70 ㎜×1.6 ㎜
①2-layer board
②2-layer board
③4-layer board
50
(back surface copper foil area :15 ㎜×15 ㎜)
(back surface copper foil area :70 ㎜×70 ㎜)
(back surface copper foil area :70 ㎜×70 ㎜)
(board contains a thermal)
Fig.15
75
①θja=54.3(℃/W)
②θja=22.7(℃/W)
③θja=17.1(℃/W)
100
125
150
Technical Note
2010.11 - Rev.A