ba00dd0w ROHM Co. Ltd., ba00dd0w Datasheet - Page 6

• Manufacturer Part Number: ba00dd0w
• Description: Standard Variable Output Ldo Regulator
• Manufacturer: ROHM Co. Ltd.

●Thermal Design
●Terminal Vicinity Settings and Cautions
●Vo Terminal
10
9
8
7
6
5
4
3
2
1
0
0
change due to factors such as temperature changes, which may cause oscillations. Please use a tantalum capacitor or
aluminum electrolytic capacitor with favorable characteristics and small external series resistance (ESR) even at low
temperatures. The output oscillates regardless of whether the ESR is large or small. Please use the IC within the stable
operating region while referring to the ESR characteristics reference data shown in Figs.33 through 35. In cases where there
are sudden load fluctuations, the a large capacitor is recommended.
series.
method.
HRP-5
When using at temperatures over Ta=25℃, please refer to the heat reducing characteristics shown in Fig.30 through 32.
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 Tj
Fig.31 shows the acceptable loss and heat reducing characteristics of the TO220FP package The portion shown by the
diagonal line is the acceptable loss range that can be used with the IC alone. 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 :
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
Example 1) When Ta=85℃, Vcc=8.3V, Vo=3.3V, BA33DD0WT
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 :
・Vcc Terminal
・CTL Terminal
Please attach an anti-oscillation capacitor between V
Below figure , it is ESR-to-Io stability Area characteristics ,measured by 22μＦ-ceramic-capacitor and resistor connected in
This characteristics is not equal value perfectly to 22μＦ-aluminum electrolytic capacitor in order to measurement
③ 7.3W
② 5.5W
① 2.3W
Please attach a capacitor (greater than 0.33μF) between the Vcc and GND.
Board size : 70×70×1.6 ㎜
Board front copper foil area : 10.5×10.5 ㎜
①2-layer board (back surface copper foil area :15×15 ㎜
②2-layer board (back surface copper foil area :70×70 ㎜
③4-layer board (back surface copper foil area :70×70 ㎜
The capacitance values differ depending on the application, so please chose a capacitor with sufficient margin and verify
the operation on an actual board.
The CTL terminal is turned ON at 2.0V and higher and OFF at 0.8V and lower within the operating power supply voltage
range.
The power supply and the CTL terminal may be started up and shut down in any order without problems.
Pc = (Vcc-Vo)×Io＋Vcc×Icca
Acceptable loss Pd≦Pc
25
Io≦
Io≦
Io≦200mA (Icca : 2mA)
Pc=Vcc×(Icca＋Ishort)
Ambient temperature:Ta(℃）
Pd – Vcc×Icca
1.04－8.3×Icca
50
Vcc－Vo
Fig.30
75
3
（board contains a thermal）
5
100
2
125
（Please refer to Figs.8 and 20 for Icca.）
2
2
2
)
)
)
150
With the IC alone : θja=62.5℃/W → -16mW/℃
25℃=2000mW → 85℃=1040mW
25
20
15
10
5
0
（ 1 ） 20.0
（ 2 ） 2.0
0
To225FP-5
（1）
（2）
25
When using a maximum heat sick : θj-c=6.25(℃/W)
When using an IC alone : θj-c=62.5(℃/W)
Ambient temperature:Ta(℃）
50
OUT
MAX
6/8
Fig.31
and GND. The capacitance of the capacitor may significantly
with respect to the applied voltage Vcc at the time of thermal
MAX
Ishort : Short circuit current
75
.
100
125
150
Icca：
Vcc：
2.0
1.6
1.2
0.8
0.4
0.0
Vo：
Io：
TO252-5
0
1.30
Input voltage
Output voltage
Load current
Circuit current
Mounted on a Rohm standard board
Board size : 70×70×1.6 ㎜
Copper foil area :7×7 ㎜
TO252-5θja=96.2(℃/W)
25
Ambient temperature:Ta(℃）
50
Fig.32
75
100
125
150