Fig.30 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.
Vcc：
Vo：
Io：
Input voltage
Output voltage
Load current
Circuit current
The method of calculating the power consumption Pc(W) is as follows.
Pc = (Vcc-Vo) × Io ＋ Vcc × Icca
Acceptable loss Pd≦Pc
Icca：
Solving this for load current IO in order to operate within the acceptable loss:
Pd – Vcc×Icca
Io≦
Vcc－Vo
（Please refer to Figs.8 and 20 for Icca.）
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=8.3V, Vo=3.3V, BA33DD0WT
1.04－8.3×Icca
Io≦
With the IC alone : θja=62.5℃/W → -16mW/℃
25℃=2000mW → 85℃=1040mW
5
Io≦200mA (Icca : 2mA)
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
●Peripheral Circuit Considerations
・Vcc Terminal
Please attach a capacitor (greater than 0.33μF) between the Vcc and GND.
The capacitance values will differ depending on the application, so please take this into account when configuring the
terminal.
・GND Terminal
Please be sure to keep the set ground and IC ground at the same potential level so that a potential difference does not arise
between them.
If a potential difference arises between the set ground and the IC ground, the preset voltage will not be outputted, causing
the system to become unstable. Therefore, please reduce the impedance by making the ground patterns as wide as
possible and by reducing the distance between the set ground and the IC ground as much as possible.
・CTL Terminal
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.
●Vo Terminal
100
100
Unstable operating region
Unstable operating region
10
1
10
Stable operating region
OUT
Stable operating region
IC
22μF
1
Unstable operating region
Unstable operating region
0.1
1
0.1
200
600
800
1000
400
100
0
10
1000
OUTPUT CURRENT：lo(mA)
OUTPUT CURRENT：lo(mA)
Fig.32 Output Equivalent Circuit
Fig.33 ESR-Io Characteristics
Fig.34 ESR vs Io Characteristics
(BA□□CC0,22μF)
（BA□□DD0,22μF）
Please attach an anti-oscillation capacitor between Vcc and GND. The capacitance of the capacitor may significantly change
due to factors such as temperature changes, making it impossible to completely stop oscillations. Please use a tantalum
capacitor or aluminum electrolysis capacitor with favorable characteristics and small internal series resistance (ESR) even at
low temperatures. The output fluctuates 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.32 through 34. In applications where
there are sudden load fluctuations, the use of a capacitor with large capacitance is recommended.
Below figure , it is ESR-to-Io stability Area characteristics ,measured by 22μＦ-ceramic-capacitor and resistor connected in
series.
This characteristics is not equal value perfectly to 22μＦ-aluminum electrolytic capacitor in order to measurement
method.
Note, however, that the stable range suggested in the figure depends on the IC and the resistance load involved, and can vary
with the board’s wiring impedance, input impedance, and/or load impedance. Therefore, be certain to ascertain the final status
of these items for actual use.
Keep capacitor capacitance within a range of 22μF～1000μF. It is also recommended that a 0.33μF bypass capacitor be
connected as close to the input pin-GND as location possible. However, in situations such as rapid fluctuation of the input
voltage or the load, please check the operation in real application to determine proper capacitance.
6/8
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