BA3259HFP-TR(2009) Ver la hoja de datos (PDF) - ROHM Semiconductor

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BA3259HFP-TR
(Rev.:2009)

Dual-output Secondary Fixed/Variable Output LDO Regulators for Local Power Supplies

ROHM Semiconductor 

BA3259HFP,BA30E00WHFP

Technical Note

 Input / Output Equivalent Circuits

BA3259HFP

Vcc

Vcc

Vo2

Vo1

ADJ

Fig.30 BA3259HFP I/O Equivalent Circuits

BA30E00WHFP

Vcc1Vcc1

Vo1

Vcc2

Vo2

ADJ

Fig.31 BA30E00WHFP I/O Equivalent Circuit

Explanation of external components

BA3259HFP

1) Vcc (Pin 1)

It is recommended that a ceramic capacitor with a capacitance of approximately 3.3F is placed between Vcc and GND at

a position closest to the pins as possible.

2) Vo (Pins 4 and 5)

Insert a capacitor between Vo and GND in order to prevent output oscillation. The capacitor may oscillate if the

capacitance changes as a result of temperature fluctuations. Therefore, it is recommended that a ceramic capacitor with a

temperature coefficient of X5R or above and a maximum capacitance change (resulting from temperature fluctuations) of

±10% be used. The capacitance should be between 1F and 1,000F. (Refer to Fig. 28.)

BA33E00HFP

1) Vcc1 (Pin 3) and Vcc2 (Pin 2)

Insert capacitors with a capacitance of 1F between Vcc1 and GND and Vcc2 and GND. The capacitance value will vary

depending on the application. Be sure to implement designs with sufficient margins.

2) Vo1 (Pin 5) and Vo2 (Pin 6)

Insert a capacitor between Vo and GND in order to prevent oscillation. The capacitance of the capacitor may greatly vary

with temperature changes, making it impossible to completely prevent oscillation. Therefore, use a tantalum aluminum

electrolytic capacitor with a low ESR (Equivalent Serial Resistance) that ensures good performance characteristics at low

temperatures. The output oscillates if the ESR is too high or too low. Refer to the ESR characteristics in Fig. 29 and

operate the IC within the stable operating region. If there is a sudden load change, use a capacitor with a higher

capacitance . A capacitance between 47F and 1,000F is recommended.

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© 2009 ROHM Co., Ltd. All rights reserved.

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2009.04 - Rev.A

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