Technical Note

BA00DD0WCP-V5,BA00DD0WHFP,BA00DD0WT,

BA00CC0WT,BA00CC0WT-V5,BA00CC0WCP-V5,BA00CC0WFP

7/9

www.rohm.com

2010.02 - Rev.B

© 2010 ROHM Co., Ltd. All rights reserved.

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Vo Terminal

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.

Fig.33:Output equivalent circuit

Fig.34:Io vs. ESR characteristics

Fig.35: Io vs. ESR characteristics

(BA□□CC0)

(BA□□DD0)

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Other

1) Protection Circuits

Overcurrent Protection Circuit

A built-in overcurrent protection circuit corresponding to the current capacity prevents the destruction of the IC when there

are load shorts. This protection circuit is a “7”-shaped current control circuit that is designed such that the current is

restricted and does not latch even when a large current momentarily flows through the system with a high-capacitance

capacitor. However, while this protection circuit is effective for the prevention of destruction due to unexpected accidents, it

is not suitable for continuous operation or transient use. Please be aware when creating thermal designs that the overcurrent

protection circuit has negative current capacity characteristics with regard to temperature (Refer to Figs.4 and 16).

Thermal Shutdown Circuit (Thermal Protection)

This system has a built-in temperature protection circuit for the purpose of protecting the IC from thermal damage. As

shown above, this must be used within the range of acceptable loss, but if the acceptable loss happens to be continuously

exceeded, the chip temperature Tj increases, causing the temperature protection circuit to operate.

When the thermal shutdown circuit operates, the operation of the circuit is suspended. The circuit resumes operation

immediately after the chip temperature Tj decreases, so the output repeats the ON and OFF states (Please refer to

Figs.12 and 24 for the temperatures at which the temperature protection circuit operates).

There are cases in which the IC is destroyed due to thermal runaway when it is left in the overloaded state. Be sure to

avoid leaving the IC in the overloaded state.

Reverse Current

In order to prevent the destruction of the IC when a reverse current flows through the IC, it is recommended that a diode

be placed between the Vcc and Vo and a pathway be created so that the current can escape (Refer to Fig.36).

2) This IC is bipolar IC that has a P-board (substrate) and P+ isolation layer

between each devise, as shown in Fig.37. A P-N junction is formed between

this P-layer and the N-layer of each device, and the P-N junction operates as a

parasitic diode when the electric potential relationship is GND> Terminal A,

GND> Terminal B, while it operates as a parasitic transistor when the electric

potential relationship is Terminal B GND> Terminal A. Parasitic devices are

intrinsic to the IC. The operation of parasitic devices induces mutual

interference between circuits, causing malfunctions and eventually the

destruction of the IC itself. It is necessary to be careful not to use the IC in ways

that would cause parasitic elements to operate. For example, applying a

voltage that is lower than the GND (P-board) to the input terminal.

Fig. 37: Example of the basic structure of a bipolar IC

22μF

OUT

IC

C(ADJ)

200

400

800

1000

0.1

1

10

Stable operating region

100

0

600

Unstable operating region

Unstable operating region

1

0.1

1

10

100

10

100

1000

OUTPUT CURRENT：lo(mA)

OUTPUT CURRENT：lo(mA)

Unstable operating region

Unstable operating region

Stable operating region

GND

N

P

N

P+

P+

Parasitic element

or transistor

(Pin B)

B

E

Transistor (NPN)

N

P

N

GND

O

(Pin A)

GND

N

P+

Resistor

Parasitic element

P

N

P

P+

N

(Pin A)

Parasitic element

or transistor

(Pin B)

GND

C

B

E

Parasitic element

GND

Fig. 36:Bypass diode

OUT

Vcc

CTL

GND

Reverse current