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BD3021HFP-M

Regulator with Voltage Detector and Watchdog Timer

ROHM Semiconductor 

BD3021HFP-M

Technical Note

●Notes for use

1. Absolute maximum ratings

Use of the IC in excess of absolute maximum ratings (such as the input voltage or operating temperature range) may

result in damage to the IC. Assumptions should not be made regarding the state of the IC (e.g., short mode or open mode)

when such damage is suffered. If operational values are expected to exceed the maximum ratings for the device, consider

adding protective circuitry (such as fuses) to eliminate the risk of damaging the IC.

2. Electrical characteristics described in these specifications may vary, depending on temperature, supply voltage, external

circuits and other conditions. Therefore, be sure to check all relevant factors, including transient characteristics.

3. GND potential

The potential of the GND pin must be the minimum potential in the system in all operating conditions. Ensure that no pins

are at a voltage below the GND at any time, regardless of transient characteristics.

4. Ground wiring pattern

When using both small-signal and large-current GND traces, the two ground traces should be routed separately but

connected to a single ground potential within the application in order to avoid variations in the small-signal ground caused

by large currents. Also ensure that the GND traces of external components do not cause variations on GND voltage. The

power supply and ground lines must be as short and thick as possible to reduce line impedance.

5. Inter-pin shorts and mounting errors

Use caution when orienting and positioning the IC for mounting on printed circuit boards. Improper mounting may result in

damage to the IC. Shorts between output pins or between output pins and the power supply or GND pins (caused by poor

soldering or foreign objects) may result in damage to the IC.

6. Operation in strong electromagnetic fields

Using this product in strong electromagnetic fields may cause IC malfunction. Caution should be exercised in applications

where strong electromagnetic fields may be present.

7. Testing on application boards

When testing the IC on an application board, connecting a capacitor directly to a low-impedance pin may subject the IC to

stress. Always discharge capacitors completely after each process or step. The IC’s power supply should always be

turned off completely before connecting or removing it from a jig or fixture during the evaluation process. To prevent

damage from static discharge, ground the IC during assembly and use similar precautions during transport and storage.

8. Thermal consideration

Use a thermal design that allows for a sufficient margin in light of the Pd in actual operating conditions.

Consider Pc that does not exceed Pd in actual operating conditions. (Pd≧Pc)

Tjmax : Maximum junction temperature=150℃, Ta : Peripheral temperature[℃] ,

θja : Thermal resistance of package-ambience[℃/W], Pd : Package Power dissipation [W],

Pc : Power dissipation [W], Vcc : Input Voltage, VOUT : Output Voltage, Io : Load, Icc2 : Bias Current2

Package Power dissipation : Pd (W)=(Tjmax－Ta)/θja

Power dissipation

: Pc (W)=(Vcc－VOUT)×Io+Vcc×Icc2

9. Over current protection circuit (OCP)

The IC incorporates an integrated over-current protection circuit that operates in accordance with the rated output capacity.

This circuit serves to protect the IC from damage when the load becomes shorted. It is also designed to limit output current

(without latching) in the event of a large and instantaneous current flow from a large capacitor or other component. These

protection circuits are effective in preventing damage due to sudden and unexpected accidents. However, the IC should

not be used in applications characterized by the continuous or transitive operation of the protection circuits.

10. Thermal shutdown circuit (TSD)

The IC incorporates a built-in thermal shutdown circuit, which is designed to turn the IC off completely in the event of

thermal overload. It is not designed to protect the IC from damage or guarantee its operation. ICs should not be used after

this function has activated, or in applications where the operation of this circuit is assumed.

11. Applications or inspection processes where the potential of the Vcc pin or other pins may be reversed from their normal

state may cause damage to the IC's internal circuitry or elements. Use an output pin capacitance of 1000µF or lower in

case Vcc is shorted with the GND pin while the external capacitor is charged. Insert a diode in series with Vcc to prevent

reverse current flow, or insert bypass diodes between Vcc and each pin.

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12/14

2010.11 - Rev.A

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