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BD3004HFP

Regulators with Voltage Detector and Watchdog Timer

ROHM Semiconductor 

zOperation Notes

1. Absolute maximum ratings

An excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc., can

break down the devices, thus making impossible to identify breaking mode, such as a short circuit or an open circuit. If

any over rated values will expect to exceed the absolute maximum ratings, consider adding circuit protection devices,

such as fuses.

2. GND voltage

The potential of GND pin must be minimum potential in all operating conditions.

3. Thermal design

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

4. Inter-pin shorts and mounting errors

Use caution when positioning the IC for mounting on printed circuit boards. The IC may be damaged if there is any connection error or if

pins are shorted together.

5. Actions in strong electromagnetic field

Use caution when using the IC in the presence of a strong electromagnetic field as doing so may cause the IC to malfunction.

6. Testing on application boards

When testing the IC on an application board, connecting a capacitor to a pin with low impedance subjects the IC to stress. Always

discharge capacitors after each process or step. Always turn the IC's power supply off before connecting it to or removing it from a jig or

fixture during the inspection process. Ground the IC during assembly steps as an antistatic measure. Use similar precaution when

transporting or storing the IC.

7. Regarding input pin of the IC

This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them isolated.

P-N junctions are formed at the intersection of these P layers with the N layers of other elements, creating a parasitic diode or transistor.

For example, the relation between each potential is as follows:

When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.

When GND > Pin B, the P-N junction operates as a parasitic transistor.

Parasitic diodes can occur inevitable in the structure of the IC. The operation of parasitic diodes can result in mutual interference among

circuits, operational faults, or physical damage. Accordingly, methods by which parasitic diodes operate, such as applying a voltage that

is lower than the GND (P substrate) voltage to an input pin, should not be used.

(Pin A)

Resistor

P+

N

P

P

N

P+

N

Parasitic element

GND

(Pin B)

Transistor (NPN)

B

C

E

P+

N

P

N

P+

N

P substrate

Parasitic element

or transistor

GND

Fig. 18 Example of IC structure

(Pin B)

BC

E

GND

Parasitic element or

transistor

(Pin A)

Parasitic element

8. Ground Wiring Pattern

When using both small signal and large current GND patterns, it is recommended to isolate the two ground patterns, placing a single

ground point at the ground potential of application so that the pattern wiring resistance and voltage variations caused by large currents do

not cause variations in the small signal ground voltage. Be careful not to change the GND wiring pattern of any external components,

either.

9. Thermal shutdown circuit (TSD)

The IC incorporates a built-in thermal shutdown circuit (TSD circuit). The thermal shutdown circuit (TSD circuit) is designed only to shut

the IC off to prevent runaway thermal operation. It is not designed to protect the IC or guarantee its operation. Do not continue to use the

IC after operating this circuit or use the IC in an environment where the operation of this circuit is assumed.. (See Fig. 12)

10. Overcurrent protection circuit (OCP)

The IC incorporates a built-in overcurrent protection circuit that operates according to the output current capacity. This circuit serves to

protect the IC from damage when the load is shorted. The protection circuit is designed to limit current flow by not latching in the event of

a large and instantaneous current flow originating 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 operation or transitioning of the protection circuits. At the time of thermal designing, keep in mind that the current capability

has negative characteristics to temperatures. (See Fig. 3)

11. Negative surge application to Vcc pin

The IC incorporates a built-in reverse connection breakdown prevention circuit that prevents IC damage even if Vcc carries a lower

voltage than the GND pin. However, note that the absolute maximum rating for the negative power supply voltage is -15 V.

12. Back current flow when the Vcc power supply is suddenly interrupted

These ICs limit generation of back current flow when the Vcc power supply is suddenly interrupted to protect the IC from damage. Sinking

current is also limited, making the series compatible with designs where high-capacitance capacitors are used to lengthen the amount of

time over which the output voltage can be maintained.

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