bd4912 ROHM Co. Ltd., bd4912 Datasheet - Page 13

• Manufacturer Part Number: bd4912
• Description: Dmos System Power Supply Ics With Low Current Consumption Now Available
• Manufacturer: ROHM Co. Ltd.

8. Ground Wiring Pattern
9. Recommended operating ranges
10. Output capacitors
11. Applications or inspection processes with modes where the potentials of the V
12. Overcurrent protection circuits
13. Overvoltage protection circuit
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.
The circuit functional operations are guaranteed within the Operating Voltage Range and Operating Temperature Range.
Although standard electrical characteristics values are not guaranteed, characteristics values will not vary suddenly within
these ranges. However, careful consideration must be taken in designing the circuit.
Capacitors used to eliminate oscillation must be placed between the V
P.CON (pin 4), P.ANT (pin 3), and SW5V (pin 8) output pins and the GND pin.
Connect a capacitance of at least 0.1 µF. Ceramic capacitors can be used. Abrupt input voltage and load fluctuations can
affect output voltages. Output capacitor capacitance values should be determined after sufficient testing using the actual
application.
their normal states may cause damage to the IC's internal circuitry or elements. For example, such damage might occur
when V
listed for each pin in Table 1. It is recommended to insert a diode to prevent back current flow in series with V
diodes between V
between the V
The IC incorporates built-in overcurrent protection circuits for the V
P.CON (pin 4), P.ANT (pin 3), and SW5V (pin 8) output pins. Each circuit is specifically designed for the current capacity of
the corresponding pin and acts to prevent damage to the IC when an overcurrent flows. The protection circuits use
dropping fold-back type current limiting and are designed to limit current flow by not latching up in the event of a large and
instantaneous current flow, originating from a large capacitor or other component. Their design allows for sufficient safety
margins.
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 (for
example, applications where the IC is continuously connected to a load that significantly exceeds the output current
capacity). Use caution regarding thermal design, as the output current capacity varies negatively with the temperature
characteristics.
The overvoltage protection circuit is designed to turn off all output other than V
differential between the V
SW5V output are turned off when the voltage differential between the V
approximately 30 V (at room temperature).
Output pin
AUDIO
P.CON
SW5V
P.ANT
CC
V
ILM
AM
DD
is shorted with the GND pin while an external capacitor is charged. Use capacitors that fall within the range
CC
Table 1
and GND pins.
CC
0.1 µF to 2200 µF
0.1 µF to 2200 µF
0.1 µF to 2200 µF
0.1 µF to 220 µF
Output capacitor
and each pin. If the V
0.1 µF to 10 µF
0.1 µF to 10 µF
0.1 µF to 47 µF
CC
1 (pin 6) and GND (pin 1) pins exceeds approximately 30 V (at room temperature). V
CC
Fig.49 Example of Bypass Diode Insertion to Prevent Back Current Flow
pin carries a lower voltage than the GND pin, insert a protective diode
13/16
Protective
diode
Diode for preventing back current flow
Bypass diode
DD
(pin 9), AUDIO (pin 7), AM (pin 5), ILM (pin 2),
DD
CC
(pin 9), AUDIO (pin 7), AM (pin 5), ILM (pin 2),
2 (pin 10) and GND (pin 1) pins exceeds
CC
DD
pin and other pins may be reversed from
V
and SW5V output when the voltage
CC
Output pin
CC
, or bypass
DD
and