TN7D51

No. A0866-10/11

Continued from preceding page.

SS terminal (5 pin) also acts as standby mode switch. By setting SS terminal (5 pin) voltage to be equal or less than

0.3Vtyp, the output ON/OFF is able to be controlled by external signals.

ON/OFF Control Circuit Example

In addition, confirmation of the following points is necessary in actual circuit.

1) How the output ON/OFF control operates and its effects.

2) Is there any malfunction due to the ambient temperature change of each device or exogenous noises?

Points to Remember in Pattern Designing

1) Transient large current flows to VIN terminal (1 pin), so we recommend the input capacitor should be 3000µF and

above. In addition, (+) (-) terminals of the input capacitor should be set near to VIN terminal (1 pin) and GND

terminal (2 pin).

2) Large current flows to C1A to C, VIN terminal (1 pin) of IC1, SWOUT terminal (3 pin), D1, L1, and C2A. So, the

wiring should be thick and short.

3) FB terminal (4 pin) of IC1 is the feedback terminal from output voltage. It should be near to the output capacitor

C2A.

•

For the purpose of ensuring the stability of oscillation, a capacitor should be inserted between SS terminal (5 pin) and

GND terminal (2 pin).

•

The absolute maximum rated voltage of SS terminal (5 pin) is 7V. The absolute maximum rated voltage of FB

terminal (4 pin) is within the range of 5 to 30V according to the output voltage type. When a voltage equal or

higher than the rated value is applied to SS terminal (5 pin) or FB terminal (4 pin) in some cases such as abnormal

test, protection measures like inserting fuses should be taken.

•

The built-in over-heat protection is a function to prevent the circuit from overheat state caused by transient

temperature rise, but not a function to prevent from abnormal caused by a sudden heat generation. In addition,

the reliability of over-heat protection function is not guarantee.

+

+

VIN

GND

GND

Signal

IT12641

VOUT

1

FUSE

F1

IC1

NPN

5

23 4