NCP400

http://onsemi.com

11

APPLICATION INFORMATION

Low Dropout Voltage Regulator

−Input Decoupling

A 1.0

mF capacitor either ceramic or tantalum is

recommended and should be connected close to the NCP400

package. Higher values and lower ESR will improve the

overall line transient response.

−Output Decoupling

The NCP400 is a stable Regulator and does not require

any specific Equivalent Series Resistance (ESR) or a

minimum output current. Capacitors exhibiting ESRs

ranging from a few m

W up to 10 W can thus safely be used.

The minimum decoupling value is 1.0

mF and can be

augmented to fulfill stringent load transient requirements.

The regulator accepts ceramic chip capacitors as well as

tantalum devices. Larger values improve noise rejection and

load regulation transient response. Figure 25 shows the

stable area of the regulator with different output capacitor

ESR and output current.

Figure 25. Output Capacitor versus Output Current

0.01

0.1

1

10

100

0

25

50

75

100

125

150

UNSTABLE

UNSTABLE

STABLE

−Thermal Protection

Internal thermal shutdown circuit is provided to protect

the integrated circuit in the event that the maximum junction

temperature is exceeded. When the thermal protection

activated, higher than 150

°C, the regulator turns off. This

feature is provided to prevent failures from accidental

overheating.

−Hints

Please be sure the Vin and GND lines are sufficiently

wide. When the impedance of these lines is high, there is a

chance to pick up noise or cause the regulator to

malfunction. Set external components, especially the output

capacitor, as close as possible to the circuit, and make leads

a short as possible.

Voltage Detector

The voltage detector has built−in hysteresis to prevent

erratic reset operation. This device is specifically designed

for use as reset controllers in portable microprocessor based

systems, it can offer a cost−effective solution in numerous

applications where precise voltage monitoring and time

delay are required. Figures 26 through 27 shows various

application examples.