NCP5663, NCV5663

http://onsemi.com

9

APPLICATION INFORMATION

The NCP5663/NCV5663 is a high performance low

dropout 3.0 A linear regulator suitable for high power

applications, featuring an ultra−fast response time and low

noise without a bypass capacitor. It is offered in both fixed

and adjustable output versions with voltages as low as 0.9 V.

Additional features, such as Enable and Error Flag (fixed

output

version)

increase

the

utility

of

the

NCP5663/NCV5663. It is thermally robust and includes the

safety features necessary during a fault condition, which

provide for an attractive high current LDO solution for

server, ASIC power supplies, networking equipment

applications, and many others.

Input Capacitor

The recommended input capacitor value is a 150

mF

OSCON with an Equivalent Series Resistance (ESR) of

50 m

W. It is especially required if the power source is

located

more

than

a

few

inches

from

the

NCP5663/NCV5663. This capacitor will reduce device

sensitivity and enhance the output transient response time.

The PCB layout is very important and in order to obtain the

optimal solution, the Vin and GND traces should be

sufficiently wide to minimize noise and unstable operation.

Output Capacitor

Proper output capacitor selection is required to maintain

as 10

mF (Figures 15 and 16) and guaranteed to be stable at

50 m

W and 300 mW over the output current range of 10 mA

to 3.0 A. For PCB layout considerations, place the

recommended ceramic capacitor close to the output pin and

keep the leads short. This should help ensure ultra−fast

transient response times.

Adjustable Output Operation

The application circuit for the adjustable output version is

shown in Figure 1. The reference voltage is 0.9 V and the

adjustable pin current is typically 40 nA. A resistor divider

network, R1 and R2, is calculated using the following

formula:

R1 + R2

Vout

Vref

* 1

Input

Output

NCP5663

Enable

ON

OFF

EN

ADJ

GND

Figure 17. To achieve the minimum output voltage,

Current Limit Operation

As the peak output current increases beyond its limitation,

the device is internally clampled to 4.5 A, thus causing the

output voltage to decrease and go out of regulation. This

allows the device never to exceed the maximum power

dissipation.

Error Flag Operation

The Error Flag pin on the NCP5663/NCV5663 will

produce a logic Low when it drops below the nominal output

voltage. Refer to the electrical characteristics for the

threshold values at which point the Error Flag goes Low.

When the NCP5663/NCV5663 is above the nominal output

voltage, the Error Flag will remain at logic High.

The external pullup resistor needs to be connected

approximately 100 k

W is recommended to minimize the

current consumption. No pullup resistor is required if the

Error Flag output is not being used.

Thermal Consideration

This series contains an internal thermal limiting circuit

that is designed to protect the regulator in the event that the

maximum junction temperature is exceeded. This feature

provides protection from a catastrophic device failure due to

accidental overheating. It is not intended to be used as a

substitute for proper heat sinking. The maximum device

power dissipation can be calculated by:

The bipolar process employed for this IC is fully

To avoid damaging the part or degrading it’s reliability,

power dissipation transients should be limited to under 30 W