NJM2829 datasheet(4/9 Pages) NJRC

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NJM2829

- 4 -

Ver.2011-01-27

TYPICALAPPLICATION

ON/OFF control

ON/OFF control can be achieved by applying positive control voltage to CONTROL terminal.

Apply positive Vcont ("H") to make chip to be ON (Enabled), and either Vcont is "L" or open (High Z) to make chip to

be OFF (Disabled).

The relations between Vcont and the state is as follows:

Vcont +1.6V

≤ Vcont ≤ +5V ("H" level):

ON state

Vcont 0V

≤ Vcont ≤ +0.6V ("L" level):

OFF state

Vcont +0.6V < Vcont < +1.6V ("L" level):

Undefined

In case ON/OFF control is not used, keep applying positive Vcont to CONTROL terminal to make chip ON.

Note that negative Vcont does not make the chip enabled.

VIN

VOUT

CONTROL

GND

0.1µF

2.2µF*3

VOUT

VIN

CONTROL

0.047µF

NJM2829

*3) Vo>-0.9V version: Co=4.7

µ F(Ceramic)

* In the case of using a resistance "R" between VIN and control.

The current flow into the control terminal while the IC is ON state (ICONT) can be reduced when a pull up resistance

"R" is inserted between VIN and the control terminal.

The minimum control voltage for ON state (VCONT(ON)) is increased due to the voltage drop caused by ICONT and the

resistance "R".

* Input Capacitance CIN

Input Capacitance CIN is required to prevent oscillation and reduce power supply ripple for applications with high

power supply impedance or a long power supply line.

Use the CIN value of 0.1µF greater to avoid the problem.

CIN should connect between GND and VIN as short as possible.

*Output Capacitance CO

Output capacitor (Co) is required for a phase compensation of the internal error amplifier. The capacitance and the

equivalent series resistance (ESR) influences stability of the regulator.

This product is designed to work with a low ESR capacitor for the Co; however, use of recommended capacitance or

greater value is essential for stable operation.

Use of a smaller Co may cause excess output noise or oscillation of the regulator due to lack of the phase

compensation.

Therefore, use Co with the recommended capacitance or greater value and connect between Vo terminal and GND

terminal with minimal wiring. The recommended capacitance depends on the output voltage. Low voltage regulator

requires greater value of the Co. Thus, check the recommended capacitance for each output voltage.

Use of a greater Co reduces output noise and ripple output, and also improves transient response of the output

voltage against rapid load change.

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