MC78BC43NTR Просмотр технического описания (PDF) - ON Semiconductor

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MC78BC43NTR

Micropower Voltage Regulator

ON Semiconductor 

MC78BC00 Series

APPLICATIONS INFORMATION

Introduction

The MC78BC00 series of micropower voltage regulators

are specifically designed for ultra-low dropout voltage and

an output current which ranges from several tens of mA to

several hundreds of mA making them ideal for

battery-powered equipment. These regulators also have a

chip enable function which minimizes supply current in

stand-by mode. An input bypass capacitor is recommended

if the regulator is located an appreciable distance (≥ 4

inches) from the input voltage source. These regulators

require a 10 mF capacitance between the output terminal and

ground for stability. Most types of aluminum, tantalum or

multilayer ceramic will perform adequately. Solid tantalums

or other appropriate capacitors are recommended for

operation below 25°C. The bypass capacitors should be

mounted with the shortest possible leads or track lengths

directly across the regulator input and output terminals.

With economical electrolytic capacitors, cold temperature

operation can pose a serious stability problem. As the

electrolyte freezes, around -30°C, the capacitance will

decrease and the equivalent series resistance (ESR) will

increase drastically, causing the circuit to oscillate. Quality

electrolytic capacitors with extended temperature ranges of

-40 ° to +85°C are readily available. Solid tantalum

capacitors may be the better choice if small size is a

requirement. However, a maximum ESR limit of 3.0 W must

be observed over temperature to maintain stability.

External PNP Transistor

2

In

Vin

4 Ext

VO

3

RA

Error

Amplifier

RB

Vref

Gnd

1

CE 5

Figure 9. Typical Operation

Out

10 mF

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