MCCF33095D 查看數據表（PDF） - Motorola => Freescale

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MCCF33095D

INTEGRAL ALTERNATOR REGULATOR

Motorola => Freescale 

MCCF33095 MC33095

FUNCTIONAL DESCRIPTION

Introduction

This ignition control circuit was originally designed and

offered as an MCCF33095 Flip–Chip for use in 12 V

automotive alternator charging systems. The MCCF33095

consists of many protection features which are entailed in a

ten pin flip–chip package. The device was subsequently

made available in a 14 pin surface mount version

(MC33095D). Both versions perform in a similar manner. The

Flip–Chip version has an advantage over the surface mount

version where minimized space and higher operating

ambient temperatures are of major concern. Device

operation and application suggestions for both versions are

given below.

Oscillator

The oscillator frequency is determined by the value of an

external capacitor from the Oscillator pin to ground (see

applications circuit). The oscillator frequency in a typical

application is approximately 175 Hz, but a range of 50 Hz to

500 Hz can reasonably be used. The waveform generated

consists of a positive linear slope followed by relatively fast

negative fall (sawtooth). The flip–flops are reset by the falling

edge of the sawtooth signal as shown on the logic diagram.

The oscillator signal peaks at approximately 3.0 V and

provides the timing required for the device.

Ignition

The Ignition input signal enables the device turn–on when

the Ignition pin voltage is greater than 1.4 V. This signal

normally originates from the ignition switch of automotive

systems.

Sense

The Sense pin functions as a voltage sensor. It

proportionally senses the battery voltage and determines the

amount of time the Darlington transistor is high over the next

cycle. A low voltage at the Sense pin will result in a long duty

cycle for the Darlington while a high voltage produces a short

duty cycle. In the application, proportional control is used to

determine the duty cycle. Proportional control is defined as

the sense ratio of battery voltage, present on the Sense pin,

required to obtain a 20% to 95% duty cycle range in the

application. The 20% duty cycle value will correlate to the

maximum battery in the application. Normally the sense ratio

of battery voltage is an end product trim adjustment.

Lamp

The Lamp output pin functions as a warning indicator for

overvoltage and stopped engine or broken belt conditions

existing in the system.

Stator

The Stator pin senses the voltage from the stator in the

application circuit, and keeps the device powered up while

the stator voltage is high. Furthermore, it acts as a sense for

a stopped engine or broken belt condition. If this condition is

detected, the Stator turns “on” the Lamp.

Power Supply, VCC

The VCC pin powers the entire device and disables all

outputs during any overvoltage condition.

Roll–Off

The Roll–Off pin provides thermal protection for the circuit.

This capability exists, but has not been characterized and is

not tested for at this time. Therefore, it is recommended that

this pin be connected to ground. The surface mount version

has this pin internally connected to ground.

Darlington Drive

The purpose of the Darlington Drive output pin is to turn on

an external power Darlington transistor. The Sense pin

voltage determines the duty cycle of the Darlington. The

oscillator is set to maintain a minimum duty cycle, except

during overvoltage and short circuit conditions.

Short Circuit

The Short Circuit pin monitors the field voltage. When the

Darlington Drive and Short Circuit pins are simultaneously

high for a duration greater than the slew rate period, a short

circuit condition is noted. The detection time required

prevents the device from reacting to false shorts. As a result

of short circuit detection, the output is disabled. During a short

circuit condition, the device automatically retries with a 2%

duty cycle (Darlington “on” time). Once the short circuit

condition ceases, normal device operation resumes.

Application Notes

A capacitor should be used in parallel with the VCC pin to

filter out noise transients on the supply or battery line.

Likewise, a capacitor should be used in parallel with the

Sense pin to create a dominant closed loop pole. Resistors

connected to inputs, as mentioned in Notes 1 through 5 of the

Electrical Characteristic table, should be used.

6

MOTOROLA ANALOG IC DEVICE DATA

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