33989 datasheet(40/66 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33989

TYPICAL APPLICATIONS

SUPPLEMENTAL APPLICATION NOTES

Voltage Regulator

The MC33989 contains two 5 V regulators: The V1

regulator, fully integrated and protected, and the V2 regulator

which operates with an external ballast transistor. This is

illustrated in the following device typical application

schematic.

Figure 21. Device Typical Application Schematic

V1 Regulator

The V1 regulator is 5 V output, 2% accuracy with current

capability of 200 mA max. It requires external decoupling and

stabilizing capacitors. The minimum recommended value

are:

• C4: 100 nF

• C3: 10

µF < C3 < 22 µF, esr < 1 ohms. 22 µF < C3 <

µF, esr < 5 ohms. C3 > = 47 µF, esr < 10 ohms

V2 Regulator: Operation with External Ballast Transistor

The V2 regulator is a tracking regulator of the V1 output.

Its accuracy relative to V1 is ±1%. It requires external

decoupling and stabilizing capacitors. The recommended

value are: 22

µF esr < 5 ohms, and 47 µF esr < 10 ohms.

The V2 pin has two functions: sense input for the V2

regulator and 5 V power supply input to the CAN interface.

Ballast transistor selection: PNP or PMOS transistors can be

used. A resistor between base and emitter (or source and

drain) is necessary to ensure proper operation and optimized

performances. Recommended bipolar transistor is MJD32C.

V2 Regulator: Operation without Ballast Transistor

The external ballast transistor is optional. If the application

does not requires more than the maximum output current

capability of the V1 regulator, then the ballast transistor can

be omitted. The thermal aspects must be analyzed as well.

The electrical connections are shown in Figure 22.

Figure 22. V2 Regulator Operation

VDD1

VSUP

V2CTRL

RST

INT

MISO

MOSI

SCK

CANH

CANL

HS1

GND

CAN

SPI

VDD

RST

Auxiliary 5V

CAN bus

MCU

Safe circuitry

Rp0

Rs0

CL0

Components list:

C1: 22uF, C2: 100nF

C3: >10uF

C4: 100nF

C5: >10uF

C6: 100nF

R1: 2.2k

Rt: 60 - 120

Rp0 to Rp3: 22k

Rs0 to Rs3: 22 k

CL0 to CL3: 10nF

Q1: MJD32C

MC33989

INT

VDD1

VSUP

V2CTRL

RST

VDD

no connect

Components list:

C1: 22uF, C2: 100nF

C3: >10uF

C4: 100nF

MCU

partial view

MC33989

Partial View

RST

33989 Datasheet(PDF) 40 Page - Freescale Semiconductor, Inc

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