MC33129 Просмотр технического описания (PDF) - Motorola => Freescale

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производитель

MC33129

High Performance Current Mode Controllers

Motorola => Freescale 

FreescalMeCS34e1m29iMcCo3n3d1u29ctor, Inc.

Figure 24. Current Sensing Power MOSFET

8

1.25V

9

+

–

10

11

Vin

VRS ≈

RS ⋅ Ipk ⋅ rDS(on)

rDM(on) + rS

If: SENSEFET = MTP10N10M

RS = 200

Then: VRS ≈ 0.075 Ipk

D

SENSEFET

1

S

GM K

2

3

RS

1/4W

Control Circuitry Ground:

To Pin 7

Power Ground:

To Input Source

Return

Virtually lossless current sensing can be achieved with the implementation of a

SENSEFET power switch.

Figure 25. Current Waveform Spike Suppression

Vin

Q1

1

2

3

R

C RS

The addition of the RC filter will eliminate instability caused by the

leading edge spike on the current waveform.

Figure 26. MOSFET Parasitic Oscillations

Vin

Q1

1 Rg

2

3

RS

Series gate resistor Rg will damp any high frequency parasitic

oscillations caused by the MOSFET input capacitance and any

series wiring inductance in the gate–source circuit.

Figure 27. Bipolar Transistor Drive

IB

+

0

–

1

2

Vin

t

Base Charge

Removal

C1

Q1

3

RS

The totem–pole output can furnish negative base current for enhanced

transistor turn–off, with the addition of capacitor C1.

12

For More Information On This ProdMuOcTt,OROLA ANALOG IC DEVICE DATA

Go to: www.freescale.com

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