MAX1980 데이터 시트보기 (PDF) - Maxim Integrated

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MAX1980

Quick-PWM Slave Controller with Driver Disable for Multiphase DC-DC Converter

Maxim Integrated 

Quick-PWM Slave Controller with

Driver Disable for Multiphase DC-DC Converter

Table 2. Component Suppliers

MANUFACTURER

MOSFETS

Fairchild Semiconductor

International Rectifier

Siliconix

CAPACITORS

Kemet

Panasonic

Sanyo

Taiyo Yuden

INDUCTORS

Coilcraft

Coiltronics

Sumida

PHONE

COUNTRY CODE

1-888-522-5372

1-310-322-3331

1-203-268-6261

1-408-986-0424

1-847-468-5624

65-281-3226 (Singapore)

1-408-749-9714

03-3667-3408 (Japan)

1-408-573-4150

1-800-322-2645

1-561-752-5000

1-408-982-9660

WEBSITE

www.fairchildsemi.com

www.irf.com

www.vishay.com

www.kemet.com

www.panasonic.com

www.secc.co.jp

www.t-yuden.com

www.coilcraft.com

www.coiltronics.com

www.sumida.com

The trigger input’s polarity is selected by connecting

POL to VCC (rising edge) or to GND (falling edge).

At the slave controller’s core is the one-shot that sets

the high-side switch’s on-time. This fast, low-jitter one-

shot adjusts the on-time in response to the input volt-

age and the difference between the inductor currents in

the master and the slave. Two identical transconduc-

tance amplifiers (GMM = GMS) integrate the difference

between the master and slave current-sense signals.

The summed output is connected to COMP, allowing

adjustment of the integration time constant with a com-

pensation capacitor connected at COMP. The resulting

compensation current and voltage may be determined

by the following equations:

( ) ( ) ICOMP = GMM VCM+ - VCM- - GMS VCS+ - VCS-

VCOMP = VOUT + ICOMPZCOMP

where ZCOMP is the impedance at the COMP output.

The PWM controller uses this integrated signal (VCOMP)

to set the slave controller’s on time. When the master

and slave current-sense signals (CM+ to CM- and CS+

to CS-) become unbalanced, the transconductance

amplifiers adjust the slave controller’s on time, allowing

the slave inductor current to increase or decrease until

the current-sense signals are properly balanced:

tON

=



K 

VCOMP

VIN





=

K





VOUT

VIN





+

K





ICOMPZC

VIN





= (Master’s on time) + (Slave’s on-time

correction due to current imbalance)

This control algorithm results in balanced inductor cur-

rents with the slave switching frequency synchronized to

the master. Since the master operates at nearly constant

frequency, the slave will as well. The benefits of a con-

stant switching frequency are twofold: first, the frequency

can be selected to avoid noise-sensitive regions of the

spectrum; second, the inductor ripple-current operating

point remains relatively constant, resulting in easy design

methodology and predictable output-voltage ripple.

Multiple phase switching effectively distributes the load

among the external components, thereby improving the

overall efficiency. Distributing the load current between

multiple phases lowers the peak inductor current by the

number of phases (1/η) when compared to a single-

phase converter. This significantly reduces the I2R losses

across the inductor’s series resistance, the MOSFETs

on-resistance, and the board resistance.

12 ______________________________________________________________________________________

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