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LTC7106

Rev A

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Case One

Assume that the LTC7150S, a monolithic buck regula-

tor, provides a 1.5V output and requires to margin low

VOUT from 1.5V to 1.0V (see Figure 9). The VFB is 0.6V

and the voltage dividers are external. In order to achieve

the best accuracy of the LTC7106, it is recommended to

design IDAC in nominal range. Also within certain current

range (nominal, high or low), the larger the absolute IDAC

current amplitude is, the better accuracy the LTC7106

can achieve. So it is easy to choose RTOP = 10kΩ and

RBOT = 6.65kΩ. Then IDAC = (1.5V – 1.0V)/10kΩ = + 50μA.

Choose MFR_CONTROL [6:5] = 00 (Range = Nominal) to

set IDAC LSB =1μA.

By looking in Table 2, choose DAC [6:0] = 0110010 to set

theIDAC=+50μA,whichwillmarginVOUTfrom1.5Vto1.0V.

Figure 9. Using the LTC7106 to Margin Low Monolithic Buck Regulator LTC7150S Providing 1.5V to 1.0V at 20A

APPLICATIONS INFORMATION

GPO

VOUT

1µF

10k

330µF

0.25µH

22pF

4.7 F

LTC7106

VDD

GND

SDA

SCL

ALERT

GPO

ASEL0

ASEL1

VDD

2.5V TO 5.5V

SDA

ALERT

SCL

+50µA

LTC7150S

PGOOD

INTVCC

RUN

TRACK/SS

ITH

VOUT–

MODE/SYNC

SGND

1.5V/20A

6.65k

10k

100µF

×2

TO MARGIN LOW VOUT

FROM 1.5V TO 1V

PVIN

SVIN

PHMODE

CLKOUT

10k

162k

1nF

VIN

3.1V TO 20V

22µF

×2

IDAC

7106 F09

PMBus INTERFACE

10k

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