MAX1715EEI(2000) データシートの表示（PDF） - Maxim Integrated

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MAX1715EEI
(Rev.:2000)

Ultra-High Efficiency, Dual Step-Down Controller for Notebook Computers

Maxim Integrated 

Ultra-High Efficiency, Dual Step-Down

Controller for Notebook Computers

Standard Application Circuit

The standard application circuit (Figure 1) generates

two low-voltage rails for general-purpose use in note-

book computers (I/O supply, fixed CPU core supply,

DRAM supply). This DC-DC converter steps down a

battery or AC adapter voltage to voltages from 1.0V to

5.5V with high efficiency and accuracy.

See Table 1 for a list of components for common appli-

cations. Table 2 lists component manufacturers.

Detailed Description

The MAX1715 buck controller is designed for low-volt-

age power supplies for notebook computers. Maxim’s

proprietary Quick-PWM pulse-width modulator in the

MAX1715 (Figure 2) is specifically designed for han-

dling fast load steps while maintaining a relatively con-

stant operating frequency and inductor operating point

over a wide range of input voltages. The Quick-PWM

architecture circumvents the poor load-transient timing

problems of fixed-frequency current-mode PWMs while

also avoiding the problems caused by widely varying

switching frequencies in conventional constant-on-time

and constant-off-time PWM schemes.

+5V Bias Supply (VCC and VDD)

The MAX1715 requires an external +5V bias supply in

addition to the battery. Typically, this +5V bias supply

is the notebook’s 95% efficient +5V system supply.

Keeping the bias supply external to the IC improves

efficiency and eliminates the cost associated with the

+5V linear regulator that would otherwise be needed to

supply the PWM circuit and gate drivers. If stand-alone

capability is needed, the +5V supply can be generated

with an external linear regulator such as the MAX1615.

VDD = 5V

BIAS SUPPLY

C9

C8

4.7µF

1µF

R1

20Ω

C11

1µF

OUTPUT1

1.8V

C3

D3

CMPSH-3A

C1

N1

L1

D1 N2

C7

0.22µF

C5

0.1µF

4

20 VDD

V+

21 VCC

3 ILIM1

12 ILIM2

ON1 10

ON2 11

ON1 MAX1715

25 BST1

BST2 18

26

DH1

17

DH2

27 LX1

24 DL1

5

TON

1

OUT1

9

REF

2

FB1

8 AGND

LX2 16

DL2 19

22

PGND

14

OUT2

6

SKIP

13

FB2

PGOOD 7

N3

C6

0.1µF

N4

+5V

100k

VIN

4.5V TO 28V

ON/OFF

CONTROLS

C2

L2

D2

OUTPUT2

2.5V

C4

POWER-GOOD

INDICATOR

PINS 15, 23, 28 = N.C.

Figure 1. Standard Application Circuit

10 ______________________________________________________________________________________

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