MAX1700EEE 查看數據表（PDF） - Maxim Integrated

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MAX1700EEE

1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters

Maxim Integrated 

1-Cell to 3-Cell, High-Power (1A),

Low-Noise, Step-Up DC-DC Converters

Reference

The MAX1700/MAX1701 have an internal 1.250V, 1%

bandgap reference. Connect a 0.22µF bypass capaci-

tor to GND within 0.2in. (5mm) of the REF pin. REF can

source up to 50µA of external load current.

Power-OK (MAX1701)

The MAX1701 features a power-good comparator. This

comparator’s open-drain output (POK) is pulled low

when the output voltage falls to 10% below the regula-

tion point.

IN

Gain Block (MAX1701)

The MAX1701’s gain block can function as a third com-

parator or can be used to build a linear regulator using

an external P-channel MOSFET pass device. The gain-

block output is a single-stage transconductance ampli-

fier that drives an open-drain N-channel MOSFET.

Figure 9 shows the gain block used in a linear regula-

tor. The output of an external P-channel pass element is

compared to the internal reference. The difference is

amplified and used to drive the gate of the pass ele-

ment. Use a logic-level PFET such as the Fairchild

NDS336P (RDS(ON) = 270mΩ). If the PFET RDS(ON) is

less than 250mΩ, the linear regulator output filter

capacitance may need to be increased to above 47µF.

LX

MAX1701

AO

N

2x

100µF

P

20k

47µF

__________________Design Procedure

Setting the Output Voltages

Set the output voltage between 2.5V and 5.5V by con-

necting a resistor voltage-divider to FB from OUT to

GND, as shown in Figure 2. The resistor values are then

as follows:

R1 = R2 (VOUT/VFB - 1)

AIN

R5

REF

R6

Figure 9. Using Gain Block as a Linear Regulator

where VFB, the boost-regulator feedback setpoint, is

1.23V. Since the input bias current into FB is less than

20nA, R2 can have a large value (such as 270kΩ or

less) without sacrificing accuracy. Connect the resistor

voltage-divider as close to the IC as possible, within

0.2in. (5mm) of the FB pin.

Table 4. Component Suppliers

SUPPLIER

PHONE

FAX

AVX

USA: (803) 946-0690

(800) 282-4975

(803) 626-3123

Coilcraft

Matsuo

Motorola

USA: (847) 639-6400

USA: (714) 969-2491

USA: (602) 303-5454

(847) 639-1469

(714) 960-6492

(602) 994-6430

Sanyo

USA: (619) 661-6835 (619) 661-1055

Japan: 81-7-2070-6306 81-7-2070-1174

Sumida

USA: (847) 956-0666 (847) 956-0702

Japan: 81-3-3607-5111 81-3-3607-5144

Table 5. Component Selection Guide

Inductor Selection

The MAX1700/MAX1701’s high switching frequency

allows the use of a small surface-mount inductor. A

10µH inductor should have a saturation-current rating

that exceeds the N-channel switch current limit of 1.6A.

However, it is generally acceptable to bias the inductor

current into saturation by as much as 20%, although

this will slightly reduce efficiency. For high efficiency,

choose an inductor with a high-frequency core material

(such as ferrite) to reduce core losses. To minimize

radiated noise, use a toroid, pot core, or shielded bob-

bin inductor. Connect the inductor from the battery to

the LX pin as close to the IC as possible. See Table 4

for a list of component suppliers and Table 5 for sug-

gested components.

PRODUCTION

INDUCTORS

CAPACITORS

DIODES

Surface Mount

Sumida CDR63B, CD73, CDR73B, CD74B series

Coilcraft DO1608, DO3308, DT3316 series

Matsuo 267 series

Sprague 595D series

AVX TPS series

Motorola MBR0520L

Through Hole

Sumida RCH654 series

Sanyo OS-CON series

Nichicon PL series

1N5817

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