MAX1703ESE原理图各脚功能电路原理芯片引脚定义引脚图及功能-中国IC网-芯三七

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产品型号MAX1703ESE的概述

芯片MAX1703ESE的概述 MAX1703ESE是一款由Maxim Integrated（现为Analog Devices的一部分）生产的高效率、低功耗的电源管理集成电路。这款芯片主要用于便携式设备，它能够通过其优越的性能和多种功能满足现代电子产品对于能源效率和空间利用的高要求。MAX1703ESE特别适合电池供电的应用，尤其是针对手机、便携式游戏机和其它移动设备。该芯片采用高效的buck转换技术，可以从高电压源（如锂电池）中获得稳定的低电压，并具备较宽的工作电压范围。在这个过程中，MAX1703ESE不仅提供高效率的电源转换，同时也可以通过其内置的控制电路来最小化待机功耗，延长电池使用寿命。芯片的详细参数 MAX1703ESE的关键性能参数包括： - 输入电压范围：2.7V至5.5V - 输出电压范围：可调，从1.25V到3.3V - 最大输出电流：可达600mA - 转换效...

产品型号MAX1703ESE的Datasheet PDF文件预览

19-1336; Rev 2; 11/98

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

MAX1703

________________General Description

____________________________Features

♦ Up to 95% Efficiency

The MAX1703 is a high-efficiency, low-noise, step-up

DC-DC converter intended for use in battery-powered

wireless applications. It uses a synchronous-rectified

pulse-width-modulation (PWM) boost topology to gen-

erate a 2.5V to 5.5V output from battery inputs, such as

one to three NiCd/NiMH cells or one Li-Ion cell. The

device includes a 2A, 75mΩ, N-channel MOSFET

switch and a 140mΩ, P-channel synchronous rectifier.

♦ Up to 1.5A Output

♦ Fixed 5V or Adjustable Step-Up Output

(2.5V to 5.5V)

♦ 0.7V to 5.5V Input Range

♦ Low-Power Mode (300µW)

♦ Low-Noise, Constant-Frequency Mode (300kHz)

With its internal synchronous rectifier, the MAX1703

delivers up to 5% better efficiency than similar nonsyn-

chronous converters. It also features a pulse-frequency-

modulation (PFM) low-power mode to improve efficiency

at light loads, and a 1µA shutdown mode.

♦ Synchronizable Switching Frequency

(200kHz to 400kHz)

♦ 1µA Logic-Controlled Shutdown

♦ Power-Good Comparator

♦ Uncommitted Gain Block

The MAX1703 comes in a 16-pin narrow SO package

and includes an uncommitted comparator that generates

a power-good or low-battery-warning output. It also

contains a linear gain block that can be used to build a

linear regulator.

Ordering Information

PART

TEMP. RANGE

PIN-PACKAGE

For lower-power outputs and a smaller package, refer

to the MAX1700/MAX1701. For dual outputs (step-up

plus linear regulator), refer to the MAX1705/MAX1706.

For an on-board analog-to-digital converter, refer to the

MAX848/MAX849.

MAX1703ESE

-40°C to +85°C

16 Narrow SO

________________________Applications

Digital Cordless Phones Personal Communicators

The MAX1703 evaluation kit is available to speed designs.

PCS Phones

Palmtop Computers

Wireless Handsets

Two-Way Pagers

Hand-Held Instruments

Typical Operating Circuit

Pin Configuration

INPUT

0.7V TO 5.5V

OUTPUT

TOP VIEW

5V OR ADJ

MAX1703

UP TO 1.5A

REF

16 ON

LXP, LXN

OFF

15 POUT

14 LXP

POUT

OUT

PWM

POKIN

OUT

GND

AIN

CLK/

SEL

PFM

SYNC

MAX1703

13 POUT

12 PGND

11 LXN

POWER-GOOD

INPUT

POKIN

POWER-GOOD

OUTPUT

GAIN-BLOCK

OUTPUT

POK

AIN

REF

10 PGND

GAIN-BLOCK INPUT

POK

CLK/SEL

FB GND PGND

Narrow SO

________________________________________________________________ Maxim Integrated Products

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

ABSOLUTE MAXIMUM RATINGS

Operating Temperature Range ...........................-40°C to +85°C

OUT, ON, AO, POK to GND .....................................-0.3V to +6V

Junction Temperature......................................................+150°C

Storage Temperature Range.............................-65°C to +160°C

Lead Temperature (soldering, 10sec) .............................+300°C

PGND to GND.....................................................................±0.3V

LXP, LXN to PGND .................................-0.3V to (V

POUT, CLK/SEL, AIN, REF, FB,

+ 0.3V)

POUT

POKIN to GND.......................................-0.3V to (V

OUT

Continuous Power Dissipation (T = +70°C)

Narrow SO (derate 8.70mW/°C above +70°C) .............696mW

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

MAX1703

ELECTRICAL CHARACTERISTICS

(CLK/SEL = AIN = ON = POKIN = FB = PGND = GND, OUT = POUT, LXP = LXN, V

= 5.3V (Note 1), T = 0°C to +85°C, unless

OUT

otherwise noted. Typical values are at T = +25°C.)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

DC-DC CONVERTER

Input Supply Range

(Note 2)

0.7

0.9

5.5

1.1

300

Minimum Start-Up Voltage

Frequency in Start-Up Mode

< 1mA, T = +25°C (Note 3)

LOAD

= 1.5V

140

kHz

OUT

Output Voltage

(Note 4)

< 0.1V, CLK/SEL = OUT,

4.87

5.05

5.20

0 ≤ I ≤ 1.1A, V

= 3.7V

BATT

Adjustable output, CLK/SEL = OUT,

0 ≤ I ≤ 1.1A, V = 2.2V, V = 3.3V

FB Regulation Voltage

1.21

1.24

0.1

1.255

BATT

OUT

FB Input Current

= 1.25V

5.5

2.3

Output Voltage Adjust Range

Output Voltage Lockout Threshold

Load Regulation (Note 6)

Supply Current in Shutdown

Supply Current in Low-Power Mode

Supply Current in Low-Noise Mode

DC-DC SWITCHES

2.5

2.0

(Note 5)

2.15

-1.6

0.1

CLK/SEL = OUT, no load to full load

ON = OUT

µA

CLK/SEL = GND (Note 1)

CLK/SEL = OUT (Note 1)

120

300

150

POUT, LXP Leakage Current

LXN Leakage Current

= 0V, V

= V = 5.5V

0.1

µA

LXP

OUT

= V

= 5.5V

LXN

OUT

CLK/SEL = GND

CLK/SEL = OUT

0.14

0.075

0.13

2700

800

0.25

0.13

0.25

3200

1100

260

Switch On-Resistance

N-channel

P-channel

Ω

CLK/SEL = OUT

2200

500

N-Channel Current Limit

CLK/SEL = GND

P-Channel Turn-Off Current

POWER-GOOD COMPARATOR

POKIN Trip Level

160

Rising V

1.225

-20

1.250

1.275

POKIN

POKIN Input Current

= 0.7V

POKIN

(POK) = 1mA, V

(POK) = 20µA, V

= 3.6V or

SINK

OUT

POK Low Voltage

0.03

0.01

0.4

= 1V

SINK

OUT

POK High Leakage Current

= V

= 5.5V

µA

OUT

POK

_______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

MAX1703

ELECTRICAL CHARACTERISTICS (continued)

(CLK/SEL = AIN = ON = POKIN = FB = PGND = GND, OUT = POUT, LXP = LXN, V

= 5.3V (Note 1), T = 0°C to +85°C, unless

OUT

otherwise noted. Typical values are at T = +25°C.)

PARAMETER

GAIN BLOCK

CONDITIONS

MIN

TYP

MAX

UNITS

AIN Reference Voltage

AIN Input Current

= 20µA

1.237

-30

1.25

1.263

= 1.5V

AIN

Transconductance

10µA < I

< 100µA

0.1

mmho

AO Output Low Voltage

AO Output High Leakage

REFERENCE

= 0.5V, I

= 100µA

0.4

AIN

= 1.5V, V

= 5.5V

0.01

µA

Reference Output Voltage

REF Load Regulation

REF Supply Rejection

LOGIC INPUTS

= 0µA

1.237

1.250

1.263

REF

-1µA < I

< 50µA

REF

2.5V < V

< 5.5V

0.2

OUT

0.2V

ON, 1.2V < V

< 5.5V (Note 7)

OUT

Input Low Voltage

Input High Voltage

CLK/SEL, V

= 2.5V

0.2V

OUT

0.8V

ON, 1.2V < V

< 5.5V

OUT

CLK/SEL, V

= 5.5V

0.8V

OUT

Logic Input Current

-1

0.01

300

µA

kHz

ON, CLK/SEL

CLK/SEL = OUT, V = 0.5V

Internal Oscillator Frequency

Oscillator Maximum Duty Cycle

External Clock Frequency Range

Minimum CLK/SEL Pulse Width

Maximum CLK/SEL Rise/Fall Time

260

340

CLK/SEL = OUT, V = 0.5V

200

400

kHz

200

100

ELECTRICAL CHARACTERISTICS

(CLK/SEL = AIN = ON = POKIN = FB = PGND = GND, OUT = POUT, LXP = LXN, V

= 5.3V (Note 1), T = -40°C to +85°C, unless

OUT

otherwise noted. Typical values are at T = +25°C.) (Note 8)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

DC-DC CONVERTER

< 0.1V, CLK/SEL = OUT,

Output Voltage (Note 4)

FB Regulation Voltage

4.87

5.20

1.27

0 ≤ I ≤ 1.1A, V

= 3.7V

BATT

Adjustable output, CLK/SEL = OUT,

0 ≤ I ≤ 1.1A, V

1.20

2.0

= 3.3V, V

= 2.2V

OUT

BATT

Output Voltage Lockout Threshold

Supply Current in Shutdown

(Note 5)

2.3

µA

ON = OUT

Supply Current in Low-Power Mode

Supply Current in Low-Noise Mode

CLK/SEL = GND (Note 1)

CLK/SEL = OUT (Note 1)

120

300

_______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

ELECTRICAL CHARACTERISTICS (continued)

(CLK/SEL = AIN = ON = POKIN = FB = PGND = GND, OUT = POUT, LXP = LXN, V

= 5.3V (Note 1), T = -40°C to +85°C, unless

OUT

otherwise noted. Typical values are at T = +25°C.) (Note 8)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

DC-DC SWITCHES

CLK/SEL = GND

CLK/SEL = OUT

0.25

0.13

0.25

3600

1100

N-channel

Switch On-Resistance

Ω

MAX1703

P-channel

CLK/SEL = OUT

N-Channel Current Limit

2200

500

CLK/SEL = GND

POWER-GOOD COMPARATOR

POKIN Trip Level

Rising V

1.225

1.275

POKIN

GAIN BLOCK

AIN Reference Voltage

Transconductance

= 20µA

1.23

1.27

10µA < I

< 100µA

mmho

REFERENCE

Reference Output Voltage

LOGIC INPUTS

= 0µA

1.23

1.27

REF

Internal Oscillator Frequency

Oscillator Maximum Duty Cycle

CLK/SEL = OUT, V = 0.5V

260

340

kHz

CLK/SEL = OUT, V = 0.5V

Note 1: Supply current from the 5.05V output is measured between the 5.05V output and the OUT pin. This current correlates

directly to the actual battery supply current, but is reduced in value according to the step-up ratio and efficiency. Set

= 5.3V to keep the internal switch open when measuring the device operating current.

OUT

Note 2: Minimum operating voltage. Since the regulator is bootstrapped to the output, once started it will operate down to a 0.7V

input.

Note 3: Start-up is tested with the circuit of Figure 2.

Note 4: In low-power mode (CLK/SEL = GND) the output voltage regulates 1% higher than low-noise mode (CLK/SEL = OUT or

synchronized).

Note 5: The regulator is in start-up mode until this voltage is reached. Do not apply full-load current below this voltage.

Note 6: Load regulation is measured from no-load to full load, where full load is determined by the N-channel switch current limit.

Note 7: The ON input has a total hysteresis of approximately 0.15 x V

OUT

Note 8: Specifications to -40°C are guaranteed by design and not production tested.

_______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

MAX1703

__________________________________________Typical Operating Characteristics

(V = +3.6V, V

= 5V, T = +25°C, unless otherwise noted.)

OUT

EFFICIENCY vs. LOAD CURRENT

(V = 5V)

NO-LOAD BATTERY CURRENT

vs. INPUT VOLTAGE

EFFICIENCY vs. LOAD CURRENT

OUT

= 3.3V)

OUT

100

= 3.6V

= 2.4V

= 1.2V

LOW-POWER MODE

= 2.4V

= +85°C

= 0.9V

= 1.2V

= +25°C

PFM

PWM

PFM

PWM

= -40°C

0.1

100

1000

10,000

0.1

100

1000

10,000

LOAD CURRENT (mA)

INPUT VOLTAGE (V)

SHUTDOWN SUPPLY CURRENT

vs. INPUT VOLTAGE

REFERENCE VOLTAGE

vs. TEMPERATURE

START-UP VOLTAGE vs. LOAD CURRENT

2.5

2.0

1.8

1.6

1.2550

INCLUDES ALL EXTERNAL

COMPONENT LEAKAGES.

CAPACITOR LEAKAGE

= 5V

OUT

PWM MODE

2.0

1.5

1.0

0.5

1.2530

DOMINATES AT T = +85°C

= +85°C

1.2510

1.2490

1.4

1.2

1.0

0.8

= +25°C,

= -40°C

1.2470

1.2450

0.6

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

INPUT VOLTAGE (V)

0.01

0.1

100

1000

-40 -20

100

LOAD CURRENT (mA)

TEMPERATURE (°C)

REFERENCE VOLTAGE

vs. REFERENCE CURRENT

1.2520

NOISE SPECTRUM

= 3.6V

OUT

LOAD

= 5V

OUT

= 5V

= 3.6V

1.2510

1.2500

1.2490

1.2480

1.2470

LOW-POWER MODE

= 500mA

1.2460

-1

10 20 30 40 50 60 70 80 90

100

10k

100k

10M

REFERENCE CURRENT (µA)

FREQUENCY (Hz)

_______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

_________________________________Typical Operating Characteristics (continued)

(V = +3.6V, V

= 5V, T = +25°C, unless otherwise noted.)

OUT

PEAK INDUCTOR CURRENT LIMIT

vs. OUTPUT VOLTAGE

FREQUENCY vs. TEMPERATURE

340

330

320

310

300

290

280

3.5

3.0

2.5

2.0

1.5

1.0

0.5

PWM

MAX1703

= 5V

OUT

= 3.3V

LOW POWER (PFM)

OUT

270

260

-40 -20

100

2.5

3.0

3.5

4.0

4.5

5.0

5.5

TEMPERATURE (°C)

OUTPUT VOLTAGE (V)

LINE-TRANSIENT RESPONSE

HEAVY LOAD SWITCHING

MAX1703-09

MAX1703-08

OUT

(50mV/div)

2ms/div

2µs/div

V = 2.6V TO 3.6V, V IS AC COUPLED

IN OUT

= 1.5A, C7 = 0.47µF

LOAD

POWER-ON DELAY

(PFM MODE)

LOAD-TRANSIENT RESPONSE

MAX1703-11

MAX1703-10

OUT

(50mV/div)

OUT

(2V/div)

1.0A

(0.2A/div)

0.5A

1ms/div

2ms/div

IS AC COUPLED

OUT

= 2.6V TO 3.6V, V IS AC COUPLED

OUT

LOAD CURRENT = 0A TO 1.5A

_______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

MAX1703

_________________________________Typical Operating Characteristics (continued)

(V = +3.6V, V

= 5V, T = +25°C, unless otherwise noted.)

OUT

GSM LOAD-TRANSIENT RESPONSE

DECT LOAD-TRANSIENT RESPONSE

MAX1703-12

MAX1703-13

OUT

(100mV/div)

LOAD

(0.5A/div)

(0.2A/div)

1ms/div

2ms/div

= 3.6V, V

= 5V, C

= 470µF,

OUT

= 1.2V, V

= 3.3V, C

= 470µF,

OUT

PULSE WIDTH = 577µs, LOAD CURRENT = 100mA TO 1A

PULSE WIDTH = 416µs, LOAD CURRENT = 50mA TO 400mA

Pin Description

NAME

FUNCTION

Reference Output. Bypass with a 0.22µF bypass capacitor to GND.

REF

Dual-Mode™ Feedback Input. Connect FB to ground to set a fixed output voltage of +5V. Connect a

divider between the output voltage and GND to set the output voltage from 2.5V to 5.5V.

POKIN

OUT

Power-Good Comparator Input. Threshold is 1.250V, with 1% hysteresis on the threshold’s rising edge.

DC-DC Converter Output. Power source for the IC.

Ground

GND

Gain-Block Input. When AIN is low, AO sinks current. The nominal transconductance from AIN to AO is

10mmhos.

AIN

Gain-Block Output. This open-drain output sinks current when V

< V

AIN

REF

POK

Power-Good Comparator Output. This open-drain N-channel output is low when V

< 1.250V.

POKIN

Switch-Mode Selection and External-Clock Synchronization Input:

• CLK/SEL = Low: Low-power, low-quiescent-current PFM mode. Delivers up to 10% of full load current.

• CLK/SEL = High: High-power PWM mode. Full output power available. Operates in low-noise, constant-

frequency mode.

CLK/SEL

• CLK/SEL = External Clock: High-power PWM mode with the internal oscillator synchronized to the exter-

nal CLK

Turning on with CLK/SEL = 0V also serves as a soft-start function, since peak inductor current is limited to

25% of that allowed in PWM mode.

10, 12

PGND

LXN

Source of N-Channel Power MOSFET Switch

Drain of N-Channel Power Switch. Connect LXP to LXN.

Source of P-Channel Synchronous Rectifier MOSFET Switch. Connect an external Schottky diode from LXN

and LXP to POUT.

13, 15

POUT

LXP

Drain of P-Channel Synchronous Rectifier. Connect LXP to LXN.

On/Off Input. When ON is low, the IC turns on.

Dual Mode is a trademark of Maxim Integrated Products.

_______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

UNDERVOLTAGE LOCKOUT

OUT

IC POWER

2.15V

PFM/PWM

CONTROLLER

POUT

START-UP

OSCILLATOR

MAX1703

OUT

LXP

LXN

RDY

REFERENCE

OSC

1.25V

REF

300kHz

OSCILLATOR

OUT

GND

CLK/SEL

PFM/PWM

MODE

PGND

POK

DUAL

MODE/

COMPARATOR

POKIN

REF

MAX1703

AIN

GAIN

BLOCK

REF

Figure 1. Functional Block Diagram

The MAX1703 is optimized for use in cellular phones

and other applications requiring low noise during full-

power operation, as well as low quiescent current for

maximum battery life in low-power mode and shut-

down. It features constant-frequency (300kHz), low-

noise PWM operation with up to 1.5A output capability.

See Table 1 for typical outputs. A low-quiescent-cur-

rent, low-power mode offers an output up to 150mA

and reduces quiescent power consumption to 300µW.

In shutdown mode, the quiescent current is further

reduced to just 1µA. Figure 2 shows the standard appli-

cation circuit for the MAX1703.

_______________Detailed Description

The MAX1703 is a highly efficient, low-noise power

supply for portable RF and data-acquisition instru-

ments. It combines a boost switching regulator, N-

channel power MOSFET, P-channel synchronous

rectifier, precision reference, shutdown control, versa-

tile gain block, and power-good (POK) comparator

(Figure 1) in a 16-pin narrow SO package.

The switching DC-DC converter boosts a 1- to 3-cell

input to a fixed 5V or an adjustable output between

2.5V and 5.5V. Typically the MAX1703 starts from a

low, 0.9V input and remains operational down to 0.7V.

_______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

MAX1703

Table 1. Typical Available Output Current

Table 2. Selecting the Operating Mode

INPUT

VOLTAGE

(V)

OUTPUT

VOLTAGE

(V)

OUTPUT

CURRENT

(mA)

CLK/SEL

MODE

FEATURES

NO. OF CELLS

Low power

Low supply current

Low noise,

high output current

PWM

1 NiCd/NiMH

2 NiCd/NiMH

3 NiCd/NiMH

1.2

2.4

3.6

3.3

5.0

600

1400

950

External Clock

(200kHz to 400kHz)

Synchronized

PWM

Low noise,

high output current

1600

Step-Up Converter

The step-up switching DC-DC converter generates an

adjustable output from 2.5V to 5.5V. The internal N-

channel MOSFET switch is turned on during the first

part of each cycle, allowing current to ramp up in the

inductor and store energy in a magnetic field. During

the second part of each cycle, when the MOSFET is

turned off, the voltage across the inductor reverses and

forces current through the diode and synchronous rec-

tifier to the output filter capacitor and load. As the ener-

gy stored in the inductor is depleted, the current ramps

down and the output diode and synchronous rectifier

turn off. Depending on the CLK/SEL pin setting, voltage

across the load is regulated using either low-noise

PWM or low-power operation (Table 2).

BATT

100µF

4.7µH

MBR0520L

CLK/SEL

LXP, LXN

2 x 220µF

POUT

0.22µF

10Ω

MAX1703

OUT

0.22µF

Low-Noise PWM Operation

When CLK/SEL is pulled high, the MAX1703 operates

in a high-power, low-noise PWM mode. During PWM

operation, the MAX1703 switches at a constant fre-

quency (300kHz), and modulates the MOSFET-switch

pulse width to control the power transferred per cycle

and regulate the voltage across the load. In PWM mode

the device can output up to 1.5A. Switching harmonics

generated by fixed-frequency operation are consistent

and easily filtered. See the Noise Spectrum plot in the

Typical Operating Characteristics.

AIN

POK

POKIN

REF

PGND

GND

0.22µF

SIGNAL GROUND

POWER GROUND

During PWM operation, each of the internal clock’s ris-

ing edges sets a flip-flop, which turns on the N-channel

MOSFET switch (Figure 3). The switch turns off when

the sum of the voltage-error, slope-compensation, and

current-feedback signals trips a multi-input comparator

and resets the flip-flop; the switch remains off for the

rest of the cycle. When a change occurs in the output

voltage error signal, the comparator shifts the level to

which the inductor current ramps during each cycle. A

second comparator enforces an inductor current limit of

2.7A (typical).

NOTE: HEAVY LINES INDICATE HIGH-CURRENT PATHS.

Figure 2. MAX1703 in High-Power PWM Mode

Additional features include synchronous rectification for

high efficiency and improved battery life, and an

uncommitted comparator (POK) for monitoring the reg-

ulator’s output or battery voltage. The MAX1703 also

includes a gain block that can be used to build a linear

regulator using an external P-channel MOSFET pass

device; this gain block can also function as a second

comparator. A CLK input allows frequency synchro-

nization to reduce interference.

_______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

LOGIC HIGH

POUT

REF

LXP

LXN

ERROR

COMPARATOR

MAX1703

LXP

LXN

REF

2.7A TYP

CURRENT

LIMIT

800mA TYP

CURRENT

LIMIT

PGND

OSC

PGND

Figure 3. Simplified PWM Controller Block Diagram

Figure 4. Controller Block Diagram in Low-Power PFM Mode

Synchronized PWM Operation

The MAX1703 can be synchronized in PWM mode to a

200kHz to 400kHz frequency by applying an external

clock to CLK/SEL. This allows the user to set the har-

monics to avoid IF bands in wireless applications. The

synchronous rectifier is also active during synchronized

PWM operation.

nal, inhibits the error comparator from initiating another

cycle until the energy stored in the inductor is transferred

to the output filter capacitor and the synchronous rectifier

current has ramped down to 80mA. This forces operation

with a discontinuous inductor current.

Synchronous Rectifier

The MAX1703 features an internal 140mΩ, P-channel

synchronous rectifier to enhance efficiency. Synchro-

nous rectification provides a 5% efficiency improve-

ment over similar nonsynchronous boost regulators. In

PWM mode, the synchronous rectifier is turned on dur-

ing the second half of each switching cycle. In low-

power mode, an internal comparator turns on the

synchronous rectifier when the voltage at LX exceeds

the boost regulator output, and then turns it off when

the inductor current drops below 80mA.

Low-Power PFM Operation

Pulling CLK/SEL low places the MAX1703 in a low-

power mode. During low-power mode, PFM operation

regulates the output voltage by transferring a fixed

amount of energy during each cycle, and then modulat-

ing the pulse frequency to control the power delivered

to the output. The devices switch only as needed to

service the load, resulting in the highest possible effi-

ciency at light loads. Output current capability in PFM

mode is 150mA (max). The output voltage is typically

1% higher than in PWM mode.

Low-Voltage Start-Up Oscillator

The MAX1703 uses a CMOS, low-voltage start-up oscil-

lator for a 1.1V guaranteed minimum start-up input volt-

age at +25°C. On start-up, the low-voltage oscillator

switches the N-channel MOSFET until the output volt-

age reaches 2.15V. Above this level, the normal boost-

converter feedback and control circuitry take over.

Once the device is in regulation, it can operate down to

a 0.7V input, since internal power for the IC is boot-

strapped from the output via the OUT pin. Do not apply

full load until the output exceeds 2.3V (max).

During PFM operation, the error comparator detects the

output voltage falling out of regulation and sets a flip-

flop, which turns on the N-channel MOSFET switch

(Figure 4). When the inductor current ramps to the PFM

mode current limit (800mA typical) and stores a fixed

amount of energy, the current-sense comparator resets

a flip-flop. The flip-flop turns off the N-channel switch

and turns on the P-channel synchronous rectifier. A

second flip-flop, previously reset by the switch’s “on” sig-

10 ______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

MAX1703

Shutdown

Reference

The MAX1703 has an internal 1.250V, 1% bandgap ref-

erence. Connect a 0.22µF bypass capacitor to GND

within 0.2in. (5mm) of the REF pin. REF can source up

to 50µA of external load current.

The MAX1703 shuts down to reduce quiescent current

to 1µA. During shutdown (ON = V

), the reference,

OUT

low-battery comparator, gain block, and all feedback

and control circuitry are off. The boost converter’s out-

put drops to one Schottky diode drop below the input.

Gain Block

The MAX1703 gain block can function as a second

comparator, 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

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

Power-Good (POK) Comparator

The MAX1703 features an uncommitted POK compara-

tor. The internal POK comparator has an open-drain

output (POK) capable of sinking 1mA. When the input

(POKIN) rises above the 1.25V reference, the POK

open-drain output turns off. The POKIN input has 10mV

of hysteresis.

The g of the entire gain-block stage is 10mmho.

Figure 6 shows the gain block used in a linear-regulator

application. The output of an external P-channel pass

element is compared to the internal reference. The dif-

ference is amplified and used to drive the gate of the

pass element. Use a logic-level PFET, such as an

To provide a power-good signal, connect the POKIN

input to an external resistor-divider between OUT and

GND (Figure 5). Calculate the resistor values as follows:

R3 = R4(V / V

- 1)

REF

NDS336P (R

= 270mΩ) from Fairchild. This con-

DS(ON)

where V is the desired input voltage trip threshold.

figuration allows ripple reduction at the output. If a

lower R

PFET is used, then the linear regulator

DS(ON)

Since the input bias current into POKIN is less than

20nA, R4 can be a large value (such as 270kΩ or less)

without sacrificing accuracy. Connect the resistor volt-

age-divider as close to the IC as possible, within 0.2in.

(5mm) of POKIN.

output filter capacitance may need to be increased.

To use the gain block as a comparator, refer to the

Power-Good (POK) Comparator section.

BOOST

100µF

4.7µH

OUTPUT

100µF

4.7µH

LINEAR

REGULATED

OUTPUT

MBR0520L

CLK/SEL

OUTPUT

MBR0520L

CLK/SEL

LXP, LXN

2 x 220µF

330µF

POUT

47µF

20k

POUT

0.22µF

10Ω

MAX1703

10Ω

0.22µF

OUT

0.22µF

AIN

POKIN

REF

POK

REF

PGND

GND

0.22µF

PGND

GND

100k

SIGNAL GROUND

POWER GROUND

SIGNAL GROUND

POWER GROUND

NOTE: HEAVY LINES INDICATE HIGH-CURRENT PATHS.

Figure 5. Adjustable Output (PWM Mode)

Figure 6. Using the Gain Block as a Linear Regulator

______________________________________________________________________________________ 11

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

Table 3. Component Selection Guide

PRODUCTION

INDUCTORS

Sumida CDR125

CAPACITORS

Matsuo 267 series

DIODES

Surface Mount

Motorola MBR0520L

Sprague 595D series

AVX TPS series

Coilcraft DO3316

Sanyo OS-CON series

Nichicon PL series

Through Hole

Sumida RCH654 series

1N5817

MAX1703

__________________Design Procedure

Table 4. Component Suppliers

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:

SUPPLIER

PHONE

FAX

USA: (803) 946-0690

(800) 282-4975

AVX

(803) 626-3123

Coilcraft

Matsuo

USA: (847) 639-6400

USA: (714) 969-2491

USA: (602) 303-5454

(847) 639-1469

(714) 960-6492

(602) 994-6430

R1 = R2(V

/ V - 1)

OUT

where V , the boost-regulator feedback setpoint, is

Motorola

1.24V. 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.

USA: (619) 661-6835

Japan: 81-7-2070-6306

(619) 661-1055

81-7-2070-1174

Sanyo

USA: (847) 956-0666

Japan: 81-3-3607-5111

(847) 956-0702

81-3-3607-5144

Sumida

Inductor Selection

The MAX1703’s high switching frequency allows the

use of a small surface-mount inductor. A 4.7µH induc-

tor should have a saturation-current rating that exceeds

the N-channel switch current limit. However, it is gener-

ally acceptable to bias the inductor current into satura-

tion by as much as 20%, although this will slightly

reduce efficiency. For high efficiency, choose an induc-

tor with a high-frequency core material, such as ferrite,

to reduce core losses. To minimize radiated noise, use

a toroid, pot core, or shielded bobbin inductor. See

Table 3 for suggested components and Table 4 for a

list of component suppliers. Connect the inductor from

the battery to the LX pins as close to the IC as possible.

Input and Output Filter Capacitors

Choose input and output filter capacitors that will ser-

vice the input and output peak currents with accept-

able voltage ripple. Choose input capacitors with

working voltage ratings over the maximum input volt-

age, and output capacitors with working voltage ratings

higher than the output.

A 330µF, 100mΩ, low-ESR tantalum capacitor is recom-

mended for a 5V output. For full output load current,

one 470µF or two 220µF, 100mΩ low-ESR tantalum

capacitors are recommended for a 3.3V output. The

input filter capacitor (C ) also reduces peak currents

drawn from the input source and reduces input switch-

ing noise. The input voltage source impedance deter-

mines the required size of the input capacitor.

Output Diode

Use a Schottky diode such as a 1N5817, MBR0520L, or

equivalent. The Schottky diode carries current during

both start-up and PFM mode after the synchronous recti-

fier turns off. Thus, its current rating only needs to be

500mA. Connect the diode between LXN/LXP and

POUT, as close to the IC as possible. Do not use ordi-

nary rectifier diodes, since slow switching speeds and

long reverse recovery times will compromise efficiency

and load regulation.

When operating directly from one or two NiCd cells

placed close to the MAX1703, use a 100µF, low-ESR

input filter capacitor.

Sanyo OS-CON and Panasonic SP/CB-series ceramic

capacitors offer the lowest ESR. Low-ESR tantalum

capacitors are a good choice and generally offer a

good tradeoff between price and performance. Do not

exceed the ripple current ratings of tantalum capaci-

tors. Avoid most aluminum-electrolytic capacitors,

because their ESR is often too high.

12 ______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

MAX1703

Bypass Capacitors

A few ceramic bypass capacitors are required for proper

operation. Bypass REF with a 0.22µF capacitor to GND.

Connect a 0.22µF ceramic capacitor from OUT to GND.

Each of these should be placed as close to their respec-

tive pins as possible, within 0.2in. (5mm) of the DC-DC

converter IC. See Table 4 for suggested suppliers.

4.7nF

11, 14

LXP, LXN

__________ Applications Information

OUT

2 x 220µF

Intermittent Supply/Battery Connections

When boosting an input supply connected via a

mechanical switch, or a battery connected via spring

contacts, input power may sometimes be intermittent

as a result of contact bounce. When operating in PFM

mode with input voltages greater than 2.5V, restarting

after such dropouts may initiate high current pulses that

interfere with the MAX1703’s internal MOSFET switch

control. If contact or switch bounce is anticipated in the

design, use one of the following solutions:

MAX1703

OUT

15, 13

POUT

1) Connect a capacitor (C ) from ON to V and a

Figure 7. Connecting C

Contact Bounce is Anticipated

and R

when Switch or Battery-

1MΩ resistor (R ) from ON to GND, as shown in

Figure 7. This resistor-capacitor network differenti-

ates fast input edges at V and momentarily holds

Designing a PC Board

the IC off until V settles. The appropriate value of

is 10^-5times the total output filter capacitance

High switching frequencies and large peak currents

make PC board layout an important part of design.

Poor design can cause excessive EMI and ground

bounce, both of which can cause instability or regula-

tion errors by corrupting the voltage and current feed-

back signals.

), so a C

of 440µF results in C

= 4.7nF.

OUT

2) Use the system microcontroller to hold the MAX1703

in shutdown from the time when power is applied (or

reapplied) until C

has charged to at least the

OUT

input voltage. Standard power-on-reset times

Power components—such as the inductor, converter

IC, filter capacitors, and output diode—should be

placed as close together as possible, and their traces

should be kept short, direct, and wide. A separate low-

noise ground plane containing the reference and signal

grounds should only connect to the power-ground

plane at one point. This minimizes the effect of power-

ground currents on the part.

accomplish this.

3) Ensure that the IC operates, or at least powers up, in

PWM mode (CLK/SEL = high). Activate PFM mode

only after the output voltage has settled and all of

the system’s power-on-reset flags are cleared.

Use in a Typical Wireless

Phone Application

The MAX1703 is ideal for use in digital cordless and

PCS phones. The power amplifier (PA) is connected

directly to the boost-converter output for maximum volt-

age swing (Figure 8). Low-dropout linear regulators are

used for post-regulation to generate low-noise power

for DSP, control, and RF circuitry. Typically, RF phones

spend most of their life in standby mode with only short

periods in transmit/receive mode. During standby, max-

imize battery life by setting CLK/SEL = 0; this places

the IC in low-power mode (for the lowest quiescent

power consumption). See Gain Block section for infor-

mation on configuring an external MOSFET as a linear

regulator.

Keep the voltage feedback network very close to the

IC, within 0.2in. (5mm) of the FB pins. Keep noisy

traces, such as from the LX pin, away from the voltage

feedback networks and separated from them using

grounded copper. Consult the MAX1703 EV kit for a full

PC board example.

Soft-Start

To implement soft-start, set CLK/SEL low on power-up;

this forces PFM operation and reduces the peak

switching current to 800mA max. Once the circuit is in

regulation and start-up transients have settled,

CLK/SEL can be set high for full-power operation.

______________________________________________________________________________________ 13

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

___________________Chip Information

TRANSISTOR COUNT: 554

SUBSTRATE CONNECTED TO GND

POUT

LDOs

MAX8865/MAX8866

MAX1703

µC

RADIO

Figure 8. Typical Phone Application

14 ______________________________________________________________________________________

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

MAX1703

________________________________________________________Package Information

______________________________________________________________________________________ 15

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

NOTES

MAX1703

16 ______________________________________________________________________________________

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MAX1703ESE产品参数

型号:	MAX1703ESE
是否无铅：	含铅
是否Rohs认证：	不符合
生命周期：	Obsolete
IHS 制造商：	MAXIM INTEGRATED PRODUCTS INC
零件包装代码：	SOIC
包装说明：	0.150 INCH, SOIC-16
针数：	16
Reach Compliance Code：	not_compliant
ECCN代码：	EAR99
HTS代码：	8542.39.00.01
风险等级：	5.2
Is Samacsys：	N
模拟集成电路 - 其他类型：	SWITCHING REGULATOR
控制模式：	VOLTAGE-MODE
控制技术：	PULSE WIDTH MODULATION
最大输入电压：	5.5 V
标称输入电压：	.7 V
JESD-30 代码：	R-PDSO-G16
JESD-609代码：	e0
长度：	9.9 mm
湿度敏感等级：	1
功能数量：	1
端子数量：	16
最高工作温度：	85 °C
最低工作温度：	-40 °C
最大输出电流：	3.2 A
标称输出电压：	5.05 V
封装主体材料：	PLASTIC/EPOXY
封装代码：	SOP
封装等效代码：	SOP16,.25
封装形状：	RECTANGULAR
封装形式：	SMALL OUTLINE
峰值回流温度（摄氏度）：	240
认证状态：	Not Qualified
座面最大高度：	1.75 mm
子类别：	Switching Regulator or Controllers
最大供电电流 (Isup)：	0.3 mA
表面贴装：	YES
切换器配置：	BOOST
最大切换频率：	340 kHz
技术：	CMOS
温度等级：	INDUSTRIAL
端子面层：	Tin/Lead (Sn85Pb15)
端子形式：	GULL WING
端子节距：	1.27 mm
端子位置：	DUAL
处于峰值回流温度下的最长时间：	20
宽度：	3.9 mm
Base Number Matches：	1

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