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产品型号MAX1760EUB的概述

MAX1760EUB芯片概述 MAX1760EUB是Maxim Integrated（现在是Analog Devices, Inc.的一部分）推出的一款高效的DC-DC转换器芯片。该芯片特别设计用于在低输入电压范围内提供稳定的输出电压，通常用于移动设备、便携式电子设备以及可穿戴设备等需要高效率和小型化的应用场景。MAX1760支持多种输出电压并能够在不同的负载条件下保持优异的电源管理性能。芯片详细参数从电气性能上看，MAX1760EUB具有以下关键参数： - 输入电压范围：2.5V至5.5V，适合多种电池供电的应用。 - 输出电压：可调节输出，在1.25V至5V之间可调；也可以提供固定输出版本。 - 输出电流：最大输出电流可达到500mA。 - 开关频率：内部设定开关频率为1MHz，可提高整体效率。 - 效率：在不同的负载状态下，效率可达到90%以上，有利于延长电池使用寿命和减少热...

产品型号MAX1760EUB的Datasheet PDF文件预览

19-1660; Rev 1; 1/01

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

General Description

Features

ꢀ Up to 94% Efficiency

The MAX1760 is a high-efficiency, low-noise, step-up

DC-DC converter intended for use in battery-powered

wireless applications. It maintains exceptionally low qui-

escent supply current (100µA) despite its high 1MHz

operating frequency. Small external components and a

tiny 10-pin µMAX package make this device an excel-

lent choice for small hand-held applications requiring

the longest possible battery life.

ꢀ 0.7V to 5.5V Input Range

ꢀ Up to 800mA Output

ꢀ Fixed 3.3V Output (or adj from 2.5V to 5.5V)

ꢀ PWM Synchronous Rectified Topology

ꢀ Low-Noise, Constant Frequency Operation (1MHz)

ꢀ 0.1µA Logic-Controlled Shutdown

ꢀ Synchronizable Switching Frequency

ꢀ Adjustable Current Limit

The MAX1760 uses a synchronous-rectified pulse-

width-modulation (PWM) boost topology to generate

2.5V to 5.5V outputs from a wide range of input

sources, such as 1 to 3 alkaline or NiCd/NiMH cells or a

single lithium-ion (Li+) cell. Maxim's proprietary Idle-

Mode™ circuitry significantly improves efficiency at

light load currents while smoothly transitioning to fixed-

frequency PWM operation at higher load currents to

maintain excellent full-load efficiency.

ꢀ Adjustable Soft-Start

ꢀ 10-Pin µMAX Package

Low-noise, forced PWM mode is available for applica-

tions requiring constant-frequency operation at all load

currents. The MAX1760 may also be synchronized to

an external clock to protect sensitive frequency bands

in communications equipment. Analog soft-start and

adjustable current limit permit optimization of efficiency,

external component size, and output voltage ripple.

Ordering Information

PART

TEMP. RANGE

PIN-PACKAGE

MAX1760EUB

-40°C to +85°C

10 µMAX

Applications

Digital Cordless Phones

Wireless Handsets

Palmtop Computers

Two-Way Pagers

PCS Phones

Hand-Held Instruments

Personal Communicators

Typical Operating Circuit

Pin Configuration

TOP VIEW

INPUT = 0.7V

TO V

OUT

MAX1760

ISET

REF

GND

10 ON

CLK/SEL

POUT

= 3.3V,

OUT

800mA

POUT

MAX1760

ISET

REF

PGND

CLK/SEL

OUT

GND PGND

µMAX

Idle Mode is a trademark of Maxim Integrated Products.

________________________________________________________________ Maxim Integrated Products

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

ABSOLUTE MAXIMUM RATINGS

ON, OUT, CLK/SEL to GND .....................................-0.3V to +6V

Continuous Power Dissipation (T = +70°C)

10-Pin µMAX (derate 5.6mW/°C above +70°C)...........444mW

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

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

Storage Temperature Range.............................-65°C to +150°C

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

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

LX to PGND ............................................-0.3V to (V

+ 0.3V)

POUT

POUT to OUT...................................................................... 0.3V

REF, FB, ISET, POUT to GND...................-0.3V to (V + 0.3V)

OUT

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.

ELECTRICAL CHARACTERISTICS

(CLK/SEL = ON = FB = PGND = GND, ISET = REF, OUT = POUT, V

= 3.6V, T = 0°C to +85°C. Typical values are at T =

A A

OUT

+25°C, unless otherwise noted.)

PARAMETER

DC-DC CONVERTER

CONDITIONS

MIN

TYP

MAX

UNITS

Input Voltage Range (Note 1)

0.7

0.9

-2.3

500

5.5

1.1

Minimum Startup Voltage (Note 2)

Temperature Coefficient of Startup Voltage

Frequency in Startup Mode

< 1mA, T = +25°C

LOAD

< 1mA

= 1.5V

mV/°C

kHz

MHz

125

0.8

1000

1.2

OUT

Internal Oscillator Frequency

CLK/SEL = OUT

Oscillator Maximum Duty Cycle (Note 3)

External Clock Frequency Range

0.5

1.2

MHz

< 0.1V, CLK/SEL = OUT, includes load

Output Voltage

3.17

3.3

3.38

regulation for 0 < I < 0.55A

Adjustable output, CLK/SEL = OUT, includes

FB Regulation Voltage

FB Input Leakage Current

Load Regulation

1.215

1.240

0.01

-1.5

1.270

100

load regulation for 0 < I < 0.55A

= 1.35V

CLK/SEL = OUT, no load to full load

(0 < I < 1.0A)

Output Voltage Adjust Range

Output Voltage Lockout Threshold (Note 4)

ISET Input Leakage Current

Supply Current in Shutdown

No-Load Supply Current (Note 5)

No-Load Supply Current Forced PWM Mode

DC-DC SWITCHES

2.5

5.5

2.30

Rising edge

2.00

2.15

0.01

0.1

= 1.25V

= 3.6V

µA

ISET

CLK/SEL = GND

CLK/SEL = OUT

100

2.5

185

POUT Leakage Current

= 0, V

= 5.5V

0.1

µA

OUT

LX Leakage Current

= V

= 5.5V

OUT

N-channel

P-channel

0.15

0.25

1.25

0.28

0.45

1.6

Switch On-Resistance

Ω

N-Channel Current Limit

1.0

P-Channel Turn-Off Current

CLK/SEL = GND

120

_______________________________________________________________________________________

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

ELECTRICAL CHARACTERISTICS (continued)

(CLK/SEL = ON = FB = PGND = GND, ISET = REF, OUT = POUT, V

= 3.6V, T = 0°C to +85°C. Typical values are at T = +25°C

A A

OUT

unless otherwise noted.)

PARAMETER

REFERENCES

CONDITIONS

MIN

TYP

MAX

UNITS

Reference Output Voltage

Reference Load Regulation

Reference Supply Rejection

LOGIC INPUTS

= 0

1.230

1.250

1.270

REF

-1µA < IREF < 50µA

2.5V < V

< 5V

0.2

OUT

CLK/SEL Input Low Level

CLK/SEL Input High Level

ON Input Low Level (Note 6)

2.5V ≤ V

≤ 5.5V

(0.2)V

OUT

(0.8)V

OUT

1.1V ≤ V

1.8V ≤ V

≤ 1.8V

≤ 5.5V

0.2

0.4

OUT

1.1V ≤ V

≤ 1.8V

- 0.2

OUT

1.6

ON Input High Level (Note 6)

1.8V ≤ V

≤ 5.5V

OUT

Input Leakage Current

CLK/SEL, ON

0.01

200

100

µA

Minimum CLK/SEL Pulse Width

Maximum CLK/SEL Rise/Fall Time

ELECTRICAL CHARACTERISTICS

(CLK/SEL = ON = FB = PGND = GND, ISET = REF, OUT = POUT, V

= 3.6V, T = -40°C to +85°C, unless otherwise noted.) (Note 7)

OUT

PARAMETER

DC-DC CONVERTER

CONDITIONS

MIN

MAX

UNITS

< 0.1V, CLK/SEL = OUT, includes load

Output Voltage

3.17

3.38

regulation for 0 < I < 0.55A

Adjustable output, CLK/SEL = OUT, includes

load regulation for 0 < I < 0.55A

FB Regulation Voltage

1.215

1.270

Internal Oscillator Frequency

CLK/SEL = OUT

0.75

1.2

MHz

Oscillator Maximum Duty Cycle (Note 3)

Output Voltage Lockout Threshold (Note 4)

Supply Current in Shutdown

Rising edge

2.00

2.30

= 3.6V

µA

No-Load Supply Current (Note 5)

DC-DC SWITCHES

CLK/SEL = GND

185

N-channel

P-channel

0.28

0.45

1.6

Switch On-Resistance

Ω

N-Channel Current Limit

REFERENCE

1.0

Reference Output Voltage

= 0

1.230

1.270

REF

_______________________________________________________________________________________

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

ELECTRICAL CHARACTERISTICS (continued)

(CLK/SEL = ON = FB = PGND = GND, ISET = REF, OUT = POUT, V

= 3.6V, T = -40°C to +85°C, unless otherwise noted.) (Note 7)

OUT

PARAMETER

LOGIC INPUTS

CONDITIONS

MIN

MAX

UNITS

CLK/SEL Input Low Level

CLK/SEL Input High Level

2.5V ≤ V

1.1V ≤ V

1.8V ≤ V

1.1V ≤ V

1.8V ≤ V

≤ 5.5V

(0.2)V

OUT

≤ 5.5V

≤ 1.8V

≤ 5.5V

≤ 1.8V

≤ 5.5V

(0.8)V

OUT

0.2

0.4

ON Input Low Level (Note 6)

+ 0.2

OUT

1.6

ON Input High Level (Note 6)

Input Leakage Current

CLK/SEL, ON

µA

Note 1: Operating voltage—since the regulator is bootstrapped to the output, once started the MAX1760 will operate down

to 0.7V input.

Note 2: Startup is tested with the circuit shown in Figure 6.

Note 3: Defines maximum step-up ratio.

Note 4: The regulator is in startup mode until this voltage is reached. Do not apply full load current until the output exceeds 2.3V.

Note 5: Supply current into 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.

Note 6: ON has a hysteresis of approximately 0.15 × V

OUT

Note 7: Specifications to -40°C are guaranteed by design and not production tested.

Typical Operating Characteristics

(Circuit of Figure 2, V = 2.4V, V

= 3.3V, T = +25°C, unless otherwise noted.)

OUT

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE

EFFICIENCY vs. OUTPUT CURRENT

= 5V

EFFICIENCY vs. OUTPUT CURRENT

= 3.3V

OUT

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

100

= 3.3V

OUT

= 5V

OUT

= AUTO MODE

= FPWM MODE

= AUTO MODE

= FPWM MODE

A: V = 3.6V

A: V = 2.4V

B: V = 2.4V

B: V = 1.2V

C: V = 1.2V

C: V = 0.9V

0.0001

0.001

0.01

0.1

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

INPUT VOLTAGE (V)

0.0001

0.001

0.01

0.1

OUTPUT CURRENT (A)

_______________________________________________________________________________________

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

Typical Operating Characteristics (continued)

(Circuit of Figure 2, V = 2.4V, V

= 3.3V, T = +25°C, unless otherwise noted.)

OUT

NO-LOAD BATTERY CURRENT

vs. INPUT VOLTAGE

TOTAL SHUTDOWN CURRENT

(I + I ) vs. INPUT VOLTAGE

INTERNAL OSCILLATOR

FREQUENCY vs. TEMPERATURE

LX OUT

2.5

2.0

1.5

1.0

0.5

0.0

1.20

1.15

1.10

1.05

1.00

0.95

0.90

0.85

0.80

0.75

= 5V

OUT

= 3.3V

OUT

0.1

-40

-15

INPUT VOLTAGE (V)

TEMPERATURE (°C)

STARTUP VOLTAGE

vs. OUTPUT CURRENT

PEAK INDUCTOR CURRENT vs. V

HEAVY-LOAD SWITCHING WAVEFORMS

ISET

3.0

2.5

2.0

1.5

1.0

0.5

0.0

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

A = +85°C

B = +25°C

C = -40°C

CIRCUIT OF FIGURE 6

0.001 0.01

OUTPUT CURRENT (A)

0.1

0.3

0.5

0.7

0.9

1.1

1.3

A = LX PIN, 5V/div

B = INDUCTOR CURRENT, 200mA/div

C = OUTPUT RIPPLE, 50mV/div AC-COUPLED

t = 400ns/div

(V)

ISET

LOAD-TRANSIENT RESPONSE

LIGHT-LOAD SWITCHING WAVEFORMS

LINE-TRANSIENT RESPONSE

t = 200ms/div

400µs/div

t = 400ns/div

= 1.1V, V = 3.3V, I = 0 AND 0.2A

OUT

_IN= 2.4V TO 1.4V, I_OUT= 70mA

A = LX PIN, 5V/div

OUT

A = I , 100mA/div

A = V , 1V/div

B = INDUCTOR CURRENT, 200mA/div

B = V , 50mV/div, AC-COUPLED

B = V , 5mA/div, AC-COUPLED

OUT

C = OUTPUT RIPPLE, 50mV/div, AC-COUPLED

_______________________________________________________________________________________

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

Typical Operating Characteristics (continued)

(Circuit of Figure 2, V = 2.4V, V

= 3.3V, T = +25°C, unless otherwise noted.)

OUT

TURN-ON WAVEFORMS

NO SOFT-START COMPONENTS

SOFT-START WAVEFORMS

NOISE SPECTRUM

= 500kΩ, C = 0.1µF

0.1

t = 2ms/div

A = ON, 5V/div

2.00ms/div

FREQUENCY (MHz)

A = ON, 5V/div

B = INPUT CURRENT, 500mA/div

B = INPUT CURRENT, 100mA/div

C = V , 2V/div

OUT

Pin Description

NAME

FUNCTION

N-Channel Current-Limit Control. For maximum current limit, connect to REF. To reduce current, supply a

voltage between REF and GND by means of a resistive voltage-divider. If soft-start is desired, connect a

ISET

capacitor from ISET to GND. When ON = high, or V

<80% of nominal value, an on-chip 100kΩ switched

REF

resistor discharges this pin to GND.

1.250V Voltage Reference Bypass. Connect a 0.22µF ceramic bypass capacitor to GND. Up to 50µA of

external load current is allowed.

REF

GND

Ground. Connect to PGND with short trace.

DC-DC Converter Feedback Input. To set fixed output voltage of +3.3V, connect FB to ground. For

adjustable output of 2.5V to 5.5V, connect to a resistive divider from OUT to GND. FB set point = 1.24V.

IC Power, Supplied from the Output. Bypass to GND with a 0.68µF ceramic capacitor, and connect to POUT

with a series 4.7Ω resistor (Figure 2).

OUT

Clock Input for the DC-DC Converter. Also serves to program operating mode of switcher as follows:

CLK/SEL = LO: Normal operation—operates at a fixed frequency, automatically switching to low-power

mode if load is minimized.

CLK/SEL = HI: Forced PWM mode—operates in low-noise, constant-frequency mode at all loads.

CLK/SEL = Clocked: Forced PWM mode with the internal oscillator synchronized to CLK in 500kHz to

1200kHz range.

CLK/SEL

PGND

Source of N-Channel Power MOSFET Switch

Inductor Connection

POUT

Power Output. P-channel synchronous-rectifier source.

Shutdown Control Input. When ON = high, the IC is in shutdown. Connect ON to GND for normal operation.

_______________________________________________________________________________________

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

UNDERVOLTAGE LOCKOUT

OUT

IC POWER

2.15V

CONTROLLER

POUT

STARTUP

PCH

NCH

OSCILLATOR

RDY

REFERENCE

OSC

1.25V

REF

REF GND

OSCILLATOR

1MHz

GND

MODE

CLK/SEL

PGND

CLK/SEL

ISET

MAX1760

Figure 1. Functional Diagram

Detailed Description

The MAX1760 is a highly efficient, low-noise power sup-

ply for portable RF and hand-held instruments. It com-

bines a boost switching regulator, N-channel power

MOSFET, P-channel synchronous rectifier, precision

reference, and shutdown control (Figure 1).

3.3µH

= 2.4V

33µF

CLK/SEL

MAX1760

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

voltage input to a fixed 3.3V or adjustable voltage

between 2.5V and 5.5V. An external Schottky diode is

required for output voltages greater than 4V. The

MAX1760 guarantees startup with an input voltage as

low as 1.1V and remains operational down to an input

of just 0.7V. It is optimized for use in cellular phones

and other applications requiring low noise and low qui-

escent current for maximum battery life. It features

fixed-frequency operation at medium and heavy loads,

but at light loads, switches only as needed for optimum

efficiency. This device is also capable of constant-fre-

quency (1MHz), low-noise PWM operation at all load

currents, or frequency-synchronized PWM operation

when connected to an external clock. Table 1 lists

some typical outputs. Shutdown reduces quiescent cur-

rent to just 1µA. Figure 2 shows the standard applica-

tion circuit for the MAX1760.

= 3.3V,

OUT

POUT

800mA

ISET

REF

4.7Ω

100µF

OUT

0.68µF

0.22µF

GND PGND

Figure 2. Standard Application Circuit

Step-Up Converter

During DC-DC converter operation, the internal N-chan-

nel MOSFET switch turns on for 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, the MOSFET turns off and inductor

current flows through the synchronous rectifier to the

_______________________________________________________________________________________

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

Table 1. Typical Available Output Current

NUMBER OF NiCd/NiMH

CELLS

INPUT VOLTAGE

(V)

OUTPUT VOLTAGE

(V)

OUTPUT CURRENT

(mA)

1.2

2.4

3.6

3.3

5.0

350

800

500

750

Table 2. Selecting the Operating Mode

CLK/SEL

MODE

FEATURES

Normal Operation

Forced PWM

High efficiency at all loads. Fixed frequency at all but light loads.

Low noise, fixed frequency at all loads.

External Clock

500kHz to 1.2MHz

Synchronized PWM

Low noise, fixed frequency at all loads.

output filter capacitor and the load. As the energy

stored in the inductor is depleted, the current ramps

down and the synchronous rectifier turns off. At light

loads, the device operates at fixed frequency or only as

needed to maintain regulation, depending on the

CLK/SEL setting (Table 2).

Synchronous Rectifier

The MAX1760 features an internal, P-channel synchro-

nous rectifier to enhance efficiency. Synchronous recti-

fication provides 5% improved efficiency over similar

nonsynchronous boost regulators. In PWM mode, the

synchronous rectifier is turned on during 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 turns it off when the inductor current drops

below 60mA. When setting output voltages greater than

4V, an external 0.5A Schottky diode must be connected

in parallel with the on-chip synchronous rectifier.

Normal Operation

Pulling CLK/SEL low selects the MAX1760’s normal

operating mode. In this mode, the device operates in

PWM when driving medium-to-heavy loads, and auto-

matically switches to PFM if the load requires less

power. PFM operation allows higher efficiency than

PWM under light load conditions.

Low-Voltage Startup Oscillator

The MAX1760 uses a CMOS, low-voltage startup oscil-

lator for a 1.1V guaranteed minimum startup input volt-

age. At startup, the low-voltage oscillator switches the

N-channel MOSFET until the output voltage 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 0.7V

input since internal power for the IC is bootstrapped

from the output through OUT. Do not apply full load

until the output exceeds 2.3V.

Forced PWM Operation

When CLK/SEL is high, the MAX1760 operates in a low-

noise PWM-only mode. During forced PWM operation,

the MAX1760 switches at a constant frequency (1MHz),

and modulates the MOSFET switch pulse width to con-

trol the power transferred per cycle to regulate the out-

put voltage. Switching harmonics generated by

fixed-frequency operation are consistent and easily fil-

tered. See the Noise Spectrum plot in the Typical

Operating Characteristics.

Synchronized PWM Operation

The MAX1760 can be synchronized in PWM mode to an

external frequency of 500kHz to 1.2MHz by applying an

external clock signal to CLK/SEL. This allows interfer-

ence to be minimized in wireless applications. The syn-

chronous rectifier is active during synchronized PWM

operation.

Shutdown

The MAX1760 has a shutdown mode that reduces qui-

escent current to 0.1µA. During shutdown (ON = high),

the reference and all feedback and control circuitry are

off. During shutdown, the output voltage is one diode

drop below the input voltage.

_______________________________________________________________________________________

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

3.3µH

= 2.4V

33µF

CLK/SEL

MAX1760

POUT

OUT

100µF

ISET

REF

4.7Ω

OUT

0.68µF

0.22µF

PGND GND

OUT

R1 = R2

(_V)

= 1.24V

Figure 3. Connecting Resistors for External Feedback

REF

SS2

= 1.25A

LIM

0.22µF

= 1.25A

(_R)

+ R

LIM

SS1

SS2

SS1

= R C

SS SS

MAX1760

= (R

R ) C

SS2 SS

SS1

ISET

SS2

≥ 470k

SS1

≥ 470k

Figure 4. Soft-Start with Maximum Switch Limit Current

Figure 5. Soft-Start with Reduced Switch Current Limit

Reference

The MAX1760 has an internal 1.250V 1% reference.

Connect a 0.22µF ceramic bypass capacitor from REF

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

source up to 50µA of external load current.

where V , the boost-regulator feedback set point, is

1.24V.

Setting the Switch Current Limit

and Soft-Start

The ISET pin adjusts the inductor current limit and

implements soft-start. With ISET connected to REF, the

inductor current limits at 1.25A. With ISET connected to

a resistive divider set from REF to GND, the current limit

is reduced according to:

Design Procedure

Setting the Output Voltages

For a fixed 3.3V output, connect FB to GND. To set

other output voltages between 2.5V and 5.5V, connect

a resistor voltage-divider to FB from OUT to GND

(Figure 3). The input bias current into FB is <20nA,

allowing large-value divider resistors without sacrificing

accuracy. Connect the resistor voltage-divider as close

to the IC as possible, within 0.2in (5mm) of FB. Choose

R2 of 270kΩ or less, then calculate R1 using:









ISET

I_LIM= 1.25A

1.25V

Implement soft-start by placing a resistor from ISET to

REF and a capacitor from ISET to GND. In shutdown,

ISET is discharged to GND through an on-chip 100kΩ

resistor. At power-up, ISET is 0V and the LX current is

zero. As the capacitor voltage rises, the current

increases and the output voltage rises. The soft-start







V_OUT

V_FB

R1 = R2

− 1







_______________________________________________________________________________________

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

Table 3. Component Selection Guide

PRODUCTION METHOD

INDUCTORS

Coilcraft DS3316P

Coilcraft LPT3305

Sumida CDRH5D18

Sumida CD43

CAPACITORS

AVX TPS series

Kemet T510 series

Sanyo POSCAP series

—

DIODES

EIC SB series

Motorola MBR0520L

Surface Mount

—

Table 4. Component Suppliers

External Diode

For output voltages greater than 4V, an external

Schottky diode must be connected from LX to POUT, in

parallel with the on-chip synchronous rectifier (Figure

6). The diode should be rated for 0.5A. Representative

devices are Motorola MBR0520L, Nihon EP05Q03L, or

generic 1N5817. This external diode is also recom-

mended for applications that must start with input volt-

ages at or below 1.8V. The Schottky diode carries

current during startup and after the synchronous rectifi-

er turns off; thus, its current rating only needs to be

500mA. Connect the diode as close to the IC as possi-

ble. Do not use ordinary rectifier diodes; their slow

switching speeds and long reverse-recovery times ren-

der them unacceptable. For circuits that do not require

startup with inputs below 1.8V, and have an output of

4V or less, no external diode is needed.

SUPPLIER

PHONE

AVX

USA: 843-448-9411

Coilcraft

EIC

USA: 847-639-6400

USA: 916-941-0712

USA: 810-287-2536

Kemet

USA: 408-629-4789

Japan: 81-45-474-7030

Motorola

Sumida

USA: 847-956-0666

Japan: 011-81-3-3667-3302

Note: Please indicate that you are using the MAX1760 when

contacting these component suppliers.

time constant is:

Input and Output Filter Capacitors

t_SS= R_SSC_SS

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-

where R ≥ 470k.

Placing a capacitor across the lower resistor of the cur-

rent-limiting resistive divider provides both current-limit

and soft-start features simultaneously (Figures 4 and 5).

Inductor Selection

The MAX1760’s high switching frequency allows the

use of a small 3.3µH surface-mount inductor. The cho-

sen inductor should generally have a saturation current

rating exceeding the N-channel switch current limit;

however, it is acceptable to bias the inductor current

into saturation by as much as 20% if a slight reduction

in efficiency is acceptable. Lower current-rated induc-

tors may be used if ISET is employed to reduce the

peak inductor current (see Setting the Switch Current

Limit and Soft-Start). For high efficiency, choose an

inductor with a high-frequency ferrite core material to

reduce core losses. To minimize radiated noise, use a

toroid or shielded inductor. See Table 3 for suggested

components and Table 4 for a list of component suppli-

ers. Connect the inductor from the battery to the LX pin

as close to the IC as possible.

3.3µH

= 0.7V

TO VOUT

33µF

CLK/SEL

MRB0520L

OUT

100µF

MAX1760

POUT

ISET

REF

4.7Ω

OUT

0.68µF

0.22µF

PGND GND

Figure 6. Connection with External Schottky Diode for Output

Voltages Greater than 4V, or to Assist Low-Voltage Startup

10 ___________________________________________________

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

age, and output capacitors with working voltage ratings

higher than the output.

bypass OUT to GND with a 0.68µF ceramic capacitor,

and connect OUT to POUT with a 4.7Ω resistor. Each of

these components should be placed as close to its

respective IC pins as possible, within 0.2in (5mm).

Table 4 lists suggested suppliers.

The input filter capacitor reduces peak currents drawn

from the input source and also reduces input switching

noise. The input voltage source impedance determines

the required value of the input capacitor. When operat-

ing directly from one or two NiMH cells placed close to

the MAX1760, use a single 33µF low-ESR input filter

capacitor. With higher impedance batteries, such as

alkaline and Li+, a higher value input capacitor may

improve efficiency.

Layout Considerations

High switching frequencies and large peak currents

make PC board layout a critical part of design. Poor

design will cause excessive EMI and ground bounce,

both of which can cause instability or regulation errors

by corrupting the voltage and current feedback signals.

The output filter capacitor reduces output ripple voltage

and provides the load with transient peak currents

when necessary. For the output, a 100µF, low-equiva-

lent-series-resistance (ESR) capacitor is recommended

for most applications.

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. Keep the volt-

age feedback network very close to the IC, within 0.2in

(5mm) of the FB pin. Keep noisy traces, such as those

from the LX pin, away from the voltage feedback net-

work and guarded from them using grounded copper.

Refer to the MAX1760 EV kit for a full PC board exam-

ple.

Sanyo POSCAP, Panasonic SP/CB, and Kemet T510

are good low-ESR capacitors. Low-ESR tantalum

capacitors offer a good tradeoff between price and

performance. Do not exceed the ripple current ratings

of tantalum capacitors. Avoid aluminum electrolytic

capacitors; their high ESR typically results in higher

output ripple voltage.

Chip Information

TRANSISTOR COUNT: 1361

Other External Components

Two ceramic bypass capacitors are required for proper

operation. Bypass REF to GND with 0.22µF. Also,

______________________________________________________________________________________ 11

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

Package Information

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are

implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

Printed USA

is a registered trademark of Maxim Integrated Products.

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MAX1760EUB产品参数

型号:	MAX1760EUB
是否无铅：	含铅
是否Rohs认证：	不符合
生命周期：	Active
IHS 制造商：	ROCHESTER ELECTRONICS LLC
零件包装代码：	TSSOP
包装说明：	MO-187C-BA, MICRO, SOP-10
针数：	10
Reach Compliance Code：	unknown
风险等级：	5.18
其他特性：	IT CAN ALSO OPERATE WITH PULSE FREQUENCY MODULATION
模拟集成电路 - 其他类型：	SWITCHING REGULATOR
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：	S-PDSO-G10
JESD-609代码：	e0
长度：	3 mm
湿度敏感等级：	1
功能数量：	1
端子数量：	10
最高工作温度：	85 °C
最低工作温度：	-40 °C
最大输出电流：	1.6 A
封装主体材料：	PLASTIC/EPOXY
封装代码：	TSSOP
封装形状：	SQUARE
封装形式：	SMALL OUTLINE, THIN PROFILE, SHRINK PITCH
峰值回流温度（摄氏度）：	240
座面最大高度：	1.1 mm
表面贴装：	YES
切换器配置：	BOOST
最大切换频率：	1200 kHz
温度等级：	INDUSTRIAL
端子面层：	TIN LEAD
端子形式：	GULL WING
端子节距：	0.5 mm
端子位置：	DUAL
处于峰值回流温度下的最长时间：	20
宽度：	3 mm
Base Number Matches：	1

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