MAXIM MAX1776 Technical data

General Description

The MAX1776 high-efficiency step-down converter pro­vides an adjustable output voltage from 1.25V to VINfrom
supply voltages as high as 24V. An internal current-limit­ed 0.4Ω MOSFET delivers load currents up to 600mA.
Operation to 100% duty cycle minimizes dropout volt­age (240mV at 600mA).

The MAX1776 has a low 15µA quiescent current to
improve light-load efficiency and conserve battery life.
The device draws only 3µA while in shutdown.

High switching frequencies (up to 200kHz) allow the
use of tiny surface-mount inductors and output capaci­tors. The MAX1776 is available in an 8-pin µMAX pack­age, which uses half the space of an 8-pin SO. For
increased output drive capability, use the MAX1626/
MAX1627 step-down controllers, which drive an exter­nal P-channel MOSFET to deliver up to 20W.

Applications

Notebook Computers

Distributed Power Systems

Keep-Alive Supplies

Hand-Held Devices

Features

♦ Fixed 5V or Adjustable Output

♦ 4.5V to 24V Input Voltage Range

♦ Up to 600mA Output Current
♦ Internal 0.4Ω P-Channel MOSFET

♦ Efficiency Over 95%

♦ 15µA Quiescent Supply Current

♦ 3µA Shutdown Current

♦ 100% Maximum Duty Cycle for Low Dropout

♦ Current-Limited Architecture

♦ Thermal Shutdown

♦ Small 8-µMAX Package

MAX1776

24V, 600mA Internal Switch, 100% Duty Cycle,

Step-Down Converter

________________________________________________________________ Maxim Integrated Products 1

Pin Configuration

Ordering Information

SHDN

V

OUT

V

IN

ILIM LX

OUT

IN

ILIM2

GNDFB

MAX1776

µMAX

Typical Operating Circuit

19-1975; Rev 2; 7/03

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.

PART TEMP RANGE PIN-PACKAGE

MAX1776EUA -40°C to +85°C 8 µMAX

8

OUT

7

MAX1776EUA

µMAX

SHDN

6

ILIM2

5

INLX

TOP VIEW

1

FB

2

GND

3

ILIM

4

MAX1776

24V, 600mA Internal Switch, 100% Duty Cycle,
Step-Down Converter

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VIN= +12V, SHDN = IN, TA= 0°C to +85°C, unless otherwise noted.)

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.

IN, SHDN, ILIM, ILIM2 to GND .................................-0.3V to 25V

LX to GND.......................................................-2V to (V

IN

+ 0.3V)

OUT, FB to GND .........................................................-0.3V to 6V

Peak Input Current .................................................................. 2A

Maximum DC Input Current.............................................. 500mA

Continuous Power Dissipation (T

A

= +70°C)

8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW

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

)

)

)

)

Dual Mode is a trademark of Maxim Integrated Products, Inc.

Input Voltage Range V

Input Supply Current I

Input Supply Current in Dropout I
Input Shutdown Current SHDN = GND 3 7 µA

Input Undervoltage Lockout
Threshold

Output Voltage (Preset Mode) V

Feedback Set Voltage
(Adjustable Mode)

OUT Bias Current V

OUT Pin Maximum Voltage 5.5 V

FB Bias Current I

FB Dual Mode™ Threshold Low 50 100 150 mV

LX Switch Minimum Off-Time t

LX Switch Maximum On-Time t

LX Switch On-Resistance R

LX Current Limit I

LX Zero-Crossing Threshold -75 +75 mV

Zero-Crossing Timeout LX does not rise above the threshold 30 µs

LX Switch Leakage Current

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IN

IN

IN(DROP

V

UVLO

OUT

V

FB

FB

OFF(MIN

ON(MAX

LX(PEAK

No load 15 28 µA

No load 50 70 µA

VIN rising 3.6 4.0 4.4

VIN falling 3.5 3.9 4.3

FB = GND 4.80 5.00 5.20 V

= 5.5V 1.65 3.5 6.25 µA

OUT

VFB = 1.3V -25 +25 nA

VFB = 1.3V 8 10 12 µs

ILIM = ILIM2 = GND 1.6 3.2

VIN = 6V

LX

VIN = 4.5V

ILIM = ILIM2 = GND 120 150 180

ILIM = GND, ILIM2 = IN 240 300 360

ILIM = IN, ILIM2 = GND 480 600 720

ILIM = ILIM2 = IN 960 1200 1440

V

= 24V,

IN

LX = GND

ILIM = GND, ILIM2 = IN 0.8 1.6

ILIM = IN, ILIM2 = GND 0.4 0.8

ILIM = ILIM2 = IN 0.4 0.8

ILIM = ILIM2 = GND 1.9 3.8

ILIM = GND, ILIM2 = IN 1.0 1.9

ILIM = IN, ILIM2 = GND 0.5 0.95

ILIM = ILIM2 = IN 0.5 0.95

TA = +25°C1

= 0°C to +85°C10

T

A

4.5 24 V

1.212 1.25 1.288 V

0.22 0.42 0.62 µs

V

Ω

mA

µA

MAX1776

24V, 600mA Internal Switch, 100% Duty Cycle,

Step-Down Converter

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= +12V, SHDN = IN, TA= 0°C to +85°C, unless otherwise noted.)

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VIN= +12V, SHDN = IN, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

)

)

)

)

Dropout Voltage V

Line Regulation VIN = 8V/24V, 200Ω load 0.1 %/V

Load Regulation No load/full load 0.9 %

Digital Input Level SHDN, ILIM2

Digital Input Leakage Current V

ILIM Input Level

Thermal Shutdown 10°C hysteresis 160 °C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

I

DROPOUT

= 525mA, ILIM = ILIM2 = IN 0.2 V

OUT

Low 0.8

High 2.4

, V

, V

SHDN

ILIM

Low 0.05

High 2.2

= 0 or 24V, VIN = 24V -1 +1 µA

ILIM2

Input Voltage Range V

Input Supply Current I

Input Supply Current in Dropout I
Input Shutdown Current SHDN = GND 7 µA

Input Undervoltage Lockout
Threshold

Output Voltage (Preset Mode) V

Feedback Set Voltage
(Adjustable Mode)

OUT Bias Current V

OUT Pin Maximum Voltage 5.5 V

FB Bias Current I

FB Dual Mode Threshold Low 45 155 mV

LX Switch Minimum Off-Time t

LX Switch Maximum On-Time t

LX Switch On-Resistance R

LX Current Limit I

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

IN

IN

IN(DROP

V

UVLO

OUT

V

FB

FB

OFF(MIN

ON(MAX

LX

LX(PEAK

No load 28 µA

No load 70 µA

VIN rising 3.6 4.4

VIN falling 3.5 4.3

FB = GND 4.75 5.25 V

= 5.5V 1.65 6.25 µA

OUT

VFB = 1.3V -25 +25 nA

VFB = 1.3V 7.5 12.5 µs

ILIM = ILIM2 = GND 3.2

VIN = 6V

VIN = 4.5V

ILIM = ILIM2 = GND 100 200

ILIM = GND, ILIM2 = IN 200 400

ILIM = IN, ILIM2 = GND 400 800

ILIM = ILIM2 = IN 800 1600

ILIM = GND, ILIM2 = IN 1.6

ILIM = IN, ILIM2 = GND 0.8

ILIM = ILIM2 = IN 0.8

ILIM = ILIM2 = GND 3.8

ILIM = GND, ILIM2 = IN 1.9

ILIM = IN, ILIM2 = GND 0.95

ILIM = ILIM2 = IN 0.95

4.5 24 V

1.2 1.3 V

0.22 0.64 µs

V

V

V

Ω

mA

1.0

-0.7

-0.8

-0.9

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

00.20.1 0.3 0.4 0.5 0.6

LOAD REGULATION, CIRCUIT 5

MAX1776 toc04

I

LOAD

(A)

V

OUTPUT

(% FROM V

OUT(NOM)

)

VIN = 24V

VIN = 12V

VIN = 15V

-3

0

-1

-2

1

2

3

513117 9 15 17 19 21 23 25

V

OUTPUT

vs. VIN,

CIRCUIT 5, V

OUTPUT

= 5V

MAX1776 toc05

VIN (V)

V

OUTPUT

(%)

I

LOAD

= 1mA

I

LOAD

= 50mA

I

LOAD

= 500mA

-1.0

0.5

0

-0.5

1.0

1.5

2.0

513117 9 15 17 19 21 23 25

V

OUTPUT

vs. VIN,

CIRCUIT 5, V

OUTPUT

= 3.3V

MAX1776 toc06

VIN (V)

V

OUTPUT

(%)

I

LOAD

= 1mA

I

LOAD

= 10mA

I

LOAD

= 50mA

-1.2

-0.8

-1.0

-0.4

-0.6

0

-0.2

0.2

0 200 300100 400 500 600 700

LOAD REGULATION,

CIRCUIT 1, V

OUTPUT

= 5V

MAX1776 toc01

I

LOAD

(mA)

V

OUTPUT

(%)

VIN = 24V

VIN = 12V

VIN = 15V

-1.0

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0200100 300 400 500 600

LOAD REGULATION,

CIRCUIT 1, V

OUTPUT

= 3.3V

MAX1776 toc02

I

LOAD

(mA)

V

OUTPUT

(%)

VIN = 24V

VIN = 12V

VIN = 15V

VIN = 5V

-1.2

-1.0

-0.6

-0.8

-0.2

0

-0.4

0.2

0 100 15050 200 250 300 350 400

LOAD REGULATION, CIRCUIT 2

MAX1776 toc03

I

LOAD

(mA)

V

OUTPUT

(%)

VIN = 24V

VIN = 12V

VIN = 15V

Typical Operating Characteristics

(Circuit of Figure 1, components from Table 3, VIN= +12V, SHDN = IN, TA= +25°C.)

MAX1776

24V, 600mA Internal Switch, 100% Duty Cycle,
Step-Down Converter

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= +12V, SHDN = IN, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

Note 1: Specifications to -40°C are guaranteed by design, not production tested.

LX Zero-Crossing Threshold -75 75 mV

LX Switch Leakage Current VIN = 24V, LX = GND 10 µA

Digital Input Level SHDN, ILIM2

Digital Input Leakage Current V

ILIM Input Level

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

Low 0.8

High 2.4

, V

, V

SHDN

ILIM

= 0 or 24V, VIN = 24V -1 1 µA

ILIM2

Low 0.05

High 2.2

V

V