MAX1761EEE-T Datasheet MAX1761EEE+, MAX1761EEE+T, MAX1761EEE-T | P1-P3

General Description

The MAX1761 dual pulse-width-modulation (PWM),

step-down controller provides high efficiency, excellent

transient response, and high DC output accuracy in an

extremely compact circuit topology. These features are

essential for stepping down high-voltage batteries to

generate low-voltage CPU core, I/O, and chipset RAM

supplies in PC board area critical applications, such as

notebook computers and smart phones.

Maxim’s proprietary Quick-PWM™ quick-response,

constant-on-time PWM control scheme handles wide

input/output voltage ratios with ease and provides

“instant-on” response to load transients while maintain-

ing a relatively constant switching frequency.

The MAX1761 achieves high efficiency at reduced cost

by eliminating the current-sense resistor found in tradi-

tional current-mode PWMs. Efficiency is further

enhanced by its ability to drive large synchronous-recti-

fier MOSFETs. The MAX1761 employs a complemen-

tary MOSFET output stage, which reduces component

count by eliminating external bootstrap capacitors and

diodes.

Single-stage buck conversion allows this device to

directly step down high-voltage batteries for the highest

possible efficiency. Alternatively, two-stage conversion

(stepping down the +5V system supply instead of the

battery) at a higher switching frequency allows the mini-

mum possible physical size.

The MAX1761 is intended for CPU core, chipset,

DRAM, or other low-voltage supplies. The MAX1761 is

available in a 16-pin QSOP package. For applications

requiring greater output power, refer to the MAX1715

data sheet. For a single-output version, refer to the

MAX1762/MAX1791 data sheet.

________________________Applications

Notebooks and PDAs

Digital Cameras

Handy-Terminals

Smart Phones

1.8V/2.5V Logic and I/O Supplies

Features

♦ Free-Running On-Demand PWM

♦ Selectable Light-Load Pulse-Skipping Operation

♦ ±1% Total DC Error in Forced-PWM Mode

♦ 5V to 20V Input Range

♦ Flexible Output Voltages

OUT1: Dual Mode™ Fixed 2.5V or 1V to 5.5V

Adjustable

OUT2: Dual Mode Fixed 1.8V or 1V to 5.5V

Adjustable

♦ Output Undervoltage Protection

♦ Complementary Synchronous Buck

♦ No Current-Sense Resistor

♦ 4.65V at 25mA Linear Regulator Output

♦ 4µA V+ Shutdown Supply Current

♦ 5µA VL Shutdown Supply Current

♦ 950µA Quiescent Supply Current

♦ Tiny 16-Pin QSOP Package

MAX1761

Small, Dual, High-Efficiency

Buck Controller for Notebooks

________________________________________________________________ Maxim Integrated Products 1

FB1 DH1

CS1

DL1

GND

DL2

CS2

DH2

TOP VIEW

MAX1761

QSOP

OUT1

REF

ON1

ON2

V+

OUT2

FB2

Pin Configuration

19-1835; Rev 0; 10/00

For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

Ordering Information

16 QSOP

PIN-PACKAGETEMP. RANGE

-40°C to +85°CMAX1761EEE

PART

Quick-PWM and Dual Mode are trademarks of

Maxim Integrated Products.

MAX1761

Small, Dual, High-Efficiency

Buck Controller for Notebooks

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, V+ = 15V, C

= 4.7µF, C

REF

= 0.1µF, VL not externally driven unless otherwise noted, T

= 0°C to +85°C, unless

otherwise noted.) (Note 1)

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.

V+ to GND ..............................................................-0.3V to +22V

VL to GND ................................................................-0.3V to +6V

VL to V+ .............................................................................+0.3V

OUT_, ON2 to GND ..................................................-0.3V to +6V

ON1, DH_ to GND ........................................-0.3V to (V+ + 0.3V)

FB_, REF, DL_ to GND.................................-0.3V to (VL + 0.3V)

CS_ to GND .....................................................-2V to (V+ + 0.3V)

REF Short Circuit to GND ...........................................Continuous

Continuous Power Dissipation

16-Pin QSOP (derate 8.3mW/°C above +70°C) ......….667mW

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

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

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

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

PWM CONTROLLERS

Input Voltage Range V+ (Note 2) 4.5 20 V

FB_ = OUT_ 0.99 1 1.01

FB1 = GND 2.475 2.5 2.525 V

DC Output Voltage Accuracy

(Note 3)

OUT_

V+

= 4.5V to 20V,

= 4.75V to 5.25V,

ON2 = VL

FB2 = GND 1.782 1.8 1.818

Output Voltage Adjust Range 1 5.5 V

OUT_ Input Resistance 80 160 300 kΩ

FB_ Input Bias Current V

FB_

= 1V, VL = 5V -0.1 0.1 µA

CS_ Input Bias Current V

CS_

= 0, VL = 5V -1 1 µA

Soft-Start Ramp Time Zero to full ILIM 1700 µs

OUT1 661 735 809

On-Time (Note 4) t

V+

= 10V, V

OUT1

= 2.5V,

OUT2

= 1.8V

OUT2 648 720 792

Minimum Off-Time (Note 4) t

OFF

400 500 ns

BIAS AND REFERENCE

FB1 = FB2 = GND, VL = 5V, V

OUT1

and

OUT2

forced above regulation point

0.60 1.20 mA

VL undriven 0.95 1.70

Quiescent Supply Current

I+

FB1 = FB2 = GND, V

OUT1

and V

OUT2

forced

above regulation point

VL = 5V 0.38 0.65

IL VL = 5V, ON1 = ON2 = GND 5 10 µA

Shutdown Supply Current

I+ VL = 0, 5V 4 10 µA

VL Output Voltage VL I

LOAD

= 0 to 25mA, V+ = 5V to 20V 4.5 4.65 4.75 V

Reference Voltage V

REF

V+ = 5V to 20V, no load 1.98 2 2.02 V

Reference Load Regulation I

REF

= 0 to 50µA 8 mV

REF Sink Current REF in regulation 10 µA

Falling edge 1.6

REF Fault Lockout Voltage

Rising edge 1.94

MAX1761

Small, Dual, High-Efficiency

Buck Controller for Notebooks

_______________________________________________________________________________________ 3

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

FAULT PROTECTION

Output Undervoltage Threshold

(Foldback)

UVFB

With respect to the regulation point, no load 60 70 80 %

Output Undervoltage Blanking

Time

UVLO

(

)

Measured from ON_ signal going high 10 32 ms

GND - CS_, positive direction 92 100 108

GND - CS_, negative direction, ON2 = floating -135 -120 -105

Current-Limit Threshold

GND - CS_, zero crossing, ON2 = 5V 2.5

Thermal Shutdown Threshold Hysteresis = 10

C 160

VL Undervoltage Lockout

Threshold

UVLO

Rising edge, hysteresis = 20mV, PWM is

disabled below this voltage

4.1 4.4 V

GATE DRIVERS

DH_ Gate Driver On-Resistance

(Pullup)

V+ = 6V to 20V, DH_, high state 3.7 8 Ω

DH_ Gate Driver On-Resistance

(Pulldown)

DH_, low state 6.2 10 Ω

DL_ Gate Driver On-Resistance

(Pullup)

DL_ , high state 3.4 8 Ω

DL_ Gate Driver On-Resistance

(Pulldown)

DL_, low state 2.0 5 Ω

DH_ Gate Driver Source/Sink

Current

DH_

= 3V, V+ = 6V 0.6 A

DL_ Gate Drive Sink Current V

DL_

= 2.5V 0.9 A

DL_ Gate Drive Source Current V

DL_

= 2.5V 0.5 A

LOGIC CONTROLS

ON_ Logic Input High Voltage 2.05 V

ON2 Logic Input Float Voltage

(Forced-PWM Mode)

2.0V < V

ON1

< VL 1.3 1.7 1.95 V

ON_ Logic Input Low Voltage 0.5 V

ON1 Logic Input Current -1 1 µA

ON2 Logic High Input Current V

ON2

> 2.0V 0 1 3 µA

ON2 Logic Low Input Current V

ON2

< 0.5V, V

ON1

> 2.0V -2 -1 0 µA

FB_ Dual Mode Threshold 50 100 150 mV

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V+ = 15V, C

= 4.7µF, C

REF

= 0.1µF, VL not externally driven unless otherwise noted, T

= 0°C to +85°C, unless

otherwise noted.) (Note 1)

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P23

MAX1761EEE-T

Mfr. #:

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MAX1761EEE-T

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