Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - DC/DC voltage regulator Boost TDFN 14 EP

19-3995; Rev 0; 3/06

MAX8627

Low V

BATT

, 20µA IQ, 1MHz Synchronous

Boost Converter with True Shutdown

EVALUATION KIT AVAILABLE

For pricing, delivery, and ordering information, please contact Maxim Direct

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

General Description

The MAX8627 step-up converter is a high-efficiency,

low-quiescent current, synchronous boost converter

with True Shutdown™ and inrush current limiting. The

MAX8627 generates any boosted output voltage from

3V to 5V from either a 2-cell NiMH/NiCd or a single-cell

Li+/Li polymer battery.

Quiescent current is only 20µA (typ), and at light loads

the converter pulses only as needed for best efficiency.

At higher loads, PWM mode maintains fixed 1MHz

operation for lowest noise and ripple.

The MAX8627 includes an internal soft-start to limit

inrush current to a maximum of 500mA. Additional fea-

tures include True Shutdown, internal compensation,

and adjustable current limit. The MAX8627 is available

in a tiny 3mm x 3mm TDFN package and is ideal for

use in handheld devices such as DSCs, PDAs, and

smartphones.

Applications

DSC Motors and Backup Power

Microprocessor/DSP Core Power

Cellphones, PDAs, MP3 Players

Portable Handheld Devices

Features

o 1MHz PWM Switching Frequency

o True Shutdown Output

o Up to 95% Efficiency

o 1.0A Guaranteed Output Current

o Soft-Start Eliminates Inrush Current

o 20µA (typ) Quiescent Current

o 0.1µA Logic-Controlled Shutdown

o Internal Synchronous Rectifier

o Internal Compensation

o Adjustable Current Limit

o Low-Noise Antiringing Feature

o Tiny 14-Pin, 3mm x 3mm, TDFN Package

MAX8627ETD+

TDFN 3mm x 3mm

TOP VIEW

245

13 11 10

ILIM

BATT

OUTSGND

AGNDON

LXPOUT

Pin Configuration

Ordering Information

Note: The device operates in the -40°C to +85°C extended oper-

ating temperature range.

EP = Exposed pad.

Denotes lead-free package.

PART

PIN-

PACKAGE

PKG

CODE

TOP

MARK

MAX8627ETD+

14 TDFN-EP*

3mm x 3mm

T1433-2 AAQ

True Shutdown is a trademark of Maxim Integrated Products, Inc.

MAX8627

BATT

ILIM

GND

POUT

OUTS

INPUT BATTERY

2.5V TO 4.2V

OUTPUT

3V TO 5V

UP TO 1A

OFF

4, 5

AGND

PGND

10, 11

6,7

8, 9

Typical Operating Circuit

Visit www.maximintegrated.com/products/patents for

product patent marking information.

Summary of content (14 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown General Description Features The MAX8627 step-up converter is a high-efficiency, low-quiescent current, synchronous boost converter with True Shutdown™ and inrush current limiting. The MAX8627 generates any boosted output voltage from 3V to 5V from either a 2-cell NiMH/NiCd or a single-cell Li+/Li polymer battery.
PAGE 2
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (TA = +70°C) 14-Pin TDFN 3mm x 3mm (derate 18.2mW/°C above +70°C) .............................1454mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) ...................
PAGE 3
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown ELECTRICAL CHARACTERISTICS (continued) (VOUTS = VPOUT = 5V, VON = VBATT = 3.6V, VILIM = GND, TA = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) PARAMETER CONDITIONS MIN p-Channel Turn-Off Current TYP MAX 10 POUT Leakage Current VLX = 0V, VPOUT = VBATT = 5.5V LX Leakage Current VLX = 0V and VPOUT = 5.5V or VLX = 5.5V and VOUTS = VPOUT = 0V Soft-Start Interval Output current = 0.
PAGE 4
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown Typical Operating Characteristics (Circuit of Figure 1, VOUTS = VPOUT = 5V, VON = VBATT = 3.6V, TA = +25°C, unless otherwise noted.) 40 VBATT = 2.4V 40 30 20 10 10 VBATT = 1.8V 1 10 100 MAX8627 toc03 VPOUT = 3.3V 2.0 1.5 1.0 VPOUT = 5V 0 0.01 1000 2.5 0.5 0 0.1 0.1 1 10 100 1.0 1000 2.0 3.0 4.0 5.0 LOAD CURRENT (mA) LOAD CURRENT (mA) INPUT VOLTAGE (V) OUTPUT VOLTAGE vs.
PAGE 5
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown Typical Operating Characteristics (continued) (Circuit of Figure 1, VOUTS = VPOUT = 5V, VON = VBATT = 3.6V, TA = +25°C, unless otherwise noted.) SOFT-START TIME vs. INPUT VOLTAGE 3.5 3.0 2.5 2.0 1.5 1.0 MAX8627 toc11 4.0 4.0 3.5 PEAK INDUCTOR CURRENT (A) 4.5 SOFT-START TIME (ms) PEAK INDUCTOR CURRENT vs. VILIM MAX8627 toc10 5.0 3.0 2.5 2.0 1.5 1.0 0.5 0.5 0 0 0.5 1.5 2.5 3.5 4.5 5.5 0.45 INPUT VOLTAGE (V) 0.
PAGE 6
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown Typical Operating Characteristics (continued) (Circuit of Figure 1, VOUTS = VPOUT = 5V, VON = VBATT = 3.6V, TA = +25°C, unless otherwise noted.) STARTUP WAVEFORMS WITH 100mA LOAD STARTUP WAVEFORMS WITH NO LOAD MAX8627 toc17 MAX8627 toc16 VON VON 2V/div 0 2V/div 0 2V/div 2V/div VPOUT VPOUT 0 ILX ILX 500mV/div 500mV/div 400µs/div 400µs/div SWITCHING FREQUENCY vs.
PAGE 7
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown Pin Description PIN NAME 1 GND 2 FB Voltage Feedback Input. Connect FB to the center of an external feedback network between OUTS and GND (see the Setting the Output Voltage section). FB regulates to 1.015V (typ). 3 ON Active-High Enable Input. Connect ON to BATT or logic high for normal operation. Connect ON to GND or logic low for True Shutdown mode. 4, 5 BATT Supply Voltage Input.
PAGE 8
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown L1 1µH INPUT: 1.5V TO 5.5V C1 22µF C2 22µF LX BATT OUTPUT: 3V TO 5V, UP TO 1A ON OFF POUT ON AGND C3 22µF MAX8627 R1 C4 22µF OUTS R3 FB ILIM GND PG R2 R4 Figure 1. Typical Applications Circuit with an Adjustable Output Voltage and Adjustable Current Limit ON 2.
PAGE 9
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown Detailed Description The MAX8627 is a current-mode step-up converter that uses a fixed-frequency PWM architecture with True Shutdown. Consuming only 20µA of quiescent current, the MAX8627 is highly efficient, with an internal switch and synchronous rectifier. Shutdown reduces the quiescent current to less than 1µA. Low quiescent current and low noise make this device ideal for powering portable equipment.
PAGE 10
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown The term “positioning” refers to setting the output voltage to a level that is dependent on load current (see Figure 3). At minimum load, the output voltage is set to a slightly higher than nominal level. At full load, the output voltage is slightly lower than the nominal level. With voltage positioning, the total voltage deviation during a transient is significantly improved over traditional highgain control loops.
PAGE 11
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown incremented by 230mA. If after 13 increments, the output is still not in regulation, the MAX8627 latches off, assuming a short-circuit overload condition exists on the output. To clear the latched condition, cycle ON. which sets peak-to-peak inductor current at 1/2 the DC inductor current: L= Fault Protection 2 x VBATT x D x (1− D) IOUT(MAX) x fSW The MAX8627 has a fault-overload protection.
PAGE 12
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown Setting the Current Limit PC Board Layout and Routing ILIM sets the current limit when the output reaches regulation. It is different from the startup current limit used during soft-start to control inrush current. For the maximum current limit of 3.5A, connect ILIM to GND. To set the current limit (ILIM) lower than 3.5A, connect ILIM to a resistor-divider from POUT to GND as shown in Figure 1.
PAGE 13
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
PAGE 14
MAX8627 Low VBATT, 20µA IQ, 1MHz Synchronous Boost Converter with True Shutdown Package Information (continued) For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.