Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - DC/DC voltage regulator Converter/amplifier TDFN 14 EP

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

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

General Description

The MAX8625A PWM step-up/down regulator is intend-

ed to power digital logic, hard disk drives, motors, and

other loads in portable, battery-powered devices such

as PDAs, cell phones, digital still cameras (DSCs), and

MP3 players. The MAX8625A provides either a fixed

3.3V or adjustable output voltage (1.25V to 4V) at up to

0.8A from a 2.5V to 5.5V input. The MAX8625A utilizes

a 2A peak current limit.

Maxim’s proprietary H-bridge topology provides a

seamless transition through all operating modes without

the glitches commonly seen with other devices. Four

internal MOSFETs (two switches and two synchronous

rectifiers) with internal compensation minimize external

components. A SKIP input selects a low-noise, fixed-

frequency PWM mode, or a high-efficiency skip mode

where the converter automatically switches to PFM

mode under light loads for best light-load efficiency.

The internal oscillator operates at 1MHz to allow for a

small external inductor and capacitors.

The MAX8625A features current-limit circuitry that shuts

down the IC in the event of an output overload. In addi-

tion, soft-start circuitry reduces inrush current during

startup. The IC also features True Shutdown

, which

disconnects the output from the input when the IC is

disabled. The MAX8625A is available in a 3mm x 3mm,

14-pin TDFN package.

Applications

PDAs and Smartphones

DSCs and Camcorders

MP3 Players and Cellular Phones

Battery-Powered Hard Disk Drive (HDD)

Features

♦ Four Internal MOSFET True H-Bridge Buck/Boost

♦ Glitch-Free, Buck-Boost Transitions

♦ Minimal Output Ripple Variation on Transitions

♦ Up to 92% Efficiency

♦ 37µA (typ) Quiescent Current in Skip Mode

♦ 2.5V to 5.5V Input Range

♦ Fixed 3.3V or Adjustable Output

♦ 1µA (max) Logic-Controlled Shutdown

♦ True Shutdown

♦ Output Overload Protection

♦ Internal Compensation

♦ Internal Soft-Start

♦ 1MHz Switching Frequency

♦ Thermal-Overload Protection

♦ Small 3mm x 3mm, 14-Pin TDFN Package

MAX8625A

High-Efficiency, Seamless Transition,

Step-Up/Down DC-DC Converter

________________________________________________________________

Maxim Integrated Products

Ordering Information

MAX8625A

SKIP

GND

OUT

LX1

LX2

INPUT

2.7V TO 5.5V

OUTPUT

3.3V

OFF

PWM

SKIP

REF

Typical Operating Circuit

19-1006; Rev 4; 4/09

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

EVALUATION KIT

AVAILABLE

Note: The device is specified over the -40°C to +85°C extended

temperature range.

Denotes a lead(Pb)-free/RoHS-compliant package.

EP = Exposed pad.

PART

PIN-

PACKAGE

TOP MARK

MAX8625AETD+

14 TDFN-EP**

ABQ

MAX8625A

TDFN-EP

TOP VIEW

245

13 11 10

GND

OUT

LX1

LX2

INLX1

GNDLX2

OUTSKIP

REFFB

EP = EXPOSED PAD.

Pin Configuration

Summary of content (16 pages)

PAGE 1
9-1006; Rev 4; 4/09 KIT ATION EVALU E L B AVAILA High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter The MAX8625A PWM step-up/down regulator is intended to power digital logic, hard disk drives, motors, and other loads in portable, battery-powered devices such as PDAs, cell phones, digital still cameras (DSCs), and MP3 players. The MAX8625A provides either a fixed 3.3V or adjustable output voltage (1.25V to 4V) at up to 0.8A from a 2.5V to 5.5V input.
PAGE 2
MAX8625A High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter ABSOLUTE MAXIMUM RATINGS IN, OUT, SKIP, ON to GND ......................................-0.3V to +6V REF, FB to GND.............................................-0.3V to (IN + 0.3V) LX2, LX1 (Note 1).........................................................±1.5ARMS Continuous Power Dissipation (TA = +70°C) Single-Layer Board (derate 18.5mW/°C above TA = +70°C) ...................................................
PAGE 3
High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter (VIN = 3.6V, ON = SKIP = IN, FB = GND, VOUT = 3.3V, LX_ unconnected, CREF = C5 = 0.1µF to GND, Figure 4. TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) (Note 2) PARAMETER FB Dual-Mode Threshold SYMBOL CONDITIONS MIN TYP MAX UNITS 75 100 125 mV VFB = 1.3V, TA = +25°C 0.001 0.1 VFB = 1.3V, TA = +85°C 0.01 VFBDM FB Leakage Current IFB ON, SKIP Input High Voltage VIH 2.5V < VIN < 5.
PAGE 4
Typical Operating Characteristics (VIN = 3.6V, SKIP = GND, TA = +25°C, Figure 4, unless otherwise noted.) 60 50 VOUT = 3.3V VIN = 2.7V, 3.0V, 3.3V, 3.6V, 4.2V, 5.0V 30 20 10 90 EFFICIENCY (%) 70 85 100mA 80 500mA 75 1 10 60 50 VOUT = 2.8V VIN = 2.7V, 3.0V, 3.3V, 3.6V, 4.2V, 5.0V 40 20 10 0 2.0 1000 100 70 30 VOUT = 3.3V LOAD CURRENT = 100mA, 300mA, 500mA 65 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 0.1 1 10 1000 100 LOAD CURRENT (mA) INPUT VOLTAGE (V) LOAD CURRENT (mA) EFFICIENCY vs.
PAGE 5
High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter (VIN = 3.6V, SKIP = GND, TA = +25°C, Figure 4, unless otherwise noted.) SWITCHING WAVEFORMS VIN = 3V, LOAD = 500mA, VOUT = 3.3V MAXIMUM LOAD CURRENT vs. INPUT VOLTAGE MAX8625A toc11 MAX8625A toc10 1000 MAXIMUM LOAD CURRENT (mA) 900 800 VOUT = 3.3V 700 VOUT 50mV/div (AC-COUPLED) VLX1 2V/div 600 500 VLX2 2V/div 400 300 ILX 500mA/div 200 100 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 1µs/div 6.
PAGE 6
Typical Operating Characteristics (continued) (VIN = 3.6V, SKIP = GND, TA = +25°C, Figure 4, unless otherwise noted.) STARTUP WAVEFORMS (FIGURE 3) VIN = 3.6V, LOAD = 30Ω, VOUT = 1.5V STARTUP WAVEFORMS VIN = 3.6V, LOAD = 5Ω, VOUT = 3.288V MAX8625A toc17 MAX8625A toc16 ON 2V/div ON 2V/div VOUT 20mV/div VOUT 1V/div ILX 500mA/div ILX 500mA/div IBATT 100mA/div IBATT 500mA/div 2ms/div 2ms/div LOAD TRANSIENT VOUT = 3.3V LINE TRANSIENT VOUT = 3.3V, LOAD = 5.
PAGE 7
High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter (VIN = 3.6V, SKIP = GND, TA = +25°C, Figure 4, unless otherwise noted.) REFERENCE vs. TEMPERATURE NO LOAD MINIMUM STARTUP VOLTAGE vs. TEMPERATURE 1.27 2.42 REFERENCE (V) MINIMUM STARTUP VOLTAGE (V) 2.44 MAX8625A toc23 VOUT = 3.3V, NO LOAD 2.46 1.28 MAX8625A toc22 2.48 2.40 2.38 2.36 1.26 1.25 1.24 2.34 2.32 VOUT = 3.3V VIN = 3.0V, 3.6V, 4.2V, 5.0V 1.23 2.30 2.28 1.
PAGE 8
High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter MAX8625A Pin Description PIN NAME FUNCTION 1, 2 LX1 Inductor Connection 1. Connect the inductor between LX1 and LX2. Both LX1 pins must be connected together externally. LX1 is internally connected to GND during shutdown. 3, 4 LX2 Inductor Connection 2. Connect the inductor between LX1 and LX2. Both LX2 pins must be connected together externally. LX2 is internally connected to GND during shutdown. 5 ON Enable Input.
PAGE 9
High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter IN MAX8625A LX1 LX2 P1 P2 OUT N2 N1 UVLO P1 CURRENT SENSE PWM/PFM CONTROL ON SKIP OSCILLATOR 1.25V REF Gm REFERENCE 125mV GND MAX8625A FB Figure 1. Simplified Block Diagram times. This reduces the ripple and removes any mode transitions from boost-only or buck-only to hybrid modes as seen in competing H-bridge converters.
PAGE 10
MAX8625A High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter FAULT TIMEOUT (ASYNCHRONOUS FROM ANYWHERE) OFF ON = 0 P1, P2 = OFF N1, N2 = ON IQ = 0µA ERROR ON = 1 P1, P2 = OFF N1, N2 = ON ON = 0 (ASYNCHRONOUS FROM ANYWHERE) TPUP REFOK = 0 OR UVLO = 0 (ASYNCHRONOUS FROM ANYWHERE) POWER-UP ON = 1, P1, P2 = OFF, N1, N2 = ON, OSC = ON AND REF = ON IF UVLO OK TRUN PHASE 2 SLOW CHARGE/ DISCHARGE OSC = ON P1, P2 = ON N1, N2 = OFF T1-2 PHASE 1 FAST-CHARGE OSC = ON P1, N2 = ON P2, N1 = OFF T
PAGE 11
High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter Forced-PWM Mode Drive SKIP high to operate the MAX8625A in forcedPWM mode. In this mode, the IC operates at a constant 1MHz switching frequency with no pulse skipping. This scheme is desirable in noise-sensitive applications because the output ripple is minimized and has a predictable noise spectrum. Forced PWM consumes higher supply current at light loads due to constant switching.
PAGE 12
MAX8625A High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter Applications Information 22µF ceramic capacitors at the input. Select two 22µF ceramic output capacitors. For best stability over a wide temperature range, use X5R or better dielectric. Selecting the Output Voltage The MAX8625A output is nominally fixed at 3.3V. Connect FB to GND to select the internally fixed-output voltage.
PAGE 13
High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter MAX8625A L 3.3µH 1 INPUT 2.7V TO 5.5V 13 14 C1, C2 22µF 2 LX1 LX1 3 4 LX2 LX2 IN IN 9 OUT 10 OUT OUTPUT 3.3V C3, C4 22µF U1 MODE SELECTION INPUT MAX8625A 6 FB 7 SKIP ON 5 OFF 8 ON REF C5 0.1µF 11 GND 12 GND Figure 4. Typical Application Circuit (Fixed 3.3V Output) Package Information Chip Information PROCESS: BiCMOS For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PAGE 14
MAX8625A High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PAGE 15
High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter COMMON DIMENSIONS PACKAGE VARIATIONS MIN. MAX. PKG. CODE N D2 E2 e JEDEC SPEC b A 0.70 0.80 T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF D 2.90 3.10 T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF E 2.90 3.10 T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF A1 0.00 0.05 T1033-1 10 1.50±0.10 2.30±0.10 0.
PAGE 16
MAX8625A High-Efficiency, Seamless Transition, Step-Up/Down DC-DC Converter Revision History REVISION NUMBER REVISION DATE 0 3/08 Initial release — 1 5/08 Added PCB Layout and Routing section 12 2 10/08 Updated Electrical Characteristics, Skip Mode and Soft-Start sections 3 12/08 Corrected P1 and P2 symbols in Figure 1 DESCRIPTION PAGES CHANGED 2, 11 9 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product.