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General Description

The MAX1709 sets a new standard of space savings for

high-power, step-up DC-DC conversion. It delivers up

to 20W at a fixed (3.3V or 5V) or adjustable (2.5V to

5.5V) output, using an on-chip power MOSFET from a

+0.7V to +5V supply.

Fixed-frequency PWM operation ensures that the

switching noise spectrum is constrained to the 600kHz

fundamental and its harmonics, allowing easy postfilter-

ing for noise reduction. External clock synchronization

capability allows for even tighter noise spectrum con-

trol. Quiescent power consumption is less than 1mW to

extend operating time in battery-powered systems.

Two control inputs (ONA, ONB) allow simple push-on,

push-off control through a single momentary pushbut-

ton switch, as well as conventional on/off logic control.

The MAX1709 also features programmable soft-start

and current limit for design flexibility and optimum per-

formance with batteries.

The MAX1709 is supplied in both a high-power TSSOP

package, which allows a 10A

RMS

switch current and a

4A output, and a narrow SO package, which supplies a

2.4A output with a switch rated at 6A

RMS

. Although the

narrow SO device has a lower RMS switch rating, it has

the same peak switch current rating as the TSSOP

device, and so can supply 4A loads intermittently. If

loads of 2A or less are required, refer to the MAX1708.

________________________Applications

Routers, Servers, Workstations, Card Racks

Local 2.5V to 3.3V or 5V Conversion

Local 3.3V to 5V Conversion

3.6V or 5V RF PAs in Communications Handsets

Features

o On-Chip 10A Power MOSFET

o 5V, 4A Output from a 3.3V Input

o Fixed 3.3V or 5V Output Voltage or

Adjustable (2.5V to 5.5V)

o Input Voltage Range Down to 0.7V

o Low Power Consumption

1mW Quiescent Power

1µA Current in Shutdown Mode

o Low-Noise, Constant Frequency Operation

(600kHz)

o Synchronizable Switching Frequency

(350kHz to 1000kHz)

MAX1709

4A, Low-Noise, High-Frequency,

Step-Up DC-DC Converter

________________________________________________________________

Maxim Integrated Products

ONB

CLK

NCLX

ONA

TOP VIEW

MAX1709

PGND

PGNDLX

218 PGNDLX

209 PGNDNC

1910 PGNDNC

1811 PGNDGND

1712 NCSS/ILM

1613 FBREF

1514 OUTGND

TSSOP-EP*

3.3/5

Pin Configuration

ONA

REF

SS/LIM

CLK

OUTPUT

3.3V, 5V,

OR ADJ

UP TO 4A

OUT

GND

1μH

OFF

INPUT

1V TO 5V

SYNC

INTERNAL

MAX1709

Typical Operating Circuit

19-1724; Rev 2; 4/07

EVALUATION KIT

AVAILABLE

Ordering Informations

PART TEMP RANGE PIN-PACKAGE

MAX1709ESE -40°C to +85°C 16 Narrow SO

MAX1709EUI+ -40°C to +85°C 28 TSSOP-EP*

Indicates lead(Pb)-free/RoHS-compliant package.

Exposed pad.

Summary of content (15 pages)

PAGE 1
9-1724; Rev 2; 4/07 KIT ATION EVALU E L B AVAILA 4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter The MAX1709 sets a new standard of space savings for high-power, step-up DC-DC conversion. It delivers up to 20W at a fixed (3.3V or 5V) or adjustable (2.5V to 5.5V) output, using an on-chip power MOSFET from a +0.7V to +5V supply.
PAGE 2
MAX1709 4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter ABSOLUTE MAXIMUM RATINGS ONA, ONB, OUT, SS/LIM, 3.3/5 to GND ...............-0.3V to +6.0V LX to PGND ...........................................................-0.3V to +6.0V FB, CLK, REF to GND.............................. -0.3V to (VOUT + 0.3V) PGND to GND .......................................................-0.3V to +0.3V Continuous Power Dissipation (TA = +70°C) 16-Pin Narrow SO (derate 16.5mW/°C above +70°C) .....1.
PAGE 3
4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter (VOUT = VCLK = +3.6V, ONA = ONB = FB = GND, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Input High Level CONDITIONS MIN ONA, ONB, 3.3/5, 1.2V < VOUT <5.5 0.8 × VOUT CLK, 2.7 V< VOUT < 5.5V 0.8 × VOUT TYP UNITS V ONA, ONB, CLK, 3.
PAGE 4
MAX1709 4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter ELECTRICAL CHARACTERISTICS (continued) (VOUT = VCLK = +3.6V, ONA = ONB = FB = GND, TA = -40°C to +85°C, unless otherwise noted.) (Note 9) PARAMETER CONDITIONS MIN TYP MAX UNITS ONA, ONB, 3.3/5, 1.2V < VOUT < 5.5V 0.2 × VOUT V CLK, 2.7V < VOUT < 5.5V 0.2 × VOUT Input Low Level (Note 7) ONA, ONB, 3.3/5, 1.2V < VOUT < 5.5V 0.8 × VOUT CLK, VOUT = 5.5V 0.8 × VOUT Input High Level Logic Input Current ONA, ONB, CLK, 3.
PAGE 5
4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter 70 60 50 40 70 VIN = 2.5V 60 50 40 30 30 20 20 10 10 0 86.0 85.5 0.01 0.1 1 10 0.01 0.1 1 LOAD REGULATION (VIN = 3.3V, VOUT = 5V) LINE REGULATION (VOUT = 5V, IOUT = 1A) 0.5 0.6 0.7 0.8 0.9 1.0 NO-LOAD INPUT CURRENT vs. INPUT VOLTAGE 1000 MAX1709 TOC05 0.6 0.4 INPUT VOLTAGE INCREASING INPUT CURRENT (mA) VOUT REGULATION (%) 0.4 OPERATING FREQUENCY (MHz) 0.8 MAX1709 TOC04 0 84.0 10 OUTPUT CURRENT (A) 1 84.5 83.
PAGE 6
Typical Operating Characteristics (continued) (Circuit of Figure 1, TA = +25°C, unless otherwise noted.) SWITCH CURRENT LIMIT vs. TEMPERATURE SWITCH CURRENT LIMIT vs. SS/LIM RESISTANCE MAX1709-12 9 HEAVY SWITCHING WAVEFORM 11.5 MAX1709 TOC10 10 11.0 CURRENT LIMIT (A) 8 CURRENT LIMIT (A) MAX1709 4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter 7 6 5 5V 10.0 VOUT = 3.3V 4A 8.5 100 150 200 250 IOUT = 2A -40 300 IL 2A/div 2A 8.0 50 VOUT 100mV/div 5V 9.5 9.
PAGE 7
4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter PIN TSSOP NARROW SO NAME 1 1 ONA 2–8 2, 3, 4 LX 11, 14 5, 8 GND FUNCTION On-Control Input. When ONA = high OR ONB = low, the device turns on Drain of n-Channel Power Switch. Connect pins 2, 3, and 4 together. Connect external Schottky diode from LX to OUT. Ground. Connect ground inputs together, then connect to PGND. Soft-Start and/or Current-Limit Input.
PAGE 8
MAX1709 4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter KEEP TRACES SHORT AND WIDE 1μH L1 VIN 1V TO 5V D1 ON-OFF CONTROL C1, C2 2 x 150μF ONA ONB LX CLK LX 3.3/5 LX PGND VOUT 5V C6, C7 2x 150μF GND GND MAX1709 SS/LIM R1 C3 PGND PGND REF FB GND OUT C4 0.22μF R2 2Ω C5 0.1μF Figure 1. Standard Operating Circuit Detailed Description The MAX1709 step-up converter offers high efficiency and high integration for high-power applications.
PAGE 9
4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter MAX1709 Table 1. On/Off Logic Control Table 2. Selecting Switching Frequency ONA 0 ONB 0 MAX1709 On 0 1 Off 1 0 On 1 1 On CLK 0 1 External clock (350kHz−1000kHz) MODE Not allowed PWM Synchronized PWM UNDERVOLTAGE LOCKOUT OUT MAX1709 IC POWER PWM CONTROLLER 2.15V EN STARTUP Q OSCILLATOR D SEE FIGURE 3. ONA ONB REF 1.260V EN ON RDY REFERENCE EN CLK FB 3.
PAGE 10
MAX1709 4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter Table 3. Component Selection Guide PRODUCTION INDUCTORS Surface mount CAPACITORS Coilcraft DO3316P-102HC Panasonic EEFUE0J151R Motorola MBRD1035CTL Coiltronics UP2B-1R0 Sanyo 6TPC100M STM-Microelectronics STPS8L30B at a different frequency, scale the inductor value with the inverse of frequency (L1 = 1µH 600kHz / fSYNC).
PAGE 11
4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter MAX1709 ON/OFF ONB VDD I/O ONA I/O Power Dissipation 270k 0.1μF Figure 5. Momentary Pushbutton On-Off Switch VD = forward voltage drop of the Schottky diode at ILIM current VOUT = output voltage D' = (VIN) / (VOUT + VD), assuming switch voltage drop is negligible f = switching frequency L1 = inductor value ILIM = minimum value of switch current limit from Electrical Characteristics or set by RSET/LIM.
PAGE 12
MAX1709 4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter Approximate equations for the MAX1709 internal loss terms are as follows. Values in {} are example values for a 3.3V input, 4V output, 4A design: {1.35W} PD(MAX1709) = PSW + PTRAN + PCAP where: PSW = (1 - D’) x ISW2 x RSW {1.08W} PTRAN = (VOUT + VD) x ISW x tSW x f / 3 {0.18W} PCAP = (CDIO + CDSW + CGSW) x (VOUT + VD)2 f {0.
PAGE 13
4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter TSSOP 4.4mm BODY.EPS ______________________________________________________________________________________ 13 MAX1709 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.
PAGE 14
MAX1709 4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.
PAGE 15
4A, Low-Noise, High-Frequency, Step-Up DC-DC Converter Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) 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.