Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - DC/DC voltage regulator Holder TQFN 36

General Description

The MAX8654 high-efficiency switching regulator delivers

up to 8A of load current at output voltages from 0.6V to

0.85 x V

. The IC operates from 4.5V to 14V, making it

ideal for on-board point-of-load and postregulation appli-

cations, with total output error less than ±1% over load,

line, and temperature ranges.

The MAX8654 is a fixed-frequency PWM mode regulator

with a switching frequency range of 250kHz to 1.2MHz

set by an external resistor or SYNC input. High-frequency

operation allows for an all-ceramic-capacitor solution. A

SYNCOUT output is provided to synchronize a second

regulator switching 180° out-of-phase with the first to

reduce the input ripple current and consequently reduce

the required input capacitance. The high operating fre-

quency minimizes the size of external components.

The on-board low R

DS(ON)

dual-nMOS design keeps

the board cooler at heavy loads while minimizing the

critical inductances, making the layout a much simpler

task with respect to the discrete solutions.

The MAX8654 comes with a high-bandwidth (20MHz)

voltage-error amplifier. The voltage-mode control archi-

tecture and the op-amp voltage-error amplifier permit a

type 3 compensation scheme to be utilized to achieve

maximum loop bandwidth, up to 20% of the switching

frequency. High loop bandwidth achieves fast transient

response resulting in less output capacitance required.

The MAX8654 offers programmable soft-start to accom-

modate different types of output capacitors and reduce

input inrush current. The MAX8654 is available in a 36-

lead TQFN package.

Applications

Features

o Internal 26mΩ R

DS(ON)

MOSFETs

o Guaranteed 8A Output Current

o Adjustable Overcurrent Protection

o 1% Output Accuracy Over Temperature

o Operates from 4.5V to 14V Supply

o Adjustable Output from 0.6V to 0.85 x V

o Soft-Start Reduces Inrush Supply Current

o 250kHz to 1.2MHz Adjustable Switching or SYNC

Input

o Compatible with Ceramic, Polymer, and

Electrolytic Output Capacitors

o SYNCOUT Synchronizes 2nd Regulator 180°

Out-of-Phase

o 36-Pin, Lead-Free, 6mm x 6mm TQFN Package

MAX8654

12V, 8A 1.2MHz

Step-Down Regulator

________________________________________________________________

Maxim Integrated Products

Ordering Information

MAX8654

BST

VDL

INPUT

4.5V TO 14V

OUTPUT

UP TO 8A

PGND

COMP

SYNC

SYNCOUT

PWRGD

GND

ILIM

REFIN

FREQ

Typical Operating Circuit

19-0588; Rev 3; 6/11

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.

Pin Configuration appears at end of data sheet.

EVALUATION KIT

AVAILABLE

PART TEMP RANGE

PIN-

PACKAGE

MAX8654ETX+ -40°C to +85°C 36 TQFN-EP*

POL Power Supplies

Servers

DDR Memory

RAID Power Supplies

Network Power Supplies

Graphic Cards

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

EP = Exposed pad.

Summary of content (17 pages)

PAGE 1
9-0588; Rev 3; 6/11 KIT ATION EVALU E L B A AVAIL 12V, 8A 1.2MHz Step-Down Regulator The MAX8654 high-efficiency switching regulator delivers up to 8A of load current at output voltages from 0.6V to 0.85 x VIN. The IC operates from 4.5V to 14V, making it ideal for on-board point-of-load and postregulation applications, with total output error less than ±1% over load, line, and temperature ranges. The MAX8654 is a fixed-frequency PWM mode regulator with a switching frequency range of 250kHz to 1.
PAGE 2
MAX8654 12V, 8A 1.2MHz Step-Down Regulator ABSOLUTE MAXIMUM RATINGS SYNC, VL, PWRGD to GND...................................-0.3V to +4.5V SYNCOUT, COMP, SS, FB, REFIN, ILIM, FREQ to GND .....................-0.3V to (VVL + 0.3V) VDL to PGND............................................................-0.3V to +6V VP, IN, EN to GND..................................................-0.3V to +16V LX Current (Note 1: -12A to +12A) BST to LX .………………………………………………-0.3V to +6V BST to GND ……………………………………..-0.
PAGE 3
12V, 8A 1.2MHz Step-Down Regulator (VIN = VEN = VVP = 12V, VVDL = 5V, VVL = 3.3V, VSYNC = 0V, VFB = 0.5V, TA = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX 0.594 0.6 0.606 UNITS ERROR AMPLIFIER FB Regulation Voltage VP = VIN = 4.
PAGE 4
MAX8654 12V, 8A 1.2MHz Step-Down Regulator ELECTRICAL CHARACTERISTICS (continued) (VIN = VEN = VVP = 12V, VVDL = 5V, VVL = 3.3V, VSYNC = 0V, VFB = 0.5V, TA = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS 1.20 MHz SYNC SYNC Capture Range SYNC Pulse Width SYNC Input Threshold SYNC Input Current 0.25 tLO 100 tHI 100 VIL 0.4 ns VIH VSYNC = 0V or 3.6V 1.6 V IIL 10 nA IIH 7 µA SYNCOUT SYNCOUT Frequency Range 0.
PAGE 5
12V, 8A 1.2MHz Step-Down Regulator VOUT = 3.3V 40 VOUT = 3.3V VOUT = 1.8V 40 50 20 20 20 10 10 0.1 OUTPUT CURRENT (A) REFERENCE VOLTAGE vs. TEMPERATURE SWITCHING FREQUENCY vs. INPUT VOLTAGE 0.600 0.595 1000 800 600 400 1400 200 -25 0 25 50 75 100 7 9 11 13 TEMPERATURE (°C) INPUT VOLTAGE (V) LOAD REGULATION SHUTDOWN SUPPLY CURRENT vs. INPUT VOLTAGE -0.10 -0.15 VOUT = 1.8V -0.20 -0.25 -0.
PAGE 6
Typical Operating Characteristics (continued) (Typical values are: VIN = VVP = 12V, VOUT = 3.3V, RFREQ = 100kΩ, and TA = +25°C, circuit of Figure 1.) EXPOSED PAD TEMPERATURE vs. LOAD CURRENT 80 TA = +85°C, 200LFM 60 TA = +25°C, NO AIR FLOW 40 20 TA = +25°C, 200LFM 0 TA = -40°C, NO AIR FLOW -20 ILOAD = 0A 0.1 MAX8654 toc11 100 0.2 OUTPUT VOLTAGE CHANGE (%) TA = +85°C, NO AIR FLOW 120 EXPOSED PAD TEMPERATURE (°C) LINE REGULATION MAX8654 toc10 140 ILOAD = 3A 0 -0.1 -0.2 ILOAD = 6A -0.
PAGE 7
12V, 8A 1.2MHz Step-Down Regulator SOFT-START TIME vs. CSS LOAD TRANSIENT MAX8654 toc16 MAX8654 toc17 10 9 AC-COUPLED IOUT 2A/div 8 SOFT-START TIME (ms) 100mV/div VOUT 7 6 5 4 3 2 0A 1 0 20µs/div 0 0.025 0.050 0.075 0.100 0.125 0.150 CSS (µF) STARTUP INTO A 0.5Ω LOAD MAX8654 toc18 10V/div VEN 0V 2A/div IIN 0 2V/div VOUT 0V VPWRGD 2V/div 0V 200µs/div SOFT-START WITH REFIN INTO A 0.
PAGE 8
MAX8654 12V, 8A 1.2MHz Step-Down Regulator Pin Description PIN NAME 1, 2, 3, 34, 35, 36 PGND 4 VDL 5–8 IN Power-Supply Input. Input supply range is from 4.5V to 14V. Bypass with two 10µF and a 0.1µF ceramic capacitors to PGND. See Figure 1. 9 VP Input of the Internal 5V LDO Regulator. Connect to IN if a 5V supply is not available. Connect to an external 5V supply to disable the internal 5V regulator. 10 VL 3.3V LDO for Internal Chip Supply. Bypass with a 1µF ceramic capacitor to GND.
PAGE 9
12V, 8A 1.2MHz Step-Down Regulator VL EN SHUTDOWN CONTROL VL REG UVLO CIRCUITRY MAX8654 VDL REG VP CURRENT-LIMIT COMPARATOR BIAS GENERATOR ILIM ILIM THRESHOLD LX BST VOLTAGE REFERENCE SS BST CAPACITOR CHARGING SWITCH SOFT-START ERROR AMPLIFIER LX CONTROL LOGIC THERMAL SHUTDOWN REFIN IN LX PWM COMPARATOR PGND VDL FB COMP 1VP-P COMP LOW DETECTOR FREQ SYNC SYNCOUT OSCILLATOR FB SHDN PWRGD 90% REFIN REFIN 0.
PAGE 10
MAX8654 12V, 8A 1.2MHz Step-Down Regulator INPUT 4.5V TO 14V IN 10µF 10µF 0.1µF BST VP 0.22µF OUTPUT 3.3V, 8A 1.0µH LX MAX8654 2 x 22µF VL VL PGND 4.99kΩ VDL 1µF 1nF 100Ω 2.2µF FB FREQ 3.57kΩ 1.1kΩ ILIM 10nF REFIN 100kΩ 75kΩ 22pF COMP SS SYNC 0.022µF VL SYNCOUT IN 20kΩ EN GND PWRGD Figure 1. Typical Application Circuit, 3.3V, 8A, 500kHz Detailed Description The MAX8654 high-efficiency, voltage-mode switching regulator is capable of delivering up to 8A of output current.
PAGE 11
12V, 8A 1.2MHz Step-Down Regulator Soft-Start and REFIN The MAX8654 utilizes an adjustable soft-start function to limit inrush current during startup. An 8µA (typ) current source charges an external capacitor connected to SS to increase the capacitor voltage in a controlled manner. The soft-start time is adjusted by the value of the external capacitor from SS to GND.
PAGE 12
MAX8654 12V, 8A 1.2MHz Step-Down Regulator Undervoltage Lockout (UVLO) Shutdown Mode The UVLO circuitry inhibits switching when VIN or VVDL is below 4.20V (typ) or VVL is below 3V. Once these voltages are above the thresholds, UVLO clears and the soft-start function activates; 100mV of hysteresis is built in for glitch immunity. Drive EN to GND to shut down the IC and reduce quiescent current to 10µA (typ). During shutdown, the outputs of the MAX8654 are high impedance.
PAGE 13
12V, 8A 1.2MHz Step-Down Regulator Input Capacitor Selection The input capacitor reduces the current peaks drawn from the input power supply and reduces switching noise in the IC.
PAGE 14
MAX8654 12V, 8A 1.2MHz Step-Down Regulator output voltage divided by the rated output current. ESR is the total equivalent series resistance (ESR) of the output filtering capacitor. If there is more than one output capacitor of the same type in parallel, the value of the ESR in the above equation is equal to that of the ESR of a single output capacitor divided by the total number of output capacitors. The high-switching frequency range of the MAX8654 allows the use of ceramic-output capacitors.
PAGE 15
12V, 8A 1.2MHz Step-Down Regulator 2) Place capacitors on VVP, VIN, VVL, VVDL, and SS as close as possible to the IC and its corresponding pin using direct traces. Keep power ground plane (connected to PGND) and signal ground plane (connected to GND) separate. 3) Keep the high-current paths as short and wide as possible. Keep the path of switching current short and minimize the loop area formed by LX, the output capacitors, and the input capacitors.
PAGE 16
MAX8654 12V, 8A 1.2MHz Step-Down Regulator Chip Information Pin Configuration LX LX LX LX LX LX BST SYNC SYNCOUT 20 19 PROCESS: BiCMOS 21 22 23 24 25 26 27 TOP VIEW Package Information LX LX 28 18 PWRGD 29 17 FB N.C. EN GND N.C. 30 16 31 15 PGND PGND 34 12 35 11 COMP SS REFIN GND FREQ ILIM PGND 36 10 VL 32 14 PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
PAGE 17
12V, 8A 1.2MHz Step-Down Regulator REVISION NUMBER REVISION DATE 0 8/06 Initial release 1 4/08 Updated Ordering Information, Pin Description, and Package Information. 2 7/09 Updated Current Limit and Input Capacitor Selection sections. 3 6/11 Updated Absolute Maximum Ratings and Electrical Characteristics. DESCRIPTION PAGES CHANGED — 1, 8, 14, 16 11, 13 2, 3 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product.