Datasheet

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General Description

The MAX8664 dual-output PWM controller is a low-cost,

high-performance solution for systems requiring dual

power supplies. It provides two individual outputs that

operate 180° out-of-phase to minimize input current

ripple, and therefore, capacitance requirements. Built-in

drivers are capable of driving external MOSFETs to

deliver up to 25A output current from each channel.

The MAX8664 operates from a 4.5V to 28V input volt-

age source and generates output voltages from 0.6V

up to 90% of the input voltage on each channel. Total

output regulation error is less than ±0.8% over load,

line, and temperature.

The MAX8664 operates with a constant switching fre-

quency adjustable from 100kHz to 1MHz. Built-in boost

diodes reduce external component count. Digital soft-

start eliminates input inrush current during startup. The

second output has an optional external REFIN2, facili-

tating tracking supply applications. Each output is

capable of sourcing and sinking current, making the

device a great solution for DDR applications.

The MAX8664 employs Maxim’s proprietary peak volt-

age-mode control architecture that provides superior

transient response during either load or line transients.

This architecture is easily stabilized using two resistors

and one capacitor for any type of output capacitors. Fast

transient response requires less output capacitance,

consequently reducing total system cost. The MAX8664B

latches off both controllers during a fault condition, while

the MAX8664A allows one controller to continue to func-

tion when there is a fault in the other controller.

Applications

Desktop and Notebook PCs

Graphic Cards

ASIC/CPU/DSP Power Supplies

Set-Top Box Power Supply

Printer Power Supply

Network Power Supply

POL Power Supply

Features

o ±0.8% Output Accuracy Over Load and Line

o Operates from a Single 4.5V to 28V Supply

o Simple Compensation for Any Type of Output

Capacitor

o Internal 6.5V Regulator for Gate Drive

o Integrated Boost Diodes

o Adjustable Output from 0.6V to 0.9 x V

o Digital Soft-Start Reduces Inrush Current

o 100kHz to 1MHz Adjustable Switching

o 180° Out-of-Phase Operation Reduces Input

Ripple Current

o Overcurrent and Overvoltage Protection

o External Reference Input for Second Controller

o Prebiased Startup Operation

MAX8664

Low-Cost, Dual-Output, Step-Down

Controller with Fast Transient Response

________________________________________________________________

Maxim Integrated Products

Ordering Information

19-0796; Rev 0; 4/07

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.

Note: This device operates over the -40°C to +85°C operating

temperature range.

Denotes lead-free package.

Pin Configuration appears at end of data sheet.

PART

PIN-

PACKAGE

PKG

CODE

FAULT

ACTION

MAX8664AEEP+

20 QSOP E20-1

Independent

MAX8664BEEP+

20 QSOP E20-1 Joint

DH1

BST1

DL1

BST2

FB2

FB1

LX1

PGND

DH2

LX2

DL2

GND

IN1

OUT2

IN2

OSC/EN12

ILIM2

PWRGD

REFIN2

ILIM1

MAX8664

OUT1

Typical Operating Circuit

EVALUATION KIT

AVAILABLE

Summary of content (26 pages)

PAGE 1
9-0796; Rev 0; 4/07 KIT ATION EVALU E L B AVAILA Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response The MAX8664 dual-output PWM controller is a low-cost, high-performance solution for systems requiring dual power supplies. It provides two individual outputs that operate 180° out-of-phase to minimize input current ripple, and therefore, capacitance requirements. Built-in drivers are capable of driving external MOSFETs to deliver up to 25A output current from each channel.
PAGE 2
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response ABSOLUTE MAXIMUM RATINGS IN to GND ...........................................................…-0.3V to +30V VL to GND...................................................................-0.3 to +8V IN, BST_ to VL ........................................................-0.3V to +30V VCC, FB_, PWRGD to GND.......................................-0.3V to +6V VL to VCC ................................................................
PAGE 3
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response (VIN = 12V, ROSC/EN12 to GND = 56.1kΩ, REFIN2 = VCC, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS PROTECTION FEATURES Overvoltage Protection (OVP) Threshold VFB1 rising 0.75 VREFIN2 = VVCC, VFB_ rising, MAX8664B Power-Good (PWRGD) Threshold VFB1 rising, MAX8664A 0.
PAGE 4
Typical Operating Characteristics (Circuit of Figure 2, 600kHz, VIN = 12V, VOUT1 = 2.5V, VOUT2 = 1.8V, TA = +25°C, unless otherwise noted.) EFFICIENCY (%) 70 60 VOUT = 2.5V 40 30 VOUT1 = 2.5V 80 70 60 VOUT1 = 1.8V 50 40 30 VOUT = 1.8V 20 20 NO LOAD ON THE OTHER REGULATOR 10 0 0.1 10 1 0.1 2.53 2.52 2.50 2.49 2.50 2.49 2.48 IOUT2 = 0A 2.46 2.45 0 2 MAX8664 toc06 VOUT2 150 100mV/div 100 5A 2.5A 2.5A 50 2.46 0 2.
PAGE 5
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response MAX8664 Typical Operating Characteristics (continued) (Circuit of Figure 2, 600kHz, VIN = 12V, VOUT1 = 2.5V, VOUT2 = 1.8V, TA = +25°C, unless otherwise noted.
PAGE 6
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response MAX8664 Pin Description PIN NAME 1 DH1 High-Side MOSFET Driver Output for Controller 1. Connect DH1 to the gate of the high-side MOSFET. DH1 is low in shutdown and UVLO. 2 LX1 External Inductor Connection for Controller 1. Connect LX1 to the switching node of the MOSFETs and inductor. Make sure LX1 is close to the source of the high-side MOSFET(s) to form a Kelvin connection for high-side current sensing.
PAGE 7
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response PIN NAME FUNCTION VCC Internal Analog Supply. VCC regulates to 1.5V below VVL. Connect a 1µF ceramic capacitor from VCC to GND. When using a 4.5V to 5.5V supply, connect a 10Ω resistor from VCC to IN. VCC is used to power the IC’s internal circuitry. 18 PWRGD Open-Drain Power-Good Output. PWRGD is high impedance when controllers 1 and 2 (using the internal reference) are in regulation.
PAGE 8
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response VCC CURRENT-LIMIT COMPARATOR UVLO CIRCUITRY BIAS GENERATOR ILIM1 BST1 50μA BST CAP CHARGING SWITCH LX1 VOLTAGE REFERENCE THERMAL EN SHUTDOWN REF REF DH1 EN SOFT-START 1 SHUTDOWN CONTROL LOGIC SHUTDOWN 1 LX1 CONTROL LOGIC SHUTDOWN 2 DL1 CLOCK 1 PWM COMPARATOR 1 FB1 SHUTDOWN 1 PGND CURRENT-LIMIT COMPARATOR VL ILIM2 0.
PAGE 9
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response The MAX8664 dual-output PWM controller is a low-cost solution for dual power-supply systems. It provides two individual outputs that operate 180° out-of-phase to minimize input capacitance requirements. Built-in drivers are capable of driving external MOSFETs to deliver up to 25A of current from each output. The MAX8664 operates from a 4.5V to a 5.5V or a 7.2V to 28V input and generates output voltages from 0.
PAGE 10
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response The threshold that trips overcurrent protection is set by a resistor connected from ILIM_ to the drain of the highside MOSFET(s). ILIM_ sinks 50µA (typ) through this resistor. When the drain-source voltage exceeds the voltage drop across this resistor during the high-side MOSFET(s) on-time, an overcurrent fault is triggered. To prevent glitches from falsely tripping the overcurrent protection, connect a filter capacitor (0.
PAGE 11
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response MAX8664 C19 0.01μF INPUT 10.8V TO 13.2V ILIM1 FB1 LX1 VCC C13 0.22μF REFIN2 BST1 N2 VL C14 4.7μF C5 1500pF R3 51.1kΩ DH1 C18 1μF C4 1000μF N1 IN C17 1μF C1 10μF C20 10μF R1 2.7kΩ L1 1μH R37 3Ω C6 47μF R4 3.92kΩ C7 47μF R5 1.15kΩ C8 47μF OUT1 2.5V/8A C23 0.1μF DL1 GND MAX8664 C25 680pF PGND C16 0.01μF VCC POWER-GOOD TO SYSTEM R9 10kΩ R2 3.01kΩ PWRGD OSC/EN12 ON OFF C3 10μF N3 DH2 R10 39.
PAGE 12
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response Table 2. Component List for Figure 2 DESIGNATION QTY DESCRIPTION C25, C26 2 680pF, 50V C0G ceramic capacitors (0603) C27 1 0.47µF ±10%, 16V ceramic capacitor (0603) L1, L2 2 1µH inductors TOKO FDV0630-1R0M N1–N4 4 n-channel MOSFETs (8-pin SO) International Rectifier IRF7821 N9 1 n-channel MOSFET (SOT23) Central 2N7002 R1 1 2.74kΩ ±1% resistor (0603) R2 1 301kΩ ±1% resistor (0603) R3, R6 2 51.
PAGE 13
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response MAX8664 C1 0.01μF VCC LX1 GND MAX8664 N3 DL1 N4 R4 3.57kΩ OUT1 1.8V/20A C9 470μF R5 3Ω BST1 C13 4.7μF R3 10kΩ C8 0.015μF L1 0.56μH C7 0.22μF REFIN2 VL C12 1000pF N2 R2 24.3kΩ C6 1μF R7 1kΩ N1 DH1 IN C5 1μF OUT1 R6 1kΩ C4 1000μF ILIM1 FB1 INPUT 10V TO 14V C3 10μF C2 10μF R1 3.16kΩ C10 470μF C11 10μF C14 2200pF PGND VCC C15 0.01μF R9 10kΩ POWER-GOOD TO SYSTEM PWRGD R10 44.2kΩ R8 2.
PAGE 14
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response Table 3. Component List for Figure 3 DESIGNATION QTY L2 1 0.47µH, 1.2mΩ inductor TOKO FDV0603-R47M 10µF, 16V X5R ceramic capacitors N1, N2 2 1 1000µF/16V aluminum electrolytic capacitor Rubycon 16MBZ1000M n-channel MOSFETs IRLR7821 (D-Pak) N3, N4 2 n-channel MOSFETs IRLR3907Z (D-Pak) C5 1 1µF, 16V X5R ceramic capacitor N5 1 n-channel MOSFET IRF7807Z (8-pin SO) C6 1 1µF, 10V X5R ceramic capacitor 1 2 0.
PAGE 15
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response MAX8664 C1 0.01μF ILIM1 FB1 5V IN C5 1μF 0.6V EXT REF VCC R7 10kΩ MAX8664 REFIN2 C14 0.01μF R8 10kΩ POWER-GOOD TO SYSTEM Q1 CMST3904 N2 IRF7821 DL1 C9 47μF R6 2Ω C15 0.01μF GND R11 3.32kΩ R10 10kΩ C10 47μF OUT1 1.8V/10A C11 0.1μF INPUT 2.97V TO 3.63V ILIM2 VCC R4 3.16kΩ C13 2200pF PGND N5 2N7002 R9 47kΩ C7 0.22μF BST1 R3 10kΩ L1 0.2μH LX1 VCC C12 1μF C8 820pF R2 17.
PAGE 16
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response Table 4. Component List for Figure 4 DESIGNATION QTY L1, L2 2 0.2µH, 2.4mΩ inductors TOKO FDV0603-R20M N1–N4 4 n-channel MOSFETs IRF7821 (8-pin SO) N5 1 n-channel MOSFET 2N7002 (SOT23) Q1 1 Transistor, bipolar, npn Central CMST3904 R1, R11 2 3.32kΩ ±1% resistors (0402 or 0603) 820pF,10V X7R ceramic capacitors R2, R14 2 17.
PAGE 17
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response MAX8664 C1 0.01μF C2 10μF R1 2.87kΩ C3 10μF C4 OPEN ILIM1 FB1 N1 INPUT 7.2V TO 20V C5 1μF LX1 C6 1μF R3 10kΩ R5 2Ω DL1 REFIN2 VL C12 4.7μF OUT1 1.5V/10A C9 470μF N2 MAX8664 R4 5.36kΩ L1 1.43μH C7 0.22μF BST1 VCC C8 4700pF R2 40.2kΩ DH1 IN C10 10μF C11 1000pF PGND C13 0.01μF GND C14 10μF ILIM2 R6 2.26kΩ VCC C15 10μF N3 DH2 POWER-GOOD TO SYSTEM R7 10kΩ C16 0.
PAGE 18
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response Table 5. Component List for Figure 5 DESIGNATION QTY DESCRIPTION C1, C13 2 0.01µF, 10V X7R ceramic capacitors C2, C3, C14, C15 4 10µF, 25V X5R ceramic capacitors C5 1 1µF, 25V X5R ceramic capacitor C6 1 C7, C16 C8, C17 DESIGNATION QTY DESCRIPTION L1, L2 2 1.43µH, 4.52mΩ inductors Panasonic ETQP3H1E4BFA N1–N4 4 n-channel MOSFETs IRF7821 (8-pin SOs) 1µF, 10V X5R ceramic capacitor N5 1 2 0.
PAGE 19
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response MAX8664 VOUT1 CHIP ENABLE REFIN2 VOUT1 MAX8664 VOUT2 ON OSC/EN12 OFF PWRGD CHIP ENABLE Figure 6b. Ratiometric Tracking Startup and Shutdown Waveforms VCC CHIP ENABLE EXTERNAL REF PWRGD REFIN2 VOUT1 MAX8664 VOUT2 ON PWRGD OSC/EN12 OFF CHIP ENABLE Figure 6c.
PAGE 20
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response VCC EXTERNAL REF CHIP ENABLE OUT2 ENABLE REFIN2 ON OFF VOUT1 OUT2 ENABLE MAX8664 VOUT2 OSC/EN12 ON PWRGD OFF CHIP ENABLE Figure 6d. Sequencing Startup and Shutdown Waveforms with System Enable 2 Signal Design Procedure Setting the Switching Frequency Connect a resistor from OSC/EN12 to GND to set the switching frequency between 100kHz and 1000kHz.
PAGE 21
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response VRIPPLE(ESR) = IP−P × ESR VRIPPLE(ESL) = VRIPPLE(C) = VIN × ESL L + ESL IP−P 8 × COUT × fS output voltage instantly changes by ESR x ΔILOAD. Before the controller can respond, the output voltage deviates further depending on the inductor and output capacitor values. After a short period of time (see the Typical Operating Characteristics ), the controller responds by regulating the output voltage back to its nominal state.
PAGE 22
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response To set the no-load output voltage (VOUT), calculate the value of R3 as follows: Finally, calculate the value of Cr as follows: VOUT (VIN − VOUT ) VIN Cr = R1× fS × | (VFB _ RIPPLE − VOUT _ RIPPLE ) | ⎛ ⎞ ⎛ R1 × R2 ⎞ VFB R3 = ⎜ ⎟ ⎟⎜ ⎝ VOUT − VFB ⎠ ⎝ R1 + R2 ⎠ where VFB is the feedback regulation voltage (0.6V when using the internal reference or VREFIN2 for external reference).
PAGE 23
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response PHSCC(MAX) = VOUT × I2LOAD(MAX) × RDS(ON) VIN(MIN) Use RDS(ON) at TJ(MAX): PHSSW(MAX) = VIN(MAX) × ILOAD(MAX) × QGD × fS IGATE where IGATE is the average DH driver output-current capability determined by: IGATE ≅ 0.
PAGE 24
MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response Input Capacitor The input filter capacitors reduce peak currents drawn from the power source and reduce noise and voltage ripple on the input caused by the circuit’s switching. The input capacitors must meet the ripple current requirement (IRMS) imposed by the switching currents.
PAGE 25
Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response Chip Information PROCESS: BiCMOS TOP VIEW DH1 1 20 ILIM1 LX1 2 19 FB1 18 PWRGD BST1 3 DL1 4 MAX8664 17 VCC 16 GND VL 5 PGND 6 15 IN 14 OSC/EN12 DL2 7 13 REFIN2 BST2 8 LX2 9 12 FB2 DH2 10 11 ILIM2 QSOP ______________________________________________________________________________________ 25 MAX8664 Pin Configuration
PAGE 26
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.) QSOP.EPS MAX8664 Low-Cost, Dual-Output, Step-Down Controller with Fast Transient Response Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.