Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - voltage regulators - DC DC switch controllers uMAX 10

AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

UCSP is a trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and

ordering information, please contact Maxim Direct

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

EVALUATION KIT AVAILABLE

General Description

The MAX668/MAX669 constant-frequency, pulse-width-

modulating (PWM), current-mode DC-DC controllers are

designed for a wide range of DC-DC conversion applica-

tions including step-up, SEPIC, flyback, and isolated-

output configurations. Power levels of 20W or more can

be controlled with conversion efficiencies of over 90%.

The 1.8V to 28V input voltage range supports a wide

range of battery and AC-powered inputs. An advanced

BiCMOS design features low operating current (220µA),

adjustable operating frequency (100kHz to 500kHz),

soft-start, and a SYNC input allowing the MAX668/

MAX669 oscillator to be locked to an external clock.

DC-DC conversion efficiency is optimized with a low

100mV current-sense voltage as well as with Maxim’s

proprietary Idle Mode™ control scheme. The controller

operates in PWM mode at medium and heavy loads for

lowest noise and optimum efficiency, then pulses only as

needed (with reduced inductor current) to reduce oper-

ating current and maximize efficiency under light loads.

A logic-level shutdown input is also included, reducing

supply current to 3.5µA.

The MAX669, optimized for low input voltages with a

guaranteed start-up voltage of 1.8V, requires boot-

strapped operation (IC powered from boosted output). It

supports output voltages up to 28V. The MAX668 oper-

ates with inputs as low as 3V and can be connected in

either a bootstrapped or non-bootstrapped (IC powered

from input supply or other source) configuration. When

not bootstrapped, it has no restriction on output voltage.

Both ICs are available in an extremely compact 10-pin

µMAX package.

Features

o 1.8V Minimum Start-Up Voltage (MAX669)

o Wide Input Voltage Range (1.8V to 28V)

o Tiny 10-Pin µMAX Package

o Current-Mode PWM and Idle Mode™ Operation

o Efficiency over 90%

o Adjustable 100kHz to 500kHz Oscillator or

SYNC Input

o 220µA Quiescent Current

o Logic-Level Shutdown

o Soft-Start

Applications

Cellular Telephones

Telecom Hardware

LANs and Network Systems

POS Systems

1.8V to 28V Input, PWM Step-Up

Controllers in µMAX

19-4778; Rev 2; 1/12

Idle Mode is a trademark of Maxim Integrated Products.

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

T = Tape and reel.

/V Denotes an automotive qualified part.

Note: Devices are also available in a lead(Pb)-free/RoHS-com-

pliant package. Specify lead-free by adding “+” to the part

number when ordering.

Ordering Information

Typical Operating Circuit

MAX669

FREQ

CS+

SYNC/

SHDN

PGND

GND

EXT

LDO

REF

OUT

= 28V

= 1.8V to 28V

SYNC/SHDN

EXT

PGNDREF

GND

FREQ

LDO

MAX668

MAX669

µMAX

TOP VIEW

CS+FB

Pin Configuration

PART TEMP RANGE PIN - PA C K A G E

MAX668EUB -40°C to +85°C 10 µMAX

MAX669EUB -40°C to +85°C 10 µMAX

MAX669EUB/V+T -40°C to +85°C 10 µMAX

MAX668/MAX669

Summary of content (18 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX LE AVAILAB General Description The MAX668/MAX669 constant-frequency, pulse-widthmodulating (PWM), current-mode DC-DC controllers are designed for a wide range of DC-DC conversion applications including step-up, SEPIC, flyback, and isolatedoutput configurations. Power levels of 20W or more can be controlled with conversion efficiencies of over 90%. The 1.
PAGE 2
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX ABSOLUTE MAXIMUM RATINGS VCC to GND ..........................................................-0.3V to +30V PGND to GND....................................................................±0.3V SYNC/SHDN to GND .............................................-0.3V to +30V EXT, REF to GND.....................................-0.3V to (VLDO + 0.3V) LDO, FREQ, FB, CS+ to GND ................................ -0.3V to +6V LDO Output Current.............
PAGE 3
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX ELECTRICAL CHARACTERISTICS (continued) (VCC = VLDO = +5V, ROSC = 200kΩ, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 4
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX ELECTRICAL CHARACTERISTICS (continued) (VCC = VLDO = +5V, ROSC = 200kΩ, TA = -40°C to +85°C, unless otherwise noted.) PARAMETER CONDITIONS MIN MAX UNITS 1.22 1.28 V -10 mV 1.2 V REF Output Voltage No load, CREF = 0.22µF REF Load Regulation REF load = 0 to 50µA REF Undervoltage Lockout Threshold Rising edge, 1% hysteresis 1.
PAGE 5
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX Typical Operating Characteristics (Circuits of Figures 2, 3, 4, and 5; TA = +25°C; unless otherwise noted.) MAX668 EFFICIENCY vs. LOAD CURRENT (VOUT = 12V) 90 VIN = 2.7V 75 VIN = 2V 70 VIN = 5V NON-BOOTSTRAPPED FIGURE 4 R4 = 200kΩ 75 BOOTSTRAPPED FIGURE 3 R4 = 200kΩ 100 1000 10 100 1000 LOAD CURRENT (mA) LOAD CURRENT (mA) MAX669 MINIMUM START-UP VOLTAGE vs. LOAD CURRENT SUPPLY CURRENT vs. SUPPLY VOLTAGE 2.0 VOUT = 12V 1.5 1.
PAGE 6
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX Typical Operating Characteristics (continued) (Circuits of Figures 2, 3, 4, and 5; TA = +25°C; unless otherwise noted.) REFERENCE VOLTAGE vs. TEMPERATURE SWITCHING FREQUENCY vs. ROSC 1.247 1.246 1.245 1.244 1.243 1.242 1.241 450 400 350 300 250 200 150 100 50 VCC = 5V 1.240 VCC = 5V 0 -40 -20 0 20 40 60 80 100 0 100 200 300 ROSC (kΩ) SWITCHING FREQUENCY vs. TEMPERATURE EXT RISE/FALL TIME vs.
PAGE 7
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX Typical Operating Characteristics (continued) (Circuits of Figures 2, 3, 4, and 5; TA = +25°C; unless otherwise noted.) ENTERING SHUTDOWN MAX668 toc14 MAX668 toc15 EXITING SHUTDOWN 0V SHUTDOWN VOLTAGE 5V/div OUTPUT VOLTAGE 5V/div INDUCTOR CURRENT 2A/div 0V 0A 0V OUTPUT VOLTAGE 5V/div 200µs/div 500µs/div MAX668, VIN = 5V, VOUT = 12V, LOAD = 1.0A, LOW VOLTAGE, NON-BOOTSTRAPPED MAX668, VIN = 5V, VOUT = 12V, LOAD = 1.
PAGE 8
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX Pin Description PIN NAME 1 LDO 5V On-Chip Regulator Output. This regulator powers all internal circuitry including the EXT gate driver. Bypass LDO to GND with a 1µF or greater ceramic capacitor. 2 FREQ Oscillator Frequency Set Input. A resistor from FREQ to GND sets the oscillator from 100kHz (ROSC = 500kΩ) to 500kHz (ROSC = 100kΩ). fOSC = 5 x 1010 / ROSC. ROSC is still required if an external clock is used at SYNC/SHDN.
PAGE 9
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX PWM Controller Bootstrapped/Non-Bootstrapped Operation The heart of the MAX668/MAX669 current-mode PWM controller is a BiCMOS multi-input comparator that simultaneously processes the output-error signal, the current-sense signal, and a slope-compensation ramp (Figure 1). The main PWM comparator is direct summing, lacking a traditional error amplifier and its associated phase shift.
PAGE 10
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX VIN = 1.8V to 12V C1 1 LDO C4 EXT MAX669 9 CS+ VOUT = 12V @ 0.5A 8 N1 D1 6 V+ C5 C8 C6 R1 C2 R2 7 PGND 10 SYNC/ SHDN 4 REF C3 L1 2 FB GND FREQ 5 3 C7 R3 R4 Figure 2. MAX669 High-Voltage Bootstrapped Configuration VIN = 1.8V to 5V 1 LDO C2 1µF EXT MAX669 9 2 CS+ L1 4.7µH FREQ VOUT = 5V @ 1A 8 N1 6 R1 0.02Ω VCC 10 SYNC/ SHDN 4 REF C3 0.
PAGE 11
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX VIN = 3V to 12V C1 68µF 20V 1 LDO C4 1µF EXT MAX668 9 C2 0.1µF 2 VOUT = 12V @ 1A 8 N1 D1 MBRS340T3 FDS6680 6 R1 0.02Ω VCC PGND 10 SYNC/ SHDN 4 REF C3 0.22µF CS+ L1 4.7µH FB GND FREQ C5 68µF 20V C6 68µF 20V 7 C8 0.1µF R2 218k 1% 5 R3 24.9k 1% C7 220pF 3 R4 100k 1% Figure 4. MAX668 High-Voltage Non-Bootstrapped Configuration VIN = 2.7V to 5.
PAGE 12
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX Table 2. Bootstrapped and Non-Bootstrapped Configurations FIGURE USE WITH: INPUT VOLTAGE RANGE* (V) OUTPUT VOLTAGE RANGE (V) COMMENTS High-Voltage, Bootstrapped Figure 2 MAX669 1.8 to 28 3V to 28 Connect VCC to VOUT. Provides maximum external FET gate drive for low-voltage (Input <3V) to highvoltage (output >5.5V) boost circuits. VOUT cannot exceed 28V. Low-Voltage, Bootstrapped Figure 3 MAX669 1.8 to 5.5 2.7 to 5.
PAGE 13
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX SYNC/SHDN and FREQ Inputs The SYNC/SHDN pin provides both external-clock synchronization (if desired) and shutdown control. When SYNC/SHDN is low, all IC functions are shut down. A logic high at SYNC/SHDN selects operation at a frequency set by ROSC, connected from FREQ to GND. The relationship between fOSC and ROSC is: ROSC = 5 x 1010 / fOSC So a 500kHz operating frequency, for example, is set with ROSC = 100kΩ.
PAGE 14
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX given output ripple. An inductance value larger than LIDEAL may also be used, but output-filter capacitance must be increased by the same proportion that L has to LIDEAL. See the Capacitor Selection section for more information on determining output filter values. Due the MAX668/MAX669’s high switching frequencies, inductors with a ferrite core or equivalent are recommended.
PAGE 15
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX not be adequate for low output voltage ripple. Since output ripple in boost DC-DC designs is dominated by capacitor equivalent series resistance (ESR), a capacitance value 2 or 3 times larger than COUT(MIN) is typically needed. Low-ESR types must be used.
PAGE 16
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX larger or smaller than the output voltage, such as when converting four NiMH, NiCd, or Alkaline cells to a 5V output. The SEPIC configuration is often a good choice for combined step-up/step-down applications. The N-channel MOSFET (Q1) must be selected to withstand a drain-to-source voltage (VDS) greater than the sum of the input and output voltages. The coupling capacitor (C2) must be a low-ESR type to achieve maximum efficiency.
PAGE 17
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX MBR0540L 47µH VIN = +5V +5V @ 400mA 220µF 10V T1 1:2 1µF MBR0540L 220µF 10V +5V RETURN VCC LDO IRF7603 EXT SHDN CS+ MAX668 FB 0.1Ω PGND REF FREQ GND 0.22µF 100k R2 301k 1% 510Ω MOC211 10k 0.1µF 0.068µF 610Ω TLV431 R3 100k 1% T1: COILTRONICS CTX03-14232 Figure 7. Isolated +5V to +5V at 400mA Power Supply Package Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.
PAGE 18
MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX Revision History REVISION NUMBER REVISION DATE 2 1/12 DESCRIPTION Added automotive qualified part and updated lead-free and leaded soldering temperatures PAGES CHANGED 1, 2 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.