Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - DC/DC voltage regulator Converter, Boost QSOP 16

________________General Description

The MAX1672 integrates a step-up DC-DC converter with a

linear regulator to provide step-up/down voltage conver-

sion. This device provides a constant output voltage for

inputs that vary above and below the output voltage. It has

a 1.8V to 11V input range and a preset 3.3V or 5V output.

The output can also be set from 1.25V to 5.5V using two

resistors. Typical efficiency is 85%.

The MAX1672’s step-up/linear-regulator configuration per-

mits the use of a single, physically smaller inductor than

can be used with competing SEPIC and flyback configura-

tions. Switch current is also selectable, permitting the use

of smaller inductors in low-current applications. The linear

regulator also acts as a filter to reduce output ripple voltage.

The MAX1672 has a low 85µA quiescent supply current, which

is further reduced to 0.1µA in logic-controlled shutdown. The

output voltage is disconnected from the input in shutdown.

The MAX1672 also has a PGI/PGO low-battery detector.

The MAX1672 comes in a 16-pin QSOP package (same size

as a standard 8-pin SO). For a larger device that delivers more

output current, refer to the MAX710/MAX711. The preassem-

bled MAX1672 evaluation kit is available to speed designs.

________________________Applications

Single-Cell, Lithium-Powered 2-Cell to 4-Cell AA Alkaline

Portable Devices Hand-Held Equipment

3.3V and Other Low-Voltage Battery-Powered Devices

Systems with AC Input Adapters

Digital Cameras

____________________________Features

♦ Step-Up/Down Voltage Conversion

♦ 1.8V to 11V Input Range

♦ 3.3V/5V or Adjustable Output Voltage Range

♦ Output Current:

300mA at 5V (V

≥ 2.5V)

150mA at 5V (V

≥ 1.8V)

♦ Smaller Inductor than SEPIC and Flybacks

♦ Load Disconnects from Input in Shutdown

♦ Supply Current from Battery:

85µA (No-Load)

0.1µA (Shutdown)

♦ PGI/PGO Low-Battery Comparator

♦ 16-Pin QSOP Package

(Same Footprint as 8-pin SO)

♦ No External FETs Required

♦ Thermal and Short-Circuit Protection

MAX1672

Step-Up/Down DC-DC Converter

in QSOP Package

________________________________________________________________ Maxim Integrated Products 1

19-1307; Rev 2; 11/02

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

Ordering Information

*Dice are tested at T

= +25°C.

LX LX

PGND

GND

REF

OUT

TOP VIEW

MAX1672

QSOP

PGND

ONA

ILIM

PGO

PGI

3/5

ONB

Pin Configuration

MAX1672

ONA

PGI

ONB

OFF

PGND GND

3.3V/5V

OUTPUT

INPUT

1.8V TO 11V

LOW-BATTERY

DETECTOR

OUTPUT

OUT

PG0

REF

OFF

3/5

ILIM

0.8A

3.3V

0.5A

Typical Operating Circuit

PART

MAX1672C/D

MAX1672EEE -40°C to +85°C

0°C to +70°C

TEMP RANGE PIN-PACKAGE

Dice*

16 QSOP

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

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

Summary of content (11 pages)

PAGE 1
9-1307; Rev 2; 11/02 ANUAL N KIT M EET IO T A U EVAL TA SH WS DA FOLLO Step-Up/Down DC-DC Converter in QSOP Package ____________________________Features The MAX1672 integrates a step-up DC-DC converter with a linear regulator to provide step-up/down voltage conversion. This device provides a constant output voltage for inputs that vary above and below the output voltage. It has a 1.8V to 11V input range and a preset 3.3V or 5V output. The output can also be set from 1.25V to 5.5V using two resistors.
PAGE 2
MAX1672 Step-Up/Down DC-DC Converter in QSOP Package ABSOLUTE MAXIMUM RATINGS IN, PS, LX, OUT, PGO to GND ......................... -0.3V to +11.5V ILIM, ONA, ONB, FB, 3/5, REF, PGI to GND......................................-0.3V to (VPS + 0.3V) PGND to GND .......................................................-0.3V to +0.3V OUT Short Circuit to GND ..........................................Continuous Output Current ..................................................................
PAGE 3
Step-Up/Down DC-DC Converter in QSOP Package (VPS = 6V, CREF = 0.1µF, COUT = 4.7µF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS Thermal Shutdown Threshold 150 °C Thermal Shutdown Hysteresis 20 °C PGI/PGO COMPARATOR PGI Input Bias Current VPGI = 1.3V 1 Hysteresis 50 nA 30 PGI Threshold Voltage TA = 0°C to +85°C 1.21 TA = -40°C to +85°C 1.19 mV 1.29 1.25 1.31 V PGO Output Leakage VPGO = 11V 0.
PAGE 4
Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) ILIM = PS (0.8A) ILIM = GND (0.5A) 100 300 ILIM = PS (0.8A) 200 ILIM = GND (0.5A) 100 MAXIMUM RECOMMENDED OUTPUT CURRENT VOUT = 5V 300 200 VOUT = 3.3V 100 VOUT = 5V TA = +25°C TA = +85°C 0 0 0 1 2 3 4 VOUT = 3.
PAGE 5
Step-Up/Down DC-DC Converter in QSOP Package TURN-OFF DELAY STARTUP DELAY OUTPUT RIPPLE (HEAVY LOAD) MAX1672-15 MAX1672-14 MAX1672-13 A A A B B B 10µs/div A: VOUT = 5V (20mV/div, AC COUPLED) B: IL1 (500mA/div) (VIN = 2.7V, IOUT = 250mA) 50µs/div A: VOUT = (2V/div) B: ONB (2V/div) (VIN = 2.7V, RLOAD = 50Ω) 200µs/div A: VOUT = (2V/div) B: ONB (2V/div) (VIN = 2.
PAGE 6
MAX1672 Step-Up/Down DC-DC Converter in QSOP Package LX REF ∆TON FIXED TOFF GENERATOR ERROR AMP 2 DRV N FB OFF ILIM 100mV IN CURRENT-LIMIT COMPARATOR INPUT MONITOR PGND OUT MAX1672 PS REF ONA REFERENCE GENERATOR ONB REF + OFFSET PS REF ERROR AMP 1 P FB2 OUT FB FB1 FB 70mV 3/5 PGO REF N N PGI Figure 1.
PAGE 7
Step-Up/Down DC-DC Converter in QSOP Package The MAX1672 integrates a step-up, switch-mode DCDC converter with a linear regulator to provide stepup/down voltage conversion. The step-up converter contains an N-channel power MOSFET switch, while the linear regulator contains a P-channel MOSFET pass element (Figure 1). The step-up converter and the linear regulator share the same precision voltage reference. The MAX1672’s input range is from +1.8V to +11V, and the regulated output is internally preset to +3.
PAGE 8
MAX1672 Step-Up/Down DC-DC Converter in QSOP Package __________________Design Procedure Output Voltage Selection For fixed output voltages of 3.3V or 5V, connect 3/5 to PS or GND and connect FB to GND (Table 2). Alternatively, adjust the output voltage from 1.25V to 5.5V by connecting two resistors, R1 and R2 (Figure 2), which form a voltage divider between OUT and FB. Choose resistor values as follows: R1 = R2[(VOUT / VREF) -1] where VREF = 1.25V.
PAGE 9
Step-Up/Down DC-DC Converter in QSOP Package 3/5 ILIM INDUCTOR VALUE (µH) 0 (5V) 0 (0.5A) 10 to 22 0 (5V) 1 (0.8A) 10 1 (3.3V) 0 (0.5A) 10 1 (3.3V) 1 (0.8A) 4.7 to 10 MAX1672 Table 3. Suggested Inductor Values Table 4. Suggested Components INDUCTORS L1 10µH Sumida CD43-100 (1.04A, 0.182Ω) CD54-100 (1.44A, 0.100Ω) CDRH73-100 (1.68A, 0.072Ω) Coilcraft DT1608C-103 (0.7A, 0.
PAGE 10
MAX1672 Step-Up/Down DC-DC Converter in QSOP Package __________Applications Information Using a Single, Pushbutton On/Off Switch A single pushbutton switch can be used to turn the MAX1672 on and off. As shown in Figure 3, ONA is pulled low and ONB is pulled high when the part is off. When the momentary switch is pressed, ONB is pulled low and the regulator turns on. The switch should be on long enough for the µC to exit reset.
PAGE 11
Step-Up/Down DC-DC Converter in QSOP Package QSOP EPS 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.