Rainbow Electronics MAX1672 User Manual

________________General Description

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. Typical efficiency is 85%.

The MAX1672’s step-up/linear-regulator configuration per­mits the use of a single, physically smaller inductor than
can be used with competing SEPIC and flyback configura­tions. 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 preassem­bled 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 (VIN≥ 2.5V)
150mA at 5V (VIN≥ 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

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone].
For small orders, phone [phone] ext. 3468.

MAX1672

Step-Up/Down DC-DC Converter

in QSOP Package

________________________________________________________________

Maxim Integrated Products

1

19-1307; Rev 0a; 11/97

EVALUATION KIT

AVAILABLE

______________Ordering Information

*

Dice are tested at TA= +25°C.

16
15
14
13
12
11
10

9

1
2
3
4
5
6
7
8

LX LX

PGND
GND
REF
IN
PS
FB
OUT

TOP VIEW

MAX1672

QSOP

PGND

ONA

ILIM

PGO

PGI

3/5

ONB

__________________Pin Configuration

MAX1672

IN

ONA

PGI

ONB

OFF

ON

PGND GND

PS

3.3V/5V
OUTPUT

INPUT

1.8V TO 11V

LOW-BATTERY
DETECTOR
OUTPUT

OUT

PG0

FB

REF

LX

OFF

3/5
ILIM

5V

0.8A

ON

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

MAX1672

Step-Up/Down DC-DC Converter
in QSOP Package

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VPS= 6V, C

REF

= 0.1µF, C

OUT

= 4.7µF, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

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 (V

PS

+ 0.3V)

PGND to GND .......................................................-0.3V to +0.3V

OUT Short Circuit to GND..........................................Continuous

Output Current..................................................................350mA

Continuous Power Dissipation (T

A

= +70°C)

16-Pin QSOP (derate above +70°C by 8.3mW/°C).......667mW

Operating Temperature Range ......................... -40°C to +85°C

Junction Temperature ....................................................+150°C

Storage Temperature Range ........................... -65°C to +160°C

Lead Temperature (soldering, 10sec)............................ +300°C

VPS= 5.5V

V

OUT

= 0V, ONA = GND, ONB = PS

VPS= 2.7V, I

OUT

= 50mA

VPS= 5.5V, I

OUT

= 50mA

ILIM = GND

VLX= 11V, ONA = GND, ONB = PS

VPS= 2.7V, ILX= 50mA

I

REF

= 0mA

VPS= 5.5V, ILX= 50mA

VIN= GND to 11V

ONA = GND, ONB = PS, current measured into PS pin

ONA = PS or ONB = GND, current measured into PS pin,
I

OUT

= 0mA

VIN= 2V, 3/5 = GND, FB = GND, I

OUT

= 10mA to 150mA

VFB= 1.3V

VIN= 3V to 5V, 3/5 = GND, I

OUT

= 100mA

Hysteresis = 15mV typical

CONDITIONS

A0.35 0.7 1.4Output PFET Current Limit

µA0.1 1Output PFET Leakage Current

Ω

2.3 4.6

1.2 2.4

Output PFET Resistance

0.3 0.5 0.7

0.35 0.5 0.65

µA0.1 1LX Leakage Current

Ω

0.9 2.0

LX On-Resistance

0.6 1.3

µA3 6IN Input Current

nA1 50FB Input Current

mV70FB Dual-Mode Trip Threshold

4.8 5.2

V0.9

V1.8 11.0Input Voltage

Startup Voltage

1.21 1.25 1.29

V1.21 1.25 1.29Reference Voltage

µA0.1 1Shutdown Quiescent Current

µA85 125Quiescent Current

4.75 5.00 5.25

V1.25 5.5

Output Voltage Adjustment
Range

%/mA0.003Output Load Regulation

%/V0.15Output Line Regulation

UNITSMIN TYP MAXPARAMETER

V

3.17 3.43

3.13 3.30 3.47

Output Voltage

FB = GND,
I

OUT

= 0mA to

150mA

TA= 0°C to +85°C
TA= -40°C to +85°C
TA= 0°C to +85°C
TA= -40°C to +85°C

V

1.20 1.30

FB Voltage

TA= 0°C to +85°C
TA= -40°C to +85°C

ILIM = PS

A

0.5 0.8 1.1

LX Current Limit

0.6 0.8 1.0

TA= 0°C to +85°C
TA= -40°C to +85°C
TA= 0°C to +85°C
TA= -40°C to +85°C

3/5 = PS

OUT = FB

3/5 = GND

MAX1672

Step-Up/Down DC-DC Converter

in QSOP Package

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VPS= 6V, C

REF

= 0.1µF, C

OUT

= 4.7µF, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

Note 1: Specifications to -40°C are guaranteed by design.

ONA, ONB, 3/5; ILIM

TA= 0°C to +85°C

V

PGO

= 11V

I

PGO

= 2mA, V

PGI

= 1.2V

CONDITIONS

mV30Hysteresis

°C20

°C150Thermal Shutdown Threshold

Thermal Shutdown Hysteresis

V0.4Input Low Voltage

1.21 1.29

µA0.1 1

PGO Output Leakage

V0.1 0.4

PGO Output Low Voltage

UNITSMIN TYP MAXPARAMETER

ONA, ONB, 3/5; ILIM

V1.6Input High Voltage

__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

100

50

0.1 1 10 100 1000

EFFICIENCY vs. OUTPUT CURRENT

(V

OUT

= 5V)

60

MAX1672-01

OUTPUT CURRENT (mA)

EFFICIENCY (%)

70

80

90

VIN = 5V

VIN = 3.6V

VIN = 1.8V

VIN = 0.9V

VIN = 2.7V

100

50

0.1 1 10 100 1000

EFFICIENCY vs. OUTPUT CURRENT

(V

OUT

= 3.3V)

60

MAX1672-02

OUTPUT CURRENT (mA)

EFFICIENCY (%)

70

80

90

VIN = 3.3V

VIN = 1.8V

VIN = 0.9V

VIN = 2.7V

50

60

70

80

90

100

0 4 52 31 6 7 8 9 10

EFFICIENCY vs. INPUT VOLTAGE

(I

OUT

= 10mA)

MAX1672-03

INPUT VOLTAGE (V)

EFFICIENCY (%)

V

OUT

= 3.3V

V

OUT

= 5V

V

PGI

= 1.3V nA1 50PGI Input Bias Current

ONA, ONB, 3/5, ILIM

nA1 100Input Bias Current

TA= -40°C to +85°C

V

1.19 1.25 1.31

PGI Threshold Voltage

PGI/PGO COMPARATOR

LOGIC AND CONTROL INPUTS

MAX1672

Step-Up/Down DC-DC Converter
in QSOP Package

4 _______________________________________________________________________________________

_____________________________Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)

0

100

200

300

400

0 21 3 4

MAXIMUM OUTPUT CURRENT vs.

INPUT VOLTAGE (V

OUT

= 5V)

MAX1672-04

INPUT VOLTAGE (V)

MAXIMUM OUTPUT CURRENT (mA)

MAXIMUM RECOMMENDED
OUTPUT CURRENT

ILIM = GND (0.5A)

ILIM = PS (0.8A)

0

100

200

300

400

0 21 3 4

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE (V

OUT

= 3.3V)

MAX1672-05

INPUT VOLTAGE (V)

MAXIMUM OUTPUT CURRENT (mA)

MAXIMUM RECOMMENDED
OUTPUT CURRENT

ILIM = GND (0.5A)

ILIM = PS (0.8A)

0

100

200

300

400

4 5 7 8 9 116 10 12

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE

(POWER DISSIPATION LIMIT)

MAX1672-06

INPUT VOLTAGE (V)

MAXIMUM OUTPUT CURRENT (mA)

MAXIMUM RECOMMENDED
OUTPUT CURRENT

V

OUT

= 5V

V

OUT

= 3.3V

TA = +25°C
T

A

= +85°C

V

OUT

= 3.3V

V

OUT

= 5V

MAXIMUM RECOMMENDED INPUT VOLTAGE

1000

10

0 1 2 3 4 5 6 7 8 9 10 11

NO-LOAD BATTERY CURRENT

vs. INPUT VOLTAGE

MAX1672-07

INPUT VOLTAGE (V)

SUPPLY CURRENT (µA)

100

V

OUT

= 5V

V

OUT

= 3.3V

A

B

2ms/div

LINE-TRANSIENT RESPONSE

MAX1672-10

A: V

OUT

= 5V (100mV/div, AC COUPLED)

B: V

IN

= 2V TO 4V (I

OUT

= 100mA)

1

0.01
0 1 2 3 4 5 6 7 8 9 10 11

SHUTDOWN CURRENT

vs. INPUT VOLTAGE

MAX1672-08

INPUT VOLTAGE (V)

SUPPLY CURRENT (µA)

0.1

70

10

0.01 1 10 1000.1 1000

LINEAR REGULATOR POWER-SUPPLY

REJECTION RATIO vs. FREQUENCY

20

MAX1672-09

FREQUENCY (kHz)

PSRR (dB)

30

40

60

50

A

B

2ms/div

LOAD-TRANSIENT RESPONSE

MAX1672-11

A: V

OUT

= 5V (50mV/div, AC COUPLED)

B: I

OUT

= 10mA TO 100mA (VIN = 2V)

A

B

10µs/div

OUTPUT RIPPLE (MEDIUM LOAD)

MAX1672-12

A: V

OUT

= 5V (20mV/div, AC COUPLED)

B: I

L1

(500mA /div) (VIN = 2.7V, I

OUT

= 80mA)