Rainbow Electronics MAX1730 User Manual

General Description

The MAX1730 regulated step-down charge pump gen­erates up to 50mA at fixed output voltages of 1.8V or

1.9V from an input voltage in the 2.7V to 5.5V range.
Specifically designed to provide high-efficiency logic
supplies in applications that demand a compact
design, the MAX1730 employs fractional conversion
techniques to provide efficiency exceeding that of a lin­ear regulator.

The MAX1730 operates at up to 2MHz, permitting the
use of small 0.22µF flying capacitors while maintaining
low 75µA quiescent supply current. Proprietary soft­start circuitry prevents excessive current from being
drawn from the supply during startup, making the
MAX1730 compatible with higher impedance sources
such as alkaline and lithium-ion cells.

The MAX1730 is available in a space-saving 10-pin
µMAX package that is only 1.09mm high and occupies
one-half the area of an 8-pin SO.

Applications

Low-Voltage Logic Supplies

Wireless Handsets

PDAs

PC Cards

Hand-Held Instruments

Features

♦ > 85% Peak Efficiency

♦ 50mA Guaranteed Output Current

♦ Dual-Mode 1.8V or 1.9V Output

♦ ±3% Output Voltage Accuracy

♦ Up to 2MHz Operating Frequency

♦ Small 0.22µF Capacitors

♦ No Inductor Required

♦ 2.7V to 5.5V Input Voltage Range

♦ Output Disconnects from Input in Shutdown Mode

♦ Small 10-Pin µMAX Package (1.09mm max height)

MAX1730

50mA Regulated Step-Down Charge Pump

for 1.8V or 1.9V Logic

________________________________________________________________ Maxim Integrated Products 1

Typical Operating Circuit

19-1618; Rev 0; 4/00

PART

MAX1730EUB -40°C to +85°C

TEMP. RANGE PIN-PACKAGE

10 µMAX

Pin Configuration

Ordering Information

For free samples and the latest literature, visit www.maxim-ic.com or phone [phone].
For small orders, phone [phone].

10

IN

9

MAX1730

µMAX

OUT

8

C2P

7

C2NC1N

PGNDGND

6

INPUT

2.7V TO 5.5V

1µF

0.22µF

TOP VIEW

1

FB

OUTPUT

OUT

C2P

C2N

1.8V OR 1.9V, UP TO 50mA

4.7µF

0.22µF

IN

SHDN

MAX1730

C1P

C1N

FB

GND

PGND

SHDN

C1P

2

3

4

5

MAX1730

50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= +3.6V, FB = GND, SHDN = IN, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

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, OUT, SHDN, FB to GND .....................................-0.3V to +6V

C1P, C1N, C2P, C2N to GND......................-0.3V to (V

IN

+ 0.3V)

GND to PGND.....................................................................±0.3V

Output Short-Circuit Duration ........................................Indefinite

Continuous Power Dissipation (T

A

= +70°C)

10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW

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

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

Storage Temperature Range .............................-65°C to +150°C

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

FB = GND

FB = IN

SHDN = IN or GND

VIN= 2.7V to 5.5V

VIN= 2.7V to 5.5V

Falling edge (100mV hysteresis)

V

OUT

= GND

V

IN

= 4.2V, SHDN = GND, V

OUT

= 1.8V or GND

SHDN = IN

OUT forced to 1.8V, VIN= 1.8V to 5.5V,
SHDN = GND

VIN= 2.7V to 5.5V,
I

OUT

= 0 to 50mA

CONDITIONS

µA

-1 1

I

SHDN

Shutdown Logic Input Current

V

0.6

V

IL

SHDN Logic Input Low Voltage

V

1.4

V

IH

SHDN Logic Input High Voltage

ms

4.1

Startup Timer

V

IN

Transition Voltage

(V

IN

Rising)

°C

15

Thermal Shutdown Threshold
Hysteresis

°C

150

Thermal Shutdown Threshold

MHz

1.5 2.0 2.5

Oscillator Frequency

V

1.746 1.80 1.854

V

OUT

Output Voltage

V

2.3 2.6

V

2.7 5.5

V

IN

Input Voltage Range

Input Undervoltage Lockout

mA

45 125

Output Short-Circuit Current

µA

15

Shutdown Supply Current

µA

75 150

No-Load Supply Current

µA

15

Output Leakage Current

1.843 1.90 1.957

UNITSMIN TYP MAXSYMBOLPARAMETER

V

4.00 4.12 4.30

3.1 3.2 3.35

From 2:3 to 1:2

From 1:1 to 2:3

FB = GND

MAX1730

50mA Regulated Step-Down Charge Pump

for 1.8V or 1.9V Logic

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS

(VIN= +3.6V, FB = GND, SHDN = IN, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

Note 1: Specifications to -40°C are guaranteed by design, not production tested.

SHDN = IN or GND

VIN= 2.7V to 5.5V

VIN= 2.7V to 5.5V

Falling edge (100mV hysteresis)

FB = GND

V

OUT

= GND

V

IN

= 4.2V, SHDN = GND

SHDN = IN

OUT forced to 1.8V, VIN= 1.8V to 5.5V,
SHDN = GND

VIN= 2.7V to 5.5V,
I

OUT

= 0 to 50mA

CONDITIONS

FB = GND

FB = IN

µA

-1 1

I

SHDN

Shutdown Logic Input Current

V

0.6

V

IL

SHDN Logic Input Low Voltage

V

1.4

V

IH

SHDN Logic Input High Voltage

V

3.1 3.35

VINTransition Voltage
(VINRising)

MHz

1.5 2.5

fOscillator Frequency

V

1.746 1.854

V

OUT

Output Voltage

V

2.3 2.6

V

2.7 5.5

V

IN

Input Voltage Range

Input Undervoltage Lockout

mA

125

Output Short-Circuit Current

µA

5

Shutdown Supply Current

µA

150

No-Load Supply Current

µA

5

Output Leakage Current

1.843 1.957

From 1:1 to 2:3

UNITSMIN MAXSYMBOLPARAMETER

From 2:3 to 1:2

4.00 4.30