Rainbow Electronics MAX758A User Manual

General Description

The MAX1605 boost converter contains a 0.5A internal
switch in a tiny 6-pin SOT23 package. The IC operates
from a +2.4V to +5.5V supply voltage but can boost
battery voltages as low as 0.8V up to 28V at the output.

The MAX1605 uses a unique control scheme providing
the highest efficiency over a wide range of load condi­tions. An internal 0.5A MOSFET reduces external com­ponent count, and a high switching frequency (up to
500kHz) allows for tiny surface-mount components. The
current limit can be set to 500mA, 250mA, or 125mA,
allowing the user to reduce the output ripple and com­ponent size in low-current applications.

Additional features include a low quiescent supply cur­rent and a shutdown mode to save power. The
MAX1605 is ideal for small LCD panels with low current
requirements but can also be used in other applica­tions. A MAX1605EVKIT evaluation kit (EV kit) is avail­able to help speed up design time.

________________________Applications

LCD Bias Generators

Cellular or Cordless Phones

Palmtop Computers

Personal Digital Assistants (PDAs)

Organizers

Handy Terminals

Features

♦ Adjustable Output Voltage up to 28V

♦ 20mA at 20V from a Single Li+ Battery

♦ 88% Efficiency

♦ Up to 500kHz Switching Frequency

♦ Selectable Inductor Current Limit

(125mA, 250mA, or 500mA)

♦ 18µA Operating Supply Current

♦ 0.1µA Shutdown Current

♦ Small 6-Pin SOT23 Package

MAX1605

28V Internal Switch LCD Bias Supply

in SOT23

________________________________________________________________ Maxim Integrated Products 1

Pin Configuration

V

IN

= 0.8V TO V

OUT

V

CC

= 2.4V TO 5.5V

V

OUT

= V

IN

TO 28V

ON

OFF

SHDN

V

CC

LIM

GND

LX

FB

MAX1605

L1

10µH

Typical Operating Circuit

19-1666; Rev 0; 7/00

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

Ordering Information

PART

MAX1605EUT-T -40°C to +85°C

TEMP.

RANGE

PIN­PACKAGE

6 SOT23-6 AAHP

SOT

MARK

TOP VIEW

SHDN

V

CC

16FB

MAX1605

2

34

SOT23-6

5 LIM

LXGND

MAX1605

28V Internal Switch LCD Bias Supply
in SOT23

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= SHDN = 3.3V, TA= 0°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.

VCC, FB, LIM, SHDN to GND....................................-0.3V to +6V

LX to GND ..............................................................-0.3V to +30V

Continuous Power Dissipation (T

A

= +70°C)

6-Pin SOT23 (derate 8.7mW/°C above +70°C) ...........696mW

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

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

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

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

)

Supply Voltage V

Inductor Input Voltage Range V

VCC Undervoltage Lockout V

Quiescent Supply Current I
Shutdown Supply Current SHDN = GND 0.1 1 µA

VCC Line Regulation ∆V

VIN Line Regulation ∆V

Load Regulation ∆V

Efficiency L1 = 100µH, VIN = 3.6V, I

Feedback Set Point V

Feedback Input Bias Current I

LX

LX Voltage Range V

LX On-Resistance R

LX Leakage Current VLX = 28V 2 µA

Maximum LX On-Time t

Minimum LX Off-Time t

CONTROL INPUTS

SHDN Input Threshold

SHDN Input Bias Current I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CC

UVLO

CC

LNR

LNR

LDR

FB

FB

LX

LX(MAX

(Note 2) 2.4 5.5 V

(Note 2) 0.8 V

IN

VCC falling, 50mV typical hysteresis 2.0 2.2 2.37 V

VFB = 1.3V 18 35 µA

V

= 18V, I

OUT

= V

V

CC

LIM

V

= 18V, I

OUT

= V

V

CC

LIM

V

= 18V, VCC = VIN = V

OUT

= 0mA to 20mA

I

LOAD

= 1mA, VIN = 5V,

LOAD

= 2.4V to 5.5V

= 1mA,

LOAD

= 5V, VIN = 2.4V to 12V

= 5V,

LIM

= 10mA 88 %

LOAD

0.1 %/V

0.15 %/V

0.1 %/mA

1.225 1.25 1.275 V

VFB = 1.3V 5 100 nA

LIM = V

CC

0.40 0.50 0.56

LIM = floating 0.20 0.25 0.285LX Switch Current Limit I

OUT

28 V

LIM = GND 0.10 0.125 0.15

LX

ON

OFF

V

V

SHDN

VCC = 5V, ILX = 100mA 0.8

VCC = 3.3V, ILX = 100mA 1 2

10 13 16 µs

VFB > 1.1V 0.8 1.0 1.2

VFB < 0.8V (soft-start) 3.9 5.0 6.0

IH

IL

2.4V ≤ VCC ≤ 5.5V

2.4V ≤ VCC ≤ 5.5V

VCC = 5.5V, V

SHDN

= 0 to 5.5V -1 1 µA

0.8 ×
V

CC

0.2 ×
V

CC

V

A

Ω

µs

V

MAX1605

28V Internal Switch LCD Bias Supply

in SOT23

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS

(VCC= SHDN = 3.3V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

ELECTRICAL CHARACTERISTICS (continued)

(VCC= SHDN = 3.3V, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

)

LIM Input Low Level 2.4V ≤ VCC ≤ 5.5V 0.4 V

LIM Input Float Level

LIM Input High Level 2.4V ≤ VCC ≤ 5.5V

LIM Input Bias Current I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

LIM

2.4V ≤ V
I

LIM

SHDN = VCC, LIM = GND or V
SHDN = GND 0.1 1

≤ 5.5V,

CC

= ±0.5µA

CC

/ 2) -

( V

C C

0.2V

V

CC

- 0.4V

-2 2

( V

C C

+ 0.2V

/ 2)

Supply Voltage V

Inductor Input Voltage Range V

VCC Undervoltage Lockout V

Quiescent Supply Current I
Shutdown Supply Current SHDN = GND 1 µA

Feedback Set Point V

Feedback Input Bias Current I

LX

LX Voltage Range V

LX On-Resistance R

LX Leakage Current VLX = 28V 2 µA

Maximum LX On-Time t

Minimum LX Off-Time t

CONTROL INPUTS

SHDN Input Threshold

SHDN Input Bias Current I

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

CC

UVLO

CC

FB

FB

LX(MAX

ON

OFF

V

V

SHDN

(Note 2) 2.4 5.5 V

(Note 2) 0.8 V

IN

VCC falling, 50mV typical hysteresis 2.0 2.37 V

VFB = 1.3V 35 µA

1.215 1.285 V

VFB = 1.3V 100 nA

LX

LIM = V

CC

LIM = floating 0.18 0.30LX Switch Current Limit I

LIM = GND 0.08 0.17

VCC = 3.3V, ILX = 100mA 2 Ω

LX

VFB > 1.1V 0.75 1.25

VFB < 0.8V 3.8 6.0

2.4V ≤ VCC ≤ 5.5V

IH

2.4V ≤ VCC ≤ 5.5V

IL

VCC = 5.5V, V

= 0 to 5.5V -1 1 µA

SHDN

0.35 0.58

917µs

0.8 ×
V

CC

OUT

28 V

0.2 ×
V

CC

V

V

µA

V

A

µs

V

70

72

76

74

78

80

2.0 3.02.5 3.5 4.0 4.5 5.0 5.5

MAX1605 toc04

SUPPLY VOLTAGE (V)

EFFICIENCY (%)

EFFICIENCY vs.

SUPPLY VOLTAGE

(L1 = 10µH)

80

VIN = 3.6V
I

LIM

= 500mA

I

OUT

= 5mA

I

OUT

= 1mA

I

OUT

= 10mA

30

50

40

70

60

80

90

063912

EFFICIENCY vs.

INPUT VOLTAGE (L1 = 10µH)

MAX1605 toc05

INPUT VOLTAGE (V)

EFFICIENCY (%)

VCC = 3.3V
I

LIM

= 500mA

I

OUT

= 5mA

I

OUT

= 1mA

74

76

78

80

82

84

86

88

90

0 5 10 15 20 25

EFFICIENCY vs. LOAD CURRENT

(L1 = 10µH)

MAX1605 toc06

LOAD CURRENT (mA)

EFFICIENCY (%)

LIM = GND

(125mA)

LIM = OPEN

(250mA)

LIM = V

CC

(500mA)

17.6

17.8

17.7

18.0

17.9

18.1

18.2

2.0 3.5 4.02.5 3.0 4.5 5.0 5.5

OUTPUT VOLTAGE vs. SUPPLY VOLTAGE

MAX1605 toc01

SUPPLY VOLTAGE (V)

OUTPUT VOLTAGE (V)

V

IN

= 3.6V

LIM = V

CC

(500mA)

I

OUT

= 5mA

I

OUT

= 1mA

19.5

20.1

19.9

19.7

20.3

20.5

20.7

20.9

21.1

21.3

21.5

036912

OUTPUT VOLTAGE vs. INPUT VOLTAGE

MAX1605 toc02

INPUT VOLTAGE (V)

OUTPUT VOLTAGE (V)

V

CC

= 3.3V

LIM = V

CC

(500mA)

I

OUT

= 5mA

I

OUT

= 1mA

17.4

17.7

17.6

17.5

17.8

17.9

18.0

18.1

18.2

18.3

18.4

0105 152025

OUTPUT VOLTAGE

vs. LOAD CURRENT

MAX1605 toc03

LOAD CURRENT (mA)

OUTPUT VOLTAGE (V)

LIM = V

CC

(500mA)

LIM = GND
(125mA)

LIM = OPEN
(250mA)

Typical Operating Characteristics

(VCC= 3.3V, VIN= 3.6V, L1 = 10µH, SHDN = LIM = VCC, V

OUT(NOM)

= 18V (Figure 3), TA= +25°C, unless otherwise noted.)

Note 1: All devices are 100% tested at T

A

= +25°C. All limits over the temperature range are guaranteed by design.

Note 2: The MAX1605 requires a supply voltage between +2.4V and +5.5V; however, the input voltage used to power the inductor

can vary from +0.8V to V

OUT

.

MAX1605

28V Internal Switch LCD Bias Supply
in SOT23

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VCC= SHDN = 3.3V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

LIM Input Low Level 2.4V ≤ VCC ≤ 5.5V 0.4 V

LIM Input Float Level

LIM Input High Level 2.4V ≤ VCC ≤ 5.5V

LIM Input Bias Current I

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

2.4V ≤ V
= ±0.5µA

I

LIM

CC

≤ 5.5V,

(V

CC

- 0.25V

V

CC

/ 2)

(VCC / 2)

+ 0.25V

- 0.4V

LIM

SHDN = VCC, LIM = GND or V

CC

SHDN = GND 1

-2 2

V

V

µA