Rainbow Electronics MAX653 User Manual

________________________________________________________________

Maxim Integrated Products

1

_______________General Description

The MAX639/MAX640/MAX653 step-down switching
regulators provide high efficiency over a wide range of
load currents, delivering up to 225mA. A current-limiting
pulse-frequency-modulated (PFM) control scheme gives
the devices the benefits of pulse-width-modulated
(PWM) converters (high efficiency at heavy loads), while
using only 10µA of supply current (vs. 2mA to 10mA for
PWM converters). The result is high efficiency over a
wide range of loads.

The MAX639/MAX640/MAX653 input range is 4V to

11.5V, and the devices provide lower preset output volt­ages of 5V, 3.3V, and 3V, respectively. Or, the output
can be user-adjusted to any voltage from 1.3V to the
input voltage.

The MAX639/MAX640/MAX653 have an internal 1A power
MOSFET switch, making them ideal for minimum-compo­nent, low- and medium-power applications. For increased
output drive capability, use the MAX649/MAX651/MAX652
step-down controllers, which drive an external P-channel
FET to deliver up to 5W.

________________________Applications

9V Battery to 5V, 3.3V, or 3V Conversion
High-Efficiency Linear Regulator Replacement
Portable Instruments and Handy-Terminals
5V-to-3.3V Converters

____________________________Features

♦ High Efficiency for a Wide Range of Load Currents
♦ 10µA Quiescent Current
♦ Output Currents Up to 225mA
♦ Preset or Adjustable Output Voltage:

5.0V (MAX639)

3.3V (MAX640)

3.0V (MAX653)

♦ Low-Battery Detection Comparator
♦ Current-Limiting PFM Control Scheme

______________Ordering Information

Ordering Information continued on last page.

* Contact factory for dice specifications.

MAX639/MAX640/MAX653

5V/3.3V/3V/Adjustable, High-Efficiency,

Low IQ, Step-Down DC-DC Converters

19-4505; Rev 3; 8/97

PART TEMP. RANGE PIN-PACKAGE

MAX639CPA

0°C to +70°C 8 Plastic DIP
MAX639CSA 0°C to +70°C 8 SO
MAX639C/D 0°C to +70°C Dice*

1
2
3
4

5

8
7
6

MAX639
MAX640
MAX653

DIP/SO

TOP VIEW

VFB

SHDN

V+
LX

VOUT

LBO

LBI

GND

__________________Pin Configuration

GND

MAX639

SHDN

LX

VOUT

LBO

LOW-BATTERY
DETECTOR
OUTPUT

ON/OFF

LBI

LOW-BATTERY

DETECTOR

INPUT

OUTPUT

5V

225mA

INPUT

5.5V TO 11.5V

V+

VFB

__________Typical Operating Circuit

MAX639ESA -40°C to +85°C 8 SO

MAX639EPA -40°C to +85°C 8 Plastic DIP

MAX639MJA -55°C to +125°C 8 CERDIP

EVALUATION KIT

INFORMATION INCLUDED

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

MAX639/MAX640/MAX653

5V/3.3V/3V/Adjustable, High-Efficiency,
Low IQ, Step-Down DC-DC Converters

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V+ = 9V for the MAX639, V+ = 5V for the MAX640/MAX653, I

LOAD

= 0mA, TA= T

MIN

to T

MAX

, typical values are at TA= +25°C,

unless otherwise noted.)

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.

PARAMETER MIN TYP MAX UNITS

91

Dropout Voltage 0.5 V

Output Voltage (Note 2)

2.88 3.00 3.12

V3.17 3.30 3.43

94
87
91
85

Supply Current

Supply Voltage 4.0 11.5 V

10 20 µA

4.80 5.00 5.20

Efficiency

89

%

CONDITIONS

MAX653

I

OUT

= 100mA, L = 100µH

MAX653, V+ = 4.0V to 11.5V, 0mA < I

OUT

< 100mA

MAX640, V+ = 4.0V to 11.5V, 0mA < I

OUT

< 100mA

MAX639

MAX640

SHDN = V+, no load
MAX639, V+ = 6.0V to 11.5V, 0mA < I

OUT

< 100mA

V+...........................................................................................12V

LX .........................................................(V+ - 12V) to (V+ + 0.3V)

LBI, LBO, VFB, SHDN

, VOUT........................-0.3V to (V+ + 0.3V)

LX Output Current (Note 1)......................................................1A

LBO Output Current............................................................10mA

Continuous Power Dissipation (T

A

= +70°C)

Plastic DIP (derate 9.09mW/°C above +70°C) .............727mW

SO (derate 5.88mW/°C above +70°C)..........................471mW

CERDIP (derate 8.00mW/°C above +70°C)..................640mW

Operating Temperature Ranges:

MAX639C_ _ .......................................................0°C to +70°C

MAX639E_ _ ....................................................-40°C to +85°C

MAX639MJA..................................................-55°C to +125°C

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

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

I

OUT

= 100mA, L = 100µH

I

OUT

= 25mA, L = 470µH

I

OUT

= 100mA, L = 100µH

I

OUT

= 25mA, L = 470µH

I

OUT

= 100mA, L = 100µH

I

OUT

= 25mA, L = 470µH

Switch On-Time

V+ = 9V, V

OUT

= 5V

V+ = 6V, V

OUT

= 3V

42.5 50.0 57.5

V+ = 9V, V

OUT

= 3.3V

V+ = 4V, V

OUT

= 3.3V

µs

10.6 12.5 14.4

V+ = 9V, V

OUT

= 3V

V+ = 4V, V

OUT

= 3V

14.2 16.7 19.2

7.5 8.8 10.1

60.7 71.4 82.1

7.1 8.3 9.5

MAX653

MAX639

MAX640

Switch Off-Time

V+ = 9V, V

OUT

= 5V

V+ = 6V, V

OUT

= 3V

14.6 17.2 19.8

V+ = 9V, V

OUT

= 3.3V

V+ = 4V, V

OUT

= 3.3V

µs

9.0 11.7 13.5

V+ = 9V, V

OUT

= 3V

V+ = 4V, V

OUT

= 3V

16.6 19.5 22.4

13.3 15.6 17.9

13.3 15.6 17.9

14.6 17.2 19.8

MAX653

MAX639

MAX640

Note 1: Peak inductor current must be limited to 600mA by using an inductor of 100µH or greater.

MAX639/MAX640/MAX653

5V/3.3V/3V/Adjustable, High-Efficiency,

Low IQ, Step-Down DC-DC Converters

_______________________________________________________________________________________ 3

__________________________________________Typical Operating Characteristics

(Circuit of Figure 3, internal feedback, L = 100µH, TA= +25°C, unless otherwise noted.)

100

50

10µ 100µ 1

EFFICIENCY vs.

OUTPUT CURRENT

60

MAX639-1

OUTPUT CURRENT (A)

EFFICIENCY (%)

70

80

90

1m 10m 100m

L = 100µH
V

+ = 9V

MAX639
MAX640
MAX653

100

50

10µ 100µ

EFFICIENCY vs.

OUTPUT CURRENT

60

MAX639-2

OUTPUT CURRENT (A)

EFFICIENCY (%)

70

80

90

1m 10m

MAX639, V+ = 6V
MAX640, V+ = 4.3V
MAX653, V+ = 4V

100m

L = 470µH

100

50

10µ 100µ

EFFICIENCY vs.

OUTPUT CURRENT

60

MAX639-3

OUTPUT CURRENT (A)

EFFICIENCY (%)

70

80

90

1m 10m

MAX639
MAX640
MAX653

100m

L = 470µH
V+ = 9V

Note 2: Output guaranteed by correlation to measurements of device parameters (i.e., switch on-resistance, on-times, off-times, and

output voltage trip points).

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 9V for the MAX639, V+ = 5V for the MAX640/MAX653, I

LOAD

= 0mA, TA= T

MIN

to T

MAX

, typical values are at TA= +25°C,

unless otherwise noted.)

PARAMETER

V

0.4 1.2

MIN TYP MAX

mAV

LBO

= 0.4V

UNITS

LBO Leakage Current 0.001 0.1 µAV

LBO

= 11.5V

LBO Delay 25 µs50mV overdrive

2.5

SHDN Threshold

0.80 1.15 2.00 V

SHDN Pull-Up Current

0.10 0.20 0.40

Ω

µA

SHDN = 0V

V

µA

TA= +25°C
TA= T

MIN

to T

MAX

MAX639
MAX640/MAX653

2.8

LX Switch Leakage

0.003 1.0

30.0
VFB Bias Current 4.0 15.0 nA
VFB Dual-Mode Trip Point

LX Switch On-Resistance

50

0.8 1.5

VFB Threshold

1.26 1.28 1.30

mV

1.24 1.28 1.32

LBI Bias Current 2 10
LBI Threshold

1.26 1.28 1.30

nA

1.24 1.28 1.32

LBO Sink Current

0.8 2.5

CONDITIONS

V+ = 6V, TA= T

MIN

to T

MAX

, MAX639

V+ = 4V, TA= T

MIN

to T

MAX

, MAX640/MAX653
V+ = 11.5V, VLX= 0V
VFB = 2V

V+ = 9V, TA= +25°C, MAX639/MAX640/MAX653

MAX6_ _C
MAX6_ _E/M
V

LBI

= 2V
MAX6_ _C
MAX6_ _E/M

0

10

MAX640

OUTPUT VOLTAGE RIPPLE vs.

INPUT VOLTAGE

25

100

MAX639-10

V+ (V)

OUTPUT VOLTAGE RIPPLE (mV)

7

75

150

3 4 5 6 8 9 11 12

I

OUT

= 25mA

L = 100µH

125

50

L = 220µH

L = 470µH

0

10

MAX653

OUTPUT VOLTAGE RIPPLE vs.

INPUT VOLTAGE

25

100

MAX639-11

V+ (V)

OUTPUT VOLTAGE RIPPLE (mV)

7

75

150

3 4 5 6 8 9 11 12

I

LOAD

= 25mA

125

50

L = 220µH

L = 470µH

L = 100µH

MAX639/MAX640/MAX653

5V/3.3V/3V/Adjustable, High-Efficiency,
Low IQ, Step-Down DC-DC Converters

4 _______________________________________________________________________________________

100

50

10µ 100µ 1

EFFICIENCY vs.

OUTPUT CURRENT

60

MAX639-4

OUTPUT CURRENT (A)

EFFICIENCY (%)

70

80

90

1m 10m 100m

L = 100µH

MAX639, V+ = 6V
MAX640, V+ = 4.3V
MAX653, V+ = 4V

100

10

MAXIMUM OUTPUT CURRENT vs.

INPUT VOLTAGE

200

MAX639-07

V+ (V)

MAXIMUM OUTPUT CURRENT (mA)

7

250

3 4 5 6 8 9 11 12

150

MAX640

MAX653

MAX639

L = 100µH

80

10

EFFICIENCY vs.

INPUT VOLTAGE

85

95

MAX639-05

V+ (V)

EFFICIENCY (%)

7

90

100

3 4 5 6 8 9 11 12

I

OUT

= 100mA

MAX639

MAX640

MAX653

80

10

EFFICIENCY vs.

INPUT VOLTAGE

85

95

MAX639-06

V+ (V)

EFFICIENCY (%)

7

90

100

3 4 5 6 8 9 11 12

L = 470µH
I

OUT

= 25mA

MAX639

MAX640

MAX653

25

10

MAXIMUM OUTPUT CURRENT vs.

INPUT VOLTAGE

65

MAX639-08

V+ (V)

MAXIMUM OUTPUT CURRENT (mA)

7

75

3 4 5 6 8 9 11 12

55

MAX640

MAX653

MAX639

45

35

L = 470µH

0

10

MAX639

OUTPUT VOLTAGE RIPPLE vs.

INPUT VOLTAGE

25

100

MAX639-09

INPUT VOLTAGE (V)

OUTPUT VOLTAGE RIPPLE (mV)

7

75

150

5 6 8 9 11 12

L = 100µH

125

50

L = 220µH

L = 470µH

I

OUT

= 25mA

_____________________________Typical Operating Characteristics (continued)

(Circuit of Figure 3, internal feedback, L = 100µH, TA= +25°C, unless otherwise noted.)