Rainbow Electronics MAX8562 User Manual

General Description

The MAX8560/MAX8561/MAX8562 step-down DC-DC
converters are optimized for applications that prioritize
small size and high efficiency. They utilize a proprietary
hysteretic-PWM control scheme that switches with fixed
frequency and is adjustable up to 4MHz, allowing cus­tomers to trade efficiency for smaller external compo­nents. Output current is guaranteed up to 500mA, while
quiescent current is only 40µA (typ).

Internal synchronous rectification greatly improves effi­ciency and eliminates the external Schottky diode
required in conventional step-down converters. Built-in
soft-start eliminates inrush current to reduce input
capacitor requirements. The MAX8561 features logic­controlled output voltage, while the MAX8562 drives an
external bypass FET.

The MAX8560 is available in a 6-pin SOT23 package.
The MAX8561/MAX8562 are available in space-saving
8-pin 3mm x 3mm Thin DFN packages.

Applications

Microprocessor/DSP Core Supplies

Cellular and Smart Phones

CDMA/RF Power-Amplifier Supplies

PDAs, DSC, and MP3 Players

Features

♦ Up to 4MHz PWM Switching Frequency

♦ 500mA Guaranteed Output Current

♦ 40µA Typical Quiescent Current

♦ Adjustable Output Voltage from 0.6V to 2.5V

♦ Logic-Controlled Output Voltage (MAX8561)

♦ Drives External Bypass FET (MAX8562)

♦ ±1.5% Initial Accuracy

♦ Soft-Start Eliminates Inrush Current

♦ Fast Voltage-Positioning Transient Response

♦ Internal Synchronous Rectifier

♦ 2.7V to 5.5V Input

♦ 0.1µA Logic-Controlled Shutdown

♦ Thermal Shutdown

♦ Tiny SOT23 or Space-Saving 3mm x 3mm Thin

DFN Packages

MAX8560/MAX8561/MAX8562

4MHz, 500mA Synchronous Step-Down

DC-DC Converters in SOT and TDFN

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

GND

IN

LX

FB

SHDNON/OFF

OUTPUT

0.6V TO 2.5V

UP TO 500mA

INPUT

2.7V TO 5.5V

L

1µH

C

OUT

2.2µF

C

IN

2.2µF

C

FF

R1

R2

MAX8560

PGND

Typical Operating Circuit

19-2954; Rev 0; 7/03

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.

EVALUATION KIT

AVAILABLE

Pin Configurations

*Future product—contact factory for availability.

PART TEMP RANGE PIN-PACKAGE

MAX8560EUT* -40°C to +85°C 6 SOT23-6 ABRY

MAX8561ETA -40°C to +85°C 8 TDFN AHD

MAX8562ETA -40°C to +85°C 8 TDFN AHE

TOP

MARK

TOP VIEW

16LXIN

MAX8560

2

GND

34

SOT23-6

GND

76

MAX8561/
MAX8562

2

PGND

TDFN

FB

3

LX

5 PGND

FBSHDN

SHDN

8

1

IN

3mm × 3mm × 0.8mm

ODO

5

4

ODI

MAX8560/MAX8561/MAX8562

4MHz, 500mA Synchronous Step-Down
DC-DC Converters in SOT and TDFN

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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, FB, SHDN, ODI, ODO to GND ............................-0.3V to +6V

LX to GND (Note 1)......................................-0.3V to (V

IN

+ 0.3V)

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

LX Current ...........................................................................1.27A

Output Short Circuit to GND

(typical operating circuit)....................................................10s

Continuous Power Dissipation (T

A

= +70°C)

6-Pin SOT23 (derate 8.7mW/°C above +70°C)............695mW

8-Pin TDFN (derate 24.4mW/°C above +70°C) .........1951mW

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

ELECTRICAL CHARACTERISTICS

(VIN= 3.6V, SHDN = IN, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted.) (Note 1)

Note 1: LX has internal clamp diodes to PGND and IN. Applications that forward bias these diodes should take care not to exceed

the IC’s package power-dissipation limits.

Supply Voltage Range V

UVLO Threshold UVLO VIN rising, 60mV hysteresis 2.4 2.5 2.6 V

Supply Current I

Output Voltage Range V

FB Threshold Voltage V

FB Threshold Line Regulation VIN = 2.7V to 5.5V 0.3 % / V

FB Threshold Load Regulation I

FB Threshold Voltage Accuracy
(Falling) (% of V

FB Threshold Voltage Hysteresis
(% of V

FB Bias Current I

Logic Input High Voltage
(SHDN, ODI)

Logic Input Low Voltage
(SHDN, ODI)

Logic Input Bias Current IIH, I

ODO Output Low Voltage
(MAX8562 Only)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IN

I

= 0mA, no switching 40 80

LOAD

IN

SHDN = GND

OUT

VFB falling 0.6 V

FB

= 0 to 500mA -0.001 %/mA

OUT

I

= 0mA

LOAD

SHDN = GND, TA = +25°C, VIN = 5.5V 0.01 0.1
SHDN = GND, TA = +85°C, VIN = 5.5V 0.1

VFB = 0.5V, TA = +25°C, VIN = 5.5V 0.01 0.1

VFB = 0.5V, TA = +85°C, VIN = 5.5V 0.1

VIN = 2.7V to 5.5V 1.41

VIN = 2.7V to 5.5V 0.4

VIN = 5.5V, SHDN = ODI = GND or IN,
T

= +25°C

A

IL

VIN = 5.5V, SHDN = ODI = GND or IN,

= +85°C

T

A

1mA sink current, VIN = 2.7V 0.02 0.1 V

FB

)

FB

V

)

HYS

V

V

V

FB

IH

IL

OL

2.7 5.5 V

TA = +25°C 0.01 0.1

T

= +85°C 0.1

A

0.6 2.5 V

TA = +25°C -1.5 +1.5

T

= -40°C to +85°C -2.5 +2.5

A

1.0 %

0.001 0.1

0.01

µA

%
%

µA

V

µA

MAX8560/MAX8561/MAX8562

4MHz, 500mA Synchronous Step-Down

DC-DC Converters in SOT and TDFN

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 3.6V, SHDN = IN, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted.) (Note 1)

)

)

Typical Operating Characteristics

(VIN= 3.6V, V

OUT

= 1.2V, L = 1µH (LQH32C-IRO), C

OUT

= 2.2µF, TA= +25°C, unless otherwise noted.)

EFFICIENCY vs. LOAD CURRENT

(V

OUT

= 2.5V)

MAX8560 toc01

LOAD CURRENT (mA)

EFFICIENCY (%)

100101

50

60

70

80

90

100

40

0.1 1000

4.7µH

2.2µH
1µH

EFFICIENCY vs. LOAD CURRENT

(V

OUT

= 1.8V)

MAX8560 toc02

LOAD CURRENT (mA)

EFFICIENCY (%)

100101

50

60

70

80

90

100

40

0.1 1000

4.7µH

2.2µH

1µH

EFFICIENCY vs. LOAD CURRENT

(V

OUT

= 1.5V)

MAX8560 toc03

LOAD CURRENT (mA)

EFFICIENCY (%)

100101

50

60

70

80

90

100

40

0.1 1000

4.7µH

2.2µH

1µH

ODO Pullup to IN (MAX8562 Only) 5 10 20 kΩ

Open-Drain Output Leakage I

Current Limit

On-Resistance

Rectifier-Off Current Threshold I

LX Leakage Current I

Minimum On- and Off-Times

Thermal Shutdown +160 °C
Thermal-Shutdown Hysteresis 20 °C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

OHLEAK

I

LIMP

I

LIMN

R

ONP

R

ONN

LXOFF

LXLKG

t

ON(MIN

t

OFF(MIN

VIN = 5.5V, ODO = IN, TA = +25°C 0.01 0.1

VIN = 5.5V, ODO = IN, TA = +85°C 0.1

PFET switch 600 990 1500

NFET rectifier 490 680 900

PFET switch, ILX = -40mA 0.8 1.5

NFET rectifier, ILX = +40mA 0.4 0.82

03060mA

V

= 5.5V, LX = GND to IN, ODO = IN,

IN

T

= +25°C, SHDN = GND

A

V

= 5.5V, LX = GND to IN, ODO = IN,

IN

T

= +85°C, SHDN = GND

A

0.1 1

1

107

95

µA

mA

Ω

µA

ns

MAX8560/MAX8561/MAX8562

4MHz, 500mA Synchronous Step-Down
DC-DC Converters in SOT and TDFN

4 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VIN= 3.6V, V

OUT

= 1.2V, L = 1µH (LQH32C-IRO), C

OUT

= 2.2µF, TA= +25°C, unless otherwise noted.)

100

90

80

70

EFFICIENCY (%)

60

EFFICIENCY vs. LOAD CURRENT

= 1.2V)

(V

OUT

4.7µH

2.2µH
1µH

MAX8560 toc04

EFFICIENCY vs. LOAD CURRENT

100

90

80

70

EFFICIENCY (%)

60

EFFICIENCY vs. LOAD CURRENT

= 0.9V)

(V

4.7µH

OUT

2.2µH
1µH

MAX8560 toc05

100

90

80

70

EFFICIENCY (%)

60

4.7µH

(LOAD = 7.5Ω)

2.2µH

MAX8560 toc06

1µH

50

40

0.1 1000
LOAD CURRENT (mA)

100101

NO-LOAD SUPPLY CURRENT

vs. SUPPLY VOLTAGE

47

46

45

44

43

42

SUPPLY CURRENT (µA)

41

40

39

2.0 5.5

SUPPLY VOLTAGE (V)

R1 = R2 = 100kΩ

5.04.52.5 3.0 3.5 4.0

LIGHT-LOAD SWITCHING WAVEFORMS

50mA LOAD

MAX8560 toc07

MAX8560 toc10

50

40

0.1 1000
LOAD CURRENT (mA)

SWITCHING FREQUENCY

vs. LOAD CURRENT

10

1µH

1

FREQUENCY (MHz)

0.1
0500

100 200 300 400

V

OUT

20mV/div

I

L

200mA/div
0

2.2µH

LOAD CURRENT (mA)

50

100101

40

0.5 2.5

OUTPUT VOLTAGE vs. LOAD CURRENT

1.24

1.23

MAX8560 toc08

1.22

1.21

1.20

4.7µH

1.19

OUTPUT VOLTAGE (V)

1.18

1.17

1.16
0500

HEAVY-LOAD SWITCHING WAVEFORMS

2.01.51.0

OUTPUT VOLTAGE (V)

(VOLTAGE POSITIONING)

R1 = R2 = 100kΩ

LOAD CURRENT (mA)

MAX8560 toc11

200mA LOAD

V

OUT

20mV/div

I

L

200mA/div
0

MAX8560 toc09

400300100 200

V

LX

2V/div

200ns/div

200ns/div

V

LX

2V/div