Rainbow Electronics MAX17062 User Manual

General Description

The MAX17062 is a high-performance step-up DC-DC
converter that provides a regulated supply voltage for
active-matrix thin-film transistor (TFT) liquid-crystal dis­plays (LCDs). The MAX17062 incorporates current­mode, fixed-frequency, pulse-width modulation (PWM)
circuitry with a built-in n-channel power MOSFET to
achieve high efficiency and fast-transient response.

Users can select 640kHz or 1.2MHz operation using a
logic input pin (FREQ). The high switching frequencies
allow the use of ultra-small inductors and low-ESR
ceramic capacitors. The current-mode architecture pro­vides fast transient response to pulsed loads. A com­pensation pin (COMP) gives users flexibility in adjusting
loop dynamics. The 22V internal MOSFET can generate
output voltages up to 20V from an input voltage
between 2.6V and 5.5V. Soft-start slowly ramps the input
current and is programmed with an external capacitor.

The MAX17062 is available in a 10-pin TDFN package.

Applications

Notebook Computer Displays

LCD Monitor Panels

LCD TV Panels

Features

o 90% Efficiency

o Adjustable Output from V

IN

to 20V

o 2.6V to 5.5V Input Supply Range

o Input Supply Undervoltage Lockout

o Pin-Programmable 640kHz/1.2MHz Switching

Frequency

o Programmable Soft-Start

o Improved EMI

o FB Regulation Voltage Tolerance < 1%

o Small 10-Pin TDFN Package

o Thermal-Overload Protection

MAX17062

TFT-LCD Step-Up DC-DC Converter

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

19-1042; Rev 0; 10/07

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

Pin Configuration

LX LX

FB

PGND

PGND

AGND

FREQ

IN

COMP

SS

EP

1

4

5

2

3

9

8

67

10

V

OUT

V

IN

2.6V TO 5.5V

SHDN

MAX17062

Minimal Operating Circuit

+

Denotes a lead-free package.

*

EP = Exposed pad.

T = Tape and reel.

PART TEMP RANGE

MAX17062ETB+T -40°C to +85°C

PIN­PACKAGE

10 TDFN-EP*
(3mm x 3mm)

PKG

CODE

T1033-2

SS

TOP VIEW

*EP = EXPOSED PAD.

FREQ

10 9 8 7 6

MAX17062

12345

FB

COMP

TDFN

(3mm x 3mm)

LX

*EP

PGND

LX

PGND

IN

SHDN

MAX17062

TFT-LCD Step-Up DC-DC Converter

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= V

SHDN

= 3V, FREQ = 3V, TA= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.) (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.

LX to AGND ............................................................-0.3V to +22V

IN, SHDN, FREQ, FB to AGND..............................-0.3V to +7.5V

COMP, SS to AGND ....................................-0.3V to (V

IN

+ 0.3V)

PGND to AGND .....................................................-0.3V to +0.3V

LX Switch Maximum Continuous RMS Current .....................3.2A

Continuous Power Dissipation (T

A

= +70°C)

10-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 +160°C

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

Input Voltage Range

Output Voltage Range 20 V

IN Undervoltage-Lockout
Threshold

IN Quie scent Current

IN Shutdown Current

Thermal Shutdown

ERROR AMPLIFIER

FB Regulation Voltage Level to produce V

FB Input Bia s Current VFB = 1.24V 75 150 225 nA

FB L ine Regulation Level to produce V

Transconductance 110 250 450 μS

Voltage Gain 2400 V/V
Shutdown FB Input Voltage SHDN = AGND 0.05 0.10 0.15 V

OSCILLATOR

Frequency

Max imum Duty C yc le 88 91 94 %

n-CHANNEL MOSFET

Current Lim it VFB = 1V, 75% duty cycle, IN = 5V 3.9 4.6 5.3 A

On-Resistance

Leakage Current VLX = 20V 11 20 μA

Current-Sense Tran sresi stance IN = 5V 0.09 0.15 0.25 V/A

SOFT-START

Reset Switch Re sistance 100 

Charge Current VSS = 1.2V 2 4 6 μA

PARAMETER CONDITIONS MIN TYP MA X UNITS

V

< 18V 2.6 5.5

OUT

18V < V

V

VFB = 1.3V, not switching 0.3 0.6

V

SHDN = AGND, TA = +25°C 0.01 10.0
SHDN = AGND, T

Temperature ris ing 160

Hysteresis 20

FREQ = AGND 500 640 780

FREQ = IN 1000 1200 1400

IN = 5V 100 170

IN = 3V 125 210

OUT

rising, typical hysteresis i s 50mV 2.30 2.45 2.57 V

IN

= 1.0V, switching 1.5 2.5

FB

< 20V 4.0 5.5

= +85°C 0.01

A

COMP

COMP

= 1.24V 1.23 1.24 1.25 V

= 1.24V, VIN = 2.6V to 5.5V 0.01 0.15 %/V

V

mA

μA

°C

kHz

m

MAX17062

TFT-LCD Step-Up DC-DC Converter

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= V

SHDN

= 3V, FREQ = 3V, TA= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.) (Note 1)

ELECTRICAL CHARACTERISTICS

(VIN= V

SHDN

= 3V, FREQ = 3V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

CONTROL I NPU TS

SHDN, FREQ Input Low Voltage VIN = 2.6V to 5.5V

SHDN, FREQ Input High Voltage VIN = 2.6V to 5.5V

SHDN, FREQ Input Hysteresis VIN = 2.6V to 5.5V

FREQ Pulldown Current 3 6 9 μA

SHDN Input Current

PARAMETER CONDITIONS MIN TYP MA X UNITS

0.3 
V

IN

0.7 
V

IN

SHDN = AGND, TA = +25°C -1 +1
SHDN = AGND, T

= +85°C 0

A

V

0.1 
V

IN

V

V

μA

Input Voltage Range

Output Voltage Range 20 V

IN Undervoltage-Lockout
Threshold

IN Quie scent Current

ERROR AMPLIFIER

FB Regulation Voltage Level to produce V

FB Input Bia s Current VFB = 1.24V 225 nA

FB L ine Regulation Level to produce V

Transconductance 110 450 μS
Shutdown FB Input Voltage SHDN = AGND 0.05 0.15 V

OSCILLATOR

Frequency

Maximum Duty Cycle 87 95 %

n-CHANNEL MOSFET

Current Lim it VFB = 1V, 75% duty c ycle, IN = 5V 3.9 5.3 A

On-Resistance

Current-Sense Tran sresi stance IN = 5V 0.09 0.25 V/A

SOFT-START

Reset Switch Re sistance 100 

Charge Current VSS = 1.2V 2 6 μA

PARAMETER CONDITIONS MIN TY P MAX UNITS

V

< 18V 2.6 5.5

OUT

18V < V

V

rising, typical hysteresis i s 50mV 2.30 2.57 V

IN

VFB = 1.3V, not switching 0.6

= 1.0V, switching 2.5

V

FB

FREQ = AGND 450 830

FREQ = IN 950 1500

IN = 5V 170

IN = 3V 210

< 20V 4.0 5.5

OUT

= 1.24V 1.227 1.253 V

COMP

= 1.24V, VIN = 2.6V to 5.5V 0.15 %/V

COMP

V

mA

kHz

m

MAX17062

TFT-LCD Step-Up DC-DC Converter

4 _______________________________________________________________________________________

Note 1: Limits are 100% tested at TA= +25°C. Maximum and minimum limits over temperature are guaranteed by design.

ELECTRICAL CHARACTERISTICS (continued)

(VIN= V

SHDN

= 3V, FREQ = 3V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)

Typical Operating Characteristics

(Circuit of Figure 1. VIN= 5V, V

MAIN

= 15V, TA= +25°C, unless otherwise noted.)

CONTROL I NPU TS

SHDN, FREQ Input Low Voltage VIN = 2.6V to 5.5V

SHDN, FREQ Input High Voltage VIN = 2.6V to 5.5V

PARAMETER CONDITIONS MIN TY P MAX UNITS

0.7 
V

IN

V

0.3 
V

IN

V

EFFICIENCY vs. LOAD CURRENT

= 5V, V

(V

f

= 640kHz

OSC

L = 4.7μH

IN

LOAD CURRENT (mA)

100

90

80

70

EFFICIENCY (%)

60

50

1 1000

= 15V)

OUT

f

= 1.2MHz

OSC

L = 2.7μH

10010

1400

1300

1200

1100

1000

900

800

SWITCHING FREQUENCY (kHz)

700

600

500

2.5 5.5

100

MAX17062 toc01

90

80

70

EFFICIENCY (%)

60

50

1 1000

SWITCHING FREQUENCY

vs. INPUT VOLTAGE

FREQ = IN

FREQ = GND

INPUT VOLTAGE (V)

EFFICIENCY vs. LOAD CURRENT

(V

IN

f

= 640kHz

OSC

L = 4.7μH

LOAD CURRENT (mA)

5.04.54.03.53.0

= 3.3V, V

MAX17062 toc04

= 9V)

OUT

f

= 1.2MHz

OSC

L = 2.7μH

10010

SUPPLY CURRENT (mA)

LOAD REGULATION

(V

1.0

MAX17062 toc02

0.5

0

LOAD REGULATION (%)

-0.5

-1.0
1 1000

OUT

LOAD CURRENT (mA)

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

2.5 5.5

SWITCHING

NONSWITCHING

SUPPLY VOLTAGE (V)

= 15V)

5.04.54.03.53.0

VIN = 5.0V

VIN = 3.3V

10010

MAX17062 toc05

MAX17062 toc03

MAX17062

TFT-LCD Step-Up DC-DC Converter

_______________________________________________________________________________________

5

Typical Operating Characteristics (continued)

(Circuit of Figure 1. VIN= 5V, V

MAIN

= 15V, TA= +25°C, unless otherwise noted.)

SOFT-START

= 30Ω)

(R

LOAD

2ms/div

MAX17062 toc06

PULSED LOAD-TRANSIENT RESPONSE

= 100mA TO 1.1A)

(I

LOAD

MAX17062 toc08

V

OUT

5V/div

OV

INDUCTOR
CURRENT
1A/div

OA

15V
V

OUT

200mV/div
AC-COUPLED

I

OUT

1A/div

0.1A

INDUCTOR
CURRENT
1A/div

0A

LOAD-TRANSIENT RESPONSE

= 50mA TO 550mA)

(I

LOAD

L = 2.7μH
R

COMP

C

COMP1

= 47k

= 560pF

100μs/div

Ω

SWITCHING WAVEFORMS

= 600mA)

(I

LOAD

MAX17062 toc07

MAX17062 toc09

15V
V

OUT

500mV/div
AC-COUPLED

0V

I

OUT

500mA/div
50mA

INDUCTOR
CURRENT
2A/div

0A

LX
10V/div

0V

INDUCTOR
CURRENT
1A/div

0A

L = 2.7μH
R

COMP

C

COMP1

= 47kΩ

= 560pF

10μs/div

1μs/div