Rainbow Electronics MAX1543 User Manual

General Description

The MAX1542/MAX1543 include a high-performance
boost regulator and two high-current operational ampli­fiers for active matrix, thin-film transistor (TFT), liquid­crystal displays (LCDs). Also included is a logic­controlled, high-voltage switch with adjustable delay.
The MAX1543 includes an additional high-voltage load
switch and features pin-selectable boost regulator
switching frequency.

The step-up DC-to-DC converter is a high-frequency
640kHz (MAX1543)/1.2MHz (MAX1542/MAX1543) cur­rent-mode regulator with a built-in power MOSFET that
allows the use of ultra-small inductors and ceramic
capacitors. It provides fast transient response to pulsed
loads while producing efficiencies over 85%.

The two easy-to-use, high-performance operational
amplifiers can drive the LCD backplane (V

COM

) and/or
the gamma correction divider string. The devices fea­ture high short-circuit current (150mA), fast slew rate
(7.5V/µs), wide bandwidth (12MHz), and Rail-to-Rail

®

inputs and outputs.

The MAX1542/MAX1543 are available in 20-pin thin
QFN packages with a maximum thickness of 0.8mm for
ultra-thin LCD panel design.

Applications

Notebook Computer Displays

LCD Monitor Panels

PDAs

Car Navigation Displays

Features

♦ Ultra-High-Performance Step-Up Regulator

Fast Transient Response to Pulsed Load Using
Current-Mode Control Architecture
High-Accuracy Output Voltage (1.3%)
Built-In 14V, 1.2A, 0.2Ω N-Channel Power
MOSFET with Lossless Current-Sensing
High Efficiency (85%)
8-Step Current-Controlled Digital Soft-Start

♦ Two High-Performance Operational Amplifiers

150mA Output Short-Circuit Current

7.5V/µs Slew Rate
12MHz -3dB Bandwidth
Rail-to-Rail Inputs/Outputs
Unity Gain Stable

♦ Logic-Controlled High-Voltage Switch with

Adjustable Delay

♦ Timer Delay Latch FB Fault Protection

♦ Thermal Protection

♦ 2.6V to 5.5V Input Operating Voltage Range

♦ 3.6mA (Switching), 0.45mA (Not Switching)

Quiescent Current

♦ Ultra-Thin 20-Pin Thin QFN Package

(5mm x 5mm x 0.8mm)

MAX1542/MAX1543

TFT LCD DC-to-DC Converter with

Operational Amplifiers

________________________________________________________________ Maxim Integrated Products 1

Pin Configurations

Ordering Information

19-2741; Rev 0; 4/03

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

PART

PIN-PACKAGE

MAX1542ETP

20 Thin QFN (5mm x 5mm)

MAX1543ETP

20 Thin QFN (5mm x 5mm)

Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.

Pin Configurations continued at end of data sheet.

TOP VIEW

PGND

AGND

COM

SRC

DRN

20

1

2

I.C.

3

4

5

6

POS1

THIN QFN (5mm x 5mm)

CTL

DEL

COMP

FB

19

18

17

16

15

FREQ

14

IN

13

MAX1543

7

8

OUT1

NEG1

9

OUT2

10

NEG2

LX

12

SUP

POS2

11

TEMP RANGE

-40°C to +85°C

-40°C to +85°C

MAX1542/MAX1543

TFT LCD DC-to-DC Converter with
Operational Amplifiers

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, CTL, COMP, FB, DEL, FREQ (MAX1543)

to AGND ...............................................................-0.3V to +6V

COMP, FB, DEL to AGND .............................-0.3V to (IN + 0.3V)

PGND to AGND ..................................................................±0.3V

LX to PGND ............................................................-0.3V to +14V

SUP, POS1, NEG1, OUT1, POS2,

NEG2, OUT2 to AGND .......................................-0.3V to +14V

POS1, NEG1, OUT1, POS2, NEG2,

OUT2 to AGND ......................................-0.3V to (SUP + 0.3V)

SRC, COM to AGND...............................................-0.3V to +30V

SRC to COM ...........................................................-0.3V to +30V

SRC to DRN (MAX1543).........................................-0.3V to +30V

COM to AGND ...........................................-0.3V to (SRC + 0.3V)

DRN (MAX1543) to AGND .........................-0.3V to (SRC + 0.3V)

DRN (MAX1543) to COM.........................................-30V to +30V

MAX1542 COM RMS Output Current ...............................+75mA

MAX1543 COM RMS Output Current ...............................±50mA

OUT1, OUT2 Continuous Output Current.........................±75mA

Continuous Power Dissipation (T

A

= +70°C)
20-Pin Thin QFN 5mm x 5mm

(derate 20.8mW/°C above +70°C).............................1667mW

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= 3V, V

SUP

= 8V, V

SRC

= 28V, FREQ = IN (MAX1543), PGND = AGND = 0, TA= 0°C to +85°C, typical values at TA= +25°C,

unless otherwise noted.)

IN Supply Range V

IN Undervoltage Lockout
Threshold

IN Quiescent Current I

Duration to Trigger Fault
Condition

Thermal Shutdown

MAIN STEP-UP REGULATOR

Output Voltage Range V

Oscillator Maximum Duty Cycle 82 87 92 %

FREQ Input Low Voltage MAX1543, VIN = 2.6V to 5.5V 0.3 x V

FREQ Input High Voltage MAX1543, VIN = 2.6V to 5.5V

FREQ Pulldown Current MAX1543, V

FB Regulation Voltage V

FB Fault Trip Level VFB falling 0.96 1 1.04 V
FB Load Regulation 0 ≤ I

FB Line Regulation VIN = 2.6V to 5.5V -0.08 ±0.15 %/V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IN

V

UVLO

MAIN

OSC

VIN rising 2.3 2.5 2.7

VIN falling 2.2 2.35 2.5

VFB = 1.3V, LX not switching 0.45 0.65

IN

VFB = 1.1V, LX switching 3.6 6.5

MAX1542 55

MAX1543

Rising edge 160

Hysteresis 15

MAX1542 1020 1200 1380

MAX1543 FREQ = AGND 512 600 768Operating Frequency f

No load

FB

≤ full load -1 %

MAIN

FREQ = AGND 51

FREQ = IN 55

FREQ = IN 1020 1200 1380

= 1.0V 3.5 5 6.5 µA

FREQ

TA = +85°C 1.224 1.240 1.256

T

= 0°C to +85°C 1.222 1.240 1.258

A

2.6 5.5 V

V

IN

0.7 x
V

IN

13 V

IN

V

mA

ms

°C

kHz

V

V

V

MAX1542/MAX1543

TFT LCD DC-to-DC Converter with

Operational Amplifiers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 3V, V

SUP

= 8V, V

SRC

= 28V, FREQ = IN (MAX1543), PGND = AGND = 0, TA= 0°C to +85°C, typical values at TA= +25°C,

unless otherwise noted.)

)

FB Input Bias Current VFB = 1.5V -40 +40 nA
FB Transconductance ∆I

FB Voltage Gain FB to COMP 700 V/V

LX On-Resistance R

LX Leakage Current I

LX Current Limit I
Current-Sense Transresistance 0.30 0.50 0.65 Ω

Soft-Start Step Size I

OPERATIONAL AMPLIFIERS

SUP Supply Range V

SUP Supply Current I

Input Offset Voltage V

Input Bias Current I

Input Common-Mode Voltage
Range

Common-Mode Rejection Ratio CMRR 0 ≤ V

Open-Loop Gain 125 dB

Output Voltage Swing High V

Output Voltage Swing Low V

Short-Circuit Current To V

Output Source-and-Sink Current

Power-Supply Rejection Ratio PSRR

Slew Rate 7.5 V/µs

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

= 5µA 75 160 280 µS

COMP

LX(ON

LX

LIM

VLX = 13V 0.01 20 µA

VFB = 1V, duty cycle = 65% 1.2 1.5 1.8 A

210 400 mΩ

MAX1542 14

SS

SUP

SUP

OS

BIAS

V

CM

OH

OL

MAX1543

Buffer configuration, V

VCM = V

/2, TA = +25°C 0 12 mV

SUP

NEG1, NEG2, POS1, POS2 +1 ±50 nA

, V

NEG_

POS_

I

= 100µA

OUT_

I

= 5mA

OUT_

I

= -100µA 2 15

OUT_

I

= -5mA 80 150

OUT_

/2

SUP

Buffer configuration, V
|∆V

< 10mV

OS|

DC, 6V ≤ V

/2

V

SUP

SUP

≤ 13V, V

FREQ = AGND 13Soft-Start Period t

FREQ = IN 14

= 4V, no load 1.3 1.9 mA

POS_

≤ V

SUP

V

V

Source 50 150

Sink 50 140

= 4V,

POS_

, V

POS_

=

NEG_

/ 8 A

LIM

4.5 13.0 V

0V

SUP

50 90 dB

SUP

-15V

SUP

-

2

-

V

SUP

150

SUP

80

-

40 mA

60 100 dB

ms

V

mV

mV

mA

-3dB Bandwidth RL = 10kΩ, CL =10pF, buffer configuration 12 MHz

Gain-Bandwidth Product GBW Buffer configuration 8 MHz

POSITIVE GATE-DRIVER TIMING AND CONTROL SWITCHES

DEL Capacitor Charge Current During startup, V

= 1V 4 5 6 µA

DEL

MAX1542/MAX1543

TFT LCD DC-to-DC Converter with
Operational Amplifiers

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS

(VIN= 3V, V

SUP

= 8V, V

SRC

= 28V, FREQ = IN (MAX1543), PGND = AGND = 0, TA= -40°C to +85°C, unless otherwise noted.)

PARAMETER

CONDITIONS

UNITS

DEL Turn-On Threshold

)

V

DEL Discharge Switch On­Resistance

During UVLO, V

IN

= 2.2V 20 Ω

CTL Input Low Voltage VIN = 2.6V to 5.5V 0.6 V

CTL Input High Voltage VIN = 2.6V to 5.5V 2 V

CTL Input Leakage Current CTL = AGND or IN -1 +1 µA

CTL-to-SRC Propagation Delay

ns

SRC Input Voltage Range 28 V

MAX1542 70

V

D RN

= 8V , C TL = IN ,

V

D E L

= 1.5V

MAX1543

SRC Input Current I

SRC

V

DRN

= 8V, CTL = AGND, V

DEL

= 1.5V 15 30

µA

DRN Input Current I

DRC

V

DRN

= 8V, CTL = AGND, V

DEL

= 1.5V,

MAX1543

90

µA

MAX1542 5 10

SRC to COM Switch On­Resistance

)

V

DEL

= 1.5V,

CTL = IN

MAX1543 15 30

Ω

DRN to COM Switch On­Resistance (MAX1543)

)

V

DEL

= 1.5V, CTL = AGND 30 60 Ω

COM to PGND Switch On­Resistance (MAX1543)

)

V

DEL

= 1.1V

Ω

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

IN Supply Range V

IN

2.6 5.5 V

VIN rising 2.3 2.7

IN Undervoltage Lockout
Threshold

V

UVLO

VIN falling 2.2 2.5

V

V

FB

= 1.3V, LX not switching

IN Quiescent Current I

IN

V

FB

= 1.1V, LX switching 6.5

mA

MAIN STEP-UP REGULATOR

Output Voltage Range V

MAIN

V

IN

13 V

MAX1542

FREQ = AGND

Operating Frequency f

OSC

MAX1543

FREQ = IN

kHz

FB Regulation Voltage V

FB

No load

V

FB Fault Trip Level VFB falling

V

FB Line Regulation VIN = 2.6V to 5.5V

%/V

FB Transconductance ∆I

COMP

= 5µA 75

µS

LX On-Resistance

)

mΩ

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 3V, V

SUP

= 8V, V

SRC

= 28V, FREQ = IN (MAX1543), PGND = AGND = 0, TA= 0°C to +85°C, typical values at TA= +25°C,

unless otherwise noted.)

SYMBOL

V

TH(DEL

MIN TYP MAX

1.178 1.240 1.302

100

130

100 180

R

SRC(ON

R

DRN(ON

R

COM(ON

R

LX(ON

350 1000 1800

1000 1400

512 768

1000 1400

1.215 1.260

0.96 1.04

150

0.65

0.15

300

400

MAX1542/MAX1543

TFT LCD DC-to-DC Converter with

Operational Amplifiers

_______________________________________________________________________________________ 5

)

)

)

)

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 3V, V

SUP

= 8V, V

SRC

= 28V, FREQ = IN (MAX1543), PGND = AGND = 0, TA= -40°C to +85°C, unless otherwise noted.)

LX Current Limit I
Current-Sense Transresistance 0.30 0.65 Ω

OPERATIONAL AMPLIFIERS

SUP Supply Range V

SUP Supply Current I

Input Offset Voltage V

Input Bias Current I

Input Common-Mode Voltage
Range

Output Voltage Swing High V

Output Voltage Swing Low V

Short-Circuit Current To V

Output Source-and-Sink Current

POSITIVE GATE-DRIVER TIMING AND CONTROL SWITCHES

DEL Capacitor Charge Current During startup, V

DEL Turn-On Threshold V

CTL Input Low Voltage VIN = 2.6V to 5.5V 0.6 V

CTL Input High Voltage VIN = 2.6V to 5.5V 2 V

SRC Input Voltage Range 28 V

SRC Input Current I

DRN Input Current I

SRC to COM Switch On­Resistance

DRN to COM Switch On­Resistance (MAX1543)

COM to PGND Switch On­Resistance (MAX1543)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

LIM

SUP

SUP

OS

BIAS

V

CM

OH

TH (DEL

SRC

DRN

R

SRC(ON

R

DRN(ON

R

COM(ON

VFB = 1V, duty cycle = 65% 1.2 1.8 A

4.5 13.0 V

Buffer configuration, V

VCM = V

/2, TA = +25ºC12mV

SUP

= 4V, no load 2.1 mA

POS_

NEG1, NEG2, POS1, POS2 ±50 nA

0V

V

-

I

OUT_

I

OUT_

I

OL

OUT_

I

OUT_

Buffer configuration, V
| ∆V

OS

= 100µA

= 5mA

= -100µA 15

= -5mA 150

SUP

/2

Source 50

Sink 50

= 4V,

POS_

| < 10mV

= 1.0V 4 6 µA

DEL

SUP

15

V

-

SUP

150

40 mA

1.178 1.302 V

V

= 8V, CTL = IN,

DRN

= 1.5V

V

DEL

V

= 8V, CTL = AGND, V

DRN

V

= 8V, CTL = AGND, V

DRN

MAX1542 130

MAX1543 180

= 1.5V 30

DEL

= 1.5V,

DEL

MAX1543

V

= 1.5V, CTL = IN

DEL

V

= 1.5V, CTL = AGND 60 Ω

DEL

V

= 1.1V 350 1800 Ω

DEL

MAX1542 10

MAX1543 30

SUP

150 µA

V

mV

mV

mA

µA

Ω

MAX1542/MAX1543

TFT LCD DC-to-DC Converter with
Operational Amplifiers

6 _______________________________________________________________________________________

Typical Operating Characteristics

(VIN= 3.3V, V

MAIN

= 8V, f

OSC

= 1.2MHz, TA= +25°C, unless otherwise noted.)

50

1 1000100

STEP-UP REGULATOR EFFICIENCY

vs. LOAD CURRENT (V

MAIN

= 8V)

65

55

85

75

95

70

60

90

80

MAX1542 toc01

LOAD CURRENT (mA)

EFFICIENCY (%)

10

MAX1543
f

OSC

= 1.2MHz

L = 4.7µH

VIN = 3.3V

VIN = 2.7V

VIN = 5V

50

1 100010010

STEP-UP REGULATOR EFFICIENCY

vs. LOAD CURRENT (V

MAIN

= 8V)

65

55

85

75

95

70

60

90

80

MAX1542 toc02

LOAD CURRENT (mA)

EFFICIENCY (%)

MAX1543
f

OSC

= 640kHz

L = 10µH

VIN = 3.3V

VIN = 2.7V

VIN = 5V

VIN = 5V

STEP-UP REGULATOR OUTPUT VOLTAGE

vs. LOAD CURRENT (V

MAIN

= 8V)

MAX1542 toc03

LOAD CURRENT (mA)

OUTPUT VOLTAGE (V)

10 100

7.6

7.7

7.8

7.9

8.0

8.1

7.5
1 1000

VIN = 3.3V
f

OSC

= 1.2MHz

MAX1542 toc04

VIN (V)

SUPPLY CURRENT (mA)

5.04.54.03.53.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0

2.5 5.5

STEP-UP REGULATOR SUPPLY CURRENT

vs. SUPPLY VOLTAGE

NO LOAD
f

OSC

= 1.2MHz

R

1

= 75kΩ

R

2

= 13.7kΩ

SUP DISCONNECTED

CURRENT INTO INDUCTOR

CURRENT INTO IN PIN

STEP-UP REGULATOR SUPPLY CURRENT

vs. TEMPERATURE

MAX1542 toc05

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

603510-15

0.4

0.8

1.2

1.6

2.0

0

-40 85

NO LOAD
V

IN

= 3.3V

f

OSC

= 1.2MHz

R

1

= 75kΩ

R

2

= 13.7kΩ

SUP DISCONNECTED

CURRENT INTO INDUCTOR

CURRENT INTO IN PIN

MAX1542 toc06

VIN (V)

SWITCHING FREQUENCY (kHz)

5.04.54.03.53.0

600

800

1000

1200

1400

400

2.5 5.5

SWITCHING FREQUENCY

vs. INPUT VOLTAGE

MAX1543
I

MAIN

= 200mA

FREQ = IN

FREQ = AGND

SUP SUPPLY CURRENT

vs. SUP VOLTAGE

MAX1542 toc07

V

SUP

(V)

I

SUP

(mA)

12.010.59.07.56.0

1.00

1.25

1.50

1.75

0.75

4.5 13.5

NO LOAD
BUFFER CONFIGURATION
POS_ = V

SUP

/2

SUP SUPPLY CURRENT

vs. TEMPERATURE

MAX1542 toc08

TEMPERATURE (°C)

I

SUP

(mA)

603510-15

1.2

1.6

2.0

0.8

-40 85

NO LOAD
BUFFER CONFIGURATION
V

POS

= V

SUP

/2

V

SUP

= 13V

V

SUP

= 8V

V

SUP

= 5V