Rainbow Electronics MAX1839 User Manual

General Description

The MAX1739/MAX1839 fully integrated controllers are
optimized to drive cold-cathode fluorescent lamps
(CCFLs) using the industry-proven Royer oscillator
inverter architecture. The Royer architecture provides
near sinusoidal drive waveforms over the entire input
range to maximize the life of CCFLs. The MAX1739/
MAX1839 optimize this architecture to work over a wide
input voltage range, achieve high efficiency, and maxi­mize the dimming range.

The MAX1739/MAX1839 monitor and limit the trans­former center-tap voltage when required. This ensures
minimal voltage stress on the transformer, which
increases the operating life of the transformer and
eases its design requirements. These controllers also
provide protection against many other fault conditions,
including lamp-out and buck short faults.

These controllers achieve 50:1 dimming range by
simultaneously adjusting lamp current and “chopping”
the CCFL on and off using a digitally adjusted pulse­width modulated (DPWM) method. CCFL brightness is
controlled by an analog voltage or is set with an
SMBusTM-compatible two-wire interface (MAX1739).

The MAX1739/MAX1839 drive an external high-side
N-channel power MOSFET and two low-side N-channel
power MOSFETs, all synchronized to the Royer oscilla­tor. An internal 5.3V linear regulator powers the MOS­FET drivers and most of the internal circuitry. The
MAX1739/MAX1839 are available in space-saving
20-pin QSOP packages and operate over the -40°C to
+85°C temperature range.

________________________Applications

Notebook/Laptop Computers

Car Navigation Displays

LCD Monitors

Point-of-Sale Terminals

Portable Display Electronics

Features

♦ Fast Response to Input Change

♦ Wide Input Voltage Range (4.6V to 28V)

♦ High Power-to-Light Efficiency

♦ Minimizes Transformer Voltage Stress

♦ Lamp-Out Protection with 2s Timeout

♦ Buck Switch Short and Other Single-Point Fault

Protection

♦ Integrated Royer MOSFET Drivers Reduce

Transformer Pin Count

♦ Buck Operation Synchronized to Royer Oscillator

♦ Synchronizable DPWM Frequency

♦ Pin-Selectable Brightness Control Interface

♦ SMBus Serial Interface (MAX1739)

♦ Analog Interface (MAX1739/MAX1839)

MAX1739/MAX1839

†

Wide Brightness Range

CCFL Backlight Controllers

________________________________________________________________ Maxim Integrated Products 1

Pin Configuration

19-1755; Rev 1; 3/01

For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

†

Patent pending

SMBus is a trademark of Intel Corp.

Ordering Information

Pin Configurations continued at end of data sheet.

PART TEMP. RANGE PIN-PACKAGE

MAX1739EEP -40°C to +85°C 20 QSOP
MAX1839EEP -40°C to +85°C 20 QSOP

TOP VIEW

REF

MINDAC

CCI

SH/SUS

CRF/SDA

CTL/SCL

CSAV

1

2

3

4

MAX1739

5

6

7

8

9

10

20

BATT

19

DH

18

LX

17

BSTCCV

VL

16

GND

15

14

CS

DL1MODE

13

12

DL2

11

SYNCCTFB

QSOP

MAX1739/MAX1839

†

Wide Brightness Range
CCFL Backlight Controllers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V+ = 8.2V, VSH/SUS = VSH= 5.5V, MINDAC = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

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.

VBATT to GND ...........................................................-0.3V to 30V

V

BST

, V

SYNC

to GND.................................................-0.3V to 34V

V

BST

to VLX.................................................................-0.3V to 6V

V

DH

to VLX.................................................-0.3V to (V

BST

+ 0.3V)

V

LX

to GND...................................................-6V to (V

BST

+ 0.3V)

VL to GND...................................................................-0.3V to 6V

V

CCV

, V

CCI

, V

REF

, V

DL1

, V

DL2

to GND .........-0.3V to (VL + 0.3V)

V

MINDAC

, V

CTFB

, V

CSAV

to GND ................................-0.3V to 6V

V

CS

to GND...................................................-0.6V to (VL + 0.3V)

V

MODE

to GND.............................................................-6V to 12V

V

CRF/SDA

, V

CRF

, V

CTL/SCL

, V

CTL

, V

SH/SUS

,

V

SH

to GND ............................................................-0.3V to 6V

Continuous Power Dissipation (T

A

= +70°C)

20-Pin QSOP (derate 9.1mW/°C above +70°C)...........727mW

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

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

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

SUPPLY AND REFERENCE

V

BATT

V

BATT

with Full Duty Cycle on DH

V

BATT

VL Output Voltage, Normal Operation
VL Output Voltage, Shutdown SH/SUS = SH = GND, no load 3.5 4.5 5.5 V

VL Undervoltage Lockout Threshold

VL Undervoltage Lockout Hysteresis 300 mV

REF Output Voltage, Normal
Operation

VL POR Threshold 0.9 2.7 V

SWITCHING REGULATOR

DH Driver On-Resistance 18 Ω
DL1, DL2 Driver On-Resistance 18 Ω

Minimum DH Switching Frequency 1/tDH, SYNC = CS or GND, not synchronized 49 56 64 kHz

DH Minimum Off-Time 250 375 500 ns

DH Maximum Duty Cycle 98 %

SYNC Synchronization Range Detect falling edges on SYNC 64 200 kHz

SYNC Input Current 0 < V

SYNC Input Threshold SYNC falling, referred to CS 400 500 600 mV

SYNC Input Hysteresis Referred to the SYNC input threshold 50 100 150 mV

SYNC Threshold Crossing to DL1,
DL2 Toggle Delay

CS Overcurrent Threshold 408 450 492 mV

PARAMETER CONDITIONS MIN TYP MAX UNITS

VL = V

Input Voltage Range

Quiescent Current, Operation

BATT

V

= open 6 28

L

DH = DL1 = DL2 = open

Quiescent Current, Shutdown SH/SUS = SH = GND 6 20 µA

6V < V

< 28V, 0 < I

BATT

VL rising (leaving lockout) 4.6

VL falling (entering lockout) 4.0 V

4.5V < VL < 5.5V, I

< 30V -2 2 µA

SYNC

V

= 0 to 5V, C

SYNC

50% point on SYNC to 50% point on DL1 or DL2

4.6 5.5

V

= 28V 3.2 6

BATT

= VL = 5V 3.2 6

V

BATT

< 15mA

LOAD

= 40µA 1.96 2.00 2.04 V

REF

DL_1

and C

DL_2

< 100pF,

5.0 5.35 5.5 V

120 ns

V

mA

MAX1739/MAX1839

†

Wide Brightness Range

CCFL Backlight Controllers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 8.2V, VSH/SUS = VSH= 5.5V, MINDAC = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

DAC AND ERROR AMPLIFIER

DAC Resolution Guaranteed monotonic 5 Bits

MINDAC Input Voltage Range 0 2 V

MINDAC Input Bias Current 0 < V

MINDAC Digital PWM Disable
Threshold

CSAV Input Voltage Range 0 0.8 V

CSAV Regulation Point

CSAV Input Bias Current -1 1 µA

CSAV to CCI Transconductance 1V < V

CTFB Input Voltage Range 0 2 V
CTFB Input Bias Current -1 1 µA

CTFB Regulation Point 570 600 630 mV

CTFB to CCV Transconductance 1V < V

TIMERS AND FAULT DETECTION

Chopping Oscillator Frequency No AC signal on MODE, not synchronized 24 28 32 kHz

Digital PWM Chop-Mode Frequency

MODE to DPWM Sync Ratio F

Lamp-Out Detection Timeout Timer
(Center-Tap Voltage Stuck at
Maximum) (Note 1)

CSAV Lamp-Out Threshold 50 75 100 mV

Fault-Detection Threshold on CCV (Note 2) 0.4 1 V

Shorted Buck-Switch Detection
Timeout Timer (UL1950 Protection)
(Note 3)

Lamp Turn-On Delay After SH/SUS or SH forces device on or SH rises 4 ms

MODE Operating Voltage Range -5.5 11 V

MODE = GND Threshold
(min Brightness = 0)

MODE = REF Threshold
(max Brightness = 0)

MODE = VL Threshold
(MAX1739 SMB Interface Mode)

MODE AC Signal Amplitude Peak to peak (Note 5) 2 V

MODE AC Signal Synchronization
Range

PARAMETER CONDITIONS MIN TYP MAX UNITS

< 2V -1 1 µA

MINDAC

MINDAC = VL 2.4 2.9 4 V

V

V

V

No AC signal on MODE 205 220 235

32kHz AC signal on MODE 250

100kHz AC signal on MODE 781

V
lamp-out
threshold

V
detection
threshold on CCV

To sync DPWM oscillator, not in shutdown
(Note 4)

To sync DPWM oscillator, not in shutdown
(Note 4)

To sync DPWM oscillator, not in shutdown
(Note 4)

Chopping oscillator synchronized to MODE AC
signal

= 0, DAC code = 11111 binary 188 194 200

MINDAC

= 0, DAC code = 00001 binary 2 6.25 16

MINDAC

= 1V, DAC code = 00000 binary 93 100 110

MINDAC

< 2.7V 100 µmho

CCI

< 2.7V 30 40 50 µmho

CCV

/ F

MODE

CSAV

CCV

DPWM

< CSAV

< fault-

No AC signal on MODE 2.06 2.33 2.73

32kHz AC signal on MODE 2.05

100kHz AC signal on MODE 0.66

No AC signal on MODE 332 291 259

32kHz AC signal on MODE 256

100kHz AC signal on MODE 82

1.4 2.6 V

VL - 0.6 V

32 100 kHz

mV

Hz

128

s

ms

0.6 V

MAX1739/MAX1839

†

Wide Brightness Range
CCFL Backlight Controllers

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 8.2V, VSH/SUS = VSH= 5.5V, MINDAC = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

ANALOG INTERFACE BRIGHTNESS CONTROL (MODE connected to REF or GND )

CRF/SDA, CRF Input Range 2.7 5.5 V

CRF/SDA, CRF Input Current

CTL/SCL, Input Range MAX1739 0

CTL Input Range MAX1839 0 CRF V

CTL/SCL, CTL Input Current MODE = REF or GND -1 1 µA

ADC Resolution Guaranteed monotonic 5 Bits

ADC Hysteresis 1 LSB

SH Input Low Voltage 0.8 V
SH Input High Voltage 2.1 V

SH/SUS Input Hysteresis when

Transitioning In and Out of Shutdown
SH Input Bias Current -1 1 µA

SYSTEM MANAGEMENT BUS BRIGHTNESS CONTROL (MAX1739, MODE connected to VL, see Figures 12 and 13)
CRF/SDA, CTL/SCL, SH/SUS Input
CRF/SDA, CTL/SCL, SH/SUS Input

CRFSDA, CTLSCL Input Hysteresis 300 mV
CRF/SDA, CTL/SCL, SH/SUS Input

CRF/SDA Output Low Sink Current V

CTL/SCL Serial Clock High Period t

CTL/SCL Serial Clock Low Period t

Start Condition Setup Time t

Start Condition Hold Time t

C RF/S D A V al id to C TL/S C L Ri si ng E d g e
S etup Ti m e, S l ave C l ocki ng i n D ata

CTL/SCL Falling Edge to CRF/SDA
Transition

CTL/SCL Falling Edge to CRF/SDA
Valid, Reading Out Data

PARAMETER CONDITIONS MIN TYP MAX UNIT

= V

V

CRF/SDA

V

CRF/SDA

CRF/SDA

HIGH

LOW

SU:STA

HD:STA

t

SU:DAT

t

HD:DAT

t

DV

= 0.4V 4 mA

= 5.5V 20 µA

CRF

= V

= 5.5V, SH/SUS = SH = 0 -1 1 µA

CRF

150 mV

2.1 V

-1 1 µA

4µs

4.7 µs

4.7 µs

4µs

250 ns

0ns

CRF/

SDA

0.8 V

1µs

V

MAX1739/MAX1839

†

Wide Brightness Range

CCFL Backlight Controllers

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS

(V+ = 8.2V, VSH/SUS = VSH= 5.5V, MINDAC = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 6)

Note 1: Corresponds to 512 DPWM cycles or 65536 MODE

cycles.

Note 2: When the buck switch is shorted, V

CTFB

goes high

causing V

CCV

to go below the fault detection threshold.

Note 3: Corresponds to 64 DPWM cycles or 8192 MODE cycles.
Note 4: The MODE pin thresholds are only valid while the part is

operating. In shutdown, V

REF

= 0 and the part only
differentiates between SMB mode and ADC mode. In
shutdown with ADC mode selected, the CRF/SDA and
CTL/SCL pins are at high impedance and will not cause
extra supply current when their voltages are not at
GND or VL.

V

AMPLITUDE

> 2V

MODE

500pF

10k

Note 5: The amplitude is measured with the following circuit:

Note 6: Specifications from -40°C to +85°C are guaranteed by

design, not production tested.

SUPPLY AND REFERENCE

V

BATT

V

BATT

VL Output Voltage, Normal Operation

VL Undervoltage Lockout Threshold

REF Output Voltage, Normal
Operation

VL POR Threshold 0.9 2.7 V

SWITCHING REGULATOR

DH Driver On-Resistance 18 Ω

DL1, DL2 Driver On-Resistance 18 Ω

SYNC Synchronization Range Detect falling edges on SYNC 64 200 kHz

CS Overcurrent Threshold 408 492 mV

DAC AND ERROR AMPLIFIER

CSAV Regulation Point V

CTFB Regulation Point 560 640 mV

CTFB to CCV Transconductance 1V < V

ANALOG INTERFACE BRIGHTNESS CONTROL (MODE connected to REF or MODE connected to GND)

SH Input Low Voltage 0.8 V
SH Input High Voltage 2.1 V

SYSTEM MANAGEMENT BUS BRIGHTNESS CONTROL (MODE connected to VL)

CRF/SDA, CTL/SCL, SH/SUS Input
Low Voltage

CRF/SDA, CTL/SCL, SH/SUS Input
High Voltage

PARAMETER CONDITIONS MIN TYP MAX UNITS

VL = V

Input Voltage Range

Quiescent Current, Shutdown SH/SUS = SH = GND 20 µA

BATT

VL = open 6 28

6V < V
0 < I

VL rising (leaving lockout) 4.6

VL falling (entering lockout) 4.0

4.5V < VL < 5.5V, I

MINDAC

< 28V,

BATT

< 15mA

LOAD

= 40µA 1.95 2.05 V

REF

= 0, DAC code = 11111 binary 186 202 mV

< 2.7V 30 50 µmho

CCV

4.6 5.5

5.0 5.6 V

0.8 V

2.1 V

V

V

CRF/SDA Output Low Sink Current V

CRF/SDA

= 0.4V 4 mA

MAX1739/MAX1839

†

Wide Brightness Range
CCFL Backlight Controllers

6 _______________________________________________________________________________________

Typical Operating Characteristics

(VIN= 12V, V

CTL

= V

CRF

, V

MINDAC

= 1V, MODE = GND, Circuit of Figure 8.)

4µs/div

WIDE INPUT RANGE

(V

BATT

= 8V)

V

CSAV

500mV/div

V

CTAP

5V/div

V

DH

20V/div

MAX1739/1839 toc01

4µs/div

WIDE INPUT RANGE

(V

BATT

= 20V)

V

CSAV

500mV/div

V

CTAP

5V/div

V

DH

20V/div

MAX1739/1839 toc02

100µs/div

V

CCI

V

CCI

V

CCI

V

CCV

V

CCV

V

CCV

WIDE INPUT RANGE

(V

BATT

= 8V, DPWM = 9%, V

CTL

= 0)

V

CSAV

500mV/div

V

CTAP

10V/div

V

CCV, VCCI

200mV/div

1.2V

MAX1739/1839 toc03

100µs/div

V

CCI

V

CCI

V

CCI

V

CCV

V

CCV

V

CCV

WIDE INPUT RANGE

(V

BATT

= 20V, DPWM = 9%, V

CTL

= 0)

V

CSAV

500mV/div

V

CTAP

10V/div

V

CCV, VCCI

200mV/div

1.2V

MAX1739/1839 toc04

20µs/div

FEED-FORWARD COMPENSATION

V

CTAP

5mV/div

V

IN

20V

10V

V

CSAV

500mV/div

V

DH

20V/div

MAX1739/1839 toc05

4µs/div

SWITCHING WAVEFORMS

V

CSAV

500mV/div

V

CTAP

10V/div

V

DH

20V/div

V

DL

5V/div

MAX1739/1839 toc08

MAX1739/MAX1839

†

Wide Brightness Range

CCFL Backlight Controllers

_______________________________________________________________________________________ 7

Typical Operating Characteristics (continued)

(VIN= 12V, V

CTL

= V

CRF

, V

MINDAC

= 1V, MODE = GND, Circuit of Figure 8.)

20ms/div

STARTUP

(ADC SOFT-START, MODE = GND)

V

CTAP

10V/div

V

BATT

V

CSAV

500mV/div

I

BATT

500mA/div

MAX1739/1839 toc09

12V

0

2ms/div

LAMP-OUT VOLTAGE LIMITING

V

SECONDARY

2kV/div

V

CTAP

5V/div

MAX1739/1839 toc10

1ms/div

SYNCHRONIZED DPWM

(f

MODE

= 100kHz, V

CTL

= V

CRF

/2)

V

CSAV

500mV/div

V

CTAP

5V/div

V

DH

20V/div

MAX1739/1839 toc07

1ms/div

SYNCHRONIZED DPWM

(f

MODE

= 32kHz, V

CTL

= V

CRF

/2)

V

CSAV

500mV/div

V

CTAP

5V/div

V

DH

20V/div

MAX1739/1839 toc06

400ms/div

LAMP-OUT VOLTAGE LIMITING

V

SECONDARY

2kV/div

V

CTAP

5V/div

MAX1739/1839 toc11

0

200

100

500

400

300

800

700

600

900

0105 152025

INPUT CURRENT vs.

INPUT VOLTAGE

MAX1739/1839 toc12

V

BATT

(V)

I

BATT

(mA)

0

2

1

5

4

3

8

7

6

9

SHUTDOWN CURRENT (µA)

SHUTDOWN

MINIMUM BRIGHTNESS

MAXIMUM BRIGHTNESS

MAX1739/MAX1839

†

Wide Brightness Range
CCFL Backlight Controllers

8 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VIN= 12V, V

CTL

= V

CRF

, V

MINDAC

= 1V, MODE = GND, Circuit of Figure 8.)

5.40

5.35

5.30

5.25

VL (V)

5.20

5.15

5.10

NORMAL OPERATION

SHUTDOWN

0.01 1 100.1 100

VL vs. I

VL

IVL (mA)

MAX1739/1839 toc13

5.36

5.35

5.34

VL (V)

5.33

VL vs. BATT VOLTAGE

NORMAL OPERATION

SHUTDOWN

0101552520

V

(V)

BATT

4.60

4.55

4.50

4.45
SHUTDOWN VL (V)

MAX1739/1839 toc14

4.6

4.5

4.4

4.3

SHUTDOWN VL (V)

4.2

4.1

4.0

VL vs. TEMPERATURE

SHUTDOWN

NORMAL OPERATION

VL (V)

MAX1739/1839 toc15

6

5

4

3

2

1

0

5.32

5.31

-40 10-15 356085

TEMPERATURE (°C)

4.40

4.35