MAX1739EEP+ Maxim Integrated Products, MAX1739EEP+ Datasheet

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MAX1739EEP+

Manufacturer Part Number
MAX1739EEP+
Description
Display Drivers Wide Brightness Rang e CCFL Backlight Con
Manufacturer
Maxim Integrated Products
Datasheet

Specifications of MAX1739EEP+

Lead Free Status / RoHS Status
Lead free / RoHS Compliant
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 maxi-
mize the dimming range.
The MAX1739/MAX1839 monitor and limit the trans-
former 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 pulse-
width modulated (DPWM) method. CCFL brightness is
controlled by an analog voltage or is set with an
SMBus
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 oscilla-
tor. An internal 5.3V linear regulator powers the MOS-
FET 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.
19-1755; Rev 1; 3/01
SMBus is a trademark of Intel Corp.
________________________Applications
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.
Pg
Notebook/Laptop Computers
Car Navigation Displays
LCD Monitors
Point-of-Sale Terminals
Portable Display Electronics
TM
-compatible two-wire interface (MAX1739).
________________________________________________________________ Maxim Integrated Products
General Description
CCFL Backlight Controllers
Wide Brightness Range
♦ 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
♦ Integrated Royer MOSFET Drivers Reduce
♦ Buck Operation Synchronized to Royer Oscillator
♦ Synchronizable DPWM Frequency
♦ Pin-Selectable Brightness Control Interface
♦ SMBus Serial Interface (MAX1739)
♦ Analog Interface (MAX1739/MAX1839)
MAX1739EEP
MAX1839EEP
Pin Configurations continued at end of data sheet.
Protection
Transformer Pin Count
TOP VIEW
PART
CRF/SDA
CTL/SCL
MINDAC
SH/SUS
MODE
CSAV
CTFB
CCV
REF
CCI
10
1
2
3
4
5
6
7
8
9
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
Ordering Information
MAX1739
QSOP
Pin Configuration
20
19
18
17
16
15
14
13
12
11
BATT
DH
LX
BST
VL
GND
CS
DL1
DL2
SYNC
PIN-PACKAGE
20 QSOP
20 QSOP
Features
1

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MAX1739EEP+ Summary of contents

Page 1

... Point-of-Sale Terminals Portable Display Electronics † Pg SMBus is a trademark of Intel Corp. ________________________________________________________________ Maxim Integrated Products 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. Wide Brightness Range CCFL Backlight Controllers ♦ Fast Response to Input Change ♦ ...

Page 2

Wide Brightness Range CCFL Backlight Controllers ABSOLUTE MAXIMUM RATINGS V to GND ...........................................................-0.3V to 30V BATT GND.................................................-0.3V to 34V BST SYNC .................................................................-0. BST .................................................-0. ...

Page 3

ELECTRICAL CHARACTERISTICS (continued) (V+ = 8.2V, V /SUS = V = 5.5V, MINDAC = GND PARAMETER DAC AND ERROR AMPLIFIER DAC Resolution MINDAC Input Voltage Range MINDAC Input Bias Current MINDAC Digital PWM Disable Threshold CSAV Input ...

Page 4

Wide Brightness Range CCFL Backlight Controllers ELECTRICAL CHARACTERISTICS (continued) (V+ = 8.2V, V /SUS = V = 5.5V, MINDAC = GND PARAMETER ANALOG INTERFACE BRIGHTNESS CONTROL (MODE connected to REF or GND ) CRF/SDA, CRF Input Range ...

Page 5

ELECTRICAL CHARACTERISTICS (V+ = 8.2V, V /SUS = V = 5.5V, MINDAC = GND PARAMETER SUPPLY AND REFERENCE V Input Voltage Range BATT V Quiescent Current, Shutdown BATT VL Output Voltage, Normal Operation VL Undervoltage Lockout Threshold ...

Page 6

Wide Brightness Range CCFL Backlight Controllers (V = 12V 1V, MODE = GND, Circuit of Figure 8.) IN CTL CRF MINDAC WIDE INPUT RANGE (V = 8V) BATT 4μs/div WIDE INPUT RANGE (V = ...

Page 7

1V, MODE = GND, Circuit of Figure 8.) IN CTL CRF MINDAC SYNCHRONIZED DPWM (f = 100kHz, V MODE CTL 1ms/div STARTUP (ADC SOFT-START, MODE = GND) 20ms/div LAMP-OUT VOLTAGE LIMITING ...

Page 8

Wide Brightness Range CCFL Backlight Controllers (V = 12V 1V, MODE = GND, Circuit of Figure 8.) IN CTL CRF MINDAC VL vs 5.40 NORMAL OPERATION 5.35 SHUTDOWN 5.30 5.25 5.20 5.15 ...

Page 9

NAME PIN MAX1739 MAX1839 1 REF REF 2 MINDAC MINDAC 3 CCI CCI 4 CCV CCV SH/SUS CRF/SDA CRF 7 CTL/SCL CTL 8 MODE MODE 9 CSAV CSAV 10 CTFB CTFB 11 SYNC SYNC 12 DL2 DL2 ...

Page 10

Wide Brightness Range CCFL Backlight Controllers Detailed Description The MAX1739/MAX1839 regulate the brightness of a CCFL in three ways: 1) Linearly controlling the lamp current. 2) Digitally pulse-width modulating (or chopping) the lamp current (DPWM). 3) Using both methods simultaneously ...

Page 11

Voltage and Current Control Loops The MAX1739/MAX1839 use two control loops. The cur- rent control loop regulates the average lamp current. The voltage control loop limits the maximum average primary- side transformer voltage. The voltage control loop is active during ...

Page 12

Wide Brightness Range CCFL Backlight Controllers Figure 2. Functional Diagram 12 ______________________________________________________________________________________ ...

Page 13

All backlight circuit designs can undergo a transient overvoltage condition when the laptop is plugged into the AC adapter and V increases. ...

Page 14

Wide Brightness Range CCFL Backlight Controllers brightness code of ob00000 corresponds to a 9.375% DPWM duty cycle, and a brightness code of ob11111 corresponds to a 100% DPWM duty cycle. The duty cycle changes by 3.125% per step, except codes ...

Page 15

Table 3. Brightness Adjustment Ranges (for 33:1 Dimming) POSITIVE- BRIGHTNESS SCALE ADC MODE = GND, Maximum MODE = REF CTL/SCL Brightness V V CRF/SDA MODE = GND, MODE = REF, Minimum CTL/SCL V Brightness V ...

Page 16

Wide Brightness Range CCFL Backlight Controllers ADC- 10k SMBus ADC+ 500pF DPWM SYNCHRONIZATION SIGNAL Figure 6. DPWM Synchronization optimized using R14 and R15 as shown in Figure 7. The resistor-divider can be used to force commutation as close to the ...

Page 17

With the buck switch short- ed, the center tap rises above its regulation point, which causes the CCV amplifier’s output (V low. To detect this, ...

Page 18

Wide Brightness Range CCFL Backlight Controllers a proven application that is useful for a wide range of CCFL tubes and power ranges. Table 5 shows the rec- ommended components for a 4.5W application. The MAX1739/MAX1839 require three external switches to ...

Page 19

1.1 S S(RMS CTFB N2A the average DC voltage at center top CT πV Nπ -NπV 2π ω Figure ...

Page 20

Wide Brightness Range CCFL Backlight Controllers transient that C is designed to protect against is CCV open tube at the beginning of DPWM pulses. Large C values reduce transient overshoots, but CCV can cause loss of regulation at low DPWM ...

Page 21

Write-Byte Format S ADDRESS WR 7 bits 1b Slave Address Read-Byte Format S ADDRESS WR ACK 7 bits 1b 1b Slave Address Send-Byte Format S ADDRESS WR ACK COMMAND 7 bits Start condition Shaded = Slave ...

Page 22

Wide Brightness Range CCFL Backlight Controllers LOW HIGH SMBCLK SMBDATA t t HD:STA SU:STA A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = ...

Page 23

Table 6. Commands Description COMMAND POR PROTOCOL BYTE* STATE 0x01 Read and 0b0XXX 0x17 Write XX01 0x02 Read and 0b0XXX 0xF9 Write XX10 0x03 Read 0b0XXX 0x96 Only XX11 0x04 Read 0b0XXX 0x00 Only XX00 0x40 Read ...

Page 24

Wide Brightness Range CCFL Backlight Controllers [STATUS1–STATUS0] (POR = 0b11) The status register returns information on fault condi- tions lamp is not connected to the secondary of the transformer, the MAX1739 will detect that the lamp cur- rent ...

Page 25

Pin Configurations (continued) TOP VIEW REF 1 20 MINDAC 2 19 CCI 3 18 CCV 4 17 MAX1839 CRF 6 15 CTL 7 14 MODE 8 13 CSAV 9 12 CTFB 10 11 QSOP ______________________________________________________________________________________ Wide Brightness ...

Page 26

... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 26 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products ...

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