19-1755; Rev 1; 3/01
KIT
ATION
EVALU
E
BL
AVAILA
Wide Brightness Range
CCFL Backlight Controllers
MAX1739/MAX1839
†
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)
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 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
TM
-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 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.
Ordering Information
PART
MAX1739EEP
MAX1839EEP
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 QSOP
20 QSOP
________________________Applications
Notebook/Laptop Computers
Car Navigation Displays
LCD Monitors
Point-of-Sale Terminals
Portable Display Electronics
TOP VIEW
REF 1
MINDAC 2
CCI 3
CCV 4
SH/SUS 5
CRF/SDA 6
CTL/SCL 7
MODE 8
CSAV 9
CTFB 10
†
Pg
Pin Configuration
20 BATT
19 DH
18 LX
17 BST
MAX1739
16 VL
15 GND
14 CS
13 DL1
12 DL2
11 SYNC
QSOP
Pin Configurations continued at end of data sheet.
1
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
MAX1739/MAX1839
†
ABSOLUTE MAXIMUM RATINGS
V
BATT
to GND ...........................................................-0.3V to 30V
V
BST
, V
SYNC
to GND.................................................-0.3V to 34V
V
BST
to V
LX
.................................................................-0.3V to 6V
V
DH
to V
LX
.................................................-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
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.
ELECTRICAL CHARACTERISTICS
(V+ = 8.2V, V
SH
/SUS = V
SH
= 5.5V, MINDAC = GND,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SUPPLY AND REFERENCE
V
BATT
Input Voltage Range
V
BATT
Quiescent Current, Operation
with Full Duty Cycle on DH
V
BATT
Quiescent Current, Shutdown
VL Output Voltage, Normal Operation
VL Output Voltage, Shutdown
VL Undervoltage Lockout Threshold
VL Undervoltage Lockout Hysteresis
REF Output Voltage, Normal
Operation
V
L
POR Threshold
SWITCHING REGULATOR
DH Driver On-Resistance
DL1, DL2 Driver On-Resistance
Minimum DH Switching Frequency
DH Minimum Off-Time
DH Maximum Duty Cycle
SYNC Synchronization Range
SYNC Input Current
SYNC Input Threshold
SYNC Input Hysteresis
SYNC Threshold Crossing to DL1,
DL2 Toggle Delay
CS Overcurrent Threshold
Detect falling edges on SYNC
0 < V
SYNC
< 30V
SYNC falling, referred to CS
Referred to the SYNC input threshold
V
SYNC
= 0 to 5V, C
DL_1
and C
DL_2
< 100pF,
50% point on SYNC to 50% point on DL1 or DL2
408
450
64
-2
400
50
500
100
1/t
DH
, SYNC = CS or GND, not synchronized
49
250
56
375
98
200
2
600
150
120
492
18
18
64
500
Ω
Ω
kHz
ns
%
kHz
μA
mV
mV
ns
mV
4.5V < VL < 5.5V, I
REF
= 40μA
1.96
0.9
V
L
= V
BATT
V
L
= open
DH = DL1 = DL2 = open
SH/SUS
=
SH
= GND
6V < V
BATT
< 28V, 0 < I
LOAD
< 15mA
SH/SUS
=
SH
= GND, no load
VL rising (leaving lockout)
VL falling (entering lockout)
4.0
300
2.00
2.04
2.7
5.0
3.5
V
BATT
= 28V
V
BATT
= V
L
= 5V
4.6
6
3.2
3.2
6
5.35
4.5
5.5
28
6
6
20
5.5
5.5
4.6
V
mV
V
V
V
mA
μA
V
V
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Wide Brightness Range
CCFL Backlight Controllers
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 8.2V, V
SH
/SUS = V
SH
= 5.5V, MINDAC = GND,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
DAC AND ERROR AMPLIFIER
DAC Resolution
MINDAC Input Voltage Range
MINDAC Input Bias Current
MINDAC Digital PWM Disable
Threshold
CSAV Input Voltage Range
CSAV Regulation Point
CSAV Input Bias Current
CSAV to CCI Transconductance
CTFB Input Voltage Range
CTFB Input Bias Current
CTFB Regulation Point
CTFB to CCV Transconductance
TIMERS AND FAULT DETECTION
Chopping Oscillator Frequency
Digital PWM Chop-Mode Frequency
MODE to DPWM Sync Ratio
Lamp-Out Detection Timeout Timer
(Center-Tap Voltage Stuck at
Maximum) (Note 1)
CSAV Lamp-Out Threshold
Fault-Detection Threshold on CCV
Shorted Buck-Switch Detection
Timeout Timer (UL1950 Protection)
(Note 3)
Lamp Turn-On Delay
MODE Operating Voltage Range
MODE = GND Threshold
(min Brightness = 0)
MODE = REF Threshold
(max Brightness = 0)
MODE = VL Threshold
(MAX1739 SMB Interface Mode)
MODE AC Signal Amplitude
MODE AC Signal Synchronization
Range
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)
Peak to peak (Note 5)
Chopping oscillator synchronized to MODE AC
signal
1.4
VL - 0.6
2
32
100
(Note 2)
V
CCV
< fault-
detection
threshold on CCV
No AC signal on MODE
32kHz AC signal on MODE
100kHz AC signal on MODE
-5.5
1V < V
CCV
< 2.7V
No AC signal on MODE, not synchronized
No AC signal on MODE
32kHz AC signal on MODE
100kHz AC signal on MODE
F
MODE
/ F
DPWM
V
CSAV
< CSAV
lamp-out
threshold
No AC signal on MODE
32kHz AC signal on MODE
100kHz AC signal on MODE
50
0.4
332
291
256
82
4
11
0.6
2.6
ms
V
V
V
V
V
kHz
2.06
1V < V
CCI
< 2.7V
0
-1
570
30
24
205
600
40
28
220
250
781
128
2.33
2.05
0.66
75
100
1
259
ms
mV
V
2.73
s
0 < V
MINDAC
< 2V
MINDAC = VL
Guaranteed monotonic
5
0
-1
2.4
0
V
MINDAC
= 0, DAC code = 11111 binary
V
MINDAC
= 0, DAC code = 00001 binary
V
MINDAC
= 1V, DAC code = 00000 binary
188
2
93
-1
100
2
1
630
50
32
235
Hz
194
6.25
100
2.9
2
1
4
0.8
200
16
110
1
μA
μmho
V
μA
mV
μmho
kHz
mV
Bits
V
μA
V
V
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1739/MAX1839
†
After
SH/SUS
or SH forces device on or
SH
rises
_______________________________________________________________________________________
3
Wide Brightness Range
CCFL Backlight Controllers
MAX1739/MAX1839
†
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 8.2V, V
SH
/SUS = V
SH
= 5.5V, MINDAC = GND,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
CRF/SDA, CRF Input Range
CRF/SDA, CRF Input Current
CTL/SCL, Input Range
CTL Input Range
CTL/SCL, CTL Input Current
ADC Resolution
ADC Hysteresis
SH
Input Low Voltage
SH
Input High Voltage
SH/SUS
Input Hysteresis when
Transitioning In and Out of Shutdown
SH
Input Bias Current
CRF/SDA, CTL/SCL,
SH/SUS
Input
CRF/SDA, CTL/SCL,
SH/SUS
Input
CRFSDA, CTLSCL Input Hysteresis
CRF/SDA, CTL/SCL,
SH/SUS
Input
CRF/SDA Output Low Sink Current
CTL/SCL Serial Clock High Period
CTL/SCL Serial Clock Low Period
Start Condition Setup Time
Start Condition Hold Time
CRF/SDA Valid to CTL/SCL Rising Edge
Setup Time, Slave Clocking in Data
CTL/SCL Falling Edge to CRF/SDA
Transition
CTL/SCL Falling Edge to CRF/SDA
Valid, Reading Out Data
V
CRF/SDA
= 0.4V
t
HIGH
t
LOW
t
SU:STA
t
HD:STA
t
SU:DAT
t
HD:DAT
t
DV
-1
4
4
4.7
4.7
4
250
0
1
2.1
300
1
-1
2.1
150
1
0.8
V
CRF/SDA
= V
CRF
= 5.5V
V
CRF/SDA
= V
CRF
= 5.5V,
SH/SUS
=
SH
= 0
MAX1739
MAX1839
MODE = REF or GND
Guaranteed monotonic
-1
0
0
-1
5
1
0.8
CONDITIONS
MIN
2.7
TYP
MAX
5.5
20
1
CRF/
SDA
CRF
1
UNIT
V
µA
µA
V
V
µA
Bits
LSB
V
V
mV
µA
V
V
mV
µA
mA
µs
µs
µs
µs
ns
ns
µs
ANALOG INTERFACE BRIGHTNESS CONTROL
(MODE connected to REF or GND )
SYSTEM MANAGEMENT BUS BRIGHTNESS CONTROL
(MAX1739, MODE connected to V
L
, see Figures 12 and 13)
4
_______________________________________________________________________________________
Wide Brightness Range
CCFL Backlight Controllers
ELECTRICAL CHARACTERISTICS
(V+ = 8.2V, V
SH
/SUS = V
SH
= 5.5V, MINDAC = GND,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 6)
PARAMETER
SUPPLY AND REFERENCE
V
BATT
Input Voltage Range
V
BATT
Quiescent Current, Shutdown
VL Output Voltage, Normal Operation
VL Undervoltage Lockout Threshold
REF Output Voltage, Normal
Operation
VL POR Threshold
SWITCHING REGULATOR
DH Driver On-Resistance
DL1, DL2 Driver On-Resistance
SYNC Synchronization Range
CS Overcurrent Threshold
DAC AND ERROR AMPLIFIER
CSAV Regulation Point
CTFB Regulation Point
CTFB to CCV Transconductance
SH
Input Low Voltage
SH
Input High Voltage
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
CRF/SDA Output Low Sink Current
V
CRF/SDA
= 0.4V
2.1
4
0.8
V
V
mA
2.1
1V < V
CCV
< 2.7V
V
MINDAC
= 0, DAC code = 11111 binary
186
560
30
202
640
50
0.8
mV
mV
µmho
V
V
Detect falling edges on SYNC
64
408
18
18
200
492
Ω
Ω
kHz
mV
VL = V
BATT
VL = open
SH/SUS
=
SH
= GND
6V < V
BATT
< 28V,
0 < I
LOAD
< 15mA
VL rising (leaving lockout)
VL falling (entering lockout)
4.5V < VL < 5.5V, I
REF
= 40µA
4.0
1.95
0.9
2.05
2.7
5.0
4.6
6
5.5
28
20
5.6
4.6
V
µA
V
V
V
V
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1739/MAX1839
†
ANALOG INTERFACE BRIGHTNESS CONTROL
(MODE connected to REF or MODE connected to GND)
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.
Note 5:
The amplitude is measured with the following circuit:
V
AMPLITUDE
> 2V
500pF
MODE
10k
Note 6:
Specifications from -40°C to +85°C are guaranteed by
design, not production tested.
5
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