Rainbow Electronics MAX1611 User Manual
19-1128; Rev 0; 9/96
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EVALUATION KIT
AVAILABLE
Digitally Controlled CCFL Backlight
Power Supplies
_______________General Description
The MAX1610/MAX1611 are fully integrated, highefficiency drivers for cold-cathode fluorescent lamps
(CCFLs). They operate from a 4.5V to 26V power
source. An on-board, high-switching-frequency power
MOSFET reduces external component count and magnetics size. The MAX1610/MAX1611 protect against
open or shorted lamps. The CCFL can be driven from
an isolated transformer secondary winding to improve
efficiency and avoid flicker at dim tube settings.
Brightness is adjusted by scaling the lamp current, or
by operating with a fixed lamp current and chopping
the CCFL on and off at a rate faster than the eye can
detect.
The MAX1610’s digital inputs increment, decrement, or
clear an internal, 5-bit up/down counter, which sets
CCFL brightness. The MAX1611 uses a System
Management Bus (SMBus) 2-wire serial interface to
directly set CCFL brightness. Both devices include
micropower shutdown and a linear regulator that eliminates the need for a separate logic supply. The digital
interface remains active in shutdown, preserving the
brightness setting.
________________________Applications
Notebook/Laptop Computers
Point-of-Sale Terminals
Portable Medical Equipment
Instrument Displays
____________________________Features
Direct Digital Control of CCFL Brightness
Low Supply Current: 3mA Max Operating
20µA Max Shutdown
Low-Voltage Operation, Down to 4.5V
Internal 26V, 0.7WPower Switch
Protection Against Open or Shorted Lamps
Supports Isolated Transformer Secondary
Winding
SMBus Serial Interface (MAX1611)
No Flicker at Low Brightness (internal 280Hz
current chopping)
High Power-to-Light Efficiency
Selectable 290kHz/145kHz Switching Frequency
Oscillator SYNC Input
16-Pin Narrow SO Package
______________Ordering Information
PART
MAX1610CSE
MAX1611CSE
TEMP. RANGE PIN-PACKAGE
0°C to +70°C
0°C to +70°C
16 Narrow SO
16 Narrow SO
MAX1610/MAX1611
__________________________________________________________Pin Configurations
TOP VIEW
UP
1
DN
2
SHDN
3
SYNC
SS
CC
CSAV
MINDAC
________________________________________________________________
4
5
6
7
8
MAX1610
SO
16
BATT
LX
15
BST
14
GND
13
VL
12
11
CS
10
OTP
9
REF
SDA
SCL
SMBSUS
SYNC
CC
CSAV
MINDAC
1
2
3
MAX1611
4
SS
5
6
7
8
SO
16
BATT
15
LX
14
BST
GND
13
VL
12
11
CS
10
OTP
9
REF
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
Digitally Controlled CCFL Backlight
Power Supplies
ABSOLUTE MAXIMUM RATINGS
BATT to GND............................................................-0.3V to 28V
BST to GND ..............................................................-0.3V to 30V
BST to LX....................................................................-0.3V to 6V
LX to GND................................................-0.6V to (BATT + 0.3V)
VL to GND...................................................................-0.3V to 6V
CS, CSAV, CC, SYNC, REF, MINDAC,
SS, OTP to GND............................................-0.3V to (VL + 0.3V)
SHDN, UP, DN to GND...............................................-0.3V to 6V
SMBSUS, SDA, SCL to GND ......................................-0.3V to 6V
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
(TA= 0°C to +70°C, BATT = 8.2V, MINDAC = 0V, unless otherwise noted. Typical values are at TA= +25°C.)
MAX1610/MAX1611
SUPPLY AND REFERENCE
BATT Input Voltage Range V
BATT Quiescent Supply Current,
Operate Mode
BATT = 25V
BATT, LX Current.....................................................................1A
SDA Current........................................................................50mA
VL Current...........................................................................50mA
Continuous Power Dissipation (T
SO (derate 8.70mW/°C above +70°C).........................696mW
Operating Temperature Range
MAX1610CSE/MAX1611CSE..............................0°C to +70°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
CONDITIONS
= +70°C)
A
MIN TYP MAXPARAMETER
4.75 26
UNITS
mA1.5 3
BATT Quiescent Supply Current,
Shutdown Mode
REF Load Regulation
SWITCHING REGULATOR
BATT-to-LX Switch On-Resistance
LX Switch Off-Leakage Current
Oscillator Frequency
SYNC Low Pulse Width
4.75V < BATT < 26V
No load
I
SOURCE
BST - LX = 4.1V
SYNC = REF
SYNC = GND
SYNC = GND or VL
SYNC = REF
SS = GND
SS = 0.5V mA2SS Sink Current
= 100µA
10 20
620
0.7 1.0
10
250 290 330
125 145 165
-1 1SYNC Input Current
2.5 4.0 5.5SS Source Current
µA
V4.25 4.5 4.75VL Output Voltage, Operate Mode
V3.0 3.6 4.75VL Output Voltage, Shutdown Mode
V1.92 2.0 2.08REF Output Voltage
mV
Ω
µA
kHz
kHz240 350Oscillator SYNC Pin Synchronization Range
ns200SYNC High Pulse Width
ns200
µA
V0.5SYNC Input Low Voltage
V4.0SYNC Input High Voltage
%89 91Power-Switch Maximum Duty Cycle
µA
2 _______________________________________________________________________________________
Digitally Controlled CCFL Backlight
Power Supplies
ELECTRICAL CHARACTERISTICS (continued)
(TA= 0°C to +70°C, BATT = 8.2V, MINDAC = 0V, unless otherwise noted. Typical values are at TA= +25°C.)
CONDITIONS
DAC AND ERROR AMPLIFIER
DAC Resolution Bits5
CSAV Regulation Point
CSAV to CC Voltage-to-Current Converter
Transconductance
CC Sink Current
OPEN AND SHORTED TUBE PROTECTION
MAX1610 LOGIC LEVELS
SHDN, UP, DN Input Low Voltage
SHDN, UP, DN Input High Voltage
SHDN, UP, DN Input Bias Current
MAX1611 LOGIC LEVELS
Guaranteed monotonic
-1 1MINDAC Input Bias Current
D/A at full scale
D/A at 1LSB 12
CC = 2V, CSAV = 1V, D/A at 1LSB
CC = 2V, CSAV = 1V, D/A at 1LSB
CC = 2V, CSAV = 0V, D/A at full scale
Referred to REF
GND < OTP < VL
V
= 0.6V mA6SDA Output Low Sink Current
SDA
OTP rising
232 247 260
-5 5CSAV Input Bias Current
-1 1OTP Input Bias Current
-1 1
-1 1SMBSUS, SDA, SCL Input Bias Current
85
80
20CC Source Current
MAX1610/MAX1611
UNITSMIN TYP MAXPARAMETER
V01MINDAC Input Voltage Range
µA
V3MINDAC Digital PWM Threshold
V0 1.0CSAV Input Voltage Range
mV
µA
µmho
µA
µA
mV-20 20OTP Voltage Trip Point
µA
mV500CS Overcurrent Cutoff Threshold
V0.8
V2.4
µA
V0.8SMBSUS, SDA, SCL Input Low Voltage
V2.2SMBSUS, SDA, SCL Input High Voltage
µA
_______________________________________________________________________________________ 3
Digitally Controlled CCFL Backlight
Power Supplies
TIMING CHARACTERISTICS—MAX1610
(Figure 1, TA= +25°C, unless otherwise noted.)
CONDITIONS
UP, DN Pulse Width High
UP, DN Pulse Width Low
UP, DN Pulse Separation
Counter Reset Time
TIMING CHARACTERISTICS—MAX1611
(Figures 2 and 3, TA= +25°C, unless otherwise noted.)
1
2
3
4
UNITSMIN TYP MAXSYMBOLPARAMETER
1t
1t
1t
1t
µs
µs
µs
µs
SCL Serial Clock High Period
SCL Serial Clock Low Period
MAX1610/MAX1611
SCL, SCA Rise Time
SCL, SDA Fall Time
Start Condition Setup Time
Start Condition Hold Time
SDA Valid to SCL Rising Edge
Setup Time, Slave Clocking in Data
SCL Falling Edge to SDA
Transition
SCL Falling Edge to SDA Valid,
Reading Out Data
Note 1: Guaranteed by design.
HIGH
LOW
R
F
SU:STA
HD:STA
SU:DAT
HD:DAT
DV
(Note 1)
(Note 1)
(Note 1) ns0t
CONDITIONS
UNITSMIN TYP MAXSYMBOLPARAMETER
4t
4.7t
1t
0.3t
4.7t
4t
500t
1t
µs
µs
µs
µs
µs
µs
ns
µs
4 _______________________________________________________________________________________
Digitally Controlled CCFL Backlight
Power Supplies
__________________________________________Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
REF OUTPUT VOLTAGE
vs. REF OUTPUT CURRENT
2.2
SHDN = VL, BATT = 5V
2.1
2.0
1.9
1.8
1.7
REF OUTPUT VOLTAGE (V)
1.6
1.5
10 100 1000 10000
1
REF OUTPUT CURRENT (µA)
VL OUTPUT VOLTAGE
vs. VL LOAD CURRENT
3.70
SHDN = GND
3.65
3.60
3.55
3.50
3.45
VL VOLTAGE (V)
3.40
3.35
3.30
0
BATT = 12V
VL LOAD CURRENT (µA)
BATT = 5V
400 800600 1000200
MAX1610/1611-TOC1
BATT CURRENT (mA)
MAX1610/1611-TOC4
BATT CURRENT (µA)
2.0
1.8
1.6
1.4
1.2
1.0
10
8
6
4
2
0
BATT SUPPLY CURRENT
vs. BATT VOLTAGE (SHDN = VL)
SHDN = VL, OTP = 3V
4 12162024288
0
BATT (V)
BATT SUPPLY CURRENT
vs. BATT VOLTAGE (SHDN = OV)
SHDN = OV
4 12162024288
0
BATT (V)
MAX1610/1611-TOC2
VL VOLTAGE (V)
MAX1610/1611-TOC5
VL (V)
VL OUTPUT VOLTAGE
vs. VL OUTPUT CURRENT
5.0
SHDN = VL, OTP = 3V
4.5
BATT = 5V
4.0
3.5
3.0
2.5
2.0
0
VL OUTPUT CURRENT (mA)
VL OUTPUT VOLTAGE
vs. BATT VOLTAGE (SHDN = OV)
5.0
NO LOAD ON VL,
SHDN = OV
4.5
4.0
3.5
3.0
2.5
2.0
0
4 12162024288
BATT (V)
BATT = 12V
MAX1610/1611-TOC3
20 30 4010
MAX1610/1611-TOC6
MAX1610/MAX1611
VL OUTPUT VOLTAGE
vs. BATT VOLTAGE (SHDN = VL)
5.0
4.5
4.0
3.5
VL (V)
3.0
2.5
2.0
NO LOAD ON VL,
SHDN = VL
0
4 12162024288
BATT (V)
MAX1610/1611-TOC7
_______________________________________________________________________________________
5
Digitally Controlled CCFL Backlight
Power Supplies
______________________________________________________________Pin Description
PIN
MAX1610 MAX1611
1 — UP
— 1 SDA
2 — DN
— 2 SCL
3 —
— 3 SMBSUS
MAX1610/MAX1611
4 4 SYNC
5 5 SS
6 6 CC
7 7 CSAV
8 8 MINDAC
9 9 REF
10 10 OTP
11 11 CS
12 12 VL
13 13 GND
14 14 BST
15 15 LX
16 16 BATT
NAME
SHDN
Logic-Level Input. A rising edge on UP increments the 5-bit counter for the 5-bit DAC.
UP = DN = 1 presets the counter to mid-scale.
System Management Bus Serial Data Input and Open-Drain Output
Logic-Level Input. A rising edge on DN decrements the 5-bit counter for the 5-bit DAC.
UP = DN = 1 presets the counter to mid-scale.
System Management Bus Serial Clock Input
Logic-Level Shutdown Input Pin. Applying a logic low to SHDN places the chip in a low-
supply-current shutdown mode.
System Management Bus Suspend Mode Input. SMBSUS Selects one of two chip-
configuration settings, which are preprogrammed serially.
Oscillator Synchronization Input. Tying SYNC to REF sets the oscillator frequency to 290kHz.
Tying SYNC to GND or VL lowers the oscillator frequency to 145kHz.
Soft-Start Pin. A 4µA current source feeds the capacitor placed on SS. The voltage on this
pin limits the peak current in the switch. When the lamp is turned off, SS pulls to GND.
Output of the Voltage-to-Current Converter; Input to the PWM Comparator, which sets the
current limit. A capacitor placed at CC sets the current-regulator-loop bandwidth.
Input to the Voltage-to-Current Converter, which averages the voltage on CSAV using the
capacitor on CC.
The voltage at MINDAC sets the DAC’s minimum-scale output voltage. Tying MINDAC to
VL enables the internal 280Hz current-chopping mode.
2.0V Reference Output. Bypass with 0.1µF to GND.
Open-Tube Protection Comparator. As long as OTP exceeds the reference voltage, the
N-channel BATT-to-LX switch is forced off.
Low-Side Current-Sense Input. The current-mode regulator terminates the switch cycle
when the voltage at CS exceeds REF - CC.
Output of the Internal Linear Regulator. VL can be overdriven by a voltage greater than 4.75V
to operate the chip from +5V ± 5%, and to conserve power. Bypass with 0.1µF to GND.
System Ground
Power Input to the High-Side Gate Driver, which switches the internal N-channel MOSFET
on and off.
Ground Connection for the Internal High-Side Gate Driver; source-connection point for the
internal N-channel MOSFET
4.5V to 25V Battery-Voltage Input Point. Connects to the internal N-channel power MOSFET’s
drain, and to the input of the internal linear regulator that powers the chip.
FUNCTION
6 _______________________________________________________________________________________
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