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PDF LX1689 Data sheet ( Hoja de datos )
| Número de pieza | LX1689 | |
| Descripción | Third Generation CCFL Controller | |
| Fabricantes | Microsemi Corporation | |
| Logotipo |  |
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INTEGRATED PRODUCTS
LX1689
Third Generation CCFL Controller
PRODUCTION DATA SHEET
DESCRIPTION
The LX1689 is the latest generation
The brightness control input allows the
Direct Drive CCFL (Cold Cathode use of either a DC voltage or a PWM
Fluorescent Lamp) Controller. It uses input to simplify design. Programmable
new circuit design techniques (patents polarity brightness control is retained,
pending) and combines digital and linear except in the case of externally clocked
circuits with an advanced BiCMOS digital dimming. Two onboard LDO
process to create a more complete regulators extend the input voltage range
controller in a small package.
of the IC up to 28 Volts without using
When compared to the original external circuitry as was required with our
LX1686 design, identical module previous controllers. The LX1689
applications use from 12 to 30 less includes a new lamp strike detection
components. New functions and scheme that saves a package pin and three
enhancements have been added to make external components. Internal circuits
the LX1689 even easier to use.
monitor lamp current pulses at the I_SNS
The on-chip PLL circuit used to input to determine if the lamp strikes and
synchronize the digital dimming burst if it stays ignited once operational.
frequency to the video frame rate, as
Integrating full wave rectifiers for
used in the LX1686, is replaced with a each of three lamp inputs has significantly
programmable counter. This counter can reduced the lamp feedback component
divide the video controller horizontal count. In addition the controller features
sync pulse, other external clock source include auto shutdown for open or broken
or the internal chip clock source to lamps, and a lamp fault detection with a
generate the burst frequency.
status reporting output.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
KEY FEATURES
3 to 28 Volt Single Fixed (±20%)
Supply Operating Range
Selectable Analog/Digital
Dimming Modes
Digital Dimming Can Synch to
External Or Internal Clocks
User Programmable Digital
Dimming Burst Frequency
252 mS Power On Delay
Flexible Lamp Current
Compensation Input
Open Lamp Shutdown and Fault
Output Indicator
“On Chip” Full Wave Lamp
Current & Voltage Rectifiers
20 Pin TSSOP Package
BENEFITS
Low Component Count /
Module Cost / Size
High “Nits/Watt” Efficiency
Operates Directly From 1 to 6
Li_Ion Cells
Lamp Current Compensation
Input Makes Indoor/Outdoor
And Wide Temperature Range
Applications Easy to Design
PRODUCT HIGHLIGHT
LX1689 CCFL Inverter Layouts Examples*
2.64in. (67mm)
Actual Inverter Size
OR
1.38in. (35mm)
.397 in.
(10mm)
.870 in.
(22mm)
Actual Inverter Size
*As Shown in Figure 1 (Typical Application)
Bill of Materials
1 LX1689CPW
1 Transformer
1 Dual FET
2 Connectors
7 Resistors
9 Capacitors
21 Total Count
Copyright 2000
Rev. 1.0b, 2003-03-31
TJ (°C)
0 to 70
-40 to 85
PACKAGE ORDER INFO
MIN VDD
3V
3V
MAX VDD
28V
28V
Plastic TSSOP
PW 20-PIN
LX1689CPW
LX1689IPW
Note: Available in Tape & Reel.
Append the letter “T” to the part number. (i.e. LX1689CPWT)
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
1 page  
INTEGRATED PRODUCTS
LX1689
Third Generation CCFL Controller
PRODUCTION DATA SHEET
RECOMMENDED OPERATING CONDITIONS
Parameter
Supply Voltage (V_BATT)
Digital Input (ENABLE)
Analog Inputs (I_SNS, OC_SNS, OV_SNS)
BRITE_IN Linear DC Voltage Range
BRITE_IN PWM Logic Signal Voltage Range
Digital Inputs (DIM_MODE, DIV_248,DIM_CLK)
Maximum Output Gate Charge (AOUT, BOUT)
LX1689
Min Typ
3
0
-3
0.5
0
0
10
Max
28
6.5
3
2
5
5.5
20
Units
V
V
VPK
V
V
V
nC
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, the following specifications apply over the operating ambient temperature: LX1689CPW: 0°C ≤ TA ≤ 70°C,
LX1689IPW: -40°C ≤ TA ≤ 85°C, except where otherwise noted.
Test conditions: V_BATT =3.3 to 28 VDC, I_R =80.6KΩ, BRITE_R = BRITE_OUT = 10KΩ, BRITE_C =open, ICOMP =100pf
Parameter
` POWER
Symbol
Test Conditions
LX1689
Units
Min Typ Max
Regulator Output Voltage
VDD_P Drop Out Voltage
Regulator Output Voltage
VDD_A Dropout Voltage
VBATT Static Current
VBATT Dynamic Current
Sleep Mode Current
Sleep Mode Current
` ENABLE INPUT
VDD_P
∆VDD_P
VDD_A
∆VDD_A
IBATT
IBATT
IBATT_SLEEP
IBATT_SLEEP
V_BATT = 6 to 28 V, I Load = 0 – 5mADC
∆VDD_P = -1% , I Load = 5mADC; TA = 25°C
V_BATT = 3.5 to 28V, I Load = 0 – 5mADC
∆VDD_A = -1% , I Load = 5mADC; TA = 25°C
CAOUT = CBOUT = 1000pF
VENABLE ≤ 0.4V; VBATT = 5V
VENABLE ≤ 0.4V; VBATT = 28V
5.05 5.3 5.55
V
50 mV
2.75 2.95 3.15
V
100 mV
5.5 9 mA
10 17 mA
2.8 5 µA
22 35 µA
Run Threshold
Shutdown Threshold
Input High Current
Input High Current
Input Low Current
` UNDER VOLTAGE LOCKOUT
VTH_ENRUN
VTL_ENSHDN
IIH_ENABLE
IIH_ENABLE
IIL_ENABLE
ENABLE = 2V
ENABLE = 5V
ENABLE = 0V
1.1 1.4
V
0.4 1.1
V
2 12 µA
35 80 µA
-1 0 1 µA
Startup Threshold
UVLO Threshold
VT_UVLO
Run Mode
Shutdown Mode
2.55 2.8
2.1 2.35
V
V
UVLO Hysteresis
VH_UVLO
200 mV
Copyright 2000
Rev. 1.0b, 2003-03-31
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
5 Page 
INTEGRATED PRODUCTS
LX1689
Third Generation CCFL Controller
PRODUCTION DATA SHEET
DESCRIPTION
FEATURE REVIEW
On-Chip LDO Regulators
Lamp Current Compensation
Two LDO regulators extend the input voltage range of the IC up The BRITE_OUT pin outputs a precision current that is
to 28 Volts without using external circuitry as was required with proportional to the BRITE_IN signal. This current can be applied to
our previous controllers.
a precision resistor to develop the brightness control voltage at the
Under Voltage Lockout
If the battery input voltage is too low for the controller to
function properly, it will turn itself off, preventing spurious
operation. If the battery voltage falls to less than 1V where UVLO
is no longer guaranteed, 10K pull down resistors on the AOUT and
BOUT pins insure the external power FETs cannot be biased on.
Power On Delay
A power up reset delays AOUT and BOUT turn on for
approximately 16384 x 1/fO milliseconds after power is applied.
This gives extra time for the BRITE_IN source voltage to stabilize
so the lamp is not inadvertently powered up at high brightness and
then suddenly lowered, creating an undesirable light flash.
Enhanced BRITE Conditioning Circuitry
The BRITE_IN input is now enhanced to accept either DC
voltage or logic PWM signals. When PWM signals are input, their
levels are clipped at 2V and 0.5V so lamp current will not be
affected by variations in logic signal level. In addition, the
BRITE_C pin permits filtering DC inputs and converting high
frequency PWM inputs to DC voltages with the addition of only a
single external capacitor. A low frequency (less than 500Hz)
error amplifiers non-inverting input. Since the output is constant
current, designers can easily compensate lamp current with respect
to temperature, input voltage, ambient or lamp light output, and
combinations of these conditions by using various temperature or
light sensitive components in combination with resistors. This
capability is very useful in automotive and outdoor applications
where operating temperatures and ambient light vary over wide
ranges. See functional pin description for details.
Strike Voltage Generation
Improved strike voltage generation circuits ramp strike voltage to
5X fO and repeats it’s cycle unless excessive high voltage is sensed
at OV_SNS. If OV_SNS is detected during strike, strike voltage
will not ramp and will hold the current voltage until total strikes
lamp cycles numbers reach 245,760. Strike potential is removed
immediately when the lamp strikes or if the time limit is reached.
Strike Detection
The LX1689 includes a new lamp strike detection scheme that
saves a package pin and three external components. Internal circuits
monitor lamp current pulses at the I_SNS input to determine if the
lamp strikes and if it stays ignited once operational.
PWM signal can be used to directly modulate the duty cycle of the Fault Time Out
lamp current. In this case the capacitor at BRITE_C is not
If the lamp fails to ignite with in approximately 1.6 seconds
installed.
(depending on Run Frequency) at maximum strike potential, or if it
Digital or Analog Dimming Modes
A DIM_MODE input pin selects either Analog or Digital mode.
In Analog mode DC voltage at BRITE_IN controls lamp current
amplitude. In Digital mode it controls digital dimming duty cycle
with amplitude fixed at a value set by the external current scaling
resistor (BRITE_R). When in Digital mode, the dimming burst
extinguishes while enabled, or the external clock frequency at the
DIM_CLK pin terminates, the output drive is shut down and the
BRITE_C pin is driven high. This pin can be monitored with a
CMOS gate to obtain a logical indication that a lamp fault has
occurred. It is especially useful in multiple lamp applications or for
system diagnostic input.
frequency can be synchronous to lamp current by selecting internal The voltage on pin BRITE_C will vary directly with BRITE
clocking, or to an external clock that may be a multiple of the input voltage, but does not exceed 1.2V unless a fault condition
video vertical frame rate. With an external clock source, three burst occurs.
rate selections are available by programming the DIV_248 input to
divide the source clock by 2,4, or 8. This clock source is further
divided by 64 generating the internal burst ramp waveform. Using
the internal clock as source the DIV_248 input changes to divide
by 4, 8, or 16. This feature allows the designer to set a burst
frequency in the range of 100 to 500Hz. The external clock source
must not be interrupted unless the BRITE_IN is set > 2V or the
lamp will extinguish.
On Chip Rectifier
Integrating full wave rectifiers for each of three lamp inputs has
significantly reduced lamp feedback component count. Current
Sense (I_SNS), Over Current Sense (OC_SNS) and Over Voltage
Sense (OV_SNS) signals are now detected using only one external
scaling resistor or capacitor each. Rectification accuracy is
improved with high performance on chip rectifiers to provide better
lamp current and voltage regulation.
Brightness Polarity Control
In Analog dimming mode or internal Digital Dimming, the IC
can be programmed to either increase or decrease lamp current
amplitude as a function of increasing signal at the BRITE_IN pin
by simply connecting the DIM_CLK input to ground or VDD_A
or open(see Dimming Table). If External Digital dimming mode is
used, lamp current amplitude is constant and its duty cycle is
always directly proportional to DC input voltage and / or PWM
Complete Fault Protection
In addition to the faulty lamp time out, lamp open, lamp shorted,
and either lamp terminal shorted to ground are detected. Open
circuit voltage can never go higher than the preset maximum strike
potential and total current from the circuit is safely limited with a
scaling resistor. UL safety specifications can now be easily met in
any application.
duty cycle at the BRITE_IN pin.
Copyright 2000
Rev. 1.0b, 2003-03-31
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet LX1689.PDF ] | |
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