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 PackageApplicationLow Component Count /
Module Cost / Size
High "Nits/Watt" Efficiency
Operates Directly From 1 to
Li_Ion Cells
Lamp Current Compensation
Input Makes Indoor/Outdoor
And Wide Temperature Range
Applications Easy to DesignPinout
SpecificationsSupply Voltage (V_BATT).................................................................................................30V
Digital Input (ENABLE).....................................................................................-0.3V to 7V
Analog Inputs Transient Peak (I_SNS, OC_SNS, OV_SNS)..............................-25V to +25V
Analog Inputs (BRITE_IN, EA_IN)..................................................................-0.3V to 5.5V
Digital Inputs (DIM_CLK,DIM_MODE, DIV_248) .........................................-0.3V to 5.5V
Digital Output (AOUT, BOUT) .................................................................-0.3V to VDD_P +0.5V
Analog Outputs (BRITE_C, I_R, BRITE_OUT, BRITE_R, EA_OUT) ...-0.3V to VDD_A_ +0.5V
Operating Temperature Range ..................................................................... -45°C 100°C
Maximum Junction Temperature ...............................................................................125°C
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal.
DescriptionThe LX1689 is the latest generation Direct Drive CCFL (Cold Cathode Fluorescent Lamp) Controller. It uses new circuit design techniques (patents pending) and combines digital and linear circuits with an advanced BiCMOS process to create a more completecontroller in a small package. When compared to the original LX1686 design, identical module applications use from 12 to 30 less components. New functions and enhancements have been added to make the LX1689 even easier to use.
The on-chip PLL circuit used to synchronize the digital dimming burst frequency to the video frame rate, as
used in the LX1689, is replaced with a programmable counter. This counter can divide the video controller horizontal sync pulse, other external clock source or the internal chip clock source to generate the burst frequency.
The brightness control input allows the use of either a DC voltage or a PWM input to simplify design. Programmable polarity brightness control is retained, except in the case of externally clocked digital dimming. Two onboard LDO regulators extend the input voltage range of the IC up to 28 Volts without using
external circuitry as was required with our previous controllers. 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.
Integrating full wave rectifiers for each of three lamp inputs has significantly reduced the lamp feedback component count. In addition the LX1689 controller features include auto shutdown for open or broken lamps, and a lamp fault detection with a status reporting output.
LX1689 Data Sheet
