Electronic Components Datasheet Search |
|
DS3994 Datasheet(PDF) 9 Page - Maxim Integrated Products |
|
DS3994 Datasheet(HTML) 9 Page - Maxim Integrated Products |
9 / 28 page 4-Channel Cold-Cathode Fluorescent Lamp Controller _____________________________________________________________________ 9 GATE DRIVERS MOSFET GATE DRIVERS GAn GBn DIGITAL CCFL CONTROLLER CHANNEL FAULT 512 x LAMP FREQUENCY [10.24MHz ~ 40.96MHz] LAMP FREQUENCY [20kHz ~ 80kHz] DIMMING PWM SIGNAL CHANNEL ENABLE 1.0V LCMn LAMP CURRENT MONITOR 400mV 2.0V LAMP OVERCURRENT LAMP STRIKE AND REGULATION LOC BIT IN CR1.0 LAMP OUT 1.0V OVDn OVERVOLTAGE DETECTOR LAMP MAXIMUM VOLTAGE REGULATION 64 LAMP CYCLE INTEGRATOR OVERVOLTAGE Figure 1. Per Channel Logic Diagram Detailed Description The DS3994 uses a push-pull drive scheme to convert a DC voltage (5V to 24V) to the high-voltage (600VRMS to 1200VRMS) AC waveform that is required to power the CCFLs. The push-pull drive scheme uses a minimal number of external components, which reduces assembly cost and makes the printed circuit board design easy to implement. The push-pull drive scheme also provides an efficient DC-to-AC conversion and produces near-sinusoidal waveforms. Each DS3994 channel drives two logic-level n-channel MOSFETs that are connected between the ends of a step-up transformer and ground (see Figure 1 and the Typical Operating Circuit). The transformer has a center tap on the primary side that is connected to a DC voltage supply. The DS3994 alternately turns on the two MOSFETs to create the high-voltage AC waveform on the secondary side. By varying the duration of the MOSFET turn-on times, the controller is able to accurately control the amount of current flowing through the CCFL. A resistor in series with the CCFL’s ground connection enables current monitoring. The voltage across this resistor is fed to the lamp current monitor (LCM) input on the DS3994. The DS3994 compares the peak resistor voltage against an internal reference voltage to deter- mine the duty cycle for the MOSFET gates. Each CCFL receives independent current monitoring and control, which results in equal brightness across all of the lamps and maximizes the lamp’s brightness and lifetime. The DS3994 can also drive more than one lamp per channel. See the Typical Operating Circuit section for implementation details when using multiple lamps per channel. EEPROM Registers and I2C-Compatible Serial Interface The DS3994 uses an I2C-compatible serial interface for communication with the on-board EEPROM configuration registers and user memory. The configuration registers, four Burst Dimming Stagger Registers (BDS1/2/3/4), and three Control Registers (CR1/2/3)—allow the user to cus- tomize many DS3994 parameters such as the time delay to stagger the burst dimming between channels, the lamp and dimming frequency sources, fault-monitoring options, and channel enabling/disabling. The three bytes of nonvolatile user memory can be used to store manu- facturing data such as date codes, serial numbers, or product identification numbers. The device is shipped from the factory with the con- figuration registers programmed to a set of default configuration parameters. To inquire about custom factory programming, please send an email to MixedSignal.Apps@dalsemi.com. |
Similar Part No. - DS3994 |
|
Similar Description - DS3994 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |