DS3994 Maxim Integrated Products, DS3994 Datasheet
DS3994
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DS3994 Summary of contents
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... The DS3994 is a 4-channel controller for cold-cathode fluorescent lamps (CCFLs) that backlight liquid crystal displays (LCDs and PC monitor applications. The DS3994’s features make it suitable for use in even the largest LCDs, while its low BOM cost makes it ideal for the entire range of LCD TVs and monitors. ...
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Cold-Cathode Fluorescent Lamp Controller ABSOLUTE MAXIMUM RATINGS Voltage Range SDA, and SCL CC Relative to Ground.............................................-0.5V to +6.0V Voltage Range on Leads Other than V SDA, and SCL…………………………..-0. Stresses beyond those listed under ...
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ELECTRICAL CHARACTERISTICS (continued +4.5V to +5.5V -40°C to +85°C PARAMETER High-Level Output Voltage (GA, GB) UVLO Threshold—V Rising CC UVLO Threshold—V Falling CC UVLO Hysteresis SVM Falling Edge Threshold SVM Hysteresis LCM and ...
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... Note 3: Voltage including the DC offset, V DCB . Note 4: This is the minimum pulse width guaranteed to generate an output burst, which will generate the DS3994’s minimum burst duty cycle. This duty cycle may be greater than the duty cycle of the PSYNC input. Once the duty cycle of the PSYNC input is greater than the DS3994’ ...
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T = +25°C, unless otherwise noted ACTIVE SUPPLY CURRENT vs. SUPPLY VOLTAGE DPWM = 100% DPWM = 50% 7 DPWM = 10 SVM < 2V GATE Q = 3.5nC ...
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Cold-Cathode Fluorescent Lamp Controller (V = +5.0V +25°C, unless otherwise noted BURST DIMMING AT 150Hz AND 50% 1ms 5. 1ms 5. 1ms 2.0V LCM 1ms 1.0V OVD LAMP STRIKE WITH ...
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... PSYNC 3 configured as a DPWM receiver. If the DS3994 is configured as a DPWM source (i.e., the DPWM signal is generated internally), the DPWM signal is output on this pin for use by other DPWM receiver DS3994s. DPWM Oscillator Resistor Adjust. A resistor to ground on this lead sets the frequency of the DPWM ...
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... POSC DPWM FREQUENCY SET/ DPWM CLOCK INPUT 8 _____________________________________________________________________ 4 DataSheet U .com EEPROM 2 CONTROL REGISTERS I C- COMPATIBLE INTERFACE 3-BYTE USER MEMORY DS3994 FAULT HANDLING 20kHz TO 80kHz x512 LFSS BIT AT PLL CR1.2 20kHz TO 80kHz OSCILLATOR (±2%) DPSS BIT 0 AT CR1.3 MUX RGSO BIT AT CR1.4 1 ...
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... RMS 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 ...
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... DPWM signal. The DS3994 can generate its own DPWM signal internally (set DPSS = 0 in CR1), which can then be sourced to other DS3994s if required, or the DPWM signal can be supplied from an external source (set DPSS = 1 in CR1 ...
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... The internally generated DPWM signal is available at the PSYNC I/O pin (set RGSO = 0 in CR1) for sourcing to other DS3994s, if any, in the circuit. This allows all DS3994s in the system to be synchronized to the same DPWM signal. The DS3994 that is generating the DPWM signal for other DS3994s in the system is referred to as the DPWM source ...
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... When the DPWM signal is provided by an external source, either from the PSYNC pin of another DS3994 or from some other user-generated source input into the PSYNC I/O pin of the DS3994. In this mode, the BRIGHT and POSC inputs are disabled and should be grounded (see Figure 4). When multiple DS3994s are used in a design, DS3994s configured to use externally generated DPWM signals are referred to as DPWM receivers ...
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... LFSS = 1 in CR1). When the lamp clock is internally generated, the frequency (20kHz to 80kHz) is set by an external resistor at the LOSC. In this case, the DS3994 can act as a lamp frequency source because the lamp clock is output at the LSYNC I/O pin for synchronizing any other DS3994s configured as lamp frequency receivers ...
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... FREQUENCY RESISTOR-SET LAMP FREQUENCY ANALOG BRIGHTNESS 2.0V OR 3.3V 0.5V OR 0.0V DIMMING CLOCK (22.5Hz TO 440Hz) RESISTOR-SET LAMP FREQUENCY DPWM SIGNAL (22.5Hz TO 440Hz) RESISTOR-SET LAMP FREQUENCY Figure 6. Frequency Configuration Options for Designs Using Multiple DS3994s 14 ____________________________________________________________________ 4 DataSheet U .com ANALOG BRIGHTNESS BRIGHT 0.5V OR 0.0V PSYNC DS3994 LAMP CLOCK LSYNC ...
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DPWM SIGNAL 22.5Hz TO 440Hz LAMP CURRENT SOFT-START LAMP CYCLE GAn/GBn MOSFET GATE DRIVERS LAMP CURRENT Figure 7. Digital PWM Dimming and Soft-Start 4 DataSheet U .com 4-Channel Cold-Cathode Fluorescent Lamp Controller SOFT-START (EXPANDED ...
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... POSCR0 and POSCR1 bit settings as shown in the Control Register 2 (CR2) in the Detailed Register Descriptions section. Example: Selecting the resistor values to configure a DS3994 to have a 50kHz lamp frequency and a 160Hz dimming clock frequency: For this configuration, POSCR0 and POSCR1 must be programmed to 1 and 0, respectively, to select 90Hz to 220Hz as the dimming clock frequency range ...
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... Figure 9 shows a flowchart of how the DS3994 controls and monitors each lamp. The steps are as follows: 1) Supply Check—The lamps will not turn on unless the DS3994 supply voltage is ≥ 4.5V and the voltage at the supply voltage monitor (SVM) input is ≥ 2V. 2) Strike Lamp—When both the DS3994 and the DC ...
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Cold-Cathode Fluorescent Lamp Controller LAMP OVERCURRENT [INSTANTANEOUS IF ENABLED VIA THE LOC BIT AT CR1.0] Figure 9. Fault-Handling Flow Chart 18 ____________________________________________________________________ 4 DataSheet U .com DEVICE AND INVERTER SUPPLIES AT PROPER LEVELS? YES RESET FAULT COUNTER AND ...
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... Detailed Register Descriptions The DS3994’s register map is shown in Table 4. Detailed register and bit descriptions follow in the sub- sequent tables. Table 4. Register Map BYTE BYTE FACTORY ADDRESS NAME DEFAULT* F0h Reserved F1h Reserved F2h Reserved F3h Reserved F4h CR1 F5h ...
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Cold-Cathode Fluorescent Lamp Controller F4h: Control Register 1 (CR1) BIT NAME Lamp Overcurrent 0 LOC 0 = Lamp overcurrent detection disabled Lamp overcurrent detection enabled. POSC Select. See POSCR0 and POSCR1 bits in Control Register 2 ...
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F5h: Control Register 2 (CR2) BIT NAME 0 UMWP 1 POSCR0 2 POSCR1 3 Reserved 4 Reserved 5 LD0 6 LD1 7 BVRS F8–FBh: Burst Dimming Stagger (BDS1/2/3/4) BIT NAME 0 BDSC0 1 BDSC1 2 BDSC2 3 BDSC3 4 ...
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Cold-Cathode Fluorescent Lamp Controller FCh: Control Register 3 (CR3) BIT NAME 0 SLOPE 1 LST0 2 LST1 3 SB0 4 SB1 5 SB2 6 IGO 7 LOFS 22 ____________________________________________________________________ 4 DataSheet U .com BRIGHT Analog Dimming Slope Select ...
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The following terminology is commonly used to 2 describe I C data transfers. Master Device: The master device controls the slave devices on the bus. The master device generates SCL clock pulses, start, and stop conditions. Slave Devices: Slave ...
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... It is possible to take advantage of that phenomenon by repeatedly addressing the DS3994, which allows the next byte of data to be written as soon as the DS3994 is ready to receive the data. The alternative to acknowl- edge polling is to wait for a maximum period of t ...
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... The transformer should be able to operate in the 20kHz 80kHz frequency range of the DS3994, and the turns ratio should be selected so the MOSFET drivers run at 28% to 35% duty cycle during steady state operation. The transformer must be able to withstand the high open-circuit voltage that will be used to strike the lamp. ...
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... C ap aci tor val affect vol tag cap aci tor m ay cause a l ong for each i ts nor ati ng l evel . — Place close to V and GND on DS3994. CC UNITS kHz W mA mΩ ...
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... U .com 4-Channel Cold-Cathode Fluorescent Lamp Controller = 5V ±10 BRIGHT V CC DUAL POWER R1 MOSFET PSYNC SVM LSYNC GAn LOSC DS3994 POSC GBn OVDn FAULT LCMn SDA C1 SCL A0 GND ____________________________________________________________________ Typical Operating Circuits SUPPLY VOLTAGE (5V ±10% TO 24V ±10%) C4 TRANSFORMER CCFL LAMP C2 R8 ...
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... Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2006 Maxim Integrated Products is a registered trademark of Dallas Semiconductor Corporation. Heaney 4 DataSheet U .com Typical Operating Circuits (continued) DEVICE SUPPLY VOLTAGE (5V ±10 DS3994 V CC GND DUAL N-CHANNEL POWER MOSFET + +12V TO +24V LCM LM339 OVD ...