DS3988T+T&R Maxim Integrated Products, DS3988T+T&R Datasheet

Page 1

... NV User Memory for Storage of Serial 33 GA8 32 OVD7 Numbers and Date Codes 31 LCM7 ♦ 4.5V to 5.5V Single-Supply Operation 30 GB7 ♦ -40°C to +85°C Temperature Range GA7 29 28 OVD6 ♦ 48-Lead TQFP (7mm x 7mm) Package 27 LCM6 GB6 26 25 GA6 ______________________________________________ Maxim Integrated Products Features 1 ...

Page 2

Cold-Cathode Fluorescent Lamp Controller ABSOLUTE MAXIMUM RATINGS Voltage SDA, and SCL CC Relative to Ground.............................................-0.5V to +6.0V Voltage on Leads Other than SDA, and SCL…………………………..-0. Stresses beyond those listed under “Absolute ...

Page 3

ELECTRICAL CHARACTERISTICS (continued +4.5V to +5.5V -40°C to +85°C PARAMETER SYMBOL High-Level Output Voltage (GA, GB) UVLO Threshold—V Rising CC UVLO Threshold—V Falling CC UVLO Hysteresis V SVM Threshold SVM Hysteresis LCM and OVD ...

Page 4

Cold-Cathode Fluorescent Lamp Controller ELECTRICAL CHARACTERISTICS (See Figure +4.5V to +5.5V, timing referenced PARAMETER SYMBOL SCL Clock Frequency f Bus Free Time Between Stop and t Start Conditions Hold ...

Page 5

T = +25°C, unless otherwise noted ACTIVE SUPPLY CURRENT vs. SUPPLY VOLTAGE f = 71kHz LF:OSC 19 DPWM = 100% GATE Q = 3.5nC DPWM = 50% 13 DPWM = 10% 11 ...

Page 6

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 2.0V OVD LAMP STRIKE WITH OPEN ...

Page 7

PINS BY CHANNEL (n = 1–8) NAME GAn GBn LCMn OVDn NAME PIN 13, 18, GND Ground Connection 24, 45 ...

Page 8

Cold-Cathode Fluorescent Lamp Controller SDA DEVICE 2 I SCL CONFIGURATION COMPATIBLE PORT A0 INTERFACE FAULT LAMP FREQUENCY LSYNC INPUT/OUTPUT EXTERNAL RESISTOR LOSC LAMP FREQUENCY SET DPWM SIGNAL PSYNC INPUT/OUTPUT ANALOG BRIGHTNESS BRIGHT CONTROL EXTERNAL RESISTOR POSC ...

Page 9

OF 8 CHANNELS CHANNEL ENABLE CHANNEL FAULT DPWM SIGNAL DIGITAL CCFL CONTROLLER 512 x LAMP FREQUENCY [20.48MHz TO 40.96MHz] PHASED LAMP FREQUENCY [40kHz TO 80kHz] Figure 1. Per Channel Logic Diagram Detailed Description The DS3988 uses a push-pull drive ...

Page 10

Cold-Cathode Fluorescent Lamp Controller Channel Phasing The lamp-frequency MOSFET gate turn-on times are equally phased among the eight channels during the burst period. This reduces the inrush current that would result from all lamps switching simultaneously, and hence eases ...

Page 11

RESISTOR-SET DIMMING CLOCK 2.0V ANALOG DIMMING CONTROL VOLTAGE 0.5V DPWM SIGNAL 22.5Hz TO 440Hz RESISTOR TO SET THE DIMMING FREQUENCY Figure 3. DPWM Source Configuration Options DPWM SIGNAL 22.5Hz TO 440Hz Figure 4. The DPWM Receiver Configuration To generate the ...

Page 12

Cold-Cathode Fluorescent Lamp Controller ANALOG BRIGHTNESS 2.0V BRIGHT 0.5V PSYNC RESISTOR-SET LSYNC DIMMING FREQUENCY POSC RESISTOR-SET LOSC LAMP FREQUENCY BRIGHT PSYNC LSYNC POSC LOSC ANALOG BRIGHTNESS 2.0V BRIGHT 0.5V PSYNC LSYNC DIMMING CLOCK POSC (22.5Hz TO 440Hz) LOSC RESISTOR-SET ...

Page 13

DPWM SIGNAL 22.5Hz TO 440Hz LAMP CURRENT SOFT-START LAMP CYCLE 1 GAn/GBn MOSFET GATE DRIVERS SOFT-START PROFILE REGISTER SSP1. 0-3 PROGRAMMABLE SOFT-START PROFILE WITH INCREASING MOSFET PULSE WIDTHS OVER A 16 LAMP CYCLE PERIOD RESULTS IN A LINEAR RAMP IN ...

Page 14

Cold-Cathode Fluorescent Lamp Controller Setting the Lamp and Dimming Clock (DPWM) Frequencies Using External Resistors Both the lamp and dimming clock frequencies can be set using external resistors. The resistance required for either frequency can be determined using the ...

Page 15

Figure 8 shows a flowchart of how the DS3988 controls and monitors each lamp. The steps are as follows: 1) Supply Check—The lamps will not turn on unless the DS3988 supply voltage is ≥4.5V and the voltage at the supply ...

Page 16

Cold-Cathode Fluorescent Lamp Controller Detailed Register Descriptions The DS3988’s Register Map is shown in Table 1. Detailed register and bit descriptions follow in the sub- sequent tables. Soft-Start Profile (SSPx) Registers—Each of the four soft-start profile registers (SSP1–4) contains ...

Page 17

Table 3. Control Register 1 (CR1) BIT NAME FUNCTION Lamp Overcurrent Lamp overcurrent detection disabled. 0 LOC 1 = Lamp overcurrent detection enabled. Note: Gate duty cycle changes during soft-start larger than 5% can cause false LOC fault. ...

Page 18

Cold-Cathode Fluorescent Lamp Controller Table 4. Control Register 2 (CR2) BIT NAME User Memory Write Protect. 0 UMWP 0 = User Memory Write Access Blocked 1 = User Memory Write Access Permitted DPWM Oscillator Range Select. When using an ...

Page 19

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 devices ...

Page 20

Cold-Cathode Fluorescent Lamp Controller Byte Write: A byte write consists of 8 bits of informa- tion transferred from the master to the slave (most sig- nificant bit first) plus a 1-bit acknowledgement from the slave to the master. The ...

Page 21

COMMUNICATIONS KEY WHITE BOXES INDICATE THE MASTER START ACK CONTROLLING SDA NOT SHADED BOXES INDICATE THE SLAVE IS P STOP N ACK CONTROLLING SDA REPEATED START WRITE A ...

Page 22

Cold-Cathode Fluorescent Lamp Controller Table 5. Transformer Specifications PARAMETER Turns Ratio (Secondary/Primary) (Notes 11, 12, 13) Frequency Output Power Output Current Primary DCR Center tap to one end Secondary DCR Primary Leakage Secondary Leakage Primary Inductance Secondary Inductance Center ...

Page 23

... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 23 © 2005 Maxim Integrated Products is a registered trademark of Dallas Semiconductor Corporation ...