Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - lighting/front end device controller CCFL controller TSSOP 24 Surface-mount

General Description

The DS3881 is a single-channel cold-cathode fluores-

cent lamp (CCFL) controller for automotive applications

that provides up to 300:1 dimming. It is ideal for driving

CCFLs used to backlight liquid crystal displays (LCDs)

in navigation and infotainment applications and for dri-

ving CCFLs used to backlight instrument clusters. The

DS3881 is also appropriate for use in marine and avia-

tion applications.

The DS3881 features EMI suppression functionality and

provides a lamp current overdrive mode for rapid lamp

heating in cold weather conditions. The DS3881 sup-

ports a single lamp configuration with fully independent

lamp control and minimal external components.

Multiple DS3881 controllers can be cascaded to sup-

port applications requiring more than one lamp. Control

of the DS3881, after initial programming setup, can be

completely achieved through I

C software communica-

tion. Many DS3881 functions are also pin-controllable if

software control is not desired.

Applications

Automotive LCDs

Instrument Clusters

Marine and Aviation LCDs

Features

♦ Single-Channel CCFL Controller for Backlighting

LCD Panels and Instrument Clusters in

Automotive Navigation/Infotainment Applications

♦ Minimal External Components Required

♦ I

C Interface

♦ Per-Channel Lamp-Fault Monitoring for Lamp-

Open, Lamp-Overcurrent, Failure to Strike, and

Overvoltage Conditions

♦ Status Register Reports Fault Conditions

♦ Accurate (±5%) Independent On-Board Oscillators

for Lamp Frequency (40kHz to 100kHz) and DPWM

Burst-Dimming Frequency (22.5Hz to 440Hz)

♦ Lamp and DPWM Frequencies can be

Synchronized with External Sources to Reduce

Visual LCD Artifacts in Video Applications

♦ Spread-Spectrum Lamp Clock Reduces EMI

♦ Lamp Frequency can be Stepped Up or Down to

Move EMI Spurs Out of Band

♦ Lamp Current Overdrive Mode with Automatic

Turn-Off Quickly Warms Lamp in Cold

Temperatures

♦ Analog or Digital Brightness Control

♦ 300:1 Dimming Range Possible Using the Digital

Brightness Control Option

♦ Programmable Soft-Start Minimizes Audible

Transformer Noise

♦ On-Board Nonvolatile (NV) Memory Allows Device

Customization

♦ 8-Byte NV User Memory for Storage of Serial

Numbers and Date Codes

♦ Low-Power Standby Mode

♦ 4.75V to 5.25V Single-Supply Operation

♦ Temperature Range: -40°C to +105°C

♦ 24-Pin TSSOP Package

DS3881

Single-Channel Automotive CCFL Controller

______________________________________________

Maxim Integrated Products

GB1

GA1SCL

SDA

FAULT

TOP VIEW

PDN

LCOBRIGHT

LOSC

GNDPSYNC

STEPPOSC

N.C.A1

OVD1GND_S

LCM1SVML

SVMH

LSYNC

TSSOP

DS3881

Pin Configuration

Rev 1; 8/07

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Denotes lead-free package.

Ordering Information

Typical Operating Circuit appears at end of data sheet.

PART TEMP RANGE PIN-PACKAGE

DS3881E+ -40°C to +105°C 24 TSSOP (173 mils)

DS3881E+T&R -40°C to +105°C 24 TSSOP (173 mils)

Summary of content (28 pages)

PAGE 1
Rev 1; 8/07 Single-Channel Automotive CCFL Controller Features The DS3881 is a single-channel cold-cathode fluorescent lamp (CCFL) controller for automotive applications that provides up to 300:1 dimming. It is ideal for driving CCFLs used to backlight liquid crystal displays (LCDs) in navigation and infotainment applications and for driving CCFLs used to backlight instrument clusters. The DS3881 is also appropriate for use in marine and aviation applications.
PAGE 2
DS3881 Single-Channel Automotive CCFL Controller ABSOLUTE MAXIMUM RATINGS Operating Temperature Range .........................-40°C to +105°C EEPROM Programming Temperature Range .........0°C to +85°C Storage Temperature Range .............................-55°C to +125°C Soldering Temperature...................See J-STD-020 Specification Voltage Range on VCC, SDA, and SCL Relative to Ground.....................................-0.5V to +6.0V Voltage Range on Leads Other than VCC, SDA, and SCL ............
PAGE 3
Single-Channel Automotive CCFL Controller (VCC = +4.75V to +5.25V, TA = -40°C to +105°C.) PARAMETER High-Level Output Voltage (GA, GB) SYMBOL VOH1 CONDITIONS IOH1 = -1mA MIN TYP MAX VCC 0.4 UNITS V UVLO Threshold: VCC Rising VUVLOR UVLO Threshold: VCC Falling VUVLOF UVLO Hysteresis VUVLOH SVML/H Threshold: Rising VSVMR 2.03 2.08 2.15 V SVML/H Threshold: Falling VSVMF 1.95 2.02 2.
PAGE 4
DS3881 Single-Channel Automotive CCFL Controller I2C AC ELECTRICAL CHARACTERISTICS (See Figure 9) (VCC = +4.75V to +5.25V, TA = -40°C to +105°C, timing referenced to VIL(MAX) and VIH(MIN).) PARAMETER SYMBOL SCL Clock Frequency fSCL Bus Free Time Between Stop and Start Conditions tBUF Hold Time (Repeated) Start Condition Low Period of SCL High Period of SCL CONDITIONS (Note 7) MIN TYP 0 MAX UNITS 400 kHz 1.3 µs 0.6 µs tLOW 1.3 µs tHD:STA (Note 8) tHIGH 0.
PAGE 5
Single-Channel Automotive CCFL Controller 6.0 5.5 SVML< 2V VCC = 4.75V 6.0 5.5 4.5 5.0 4.75 4.80 4.85 4.90 4.95 5.00 5.05 5.10 5.15 5.20 5.25 GATE QC = 3.5nC -40.0 32.5 0.2 0 -0.2 -0.4 LAMP FREQUENCY -1.0 -40.0 105 32.5 TEMPERATURE (°C) TEMPERATURE (°C) TYPICAL OPERATION AT 11V TYPICAL OPERATION AT 13V TYPICAL OPERATION AT 16V DS3881 toc04 SUPPLY VOLTAGE (V) 10μs 5.0V GA 10μs 5.0V GA 10μs 5.0V GB 10μs 5.0V GB 10μs 2.00V LCM 10μs 2.00V LCM 10μs 2.00V LCM 10μs 2.00V OVD 10μs 2.
PAGE 6
Typical Operating Characteristics (continued) (VCC = 5.0V, TA = +25°C, unless otherwise noted.) 1ms 5.0V GA 0.5s 5.0V GA 50μs 5.0V GB 1ms 5.0V GB 0.5s 5.0V GB 50μs 2.00V LCM 1ms 2.00V LCM 0.5s 2.00V LCM 50μs 2.00V OVD 1ms 2.00V OVD 0.5s 2.00 OVD DS3881 toc13 LAMP OUT (LAMP OPENED), AUTO-RETRY DISABLED 0.1s 5.0V GA 0.1s 5.0V GB LAMP OPENED 0.1s 2.00V LCM 0.1s 2.00V OVD 6 _____________________________________________________________________ DS3881 toc12 50μs 5.
PAGE 7
Single-Channel Automotive CCFL Controller PIN NAME 1, 9 A0, A1 2 SDA Serial Data Input / Output. I2C bidirectional data pin, which requires a pullup resistor to realize high logic levels. 3 SCL Serial Clock Input. I2C clock input. 4 LSYNC FUNCTION Address Select Input. Determines I2C slave address. Lamp Frequency Input/Output. This pin is the input for an externally sourced lamp frequency when the DS3881 is configured as a lamp frequency receiver.
PAGE 8
Single-Channel Automotive CCFL Controller DS3881 Functional Diagrams PDN UVLO EEPROM LCO SCL A0/A1 GND_S System SYSTEM Enable / ENABLE/ POR POR CONTROL REGISTERS SDA I2C DEVICE CONFIGURATION AND CONTROL PORT VCC [4.75V TO 5.25V] 8 BYTE USER MEMORY I2C INTERFACE VREF 2.0V SVMH SUPPLY VOLTAGE MONITOR—HIGH 2.
PAGE 9
Single-Channel Automotive CCFL Controller LAMP OUT 300mV LCM1 LAMP CURRENT MONITOR CHANNEL ENABLE LAMP OVERCURRENT CHANNEL FAULT LOCE BIT IN CR1.0 DIGITAL CCFL CONTROLLER LAMP STRIKE AND REGULATION 64 LAMP CYCLE INTEGRATOR DIMMING PWM SIGNAL 512 x LAMP FREQUENCY [20.48MHz ~ 51.20MHz] 2.5V OVERVOLTAGE OVD1 OVERVOLTAGE DETECTOR LAMP MAXIMUM VOLTAGE REGULATION LAMP FREQUENCY [40kHz ~ 80kHz] VLRT (1.0V NOMINAL) 1.0V GATE DRIVERS GA1 GB1 MOSFET GATE DRIVERS Figure 2.
PAGE 10
DS3881 Single-Channel Automotive CCFL Controller Shadowed EEPROM The DS3881 incorporates SRAM-shadowed EEPROM memory locations for all memory that needs to be retained during power cycling. At power-up, SEEB (bit 7 of the BLC register) is low, which causes the shadowed locations to act as ordinary EEPROM. Setting SEEB high disables the EEPROM write function and causes the shadowed locations to function as ordinary SRAM cells.
PAGE 11
Single-Channel Automotive CCFL Controller 2.0V ANALOG DIMMING CONTROL VOLTAGE 0.5V DPWM SIGNAL BRIGHT PSYNC 22.5Hz TO 440Hz POSC EXTERNAL RESISTOR SETS DPWM RATE DS3881 RESISTOR-SET DIMMING CLOCK EXTERNAL DIMMING CLOCK 2.0V ANALOG DIMMING CONTROL VOLTAGE BRIGHT 0.5V DPWM SIGNAL PSYNC 22.5Hz TO 440Hz POSC EXTERNAL DPWM CLOCK 22.5Hz TO 440Hz Figure 3. DPWM Source Configuration Options Analog Dimming Analog dimming changes the brightness by increasing or decreasing the lamp current.
PAGE 12
DS3881 Single-Channel Automotive CCFL Controller ANALOG BRIGHTNESS 2.0V 0.5V ANALOG BRIGHTNESS BRIGHT PSYNC RESISTOR-SET DIMMING FREQUENCY LSYNC POSC RESISTOR-SET LAMP FREQUENCY 2.0V 0.5V DS3881 LAMP FREQUENCY SOURCE DPWM SOURCE LAMP CLOCK (40kHz TO 100kHz) LSYNC POSC RESISTOR-SET DIMMING FREQUENCY LOSC ANALOG BRIGHTNESS 0.5V 2.0V BRIGHT RESISTOR-SET LAMP FREQUENCY PSYNC DS3881 LSYNC LAMP FREQUENCY RECEIVER N.C. POSC DPWM RECEIVER N.C. LOSC N.C. LOSC ANALOG BRIGHTNESS 0.
PAGE 13
Single-Channel Automotive CCFL Controller different driver duty cycles to select from to customize the soft-start ramp (see Tables 4a and 4b). The available duty cycles range from 0% to 19% in ~3% increments. In addition, the MOSFET duty cycle from the last lamp cycle of the previous burst can be used as part of the soft-start ramp by using the most recent value duty cycle code. Each programmed MOSFET gate duty cycle repeats twice to make up the 16 softstart lamp cycles. DPWM SIGNAL 22.
PAGE 14
DS3881 Single-Channel Automotive CCFL 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 following formula: ROSC = reaching the strike voltage and could potentially cause numerous other problems. Operating with the transformer voltage at too high of a level can be damaging to the inverter components.
PAGE 15
Single-Channel Automotive CCFL Controller 1) Supply Check—The lamps do not turn on unless the DS3881 supply voltage is above 4.3V and the voltage at the supply voltage monitors, SVML and SVMH, are respectively above 2.0V and below 2.0V. 2) Strike Lamp—When both the DS3881 and the DC inverter supplies are at acceptable levels, the DS3881 attempts to strike the lamp. The DS3881 slowly ramps up the MOSFET gate duty cycle until the lamp strikes.
PAGE 16
DS3881 Single-Channel Automotive CCFL Controller DEVICE AND INVERTER SUPPLIES AT PROPER LEVELS? FAULT STATE [ACTIVATE FAULT OUTPUT] YES SET FAULT_L AND FAULT_RT STATUS BITS RESET FAULT COUNTER AND FAULT OUTPUT YES FAULT WAIT [1024 LAMP CYCLES] NO FAULT COUNTER = 15? NO YES CLEAR FAULT_RT STATUS BIT LAMP OVERCURRENT [INSTANTANEOUS IF ENABLED BY THE LOCE BIT AT CR1.
PAGE 17
Single-Channel Automotive CCFL Controller Lamp Current Overdrive Functionality Another feature the DS3881 offers is the ability to overdrive the lamps to allow them to heat up quickly in cold environments. After setting the LCO0/1/2 bits in the LCOC register and enabling the LCOE bit or LCO pin, the DS3881 overdrives the nominal current settings in 12.5% steps from 112.5% up to 200%.
PAGE 18
DS3881 Single-Channel Automotive CCFL Controller Table 2. Status Register 1 (SR1) [SRAM, E0h] BIT R/W POWER-UP DEFAULT NAME FUNCTION 0 R 0 FAULT_RT 1 R 0 FAULT_L 2 R 0 STO_L 3 R 0 OV_L 4 R 0 LOUT_L 5 R 0 LOC_L 6 R 0 SVML_RT 7 R 0 SVMH_RT Fault Condition—Real Time. A real-time bit that indicates the current operating status of channel 1. 0 = Normal condition 1 = Fault condition Fault Condition—Latched. A latched bit that is set when the channel enters a fault condition.
PAGE 19
Single-Channel Automotive CCFL Controller SSP# ADDR FACTORY DEFAULT MSB SSP1 F0h 21h LST1 Lamp Cycles 3 and 4 LST0 Lamp Cycles 1 and 2 SSP2 F1h 43h RSVD Lamp Cycles 7 and 8 RSVD Lamp Cycles 5 and 6 SSP3 F2h 65h RSVD Lamp Cycles 11 and 12 RSVD Lamp Cycles 9 and 10 SSP4 F3h 77h RSVD Lamp Cycles 15 and 16 RSVD Lamp Cycles 13 and 14 DS3881 Table 4a. Soft-Start Protocol Registers (SSPx) [Shadowed-EEPROM, F0h, F1h, F2h, F3h] LSB 7 6 5 4 3 2 1 0 Table 4b.
PAGE 20
DS3881 Single-Channel Automotive CCFL Controller Table 5. Control Register 1 (CR1) [Shadowed-EEPROM, F4h] 20 BIT R/W FACTORY DEFAULT NAME 0 R/W 0 LOCE FUNCTION Lamp Overcurrent Enable 0 = Lamp overcurrent detection disabled. 1 = Lamp overcurrent detection enabled. POSC Select. See POSCR0 and POSCR1 control bits in Control Register 2 to select the oscillator range. 0 = POSC input is connected with a resistor to ground to set the frequency of the internal PWM oscillator. 1 = POSC input is a 22.
PAGE 21
Single-Channel Automotive CCFL Controller BIT R/W DEFAULT NAME 0 R/W 0 UMWP 1 2 R/W R/W 0 0 POSCR0 POSCR1 DS3881 Table 6. Control Register 2 (CR2) [Shadowed-EEPROM, F5h] FUNCTION User Memory Write Protect 0 = Write access blocked. 1 = Write access permitted. DPWM Oscillator Range Select. When using an external source for the dimming clock, these bits must be set to match the external oscillator’s frequency.
PAGE 22
DS3881 Single-Channel Automotive CCFL Controller Table 7. EMI Control Register (EMIC) [Shadowed-EEPROM, F6h] BIT R/W FACTORY DEFAULT NAME 0 R/W 0 SS0 1 R/W 0 FUNCTION LAMP OSCILLATOR SPREAD-SPECTRUM MODULATION SELECT SS1 SS0 SELECTED LAMP FREQUENCY SPREAD 0 0 SPREAD-SPECTRUM DISABLED 0 1 ±1.5% SS1 1 0 ±3.0% 1 1 ±6.0% 2 R/W 0 SSM Lamp Oscillator Spread-Spectrum Modulation Select 0 = Triangular modulation. 1 = Pseudorandom modulation. 3 ⎯ ⎯ RSVD Reserved.
PAGE 23
Single-Channel Automotive CCFL Controller BIT R/W FACTORY DEFAULT NAME DS3881 Table 8. Lamp Current Overdrive Control Register (LCOC) [Shadowed-EEPROM, F7h] FUNCTION LAMP CURRENT OVERDRIVE SELECT 0 1 2 3 R/W R/W R/W R/W 0 0 0 0 LCO0 LCO1 LCO2 LCOE LCO2 LCO1 LCO0 SELECTED LAMP CURRENT OVERDRIVE 0 0 0 Nominal Current + 12.50% 0 0 1 Nominal Current + 25.00% 0 1 0 Nominal Current + 37.50% 0 1 1 Nominal Current + 50.00% 1 0 0 Nominal Current + 62.
PAGE 24
DS3881 Single-Channel Automotive CCFL Controller I2C Definitions The following terminology is commonly used to describe I2C 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 send and receive data at the master’s request. Bus Idle or Not Busy: Time between stop and start conditions when both SDA and SCL are inactive and in their logic-high states.
PAGE 25
Single-Channel Automotive CCFL Controller I2C Communication Writing a Data Byte to a Slave: The master must generate a start condition, write the slave address byte (R/W = 0), write the memory address, write the byte of data, and generate a stop condition. Remember the master must read the slave’s acknowledgement during all byte write operations. See Figure 11 for more detail.
PAGE 26
DS3881 Single-Channel Automotive CCFL Controller NOTES COMMUNICATIONS KEY S START A ACK WHITE BOXES INDICATE THE MASTER IS CONTROLLING SDA P STOP N NOT ACK SHADED BOXES INDICATE THE SLAVE IS CONTROLLING SDA SR REPEATED START X X X X X X X X 1) ALL BYTES ARE SENT MOST SIGNIFICANT BIT FIRST. 2) THE FIRST BYTE SENT AFTER A START CONDITION IS ALWAYS THE SLAVE ADDRESS FOLLOWED BY THE READ/WRITE BIT.
PAGE 27
Single-Channel Automotive CCFL Controller PARAMETER CONDITIONS Turns Ratio (Secondary/Primary) MIN (Notes 1, 2, 3) TYP MAX UNITS 80 kHz 40 Frequency 40 Output Power Output Current 5 Primary DCR Center tap to one end 6 W 8 mA 200 mΩ Secondary DCR 500 Ω Primary Leakage 12 µH Secondary Leakage 185 mH Primary Inductance 70 µH Secondary Inductance 500 mH Secondary Output Voltage DS3881 Table 9.
PAGE 28
Single-Channel Automotive CCFL Controller DS3881 Typical Operating Circuit VCC R1 DEVICE SUPPLY VOLTAGE (5V ±5%) VCC INVERTER SUPPLY VOLTAGE (VINV) (8V TO 16V) R2 C1 C7 I2C CONFIGURATION AND CONTROL PORT SDA VCC SCL SVMH A0 SVML A1 VCC R3 R4 R5 R6 GND_S R11 FAULT DS3881 CCFL LAMP GA1 C2 C3 R7 GB1 HARDWARE CONTROL LAMP CURRENT OVERDRIVE ENABLE LCO LAMP ON/OFF PDN LAMP BRIGHTNESS BRIGHT STEP LAMP FREQUENCY TRANSFORMER DUAL POWER MOSFET OVERVOLTAGE DETECTION OVD1 LAMP CU