MAX1996AETI+ Maxim Integrated Products, MAX1996AETI+ Datasheet

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MAX1996AETI+

Manufacturer Part Number
MAX1996AETI+
Description
Display Drivers CCFL Backlight Controller
Manufacturer
Maxim Integrated Products
Datasheet

Specifications of MAX1996AETI+

Lead Free Status / Rohs Status
 Details
The MAX1996A integrated controller is optimized to
drive cold-cathode fluorescent lamps (CCFLs) using
synchronized full-bridge inverter architecture.
Synchronized drive provides near sinusoidal waveforms
over the entire input range to maximize the life of
CCFLs. The controller also operates over a wide input-
voltage range with high efficiency and broad dimming
range.
The MAX1996A includes safety features that limit the
transformer secondary voltage and protect against sin-
gle-point fault conditions including lamp-out and short-
circuit faults.
The MAX1996A regulates the CCFL brightness in three
ways: linearly controlling the lamp current, digital pulse-
width modulating (DPWM) the lamp current, or using
both methods simultaneously to achieve the widest
dimming range (>30:1). CCFL brightness can be con-
trolled with either an analog voltage or a 2-wire
SMBus™-compatible interface. The MAX1996A directly
drives the four external N-channel power MOSFETs of
the full bridge inverter. An internal 5.3V linear regulator
powers the MOSFET drivers, the synchronizable DPWM
oscillator, and most of the internal circuitry.
The MAX1996A has the same pin configuration as the
MAX1895, but with modified SMBus slave address
(0x58) and command bytes. In addition, the lamp-out
protection timer has been reduced to approximately 1s
and the DPWM frequency is guaranteed from 200Hz to
220Hz over the operating temperature range without
external components or trimming. The MAX1996A is
available in the space-saving 28-pin thin QFN package
and operates over a -40°C to +85°C temperature
range.
19-2267; Rev 1; 10/02
*Contact factory for availability.
SMBus is a trademark of Intel Corp.
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX1996AETI
MAX1996AEGI*
PART
Notebook Computers
Multibulb LCD Monitors
Portable Display Electronics
________________________________________________________________ Maxim Integrated Products
-40°C to +85°C
-40°C to +85°C
TEMP RANGE
Ordering Information
General Description
Range, CCFL Backlight Controller
Applications
High-Efficiency, Wide Brightness
PIN-PACKAGE
28 Thin QFN 5
28 QFN 5
5
5
o SMBus Slave Address (0x58) for Wide Dimming
o Guaranteed 200Hz to 220Hz DPWM Frequency
o Externally Synchronizable DPWM Frequency
o Lamp-Out Protection with 1s Timeout
o Synchronized to Resonant Frequency
o High Power-to-Light Efficiency
o Wide Dimming Range (3 Methods)
o Feed-Forward for Fast Response to Step Change
o Wide Input-Voltage Range (4.6V to 28V)
o Transformer Secondary Voltage Limiting to
o Protected Against Short-Circuit and Other Single-
o Dual-Mode Brightness Control Interface
o Small Footprint 28-Pin Thin QFN (5mm
Range Inverters
of Input Voltage
Reduce Transformer Stress
Point Faults
Package
Good Crest Factor for Longer Lamp Life
Ensures Maximum Strike Capability
Lamp Current Adjust: >3 to 1
DPWM: >10 to 1
Combined: >30 to 1
CRF/SDA
TOP VIEW
CTL/SCL
MINDAC
MODE
ILIM
GND
REF
1
2
3
4
5
6
7
5mm × 5mm
MAX1996A
THIN QFN
Pin Configuration
21
20
19
18
17
16
15
Features
GH2
LX2
BST2
BST1
LX1
GH1
GL1
5mm)
1

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MAX1996AETI+ Summary of contents

Page 1

... MAX1996AEGI* -40°C to +85°C *Contact factory for availability. SMBus is a trademark of Intel Corp. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. High-Efficiency, Wide Brightness Range, CCFL Backlight Controller ...

Page 2

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller ABSOLUTE MAXIMUM RATINGS BATT to GND..........................................................-0.3V to +30V BST1, BST2 to GND ...............................................-0.3V to +36V BST1 to LX1, BST2 to LX2 ........................................-0.3V to +6V GH1 to LX1 ...............................................-0.3V to (BST1 + 0.3V) GH2 ...

Page 3

ELECTRICAL CHARACTERISTICS (continued 12V, MINDAC = GND, V BATT +25°C.) (Note 1) A PARAMETER Minimum Current-Crossing Threshold LX1-GND, LX2-GND Current-Limit Leading-Edge Blanking D/A Converter Resolution MINDAC Input Voltage Range MINDAC Input Bias Current MINDAC Digital ...

Page 4

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller ELECTRICAL CHARACTERISTICS (continued 12V, MINDAC = GND BATT +25°C.) (Note 1) A PARAMETER MODE AC Signal Amplitude MODE AC Signal Synchronization Range CRF/SDA Input Range ...

Page 5

ELECTRICAL CHARACTERISTICS (continued 12V, MINDAC = GND BATT CC PARAMETER V Output Voltage, Normal Operation CC V Output Voltage, Shutdown CC V UVLO Threshold CC V POR Threshold CC REF Output Voltage, Normal Operation GH1, ...

Page 6

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller (V = 12V 1V, MODE = GND, circuit of Figure 1, Table 4.) BATT CTL CRF, MINDAC LOW INPUT-VOLTAGE OPERATION (V = 8V) BATT MAX1996 toc01 V FB ...

Page 7

1V, MODE = GND, circuit of Figure 1, Table 4.) BATT CTL CRF, MINDAC V LOAD REGULATION CC 5.40 NORMAL OPERATION 5.35 SHUTDOWN 5.30 5.25 5.20 5.15 5.10 0.01 0 ...

Page 8

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller PIN NAME Brightness Control and Serial Clock Input. In analog interface mode, pin CCFL brightness control input. CTL varies from 0V to REF to linearly control lamp brightness. In SMBus ...

Page 9

LX1 C5 BST1 D2-1 C7 GND C10 R4 Figure 1. Standard Application Circuit Detailed Description The MAX1996A is optimized to drive CCFLs using a synchronized full-bridge inverter architecture. The drive to the full-bridge MOSFETs is synchronized to ...

Page 10

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller V BATT NH1 ON C2 LX1 NL1 OFF (a) V BATT NH1 OFF C2 LX1 NL1 ON (BODY DIODE TURNS ON FIRST) (b) Figure 2. Resonant Operation Resonant Operation The MAX1996A drives the ...

Page 11

C S 1:N AC SOURCE C /(NxN SOURCE Figure 3. Equivalent Circuit Note that switching transitions on all four power MOSFETs occur under ZVS conditions, which reduces transient power losses and EMI. The equivalent circuit of the ...

Page 12

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller REFERENCE INPUT CRF/SDA CTL/SCL CONTROL INPUT MODE 0.15V CCV 0.5V GMV V FB CCI GMI IFB LX2 LX1 REF ILMIT GND Figure 4. Functional Diagram Transient Overvoltage Protection The MAX1996A is designed to ...

Page 13

Table 1. Interface Modes DIGITAL INTERFACE PIN MODE = V CC SH/SUS SMBus suspend CRF/SDA SMBus data I/O CTL/SCL SMBus clock input loop then slowly corrects the lamp current by increasing V which brings the circuit back into regulation. CCI, ...

Page 14

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller DPWM SETTINGS 100 BRIGHTNESS CODE Figure 5. DPWM Settings Table 2. MINDAC Functionality CONDITION DPWM disabled (always ...

Page 15

The analog interface’s internal ADC uses 1-bit hystere- sis to keep the lamp from flickering between two codes. V ’s positive threshold (V CTL CTL(TH) required to transition the brightness code as V increases and can be calculated as follows: ...

Page 16

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller MAX BRIGHTNESS CONTROL VOLTAGE CONVENTIONAL INTERFACE MIN BRIGHTNESS CONTROL VOLTAGE MAX BRIGHTNESS CONTROL VOLTAGE MAX1996A INTERFACE MIN BRIGHTNESS CONTROL VOLTAGE Figure 9. Useful Dimming Range a 500pF capacitor from an AC signal source ...

Page 17

ADC- 10kΩ SMBus ADC+ 500pF DPWM SYNCHRONIZATION SIGNAL Figure 10. DPWM Synchronization The MAX1996A includes POR and UVLO circuits. The POR resets all internal registers such as DAC output, fault conditions, and all SMBus registers. POR occurs when V is ...

Page 18

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller Table 4. Components for the Standard Application Circuit DESIGNATION DESCRIPTION C1 4.7µF, 25V X5R ceramic capacitor C2 1µF, 25V X7R ceramic capacitor 15pF, 3.1kV high-voltage ceramic C3 capacitor C4 0.015µF, 16V X7R ceramic ...

Page 19

IFB is the half-wave rectified representation of the cur- rent through the lamp. The inverter regulates the aver- age voltage at IFB, which is controlled by either the analog interface or the SMBus interface. To set the maximum lamp RMS ...

Page 20

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller NH1 NL1 LX1 C5 BST1 D2-1 C7 MAX1996A GND C10 R4 Figure 12. Dual-Lamp Application Circuit The secondary voltages of both transformers are moni- tored through the two identical capacitive ...

Page 21

Table 5. Components for the Dual-Lamp Application Circuit DESIGNATION DESCRIPTION C1 4.7µF, 25V X5R ceramic capacitor C2 1µF, 25V X7R ceramic capacitor 15pF, 3.1kV high-voltage ceramic C3, C13 capacitors C4, C11 0.015µF, 16V X7R ceramic capacitors C5–C8, C10, C12 0.1µF, ...

Page 22

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller Table 5. Components for the Dual-Lamp Application Circuit DESIGNATION DESCRIPTION R5 1kΩ ±5% resistor R7 20kΩ ±5% resistor T1, T2 1:100 transformers HIGH-CURRENT PRIMARY CONNECTION NOTE: DUAL MOSFET N2 IS ...

Page 23

Write-Byte Format S ADDRESS WR 7 bits 1b Slave Address Read-Byte Format S ADDRESS WR ACK 7 bits 1b 1b Slave Address Command Byte: selects which register you are reading from Send-Byte Format S ADDRESS WR ACK COMMAND 7 bits ...

Page 24

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller LOW HIGH SMBCLK SMBDATA t t HD:STA SU:STA A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D ...

Page 25

Table 7. Command Byte Description SMBus COMMAND POR PROTOCOL BYTE* STATE Read and 0x01 0x17 Write 0b0XXX XX01 Read and 0x02 0xF9 Write 0b0XXX XX10 0x03 Read Only 0x0C 0b0XXX XX11 0x04 Read Only 0x00 0b0XXX XX00 Read and 0xAA ...

Page 26

High-Efficiency, Wide Brightness Range, CCFL Backlight Controller Table 8. SHMD Register Bit Descriptions POR BIT NAME STATE 2 SHMD2 0 1 SHMD1 0 0 SHMD0 1 Table 9. SH/SUS and SHMD Register Truth Table SH/SUS SHMD2 ...

Page 27

For the latest package outline information go to www.maxim-ic.com/packages.) ______________________________________________________________________________________ High-Efficiency, Wide Brightness Range, CCFL Backlight Controller Package Information 27 ...

Page 28

... 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. 28 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products ...

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