MAX9673ETI 查看數據表（PDF） - Maxim Integrated

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MAX9673ETI

10-Bit, Programmable Gamma Reference Systems with MTP for TFT LCDs

Maxim Integrated 

10-Bit, Programmable Gamma Reference

Systems with MTP for TFT LCDs

gamma buffers, high-voltage linear regulator, and resis-

tor strings. The high-voltage linear regulator can be

eliminated because the DAC contains a lowpass filter

that reduces horizontal line frequency noise by 50dB.

Power sequencing is well controlled since a single chip

generates all the various reference voltages needed for

the LCD panel.

Each part has an I2C interface for programming both

the MTP memory and the I2C registers.

With the MTP memory and the I2C interface, the

MAX9672/MAX9673/MAX9674 enable automatic

gamma and automatic flicker calibration on a panel-by-

panel basis on the production line. Contact your Maxim

representative for more details.

10-Bit DACs

The voltage at REF sets the full-scale output of the

DACs. Determine the output voltage using the following

equation:

VOUT = (VREF x CODE)/2N

where CODE is the numeric value of the DAC’s binary

input code and N is the bits of resolution. For the

MAX9672/MAX9673/MAX9674, N = 10 and CODE

ranges from 0 to 1023.

The DAC can never output REF because the maximum

value of CODE is always 1 least significant bit (LSB)

less than the reference. For example, if VREF = 16V and

CODE = 1023, then the output voltage is:

VOUT = (16V x 1023)/210

= 15.98438V

Gamma Buffers

The gamma buffers are guaranteed to source or sink

10mA of DC current within 200mV of the supplies.

The source drivers can kick back a great deal of cur-

rent to the buffer outputs during a horizontal line

change or a polarity switch. The DAC output buffers

can source/sink 200mA of peak current to reduce the

recovery time of the output voltages when critical levels

and patterns are displayed.

VCOM Amplifier

The operational amplifier attached to the VCOM DAC

holds the VCOM voltage stable while providing the abil-

ity to source and sink 600mA into the backplane of a

TFT LCD panel. The operational amplifier can directly

drive the capacitive load of the TFT LCD backplane

without the need for a series resistor in most cases. The

VCOM amplifier has current limiting on its output to pro-

tect its bond wires.

If the application requires more than 600mA, buffer the

output of the VCOM amplifier with a MAX9650, a VCOM

power amplifier. The MAX9650 can source or sink 1A of

current.

Thermal Shutdown

The MAX9672/MAX9673/MAX9674 feature thermal-

shutdown protection with temperature hysteresis. When

the die temperature reaches +165°C, all of the gamma

outputs are disabled. When the die cools down by

15°C, the outputs are enabled again.

I2C Serial Interface

The MAX9672/MAX9673/MAX9674 feature an I2C/

SMBus™-compatible, 2-wire serial interface consisting of

a serial-data line (SDA) and a serial-clock line (SCL).

SDA and SCL facilitate communication between the

MAX9672/MAX9673/MAX9674 and the master at clock

rates up to 400kHz. Figure 1 shows the 2-wire interface

timing diagram. The master generates SCL and initiates

data transfer on the bus. A master device writes data to

the MAX9672/MAX9673/MAX9674 by transmitting the

SDA

tSU,DAT

tLOW

tHD,DAT

tSU,STA

tHD,STA

tBUF

tSP tSU,STO

SCL

tHD,STA

START

CONDITION

tHIGH

tR

tF

Figure 1. I2C Serial-Interface Timing Diagram

SMBus is a trademark of Intel Corp.

REPEATED

START CONDITION

STOP

START

CONDITION CONDITION

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