MAX9532AUB 데이터 시트보기 (PDF) - Maxim Integrated

부품명

상세내역

제조사

MAX9532AUB

DirectDrive Video Amplifier with Short-to-Battery Protection

Maxim Integrated 

DirectDrive Video Amplifier with

Short-to-Battery Protection

IMAGE

PROCESSOR

ASIC

0V TO 1V

DAC

150Ω

GENERIC 2V/V CONFIGURATION

LPF

2V/V

2VP-P

IMAGE

PROCESSOR

ASIC

0V TO 0.5V

DAC

75Ω

MAX9532

LPF

4V/V

2VP-P

Figure 3. Typically, a Video DAC Generates a 1VP-P Signal

Across a 150Ω Resistor Connected to Ground

Figure 4. Video DAC Generates a 0.5VP-P Signal Across a 75Ω

Resistor Connected to Ground

Table 1. Power Consumption of the MAX9532 with Different Video Signals

VIDEO SIGNAL

MAX9532 POWER CONSUMPTION (mW)

WITH 150Ω LOAD

All Black Screen

51.236

All White Screen

57.077

75% Color Bars

53.074

50% Flat Field

49.513

Note: The supply voltage is 3.3V.

MAX9532 POWER CONSUMPTION (mW)

WITH 100Ω LOAD

53.978

65.399

57.486

51.596

Interfacing to Video DACs that Produce

Video Signals Higher than 0.5VP-P

Devices designed to generate 1VP-P video signals at

the output of the video DAC can work with the

MAX9532. Most video DACs source current into a

ground-referenced resistor, which converts the current

into a voltage. Figure 3 shows a video DAC that creates

a video signal from 0V to 1V across a 150Ω resistor.

With a gain of 2V/V, the following video filter produces a

2VP-P output.

The MAX9532 accepts input signals that are 0.5VP-P

nominally. The video DAC in Figure 3 can be made to

work with the MAX9532 by scaling down the 150Ω

resistor to a 75Ω resistor, as shown in Figure 4. The

75Ω resistor is one-half the size of the 150Ω resistor,

resulting in a video signal that is one-half the amplitude.

Video Source with a Positive DC Bias

In some applications, the video source generates a sig-

nal with a positive DC voltage bias, i.e., the sync tip of

the signal is well above ground. Figure 5 shows an

example in which the outputs of the luma (Y) DAC and

the chroma (C) DAC are connected together. Since the

DACs are current-mode, the output currents sum

together into the resistor, which converts the resulting

current into a voltage representing a composite video

signal.

When the chroma DAC is connected to an independent

output resistor to ground, the chroma signal, which is a

carrier at 3.58MHz for NTSC or at 4.43MHz for PAL,

generates a positive DC bias to keep the signal above

ground at all times. When the luma DAC is connected

to an independent output resistor to ground, the luma

signal usually does not have a positive DC bias, and

the sync tip is at approximately ground. When the chro-

ma and luma signals are added together, the resulting

composite video signal generates a positive DC bias.

Therefore, the signal must be AC-coupled into the

MAX9532 because the composite video signal is above

the nominal 0V to 0.7V DC-coupled input range.

Video Signal Routing

Minimize the length of the PCB trace between the out-

put of the video DAC and the input of the MAX9532 to

reduce coupling of external noise into the video signal.

If possible, shield the PCB trace.

_______________________________________________________________________________________ 9

Share Link: