MAX11503 查看數據表（PDF） - Maxim Integrated

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MAX11503

Video Y/C Summer with Driver and Chroma Mute

Maxim Integrated 

Video Y/C Summer with

Driver and Chroma Mute

DC-Coupled Output

The MAX11503 input clamps the sync tip of the video

signal to 250mV at the IC output, forcing the blanking

level to be about 550mV on the coax cables at the ter-

mination resistor. This allows driving video to meet digi-

tal TV specifications without the need for costly

AC-coupling capacitors. Power dissipation is an espe-

cially important consideration if DC-coupling one or two

terminated video coax cables.

Minimum Supply-Voltage Considerations

The minimum supply voltage depends on the type of

video and the output configuration. Use at least the

minimum supply voltage to preserve the output amplifi-

er’s linearity and video specifications.

The following examples discuss the required minimum

supply voltage under several scenarios. Unless other-

wise specified, these examples assume:

1) The luma input is AC-coupled and therefore the

sync tip is clamped at 0.250V at the output.

2) The output amplifier needs 0.800V of overhead.

PAL

A PAL test signal is 1.235VP-P (100% color bars).

Therefore, the required minimum supply voltage is:

VCC = 2 x 1.235 + 0.250 + 0.800 = 3.5V

NTSC

A NTSC signal is 1.0VP-P (755 color bars). Therefore,

the required minimum supply voltage is:

VCC = 2 x 1.000 + 0.250 + 0.800 = 3.05V

Using SAG Correction

When using SAG correction, the output amplifier needs

an overhead of 800mV, in addition to 130% of the maxi-

mum video level at the output. Assuming an AC-cou-

pled luma input:

For PAL, the minimum required supply voltage is:

VCC = 2 x 1.235 x 1.3 + 0.250 + 0.800 = 4.26V

For NTSC, the minimum required supply voltage is:

VCC = 2 x 1.000 x 1.3 + 0.250 +0.800 = 3.65V

Thermal Considerations

The power dissipation for single 75Ω terminated load is

64mW, and for two 75Ω terminated loads is 106mW. As

a result of the exposed pad, the temperature rise is

minimized.

Short-Circuit Protection

The MAX11503 outputs are fully protected against short

circuits either to the ground or the positive supply of the

device. The short-circuit protection circuitry limits the

output current to 130mA (typical) per output.

PCB Layout Recommendations

The MAX11503 has an exposed pad on the bottom.

The pad should be externally connected to ground.

Place power-supply decoupling capacitors close to the

device with short traces connecting to the power

planes. Use ceramic 0.1µF bypass and 1µF bulk

capacitors.

For a recommended PCB layout, refer to the MAX11503

EV kit data sheet.

Pin Configuration

TOP VIEW

YIN 1

GND 2

OUT 3

SAG 4

*EXPOSED PAD

MAX11503

*

µMAX

8 CIN

7 CMUTE

6 PSAVE

5 VCC

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