ISL59834

FN6268 Rev 1.00

Page 13 of 17

June 11, 2008

Description of Operation and Application Information

Theory of Operation

The ISL59834 is a single supply video driver with a

reconstruction filter and an on-board charge pump. It is

designed to drive SDTV displays with component (YPbPr), S-

video (Y-C), or composite video (CV) signals. The input signals

can be AC or DC-coupled. When AC-coupled, a sync tip clamp

sets the blank level to ground at the output of Channel 1 and

Channel 3. Keyed clamps force the average levels of Channel

2 and Channel 4 to ground. The keyed clamps force the

outputs to ground when SYNC_INA or SYNC_INB are driven

to the logic high state. The ISL59834 outputs are capable of

driving two AC or DC-coupled standard video loads and have a

frequency set to 9MHz, providing 40dB of attenuation at

27MHz. The ISL59834 is designed to operate with a single

supply voltage range ranging from 3.0V to 3.6V. This

eliminates the need for a split supply with the incorporation of

two charge pumps capable of generating a bottom rail as much

as 1.5V below ground; providing a 4.8V range on a single 3.3V

supply. This performance is ideal for NTSC video with

negative-going sync pulses.

Output Amplifier

The ISL59834 output amplifiers provide a gain of +6dB. The

150

 or 75load to ground.

The outputs are highly-stable, low distortion, low power, high

frequency amplifiers capable of driving moderate (~10pF)

capacitive loads.

Input/Output Range

allows the device to handle high amplitude video signal inputs.

As the input signal moves outside the specified range, the

output signal will exhibit increasingly higher levels of harmonic

distortion.

Charge Pump

The ISL59834 contains two charge pumps; charge pump A

supplies Channel 1 and 2, while charge pump B supplies

Channel 3 and 4. The ISL59834 charge pumps provide a

bottom rail up to 1.5V below ground while operating on a 3.0V

to 3.6V power supply. The charge pumps are internally

regulated and are driven by internal 9.5MHz clocks. The clock

FIGURE 25. NOISE SPECTRUM

FIGURE 26. CHARGE PUMP FEEDTHROUGH AT AMPLIFIER

OUTPUT

FIGURE 28. PACKAGE POWER DISSIPATION

Typical Performance Curves

0.1

1

10

100

0M

2M

4M

6M

8M

10M

FREQUENCY (Hz)

RMS NOISE = 2.87mV

OUTPUT REFERRED

CHARGE PUMP NOISE,

CONTRIBUTES ONLY A SMALL

PERCENTAGE OF THE

OVERALL NOISE

1M

3M

5M

7M

9M

TIME SCALE = 50ns/DIV

VERTICAL SCALE = 20mV/DIV

-70

-60

-50

-40

-30

-20

-10

0

0.5

0.8

1.1

1.4

1.7

2.0

OUTPUT VOLTAGE (V)

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

AMBIENT TEMPERATURE (°C)

44 LD QFN PACKAGE

7mmx7mm