ISL59832

FN6267 Rev 1.00

Page 13 of 15

June 11, 2008

SYNC DETECTOR AND CLAMP TIMING

Channel 1 and Channel 3 also have sync detectors whose

outputs are available at SYNC_OUT.

The slice level for the sync detector is between 100 to 200mV.

This means that if the signal level is below 100mV at Channel

1, then SYNC_OUT is high. If the signal level is above 200mV

then SYNC_OUT is low. Figure 28 shows the operation of the

sync detector.

DC-Coupled Inputs (Channel 1)

When DC-coupling the inputs ensure that the lowest signal

level is greater than +50mV to prevent the clamp from turning

on and distorting the output. When DC-coupled the ISL59832

shifts the signal by -620mV.

Amplifier Disable

The ISL59832 can be disabled and its outputs placed in high

impedance states. The turn-off time is around 10ns and the

turn-on time is around 35µs. The turn-on time is longer

because extra time is needed for the charge pump to settle

before the amplifiers are enabled. When disabled, the device

supply current is reduced to 2µA typically, reducing power

consumption. The device’s power-down can be controlled by

standard TTL or CMOS signal levels at the ENABLE pin. The

applied logic signal is relative to the GND pin. Applying a signal

that is less than 0.8V above GND will disable the device. The

device will be enabled when the ENABLE signal is 2V above

GND.

Output Drive Capability

The maximum output current for the ISL59832 is ±50mA.

Maximum reliability is maintained if the output current never

exceeds ±50mA, after which the electro-migration limit of the

process will be exceeded and the part will be damaged. This limit

is set by the design of the internal metal interconnections.

Driving Capacitive Loads and Cables

The ISL59832, internally-compensated to drive 75

 cables,

will drive 10pF loads in parallel with 150

 or 75with less than

1.3dB of peaking.

Power Dissipation

With the high output drive capability of the ISL59832, it is

possible to exceed the +150°C absolute maximum junction

temperature under certain load current conditions. Therefore, it

is important to calculate the maximum junction temperature for

an application to determine if load conditions or package types

need to be modified to assure operation of the amplifier in a

safe operating area.

The maximum power dissipation allowed in a package is

determined according to Equation 1:

Where:

The maximum power dissipation actually produced by an IC is

the total quiescent supply current times the total power supply

voltage, plus the power in the IC due to the load, or:

for sourcing:

for sinking:

Where:

i = Number of output channels

+300mV

+0mV

NTSC LUMINANCE

CHANNEL 1 INPUT

+1.00V

+0mV

+3.3V

SYNC_OUT

FIGURE 28. SYNC DETECTOR SLICE LEVEL

–



JA

---------------------------------------------

=

(EQ. 1)

–



+



-----------------



=

(EQ. 2)

–



+





=

(EQ. 3)