LT6558
8
6558f
V
+
B (Pin 9): Positive Supply Voltage of Blue Channel
Amplifi er. This pin is not internally connected to other
supply voltage pins and must be externally connected to
the supply voltage bus with proper bypassing. For best
performance, see Power Supply Considerations.
OUT B (Pin 10): Blue Channel Output.
V
+
G (Pin 11): Positive Supply Voltage of Green Channel
Amplifi er. This pin is not internally connected to other
supply voltage pins and must be externally connected to
the supply voltage bus with proper bypassing. For best
performance, see Power Supply Considerations.
OUT G (Pin 12): Green Channel Output.
V
+
R (Pin 13): Positive Supply Voltage of Red Channel
Amplifi er. This pin is not internally connected to other
supply voltage pins and must be externally connected to
Power Supply Considerations
The LT6558 is optimized to provide full video signal swing
output when operated from a standard 5V single supply.
Due to the supply current involved in ultrahigh slew rate
amplifi ers like the LT6558, selection of the lowest workable
supply voltage is recommended to minimize heat genera-
tion and simplify thermal management. Temperature rise
at the internal devices (T
J
) must be kept below 150°C
(SSOP package) or 125°C (DFN package), and can be
estimated from the ambient temperature (T
A
) and power
dissipation (P
D
) as follows:
T
J
= T
A
+ P
D
• 40°C/W for DFN package
or
T
J
= T
A
+ P
D
• 110°C/W for SSOP package
where P
D
= (I
S
+ 0.5 • I
O
) • V
S(TOTAL)
The latter equation assumes (conservatively) that the output
swing is small relative to the supply and RMS load current
(I
O
) is bidirectional (as with AC coupling).
the supply voltage bus with proper bypassing. For best
performance, see Power Supply Considerations.
OUT R (Pin 14): Red Channel Output.
V
+
(Pin 15): Positive Supply Voltage of Control Circuitry.
This pin is not internally connected to other supply voltage
pins and must be externally connected to supply voltage
bus with proper bypassing. For best performance, see
Power Supply Considerations.
BCV (Pin 16): Bias Control Voltage. A resistor connected
between Pin 16 and Pin 2 (GND) will generate a DC voltage
bias at the inputs of the three amplifi ers for AC coupling
application, see Programmable Input Bias.
Exposed Pad (Pin 17, DFN Package): Ground. This pad
must be soldered to PCB and is internally connected to
GND (Pin 2).
The grounds are separately pinned for each amplifi er to
minimize crosstalk.
Operation from split supplies can be accomplished by
connecting the LT6558 ground pins to the negative rail.
With dual supplies, recommended voltages range from
nominal ±2.5V to ±3.3V.
The ultrahigh frequency (UHF) operating range of the
LT6558 requires that careful printed circuit layout prac-
tices be followed to obtain maximum performance. Trace
lengths between power pins and bypass capacitors should
be minimized (<0.1 inch) and one or more dedicated
ground planes should be employed to minimize parasitic
inductance. Poor layout or breadboarding methods can
seriously impact amplifi er stability, frequency response
and crosstalk performance. A 2.2µF and a 10µF bypass
capacitor is recommended for the LT6558 supply bus,
plus a 10nF high frequency bypass capacitor at each
individual power pin.
PIN FUNCTIONS
APPLICATIONS INFORMATION
