FMS6145MTC14X Fairchild Semiconductor, FMS6145MTC14X Datasheet - Page 7

• Manufacturer Part Number: FMS6145MTC14X
• Description: IC DRIVER VIDEO FLTR 5CH 14TSSOP
• Manufacturer: Fairchild Semiconductor
• Type: Driverr

Specifications of FMS6145MTC14X

• Applications: Recorders, Set-Top Boxes
• Mounting Type: Surface Mount
• Package / Case: 14-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: FMS6145MTC14XTR; FMS6145MTC14X_NL; FMS6145MTC14X_NLTR; FMS6145MTC14X_NLTR

© 2006 Fairchild Semiconductor Corporation
FMS6145 • Rev. 2.0.6
1.0 -> 1.02V
0.65 -> 0.67V
0.3 -> 0.32V
0.0 -> 0.02V
2.28V
1.58V
0.88V
0.28V
There is a 280mV offset from the DC input level to the
DC output level. V
0.85V
0.5V
0.15V
1.98V
1.28V
0.58V
The FMS6145 provides an internal diode clamp to sup-
port AC-coupled input signals. If the input signal does not
go below ground, the input clamp does not operate. This
allows DAC outputs to directly drive the FMS6145 without
an AC coupling capacitor. When the input is AC coupled,
the diode clamp sets the sync tip (or lowest voltage) just
below ground. The worst-case sync tip compression due
to the clamp cannot exceed 7mV. The input level set by
the clamp, combined with the internal DC offset, keeps
the output within its acceptable range.
For symmetric signals like Chroma, U, V, Pb, and Pr, the
average DC bias is fairly constant and the inputs can be
AC coupled with the addition of a pull-up resistor to set
the DC input voltage. DAC outputs can also drive these
same signals without the AC coupling capacitor. A conceptual
illustration of the input clamp circuit is shown in Figure 8.
Application Circuits
The FMS6145 Low Cost Video Filter (LCVF) provides
6dB gain from input to output. In addition, the input is
slightly offset to optimize the output driver performance.
The offset is held to the minimum required value to
decrease the standing DC-current into the load. Typical
voltage levels are shown in the diagram below:
Application Information
Figure 7. Typical Voltage Levels
V
V
V
OUT
OUT
OUT
IN
= 2 * V
V
IN
IN
+ 280mV.
Driven by:
DC-Coupled DAC Outputs
AC-Coupled and Clamped
Y, CV, R, G, B
Driven by:
AC-Coupled and Biased
U, V, Pb, Pr, C
7
External video
source must
be AC coupled
0.65V
I/O Confi gurations
For a DC-coupled DAC drive with DC-coupled outputs,
use the confi guration in Figure 9.
Alternatively, if the DAC’s average DC output level causes
the signal to exceed the range of 0V to 1.4V, it can be AC
coupled as shown in FIgure 10.
When the FMS6145 is driven by an unknown external
source or a SCART switch with its own clamping circuitry,
the inputs should be AC coupled as shown in Figure 11.
Y IN
DVD or
DVD or
Output
Output
Figure 11. SCART with DC-Coupled Outputs
DAC
DAC
STB
SoC
STB
SoC
Figure 9. DC-Coupled Inputs and Outputs
Figure 10. AC-Coupled Inputs,
Figure 8. Input Clamp Circuit
Driver
DC-Coupled Outputs
0V - 1.4V
75Ω
0.1μ
Y OUT
0.1μ
0V - 1.4V
75Ω
75Ω
0V - 1.4V
Video Cables
Video Cables
Inactive
Clamp
LCVF
Clamp
Active
LCVF
Clamp
Active
LCVF
www.fairchildsemi.com
75Ω
75Ω
75Ω
75Ω
75Ω
LOAD1
LOAD2
(optional)