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FMS3818
Triple Video D/A Converter
3 x 8 bit, 180 Ms/s Features
• • • • • ±2. 5% gain matching ±0. 5 LSB linearity error Internal bandgap voltage reference Low glitch energy Single 3. 3 Volt power supply
Description
The FMS3818 is a low-cost triple D/A converter, tailored to fit graphics and video applications where speed is critical. CMOS-level inputs are converted to analog current outputs that can drive 25–37. 5Ω loads corresponding to doublyterminated 50–75Ω loads. A sync current following SYNC input timing is added to the IOG output. BLANK will override RGB inputs, setting IOG, IOB and IOR currents to zero when BLANK = L. Although appropriate for many applications the internal 1. 25V reference voltage can be overridden by the VREF input. Few external components are required, just the current reference resistor, current output load resistors, bypass capacitors and decoupling capacitors. Package is a 48-lead LQFP. Fabrication technology is CMOS. Performance is guaranteed from 0 to 70°C.
Applications
• PC Graphics • Video signal conversion – RGB – YCBCR – Composite, Y, C
Block Diagram
SYNC BLANK SYNC IOS
G7-0
8
8 bit D/A Converter
IOG
B7-0
8
8 bit D/A Converter
IOB
R7-0 CLK
8
8 bit D/A Converter
IOR COMP RREF VREF
+1. 25V Ref
REV. 1. 2. 2 11/11/01
FMS3818
PRODUCT SPECIFICATION
Functional Description
Within the FMS3818 are three identical 8-bit D/A converters, each with a current source output. External loads are required to convert these currents to voltage outputs. Data inputs RGB7-0 are overridden by the BLANK input. SYNC = H activates sync current from IOS for sync-ongreen video signals.
VDDA IOS SYNC G7-0 VDDA
BLANK gates the D/A inputs. If BLANK = H, the D/A inputs control the output currents to be added to the output blanking level. If BLANK = L, data inputs and the pedestal are disabled.
D/A Outputs
Each D/A output is a current source from the VDDA supply. Expressed in current units, the GBR transformation from data to cu...