Fairchild Semiconductor FMS3115, FMS3110 Datasheet

www.fairchildsemi.com

FMS3110/3115

Triple Video D/A Converters

3 x 10 bit, 150 Ms/s

Features

• 10-bit resolution

• 150 megapixels per second

• ± 0.1% linearity error

• Sync and blank controls

• 1.0V p-p video into 37.5 Ω or 75 Ω load

• Internal bandgap voltage reference

• Double-buffered data for low distortion

• TTL-compatible inputs

• Low glitch energy

• Single +5 Volt power supply

Applications

• Video signal conversion – RGB – YC

– Composite, Y, C

• Multimedia systems

• Image processing

• True-color graphics systems (1 billion colors)

• Broadcast television equipment

• High-Deﬁnition Television (HDTV) equipment

• Direct digital synthesis

Description

FMS3110/3115 products are low-cost triple D/A converters that are tailored to ﬁt graphics and video applications where speed is critical. Two speed grades are available:

FMS3110 100 Ms/s FMS3115 150 Ms/s

TTL-level inputs are converted to analog current outputs that can drive 25–37.5 Ω loads corresponding to doubly-terminated 50–75 Ω loads. A sync current following SYNC is added to the I inputs, setting I

output. BLANK

, I

and I

will override RGB

currents to zero when

BLANK = L. Although appropriate for many applications the internal 1.235V reference voltage can be overridden by the V

REF

input.

Few external components are required, just the current reference resistor, current output load resistors, and decoupling capacitors.

Package is a 48-lead LQFP. Fabrication technology is CMOS. Performance is guaranteed from 0 to 70°C.

input timing

Block Diagram

SYNC

BLANK

9-0

CLOCK

+1.235V

Ref

SYNC

10 bit D/A Converter

COMP R

REF

Rev. 1.05 12/21/00

FMS3110/3115 PRODUCT SPECIFICATION

Functional Description

Within the FMS3110/3115 are three identical 10-bit D/A converters, each with a current source output. External loads are required to convert the current to voltage outputs. Data inputs RGB = H activates, sync current from I

are overridden by the BLANK

7-0

for sync-on-green video

signals.

Digital Inputs

All digital inputs are TTL-compatible. Data is registered on the rising edge of the CLK signal. Following one stage of pipeline delay, the analog output changes t edge of CLK.

and BLANK

SYNC

SYNC and BLANK inputs control the output level (Figure 1 and Table 1) of the D/A converters during CRT retrace intervals. BLANK forces the D/A outputs to the blanking level while SYNC = L turns off a current source that is connected to the green D/A converter. SYNC = H adds a 40 IRE sync pulse to the green output, SYNC = L sets the green output to 0.0 Volts during the sync tip. SYNC and BLANK are registered on the rising edge of CLK.

BLANK gates the D/A inputs and sets the pedestal voltage. If BLANK = HIGH, the D/A inputs are added to a pedestal which offsets the current output. If BLANK = Low, data inputs and the pedestal are disabled.

input. SYNC

after the rising

D/A Outputs

Each D/A output is a current source. To obtain a voltage output, a resistor must be connected to ground. Output voltage depends upon this external resistor, the reference voltage, and the value of the gain-setting resistor connected between R

and GND.

REF

Normally, a source termination resistor of 75 Ohms is connected between the D/A current output pin and GND near the D/A converter. A 75 Ohm line may then be connected with another 75 Ohm termination resistor at the far end of the cable. This “double termination” presents the D/A converter with a net resistive load of 37.5 Ohms.

The FMS3110/3115 may also be operated with a single 75 Ohm terminating resistor. To lower the output voltage swing to the desired range, the nominal value of the resistor on R

should be doubled.

REF

Voltage Reference

All three D/A converters are supplied with a common voltage reference. Internal bandgap voltage reference voltage is +1.235 Volts with a 3K Ω source resistance. An external voltage reference may be connected to the V overriding the internal voltage reference.

A 0.1µF capacitor must be connected between the COMP pin and V

to stabilize internal bias circuitry and ensure

low-noise operation.

REF

pin,

data: 660 mV max.

pedestal: 54 mV

sync: 286 mV

Figure 1. Nominal Output Levels

Power and Ground

Required power is a single +5.0 Volt supply. To minimize power supply induced noise, analog +5V should be connected to V

pins with 0.1 and 0.01 µF decoupling capacitors

placed adjacent to each V

The high slew-rate of digital data makes capacitive coupling to the outputs of any D/A converter a potential problem. Since the digital signals contain high-frequency components of the CLK signal, as well as the video output signal, the resulting data feedthrough often looks like harmonic distortion or reduced signal-to-noise performance. All ground pins should be connected to a common solid ground plane for best performance.

pin or pin pair.

REV. 1.05 12/21/00

PRODUCT SPECIFICATION FMS3110/3115

Table 1. Output Voltage Versus Input Code, SYNC

= 1.235 V, R

REF

= 590 Ω , R

REF

= 37.5 Ω

and BLANK

Blue and Red D/As Green D/A

RGB

(MSB…LSB)

9-0

SYNC BLANK V

OUT

SYNC BLANK V

11 1111 1111 X 1 0.7140 1 1 1.0000 11 1111 1111 X 1 0.7140 0 1 0.7140 11 1111 1110 X 1 0.7134 1 1 0.9994 11 1111 1101 X 1 0.7127 1 1 0.9987

•

• 10 0000 0000 X 1 0.3843 1 1 0.6703 01 1111 1111 X 1 0.3837 1 1 0.6697

•

• 00 0000 0010 X 1 0.0553 1 1 0.3413 00 0000 0001 X 1 0.0546 1 1 0.3406 00 0000 0000 X 1 0.0540 1 1 0.3400

XX XXXX XXXX X 0 0.0000 1 0 0.2860 XX XXXX XXXX X 0 0.0000 0 0 0.0000

OUT

•

Pin Assignments

G0R9R8R7R6R5R4R

484746454443424140

G G G G G G G G G

BLANK

SYNC

7 8

9 10 11 12

FMS3110/3115

131415161718192021

B0B1B2B3B4B6B

LQFP

R2R1NC

B7B8B

36 35

34 33 32 31 30 29 28 27

26 25

REF

COMP IO

B GND GND CLOCK

REV. 1.05 12/21/00

FMS3110/3115 PRODUCT SPECIFICATION

Pin Descriptions

Pin Name Pin Number Value Description Clock and Pixel I/O

CLK 26 TTL

9-0

47-37 TTL

48, 9–1 TTL

23–14 TTL

Controls

SYNC 11 TTL

Clock Input. The clock input is TTL-compatible and all pixel data is

registered on the rising edge of CLK. It is recommended that CLK be driven by a dedicated TTL buffer to avoid reflection induced jitter, overshoot, and undershoot.

Red Pixel Data Inputs. TTL-compatible Red Data Inputs are

registered on the rising edge of CLK.

Green Pixel Data Inputs. TTL-compatible Green Data Inputs are

registered on the rising edge of CLK.

Blue Pixel Data Inputs. TTL-compatible Blue Data Inputs are

registered on the rising edge of CLK.

Sync Pulse Input. Bringing SYNC LOW, turns off a 40 IRE (7.62 mA)

current source which forms a sync pulse on the Green D/A converter output. SYNC is registered on the rising edge of CLK with the same pipeline latency as BLANK and pixel data. SYNC does not override any other data and should be used only during the blanking interval.

BLANK 10 TTL

Video Outputs

33 0.714 V

32 1 V

p-p

29 0.714 V

Since this is a single-supply D/A and all signals are positive-going, sync is added to the bottom of the Green D/A range. So turning SYNC OFF means turning the current source ON. When a sync pulse is desired, the current source is turned OFF. If the system does not require sync pulses from the Green D/A converter, SYNC should be connected to GND.

Blanking Input. When BLANK is LOW, pixel inputs are ignored and

the D/A converter outputs fall to the blanking level. BLANK is registered on the rising edge of CLK and has the same pipeline latency as SYNC

Red Current Output. The current source outputs of the D/A

p-p

converters are capable of driving RS-343A/SMPTE-170M compatible levels into doubly-terminated 75 Ohm lines.

Green Current Output. The current source outputs of the D/A

converters are capable of driving RS-343A/SMPTE-170M compatible levels into doubly-terminated 75 Ohm lines. Sync pulses may be added to the Green D/A output.

Blue Current Output. The current source outputs of the D/A

p-p

converters are capable of driving RS-343A/SMPTE-170M compatible levels into doubly-terminated 75 Ohm lines.

REV. 1.05 12/21/00

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