adv473 Analog Devices, Inc., adv473 Datasheet - Page 5

• Manufacturer Part Number: adv473
• Description: Cmos 135 Mhz True-color Graphics Triple 8-bit Video Ram-dac
• Manufacturer: Analog Devices, Inc.

PIN FUNCTION DESCRIPTION
BLANK
SYNC
CLOCK
R0–R7
B0–B7
G0–G7
S0, S1
OL0–OL3
IOR, IOG, IOB
R
COMP
V
V
V
GND
WR
RD
RS0, RS1, RS2
D0–D7
CR0–CR7
REV. A
REFIN
REFOUT
AA
SET
Composite Blank Control Input (TTL Compatible). A logic zero drives the analog outputs to the blanking level.
It is latched on the rising edge of CLOCK. When BLANK is a logical zero, the pixel and overlay inputs are
ignored.
Composite SYNC Control Input (TTL Compatible). A logical zero on this input switches off a 40 IRE current
source on the analog outputs. SYNC does not override any other control or data input; therefore, it should be
asserted only during the blanking interval. It is latched on the rising edge of CLOCK. If sync information is not
required on the analog outputs, SYNC should be connected to ground.
Clock Input (TTL Compatible). The rising edge of CLOCK latches the R0–R7, G0–G7, B0–B7, S0, S1,
OL0–OL3, SYNC, and BLANK inputs. It is typically the pixel clock rate of the video system. It is
recommended that CLOCK be driven by a dedicated TTL buffer.
Red, Green and Blue Select Inputs (TTL Compatible). These inputs specify, on a pixel basis, the color value to
be written to the DACs. They are latched on the rising edge of CLOCK. R0, G0 and B0 are the LSBs. Unused
inputs should be connected to GND.
Color Mode Select Inputs (TTL Compatible). These inputs specify the mode of operation as shown in Table III.
They are latched on the rising edge of CLOCK.
Overlay Select Inputs (TTL Compatible). These inputs specify which palette is to be used to provide color
information. When accessing the overlay palette, the R0–R7, G0–G7, B0–B7, S0 and S1 inputs are ignored. They
are latched on the rising edge of CLOCK. OL0 is the LSB. Unused inputs should be connected to GND.
Red, Green, and Blue Current Outputs. These high impedance current sources are capable of directly driving a
doubly terminated 75
Full-Scale Adjust Resistor. A resistor (R
full-scale video signal. The relationship between R
Compensation Pin. These pins should be connected together at the chip and connected through 0.1 F ceramic
capacitor to V
Voltage Reference Input. This input requires a 1.2 V reference voltage. This is achieved through the on-board
voltage reference generator by connecting V
this input with a 1.2 V (typical) reference.
Voltage Reference Output. This output delivers a 1.2 V reference voltage from the device’s on-board voltage
reference generator. It is normally connected directly to the V
voltage reference, this pin may be left floating. Up to four ADV473s can be driven from V
Analog power. All V
Analog Ground. All GND pins must be connected.
Write Control Input (TTL Compatible). D0–D7 data is latched on the rising edge of WR, and RS0–RS2 are
latched on the falling edge of WR during MPU write operations. RD and WR should not be asserted
simultaneously.
Read Control Input (TTL Compatible). To read data from the device, RD must be a logical zero. RS0–RS2 are
latched on the falling edge of RD during MPU read operations. RD and WR should not be asserted
simultaneously.
Register Select Inputs (TTL Compatible). RS0–RS2 specify the type of read or write operation being performed.
Data Bus (TTL Compatible). Data is transferred into and out of the device over this eight-bit bidirectional data
bus. D0 is the least significant bit.
Control Outputs (TTL Compatible). These outputs are used to control application specific features. The output
values are determined by the contents of the command register (CR).
R
R
SET
SET
( ) = 3,195 V
( ) = 3,025 V
AA
.
AA
pins must be connected.
coaxial cable.
REF
REF
(V)/I
(V)/I
OUT
OUT
SET
(mA) SETUP = 7.5 IRE)
(mA) SETUP = 0 IRE)
) connected between this pin and GND controls the magnitude of the
REFOUT
–5–
SET
to V
and the full-scale output current on each output is:
REFIN
. If an external reference is used, it must supply
REFIN
pin. If it is preferred to use an external
REFOUT
.
ADV473