TLC34058 Datasheet, PDF (5/26 Pages) Texas Instruments – 256 × 24 COLOR PALETTE

TLC34058
256 × 24 COLOR PALETTE
PIN NAME
BLK
C0, C1
CE
CLK
CLK
COMP
D0 – D7
FS ADJ
GND
IOR, IOG
IOB
LD
OL0A – OL1A
OL0B – OL1B
OL0C – OL1C
OL0D – OL1D
OL0E – OL1E
P0A – P7A
P0B – P7B
P0C – P7C
P0D – P7D
P0E – P7E
REF
SLAS050 – D3961, NOVEMBER 1991
Terminal Functions
I/O
DESCRIPTION
I Composite blank control. This TTL-compatible blanking input is stored in the input latch on the rising edge of LD. When
low, BLK drives the DAC outputs to the blanking level, as shown in Table 6. This causes the P0 – P7 [A – E] and
OL0 – OL1 [A – E] inputs to be ignored. When high, BLK allows the device to perform in the standard manner.
I Command control inputs. The inputs specify the type of write or read operation (see Tables 1, 2, 3, and 4). These
TTL-compatible inputs are latched on the falling edge of CE.
I Chip enable. This TTL-compatible input control allows data to be stored and enables data to be written or read (see
Figure 1). When low, CE enables data to be written or read. When high, CE allows data to be internally latched on the
rising edge during write operations. Care should be taken to avoid transients on this input.
I _{Clock. This input provides the pixel clock rate. CLK and CLK inputs are designed to be driven by ECL logic using a 5-V}
single supply.
I Clock. This input is the complement of CLK and also provides the pixel clock rate.
I Compensation. This input is used to compensate the internal reference amplifier (see the video generation section).
A 0.1-µF ceramic capacitor is connected between this pin and VDD (see Figure 4). The highest possible supply voltage
rejection ratio is attained by connecting the capacitor to VDD rather than to GND.
I Data input bus. This TTL-compatible bus transfers data into or out of the device. The data bus is an 8-bit bidirectional
bus where D0 is the least significant bit.
I Full-scale adjust control. A resistor Rset, (see Figure 4) which is connected between this pin and GND, controls the
magnitude of the full-scale video signal. Note that the proportional current and voltage relationships in Figure 3 are
maintained independent of the full-scale output current. The relationships between Rset and the IOR, IOG, and IOB
full-scale output currents are:
Rset(Ω) = 11294 × Vref(V) / IOG(mA)
IOR, IOB (mA) = 8067 × Vref(V) / Rset(Ω)
Ground. All GND pins must be connected together.
O Current outputs, red, green, and blue. High-impedance red, green, and blue video analog current outputs can directly
drive a 75-Ω coaxial terminated at each end (see Figure 4).
I _{Load control. This TTL-compatible load control input latches the P0 – P7 [A – E], OL0 – OL1 [A – E], BLK, and SYNC}
inputs on its rising edge. The LD strobe occurs at 1/4 or 1/5 the clock rate and may be phase independent of the CLK
and CLK inputs. The LD duty cycle limits are specified in the timing requirements table.
l Overlay selection inputs. These TTL-compatible selection inputs for the Palette overlay registers are stored in the input
latch on the rising edge of LD. These inputs (up to 2 bits per pixel), along with bit CR6 of the command register (refer
to the command register section and Table 5), specify whether the color information is selected from the palette RAM
or the overlay registers. If the color information is selected from the overlay registers, the OL0 – OL1 [A – E] inputs
address a particular overlay register. The OL0 – OL1 [A – D] or OL0 – OL1 [A – E] inputs are simultaneously input to the
device (see the description of bit CR7 in the command register section). The OL0 – OL1 [A] inputs are processed first,
then the OL0 – OL1 [B] inputs, and so on. When obtaining the color information from the overlay registers, the P0 – P7
[A – E] inputs are ignored. Unused inputs should be connected to GND.
l Address inputs. These TTL-compatible address inputs for the Palette RAM are stored in the input latch on the rising edge
of LD. These address inputs (up to 8-bits per pixel) select one of 256 24-bit words in the palette RAM, which is
subsequently input to the red, green, and blue D/A converters as three 8-bit or 4-bit bytes. Four or five addresses are
simultaneously input to the P0 – P7 [A – D] or P0 – P7 [A – E] ports, respectively (see the description of bit CR7 in the
command register section). The word addressed by P0A – P7A is first sent to the DACs, then the word addressed by
P0B – P7B, and so on. Unused inputs should be connected to GND.
I Reference voltage. 1.235-V is supplied at this input. An external voltage reference circuit, shown in Figure 4, is sug-
gested. Generating the reference voltage with a resistor network is not recommended since low-frequency power supply
noisewill directly couple into the DAC output signals. This input must be decoupled by connecting a 0.1-µF ceramic
capacitorbetween VREF and GND.
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