BUF20800-Q1 Datasheet, PDF (10/32 Pages) Texas Instruments – 18-CHANNEL GAMMA VOLTAGE GENERATOR WITH TWO PROGRAMMABLE VCOM CHANNELS

BUF20800-Q1
SBOS571 – AUGUST 2011
www.ti.com
Method 3 uses software control. LD is maintained HIGH, and all DACs are updated when the master writes a 1
in bit 15 of any DAC register. The update will occur after receiving the 16-bit data for the currently-written
register.
The General Call Reset and the power-up reset will update the DAC regardless of the state of the latch pin.
READ/WRITE OPERATIONS
The BUF20800-Q1 is able to read from a single DAC, or multiple DACs, or write to the register of a single DAC,
or multiple DACs in a single communication transaction. DAC addresses begin with 0000 0000, which
corresponds to DAC_1, through 0001 0011, which corresponds to V_COM OUT2.
Write commands are performed by setting the read/write bit LOW. Setting the read/write bit HIGH will perform a
read transaction.
Writing
To write to a single DAC register
1. 1. Send a START condition on the bus.
2. Send the device address and read/write bit = LOW. The BUF20800-Q1 will acknowledge this byte.
3. Send a DAC address byte. Bits D7−D5 must be set to 0. Bits D4−D0 are the DAC address. Only DAC
addresses 00000 to 10011 are valid and will be acknowledged. Table 3 shows the DAC addresses.
4. Send two bytes of data for the specified DAC register. Begin by sending the most significant byte first (bits
D15−D8, of which only bits D9 and D8 are used, and bits D15−D14 must not be 01), followed by the least
significant byte (bits D7−D0). The register is updated after receiving the second byte.
5. Send a STOP condition on the bus
Table 3. DAC Addresses
DAC
DAC_1
DAC_2
DAC_3
DAC_4
DAC_5
DAC_6
DAC_7
DAC_8
DAC_9
DAC_10
DAC_11
DAC_12
DAC_13
DAC_14
DAC_15
DAC_16
DAC_17
DAC_18
V_COM OUT1
V_COM OUT2
ADDRESS
0000 0000
0000 0001
0000 0010
0000 0011
0000 0100
0000 0101
0000 0110
0000 0111
0000 1000
0000 1001
0000 1010
0000 1011
0000 1100
0000 1101
0000 1110
0000 1111
0001 0000
0001 0001
0001 0010
0001 0011
10
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