MAX7456EUI+T Maxim Integrated Products, MAX7456EUI+T Datasheet - Page 17

• Manufacturer Part Number: MAX7456EUI+T
• Description: IC DISPLAY 1CH W/EEPROM 28TSSOP
• Manufacturer: Maxim Integrated Products
• Type: OSD (On-Screen Display) Video Generatorr

Specifications of MAX7456EUI+T

• Applications: Security Systems, Video Routing
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP Exposed Pad, 28-eTSSOP, 28-HTSSOP
• Current - Supply: 58mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Interface: SPI Serial
• Display Type: OSD
• Digits Or Characters: 256 Characters
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Configuration: -
• Lead Free Status / Rohs Status: Details

The character memory is a 256-row x 64-byte wide
nonvolatile memory (NVM) that stores the characters or
graphic images, and is factory preloaded with the char-
acters shown in Figure 12. The content of the character
memory is user-programmable through the SPI-com-
patible serial interface. Each row contains the descrip-
tion of a single OSD character. Each character consists
of 12 horizontal x 18 vertical pixels where each pixel is
represented by 2 bits of data having three states: white,
black, or transparent. Thus, each character requires 54
bytes of pixel data (Figure 11).
The NVM requires reading and writing a whole charac-
ter (64 bytes) at a time. This is enabled by an additional
Figure 10. Definitions of Various Parameters
2-BIT PIXEL DEFINITIONS:
00 = BLACK, OPAQUE
10 = WHITE, OPAQUE
X1 = TRANSPARENT (EXTERNAL SYNC MODE)
OR GRAY (INTERNAL SYNC MODE)
(SEE FIGURE 11 FOR PIXEL MAP)
DISPLAY MEMORY ADDRESS
(DMAH, DMAL)
450
30
0
51
(12 x 18 PIXELS)
0
DATA USAGE
12 PIXELS
CHARACTER
52
1
53
2
______________________________________________________________________________________
(16 ROWS x 30 CHARACTERS)
Character Memory (NVM)
Single-Channel Monochrome On-Screen
DISPLAY AREA
4 PIXEL VALUES
ADDRESS LOW (CMAL)
CHARACTER MEMORY
(1 BYTE)
Display with Integrated EEPROM
0
0
0
1
1
PIXEL DATA ARRANGEMENT IN CHARACTER MEMORY (NVM)
2
2
479
29
59
DISPLAY MEMORY ADDRESS
(DMAH, DMAL)
CHARACTER
DATA
256 ROWS x 64 BYTES EEPROM
row of memory called the shadow RAM. The 64-byte
temporary shadow RAM contains all the pixel data of a
selected character (CMAH[7:0]) and is used as a buffer
for read and write operations to the NVM (Figure 13).
Accessing the NVM is always through the shadow
RAM, and is thus a two-step process. To write a char-
acter to the NVM, the user first fills the shadow RAM
using 54 8-bit SPI write operations, and then executes
a single shadow RAM write command. Similarly, read-
ing a character’s pixel values requires first reading a
character’s pixel data into the shadow RAM, and then
reading the desired pixel data from the shadow RAM to
the SPI port.
479
51
29
51
0
52
52
ADDRESS (8 BIT)
ADDRESS (8 BIT)
ADDRESS (8 BIT)
ADDRESS (CA)
CHARACTER
53
53
53
(TWO, 256 x 16-BIT SRAMs)
54
54
54
DISPLAY MEMORY
L
B
C
L
B
C
L
B
C
MEMORY
UNUSED
ADDRESS HIGH (CMAH)
B
L
K
B
L
K
B
L
K
CHARACTER MEMORY
CHARACTER
I
N
V
I
N
V
I
N
V
ATTRIBUTE
X X X X X
X X X X X
X X X X X
61
61
62
62
63
63
63
CHARACTER ATTRIBUTE BIT DEFINITIONS:
LBC = LOCAL BACKGROUND CONTROL
BLK = BLINK CONTROL
INV = INVERT CONTROL
X = DON'T CARE
CHARACTER DATA
ARRANGEMENT IN
DISPLAY MEMORY
(SRAM) 480 ROWS
x 2 BYTES SRAM
255
0
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