BUF12840_12 Datasheet, PDF (12/26 Pages) Texas Instruments – Programmable Gamma-Voltage Generator with Integrated Two-Bank Memory and External EEPROM

BUF12840
SBOS519A – OCTOBER 2010 – REVISED JULY 2011
POR
Time = 0
5ms
1.5V
POR Activates Master Mode
EEPROM Address + Acknowledge
Framing Pulse for EEPROM Query
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Time (ms)
SDA
Idle
¼
1ms
900ms
5ms
EN
¼
EN (high, '1') should be enabled prior to a query pulse and
before the 10th query attempt to remain in master mode.
General Case
Case 1
EEPROM Ready on
Fourth Read Attempt
Case 2
EEPROM Ready on
Tenth Read Attempt
Case 3
EEPROM Not Ready
in 5ms
10ms
5ms
Wait
1st
EEPROM
Query
2nd
EEPROM
Query if
1st Failed
3rd
EEPROM
Query if
2nd Failed
¼
nth
EEPROM
Query if
(n-1) Failed
¼
mth Query Successful,
Data Now Downloaded
From EEPROM
EEPROM Data Loaded
BUF12840 Eneters Slave Mode
5
6
7
n
n+1
m
(m + 10ms)
Time (ms)
5ms
Wait
1st
EEPROM
Query
2nd
EEPROM
Query if
1st Failed
3rd
EEPROM
Query if
2nd Failed
4th
EEPROM
Query if
3rd Failed
4th Query Successful,
Data Now Downloaded
From EEPROM
EEPROM Data Loaded
BUF12840 Eneters Slave Mode
5
6
7
8
9
10ms
19
Time (ms)
5ms
Wait
1st
EEPROM
Query
2nd
EEPROM
Query if
1st Failed
3rd
EEPROM
Query if
2nd Failed
5
6
7
8
¼
10th
EEPROM
Query if
9thFailed
10th Query Successful,
Data Now Downloaded
From EEPROM
EEPROM Data Loaded
BUF12840 Eneters Slave Mode
14
15
10ms
25
Time (ms)
5ms
Wait
1st
EEPROM
Query
2nd
EEPROM
Query if
1st Failed
3rd
EEPROM
Query if
2nd Failed
5
6
7
n
¼
nth
EEPROM
Query if
(n-1) Failed
n+1
¼
9th
EEPROM
Query if
8th Failed
10th
EEPROM
Query if
9th Failed
EEPROM Data Loaded
BUF12840 Eneters Slave Mode
13
14
15
Time (ms)
Figure 14. POR Master Mode Auto Read Function and Timing Diagram
MASTER MODE CLOCK SPEED
In master mode, the BUF12840 generates it own
clock and puts it on the SCL pin. The frequency is
nominally 87kHz, with a maximum value of 100kHz
and a minimum value of 71kHz. When the BUF12840
has exclusive access to the two-wire bus, it takes a
maximum of 10ms to download both banks of data
from the moment power becomes valid. However,
when the BUF12840 is in master mode, if there is
contention on the two-wire bus because of another
active master, the BUF12840 activates its clock
synchronization and arbitration engine. In this case, it
may take longer for the BUF12840 to finish the
download.
The BUF12840 can only synchronize with other
masters that operate in Standard Mode (clock speed
≤ 100kHz). It is not recommended to have another
master with higher speed operating at the same time.
Note that once in slave mode, the BUF12840
supports clock speeds up to 3.4MHz.
GENERAL-CALL RESET
The BUF12840 responds to software general-call
reset (GCR). Upon receiving a GCR command, the
BUF12840 enters master mode and downloads data
from the EEPROM as if the power supply was just
switched on.
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