LM3550_13 Datasheet, PDF (19/37 Pages) Texas Instruments – 5A Flash LED Driver with Automatic VLED and ESR Detection for Mobile Camera Systems

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LM3550
SNVS569B – MAY 2009 – REVISED MAY 2013
Shutdown
Charge
Voltage
Mode
Charge
Optimal
Charge
Mode
Flash
Torch
Charge and
Torch
Figure 48. FGATE = '1' State Diagram
I²C-Compatible Interface
DATA VALIDITY
The data on SDA line must be stable during the HIGH period of the clock signal (SCL). In other words, the state
of the data line can only be changed when SCL is LOW.
SCL
SDA
data
change
allowed
data
valid
data
change
allowed
data
valid
data
change
allowed
Figure 49. Data Validity Diagram
A pull-up resistor between VIO (Logic Power Supply) and SDA must be greater than [(VIO − V_OL) / 3.0 mA] to
meet the V_OL requirement on SDA. Using a larger pull-up resistor results in lower switching current with slower
edges, while using a smaller pull-up results in higher switching currents with faster edges.
START AND STOP CONDITIONS
START and STOP conditions classify the beginning and the end of the I²C session. A START condition is
defined as SDA signal transitioning from HIGH to LOW while SCL line is HIGH. A STOP condition is defined as
the SDA transitioning from LOW to HIGH while SCL is HIGH. The I²C master always generates START and
STOP conditions. The I²C bus is considered to be busy after a START condition and free after a STOP condition.
During data transmission, the I²C master can generate repeated START conditions. First START and repeated
START conditions are equivalent, function-wise. The data on SDA line must be stable during the HIGH period of
the clock signal (SCL). In other words, the state of the data line can only be changed when SCL is LOW.
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