LM3561TMXSLASHNOPB datasheet(21/37 Pages) TI1

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SDA

Start Condition

Stop Condition

SCL

LM3561

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SNOSB44C – MARCH 2011 – REVISED MAY 2013

INPUT VOLTAGE MONITOR FAULT

The VIN Monitor Flag (bit [7] of the Flags Register) reads back a '1' when the Input Voltage Monitor is enabled

and VIN falls below the programmed (VIN_TH). The input voltage must rise above VIN_TH and the Flags register

must be read back in order to resume normal operation after the LED current has been forced to Torch mode or

turned off due to a VIN Monitor event.

TX1 AND TX2 INTERRUPT FLAGS

The TX1 and TX2 interrupt flags (bits [3] and [4] of the Flags register) indicate a TX event on the TX1 or TX2

pins. Bit 3 will read back a '1' if TX1/TORCH is in TX1 mode and the pin has changed from low to high since the

last read of the Flags Register. Bit [4] will read back a '1' if TX2 is in TX2 mode and the pin has had a TX event

since the last read of the Flags Register. A read of the Flags Register automatically resets these bits.

A TX event can be either a high to low transition or a low to high transition depending on the setting of the TX1

or TX2 polarity bits (see Table 12).

2C-Compatible Interface

START AND STOP CONDITIONS

The LM3561 is controlled via an I2C-compatible interface. START and STOP conditions classify the beginning

and end of the I2C session. A START condition is defined as SDA transitioning from HIGH to LOW while SCL is

HIGH. A STOP condition is defined as SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C master

always generates the START and STOP conditions.

Figure 35. Start and Stop Sequences

The I2C bus is considered busy after a START condition and free after a STOP condition. During data

transmission the I2C master can generate repeated START conditions. A START and a repeated START

condition are equivalent function-wise. The data on SDA must be stable during the HIGH period of the clock

signal (SCL). In other words, the state of SDA can only be changed when SCL is LOW. Figure 4 and Figure 36

show the SDA and SCL signal timing for the I2C-compatible Bus. See the Electrical Characteristics Table for

timing values.

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