10.1.6.1 Bit Transfer

One data bit is transferred during each clock pulse. The data on the SDA line must remain stable during the high period of the clock pulse as changes in the data line at this time will be interpreted as control signals (see Figure 12).

Figure 12. Bit Transfer

10.1.6.2 Start and Stop Conditions

Both data and clock lines remain high when the bus is not busy. A high-to-low transition of the data line while the clock is high is defined as the Start condition (S). A low-to-high transition of the data line while the clock is high is defined as the Stop condition (P) (see Figure 13).

Figure 13. Start and Stop Conditions

10.1.6.3 Acknowledge

The number of data bytes transferred between the Start and the Stop conditions from transmitter to receiver is not limited. Each byte of eight bits is followed by one acknowledge bit. The acknowledge bit is a high level put on the bus by the transmitter, whereas the master generates an extra acknowledge related clock pulse.

A slave receiver that is addressed must generate an acknowledge after the reception of each byte. Also a master must generate an acknowledge after the reception of each byte that has been clocked out of the slave transmitter. The device that acknowledges has to pull down the SDA line during the acknowledge clock pulse, so that the SDA line is stable low during the high period of the acknowledge related clock pulse; set-up time and hold time must be taken into account.

A master receiver must signal an end of data to the transmitter by not generating an acknowledge on the last byte that has been clocked out of the slave. In this event, the transmitter must leave the data line high to enable the master to generate a Stop condition.

Figure 14. Acknowledge/Not Acknowledge on I²C Bus

Figure 15. Write to a Specific Register

A. See Table 3 for register definitions.

Figure 16. Write to All Registers Using Auto-Increment

Figure 17. Multiple Writes to Individual Brightness Registers Using Auto-Increment

Figure 18. Read All Registers Auto-Increment

A. In this example, several TLC59116 devices are used, and the same Sequence A is sent to each of them.

B. The ALLCALL bit in the MODE1 register is equal to 1 for this example.

C. The OCH bit in the MODE2 register is equal to 1 for this example.

Figure 19. LED All Call I²C Bus Address Programming and LED All Call Sequence

10.2.2.1 Adjusting Output Current

TLC59116 scales up the reference current (I_ref) set by the external resistor (R_ext) to sink the output current (I_out) at each output port. Table 12 shows the Configuration Code and discusses bits CM, HC, and CC[5:0]. The following formulas can be used to calculate the target output current I_OUT,target in the saturation region:

Where R_ext is the resistance of the external resistor connected to the REXT terminal, and V_REXT is the voltage of REXT, which is controlled by the programmable voltage gain (VG), which is defined by the Configuration Code.

The Current Multiplier bit (CM) sets the ratio I_OUT,target/I_ref to 15 or 5 (sets the exponent "CM – 1" to either 0 or –1). After power-on, the default value of VG is 127/128 = 0.992, and the default value of CM is 1, so that the ratio I_OUT,target/I_ref = 15. Based on the default VG and CM:

Therefore, the default current is approximately 20mA at 931 ohms.. The default relationship after power-on between I_OUT,target and R_ext is shown in Figure 1.

Figure 2 shows the output voltage versus the output current with several different resistor values on REXT. This shows the minimum voltage required at the device to have full VF across the LED. The VLED voltage must be higher than the VF plus the VOL of the driver. If the VLED is too high, more power will be dissipated in the driver. If this is the case, a resistor can be inserted in series with the LED to dissipate the excess power and reduce the thermal conditions on the driver.

If a single driver is used with LEDs that have different VF values, resistors can also be used in series with the LED to remove the excess power from the driver. In cases where not all outputs are being used, the unused outputs can be left floating without issue.