TLC5946_16 Datasheet, PDF (23/41 Pages) Texas Instruments – 16-Channel, 12-Bit PWM LED Driver with 6-Bit Dot Correction

TLC5946
www.ti.com .......................................................................................................................................................... SLVS824B – MARCH 2008 – REVISED JUNE 2008
POWER DISSIPATION CALCULATION
The device power dissipation must be below the power dissipation rate of the device package to ensure correct
operation. Equation 6 calculates the power dissipation of the device:
DCn
P_D = (V_CC ´ I_CC) +
V_OUT
´
I
OLCMax
´
N
´
63d
´ d_PWM
(6)
Where:
• P_D = device power dissipation
• V_CC = device supply voltage
• I_CC = device supply current
• V_OUT = OUTn voltage when driving LED current
• I_OLCMax = LED current adjusted by R_IREF resistor
• DCn = maximum DC value for OUTn
• N = number of OUTn driving LED at the same time
• d_PWM = duty cycle defined by BLANK pin or GS PWM value
EXTENDED SERIAL INTERFACE
The TLC5946 has an extended serial interface with the following functions:
1. Independently accessible GS shift register of OUT0 to OUT7 or OUT8 to OUT15
2. SOUT half clock delay
When XHALF is low, the extended serial interface becomes active. Either the OUT0 to OUT7 GS shift register or
the OUT8 to OUT15 GS shift register is selected in advance by counting the XLAT pulses while BLANK is high
(one XLAT pulse selects the OUT0 to OUT7 GS shift register and two XLAT pulses select the OUT8 to OUT15
GS shift register), as shown in Figure 33. One or two XLAT pulses while BLANK is high must be input before
sending the serial data.
SOUT outputs serial data at the falling edge of SCLK, delaying half a clock longer than the normal serial
interface mode. SIN reads data at the rising edge of SCLK at the same as the normal serial interface mode. This
configuration ensures a longer distance serial interface. Figure 34 shows the output timing of the extended serial
interface mode.
SOUT outputs the status information data only when the data of OUT8 to OUT15 are shifted in, as shown in
Figure 35 and Figure 36. The status information data configuration when XHALF is low is shown in Figure 37.
Figure 38 shows the recommended ac timing widths of the extended serial interface. Note that t_WL2, t_SU7, and t_H3
are only effective when XHALF is low.
Figure 39 and Figure 40 are power-on sequence examples of this mode. BLANK should be high when the device
is powered on to prevent the outputs from turning on before the proper GS and DC values are written. The
extended serial interface mode is available only in the GS PWM mode (MODE = low). When MODE is high in the
extended serial interface mode (XHALF = low), the TLC5946 becomes the DC mode that is the same as the
normal DC mode.
Copyright © 2008, Texas Instruments Incorporated
Product Folder Link(s): TLC5946
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