Texas Instruments TPS65820 Evaluation Module TPS65820EVM TPS65820EVM Datenbogen
Produktcode
TPS65820EVM
RGB Driver
GREEN
I
LEDB
RED
BLUE
FLASH
CONTROL
LED
CURRENT
SETTINGS
RGB
DUTY
CYCLE
CONTROL
LED
CONTROL
LOGIC
OUT
R
RED
R
GRN
R
BLUE
I
LEDR
I
LEDG
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SLVS663B – MAY 2006 – REVISED APRIL 2008
The TPS65820 has a dedicated driver for an RGB external LED. Three outputs are available (pins RED,
GREEN, BLUE), with common settings for operation mode (flash on/off, flash period, flash on time), LED current
and phase delay between outputs. The TPS65820 RGB driver continually flashes the external LEDs connected
to the RED, GREEN and BLUE pins using the flash operation parameters defined in register RGB_FLASH.
GREEN, BLUE), with common settings for operation mode (flash on/off, flash period, flash on time), LED current
and phase delay between outputs. The TPS65820 RGB driver continually flashes the external LEDs connected
to the RED, GREEN and BLUE pins using the flash operation parameters defined in register RGB_FLASH.
The currents for the external LEDs can be programmed via I
2
C, and external resistors are not required to limit
the LED current. However, they can be added to set the LED current if the available I
2
C values are not
compatible with the current application, as shown in the circuit below:
Figure 57. Limiting the External LED Current
The flashing-mode parameters defined in register RGB_FLASH enable setting the flashing period from 1 to 8
seconds in 0.5-s steps, or to continuous operation. Flashing operation is enabled by setting the FLASH_EN bit in
register RGB_FLASH to HI. This bit must be set HI to enable the RGB current-sink channels.
seconds in 0.5-s steps, or to continuous operation. Flashing operation is enabled by setting the FLASH_EN bit in
register RGB_FLASH to HI. This bit must be set HI to enable the RGB current-sink channels.
Each driver has an individual duty cycle control. The duty cycle modulation method used is similar to the
PWM_LED duty cycle control, with high frequency pulses being generated when the driver (RED, GREEN, or
BLUE pins) is ON. The repetition period for the RGB drivers has a total of 32 pulses, enabling a 3.125%
resolution when programming the individual RED, GREEN and BLUE drivers duty cycles. The duty cycles for
each driver can be set individually using control bits on registers RGB_RED, RGB_GREEN and RGB_BLUE.
PWM_LED duty cycle control, with high frequency pulses being generated when the driver (RED, GREEN, or
BLUE pins) is ON. The repetition period for the RGB drivers has a total of 32 pulses, enabling a 3.125%
resolution when programming the individual RED, GREEN and BLUE drivers duty cycles. The duty cycles for
each driver can be set individually using control bits on registers RGB_RED, RGB_GREEN and RGB_BLUE.
The RGB drivers can be programmed to sink 4, 8, or 12 mA, with no external current limiting resistor.
Copyright © 2006–2008, Texas Instruments Incorporated
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