Texas Instruments TPS61050-269 Evaluation Board TPS61050EVM-269 TPS61050EVM-269 TPS61050EVM-269 Datenbogen
Produktcode
TPS61050EVM-269
www.ti.com
OPERATING MODES: TORCH AND FLASH
I
FLASH
FLASH_SYNC
Free
Free
I2 C Bus
LED Current
DC/DC Turn-On Command
TC[2:0] = 000
MODE_CTRL[1:0] = 10
DC/DC Turn-Off Command
MODE_CTRL[1:0] = 00
FLASH_SYNC or (SFT)
LED CONTROL
TIMER
STIM
IFLASH
TORCH
TIME-OUT
RESET (SF)
FLASH_SYNC or (SFT)
LED CONTROL
TIMER
STIM
FLASH
TORCH
TIME-OUT
RESET (SF)
SLUS525 – MARCH 2007
DETAILED DESCRIPTION (continued)
The device operation is more easily understood by referring to the timer block diagram. Depending on the
settings of MODE_CTRL[1:0] bits the device can enter 4 different operating modes:
settings of MODE_CTRL[1:0] bits the device can enter 4 different operating modes:
•
MODE_CTRL[1:0] = 00: The device is in shutdown mode.
•
MODE_CTRL[1:0] = 01: The device is regulating the LED current to the torch current level (TC bits)
regardless of the FLASH_SYNC input and START_FLASH/TIMER (SFT) bit. The safety timer is disabled in
this operating mode.
regardless of the FLASH_SYNC input and START_FLASH/TIMER (SFT) bit. The safety timer is disabled in
this operating mode.
•
MODE_CTRL[1:0] = 11: The device is regulating a constant output voltage according to OV[1:0] bits settings.
The low-side LED current regulator is disabled and the LED is disconnected from the output. In this operating
mode, the safety timer is disabled and the general purpose timer (DCTIM) can be used to generate a
software timeout (TO) flag. DCTIM start is triggered on the rising edge of START_FLASH/TIMER (SFT).
The low-side LED current regulator is disabled and the LED is disconnected from the output. In this operating
mode, the safety timer is disabled and the general purpose timer (DCTIM) can be used to generate a
software timeout (TO) flag. DCTIM start is triggered on the rising edge of START_FLASH/TIMER (SFT).
•
MODE_CTRL[1:0] = 10: The flash pulse can be either trigger by a hardware signal (FLASH_SYNC) or by a
software bit (SFT).
software bit (SFT).
Flash strobe is level sensitive (STT = 0): LED strobe pulse follows FLASH_SYNC
•
FLASH_SYNC and (SFT) = 0: LED operation is set to the torch current level and the safety timer is disabled.
•
FLASH_SYNC or (SFT) = 1: The LED is driven at the flash current level and the safety timer is running.
The maximum duration of the flash pulse is defined in the STIM register.
Figure 31. Torch Mode Operation
Figure 32. Synchronized Flash Strobe
Figure 33. Level Sensitive Safety Timer (Timeout)
Figure 34. Level Sensitive Safety Timer (Normal
Operation + Timeout)
The safety timer is started by:
•
a rising edge of FLASH_SYNC signal.
•
a rising edge of START_FLASH/TIMER (SFT) bit.
The safety timer is stopped by:
•
a low level of FLASH_SYNC signal or START_FLASH/TIMER (SFT) bit.
•
a timeout signal (TO).
The START-FLASH/TIMER (SFT) bit is reset by the timeout (TO) signal.
19