16-bitPrescaler

Safety Timer

LEDCURRENT CONTROL

Tx-TOFF

2MHzCLOCK

EdgeDetect

Start

0: TORCHCURRENT LEVEL

1:FLASHCURRENT LEVEL

122Hz

MODE1

400kW

30.5Hz

Duty-CycleGenerator(6.3%)

LEDON/OFFCONTROL

0:LEDOFF

1: TORCHCURRENT LEVEL

LEDCURRENT CONTROL

ILED

0

0

TorchCurrent

0

1

TorchCurrent

1

0

FlashCurrent

1

1

Torch Current

Tx-TOFF

400kW

MODE0

FLASH_SYNC

TPS61054, TPS61055

www.ti.com

SLUS760B – SEPTEMBER 2007 – REVISED SEPTEMBER 2015

Functional Block Diagrams (continued)

Figure 13. Timer Block Diagram of TPS6105x

9.3 Feature Description

9.3.1 Operation

In boost mode, the duty cycle of the converter is set by the error amplifier and the saw-tooth ramp applied to the

comparator. Because the control architecture is based on a current-mode control, a compensation ramp is added

to allow stable operation at duty cycles larger than 50%. The converter is a fully-integrated synchronous-boost

converter, always operating in continuous-conduction mode. This allows low-noise operation, and avoids ringing

on the switch pin, which would be seen on a converter when entering discontinuous-conduction mode.

The TPS6105x device not only operates as a regulated current source but also as a standard voltage-boost

regulator. This additional operating mode can be useful to properly synchronize the converter when supplying

other high-power devices in the system, such as a hands-free audio power amplifier, or any other component

requiring a supply voltage higher than the battery voltage.

The mode of operation (shutdown, torch and flash modes, constant voltage regulation) selection is done through

the MODE0/1 control inputs.

Table 2. TPS6105x Operating Modes

MODE1 MODE0

OPERATING MODES

0

0

Power stage is in shutdown. The output is either connected directly to the battery through the body diode of the rectifier.

LED is turned on for torch light operation. The converter is operating in the current regulation mode (CM).

0

1

The output voltage is controlled by the forward voltage characteristic of the LED.

LED is turned on for flashlight operation. The converter is operating in the current regulation mode (CM).

1

0

The output voltage is controlled by the forward voltage characteristic of the LED.

LED is turned off and the converter is operating in voltage regulation mode (VM).

1

1

The output voltage is regulated to 5.0 V.

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