MP3336 – DUAL-CHANNEL, FLASH LED DRIVER WITH I

MP3336 Rev.1.01

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12

5/16/2017

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setting the LED1/2_EN bits to 0. These two bits

control

the

two

LED

current

sources

respectively (see Figure 3).

Figure 3: Assist Mode

Indicator Mode

When LED_MOD is set to 01 and LED_EN1/2

is set to 1, the MP3336 enters indicator mode,

which provides a low-current output (see Figure

4). In this mode, the driver current sources work

in a 31.5kHz PWM dimming mode. The current

amplitude can be set by I1_TOR and I2_TOR,

while the indicator current step ramps up more

quickly at a rate of 7.84mA/step, compared to

torch mode’s ramp-up rate of 1.25mA/step. The

final amplitude in this mode can be calculated

with Equation (1):

7.84mA x I1/2_TOR

(1)

The duty cycle is set by the INDI_PWM register.

When disabled, switch to standby mode or set

the LED1_EN and LED2_EN bits to 0.

Figure 4: Indicator Mode

In indicator mode, the MP3336 can also work in

blinking mode. If blinking is enabled, the IC

works in indicator mode during the blinking time,

and the LED current source is disabled during

the blinking time (see Figure 5). The blinking

time is set by the TBK0-1 bits in register 0FH.

Figure 5: Blinking Time

Flash Mode

The device can work in flash mode in three

ways: hardware and level trigger mode,

hardware and edge trigger mode, and software

and edge trigger mode. All of the below

description are based on bit STR_POL = 1. The

default high level is active for STR. When

STR_POL is set to 0, STR is low active.

1. Hardware and Level Trigger Mode

In this mode, STR_MOD = 1, STR_LV = 1,

LED1/2_EN = 1, LED_MOD = 11. The flash

current begins to ramp up after STR goes high.

The current is set by I1_FL and I2_FL, and the

ramp-up time is set by TUP_I. The flash current

ends when STR is pulled low or when the flash

timer ends. After flash, LED_MOD is reset to

standby mode, and LED1/2_EN is set to 0 if

LED_SD = 0. If LED_SD = 1, LED_MOD and

LED1/2_EN are not reset. The LED1 and LED2

current sources are controlled by the LED1_EN

and LED2_EN bits respectively. If the STR is

pulled low before the flash timer ends, the flash

current shuts down at the STR falling edge (see

Figure 6). Conversely, if the flash timer set by

FL_TIM ends before STR goes low, the flash

current terminates immediately. The time-out

indicator bit FT_TO is set to 1 and is not

cleared until it is read back or the input power

resets (see Figure 7).