MP3336 – DUAL CHANNEL, FLASH LED DRIVER WITH I

MP3336 Rev.1.01

www.MonolithicPower.com

11

5/16/2017

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© 2017 MPS. All Rights Reserved.

OPERATION

The MP3336 is a dual-channel, LED driver with

camera flash. The MP3336 can work in flash

mode, assist mode, torch mode, indicator mode,

and fixed 5V DC output mode. Table 1 shows

how to set these operation modes.

LED Driver Operation

The MP3336 is a synchronous, current-mode,

PWM, boost converter that can work with

1/2/3/4MHz. The MP3336 regulates the boost

loop by detecting and controlling the headroom

voltage across the current source (VOUT-

VLED1/2).

When the device is enabled by LED_EN, the

synchronous PMOS works with a 250mA

current source first to charge the output

device changes to boost switching mode if the

voltage across the current source is less than

the target reference, which is set by VTH_PAS.

boost

switching

mode

and

pass

mode

automatically to minimize power loss. In pass

mode, the synchronous PMOS is fully turned on.

During the current start-up, the current ramps

up step-by-step smoothly until the target setting

current is reached.

Table 1: Operation Mode Setting

Configuration

Mode

TX

TOR

STR

(6)

LED1/2_EN

STR_MOD

5V_MOD

LED_MOD

X

High

Float

1

X

X

00

Torch

X

X

Float

1

X

X

10

Assist

X

X

X

1

X

X

01

Indicator

0

X

High

1

1

X

11

Flash

1

X

High

1

1

X

11

Flash

X

X

X

1

0

X

11

Flash

X

X

X

X

X

1

X

5V

NOTE:

6) STR is high active when STR_POL = 1. STR is low active when STR_POL = 0. Table 1 is based on STR_POL = 1.

Standby Mode

pulled high, the device enters standby mode. In

communicate with the host.

Torch Mode

In standby mode, if TOR goes from low to high,

the device changes to torch mode and the

current ramps up step-by-step to the target

current after setting the LED1/2_EN bits to 1.

The target current for the LED can be set

through registers I1_TOR and I2_TOR. The

ramp-up slew rate can be set by the register

TUP_I. The current can be disabled by pulling

TOR to low or by setting the LED1/2_EN bits to

0. These two bits control the two LED current

sources respectively. By pulling TOR low, the

LED1/2_EN and LED_MOD bits reset to the

default automatically if LED_SD is 0 (see Figure

2).

Figure 2: Torch Mode

Assist Mode

To enter assist mode, set the LED_MOD

register to 10 and LED1/2_EN to 1. The current

ramps up to the target value, which is set by

I1_TOR and I2_TOR. The ramp-up slew rate

can be set by register TUP_I. The current can

be disabled by switching to standby mode or by