MP3332

MP3332 Rev. 1.0

www.MonolithicPower.com

12

5/1/2018

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© 2018 MPS. All Rights Reserved.

OPERATION

The MP3332 is a dual-channel, flash LED driver

cameras. It works in standby mode, flash mode,

assist mode, torch mode, indicator mode, and

fixed 5V DC output mode.

Table 1 shows how to set the operation mode

and flash trigger mode when the STR_POL bit

is set to 1. If STR_POL is set to 0, STR

switches to low.

LED Driver Operation

The MP3332 uses PWM mode with peak

current control to regulate the LED current. It

works

in

a

selectable

1M/2M/3M/4MHz

switching frequency with a synchronous rectifier

PMOS. When enabled, the synchronous PMOS

works as a 230mA current source to charge the

less

than

the

target

reference

(set

by

VTH_PAS1/2 bits, 05H register), the IC works

in boost switching mode; otherwise, it works in

pass mode. In pass mode, the synchronous

PMOS is turned on completely. During the

current start-up, the current ramps up step-by-

step to the target current.

Table 1: Operation Mode Setting and Flash Trigger Mode

Configuration

Mode

TX

Pin

TOR

Pin

STR

STR_MOD

LED1/2_EN

5V_MOD

LED_MOD

X

High

Float

X

1

X

00

Torch

High

1

Torch to flash

X

X

Float

X

1

X

10

Assist light

High

1

Assist to flash

X

X

X

X

1

X

01

Indicator

0

X

High

1

1

X

11

Flash

1

X

High

1

1

X

11

Flash

X

X

X

0

1

X

11

Flash

X

X

X

X

X

1

X

5V

Standby Mode

is ready to communicate with the host.

Torch Mode

If TOR goes high in standby mode, the device

switches to torch mode, and the current ramps

up step-by-step after setting LED1/2_EN to 1.

The LED1 and LED2 currents can be set by

registers I1_TOR and I2_TOR respectively. The

ramp-up slew rate can be set by register TUP_I.

The current can be disabled by pulling TOR low

or by setting LED1/2_EN to 0. LED1_EN and

LED2_EN control

LED1 and LED2’s current

sources respectively. After pulling TOR low, the

LED1/2_EN and LED_MOD bits are reset to the

default value automatically if LED_SD is 0. If

LED_SD is 1, LED1/2_EN does not reset (see

Figure 2).

MP3332 Torch Mode:

ILED1

ILED2

TOR

I2C

REG 0x0C/D

I1_TOR=XXXX

I2_TOR=XXXX

REG 0x01,

LED_MOD=00

REG 0x01,

LED1_EN=1

LED2_EN=1

Reset,

LED1_EN to 0

LED2_EN to 0

Figure 2: Torch Mode