MP3332

MP3332 Rev. 1.0

www.MonolithicPower.com

15

5/1/2018

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Assist Mode to Flash Mode

During assist light mode, the device can switch

to flash mode from assist light mode directly

when STR goes high if STR_MOD = 1 (see

Figure 11). After the flash, the part operates in

flash mode.

MP3332 Assist Light Mode to Flash Mode:

ILED1

ILED2

I2C

REG 0x0C/D,

I1_TOR=XXXX

I2_TOR=XXXX

REG 0x06/7,

I1_FL=XXXX

I2_FL=XXXX

REG 0x01,

LED_MOD=10

STR_MOD=1

STR_LV=1

REG 0x01,

LED1_EN=1

LED2_EN=1

REG 0x03,

FL_TIM=XXXX

Reset,

LED1_EN to 0

LED2_EN to 0

LED_MOD=00

STR

FL_TIMER

REG 0x01,

LED1_EN=1

LED2_EN=1

LED_MOD=10

STR_MOD=1

STR_LV=0

REG 0x03,

FL_TIM=XXXX

Setting Time

Reset,

LED1_EN to 0

LED2_EN to 0

LED_MOD=00

Figure 11: Assist Mode to Flash Mode

5V DC Output Mode

If 5V_MOD is set to 1, the device works in fixed

5V output mode, and the control loop is taken

over by the voltage loop (see Figure 12). Note

that the LED current source can still output a

current if the mode conditions described above

are met. Since the 5V DC directly powers the

LED, care must be taken to ensure thermal

conditions are normal. It is recommended to set

the LED1/2_EN bit to 0 during 5V mode.

MP3332 5V DC 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

VOUT

REG 0x01,

5V_MOD=1

REG 0x01,

5V_MOD=1

Figure 12: 5V DC Output Mode

Switching Frequency Setting

The maximum switching frequency can be

selected by the SW_FS bits when operating in

boost mode. 1M/2M/3M/4MHz can be selected

to optimize efficiency.

Switching Frequency Foldback

In 4/3/2MHz switching mode, if the voltage

across the current source is larger than the

value set by the register bit VTH_PAS, the IC

switches to 1MHz to improve efficiency and EMI.

When FS_SD = 0, if the voltage across the

current source is still larger than the value set

by the register bits VTH_PAS in 1MHz mode,

the switching frequency can be stretched down

to 100kHz. If the input voltage continues rising

or the load becomes lighter, the IC switches to

pass mode from 100kHz. When FS_SD = 1, the

IC switches directly to pass mode from 1MHz.

Load Balancing

To improve efficiency, the device provides a

load balancing function to reduce unbalanced

forward voltage drops between dual LEDs (see

Figure 13). To enable this function, set the bit

the LED1 current drops step-by-step while the

LED2 current rises step-by-step, and |VLED1-

The maximum adjustment range of each LED

current is limited to 10%. Because of the

limitation, if there is a large difference between

VLED1 and VLED2, the load balance function

recommended to further reduce the voltage

operation is the same.

4.35V, 2A

1A

0.25V

1A

0.55V

3.8V

4.1V

Without Load Balancing

4.25V, 2A

0.9A

0.25V

1.1A

0.35V

3.9V

4V

With Load Balancing

+/-10% Max.

Change

Figure 13: Load Balancing