MP3367

– 6-CHANNEL BOOST WLED DRIVER WITH HIGH DIM RATIO AND I2C

MP3367 Rev. 1.0

www.MonolithicPower.com

17

6/17/2019

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© 2019 MPS. All Rights Reserved.

The short protection threshold can be set one of

two ways:

The first option is to connect a resistor at STH.

STH outputs an 18

μA current source. The short

protection threshold is 10 times the voltage on

STH. The threshold is calculated using Equation

(3):

V_STH(V) = 0.18 × R_STH(kΩ)

(3)

The second option is to set the internal register

TH_S1:0 when STH is floating.

When the LEDX voltage exceeds the threshold

for 480ms (DPWM = 100%), all strings are marked

off. The IC remains on standby until the strings

release from shorting. Enable or disable this

function through SEN.

The marked-off string sends a 10

μs pulse

current to check if a short fault is removed after

every 500

μs delay, so short string protection is

recoverable.

Short LEDX to GND Protection

When LEDX shorts to GND, the COMP voltage

increases and saturates. When the COMP

saturated time lasts for 20ms or 40ms (the time

can be selected by the internal register bit

TCOMP), protection is triggered. Then FF pulls

low and SD pulls high to turn on the external P-

MOSFET. The IC also latches off.

Short VOUT to GND Protection

When VOUT shorts to GND, the output voltage

decreases. When the voltage of the OVP pin hits

the OVP UVLO threshold for 10

μs, the protection

is triggered and SD pulls high to turn off the

external P-MOSFET. VOUT disconnects from

VIN and the IC latches off.

Cycle-by-Cycle Current Limit

To prevent the external components from

exceeding the current stress rating, the IC has a

cycle-by-cycle current limit protection. When the

current exceeds the current limit value, the IC

stops switching until the next clock cycle.

Latch-Off Current Limit Protection

Device damage may be caused by extreme

conditions, such as an inductor or diode short to

GND. To avoid this, the MP3367 provides a

latch-off current limit protection when the current

flowing through the internal MOSFET hits the

threshold (7.5A), and lasts for five switching

cycles.

Thermal Protection

To prevent the IC from damage when operating

at exceedingly high temperatures, the MP3367

implements thermal protection by detecting the

silicon die temperature.

Over-Temperature LED Current Decrement

When the die temperature exceeds 140°C, the

MP3367

automatically

decreases

the

LED

current amplitude (see Figure 6).

140

Temperature (°C)

ILED

Figure 6: ILED Decrease with Temperature

This function is enabled by the over-temperature

current decrement bit (OTID).

When OTID = 0, the over-temperature current

decrement is disabled.

When OTID = 1 (default), the over-temperature

current decrement is enabled.

Thermal Shutdown

When the die temperature exceeds the upper

threshold (TST), the IC shuts down. When the

temperature drops below the lower threshold,

the IC recovers to normal operation. The

hysteresis value is typically 20°C.

I2C Interface Register Description

I2C Chip Address

The 7-bit MSB device address is 0x38. After the

start condition, the I2C-compatible master sends

a 7-bit address followed by an eighth read (read:

1) or write (write: 0) bit.

The following bit indicates the register address

to/from which the data will be written/read:

0

0

1

1

1

0

R/W

0

The I2C-Compatible Device Address