MP3312GC-Z Datasheet MP3312GC-P, MP3312GC-Z | P10-P12

MP3312 － 2.7V-5.5V INPUT, 38V OVP, DUAL-CHANNEL WHITE LED DRIVER

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Figure 2—1-wire command structure

1-wire interface defines logic 0 and logic 1 by

comparing the time of the signal low level and

high level, 1 cycle means 1 logic bit. The bit

detection starts with a falling edge on the EN

pin and ends with the next falling edge. Shown

as Figure 3

Low logic (logic 0): t

LOW

3* t

HIGH

High logic (logic 1): t

HIGH

3* t

LOW

Figure 3—1-Wire Bit Definition

The EN pin needs to distinguish EN signal and

digital dimming signal when set up boost driver.

Chip only receives 1-wire signal when EN pin

signal matches 1-wire protocol during 1ms 1-

wire detection window. 1-wire dimming

sequence is described as below, and shown in

Figure 4.

1. Pulling VIN and PWM to high.

2. Pulling data line from low to high for t

DELAY

(1-

wire detection delay time, 100us) and this

rising edge is the start of 1-wire detection

window.

3. After 1-wire detection delay time, pulling data

line to low for more than t

DETECTION

(1-wire

detection time, 260us). Then pulling data

line to high.

4. The sum of 1-wire detection delay time and

1-wire detection time should be less than t

WIN

(The time of 1-wire detection window,1ms).

Figure 4—1-Wire Dimming Sequence

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In addition, before chip starts to receive each

command with first falling edge, data line should

keep high level for t

START

(min. 2us)

time. The

transmission of each command is completed with

low level for t

EOS

(min. 2us).Shown in Figure 5.

The ACK signal feedback to master or not is

dependent on RFA bit. If ACK is needed, the

master should have an open-drain output, and

data line should be pulled high by master with a

resistor load.

Figure 5— Data-line Timing when RFA=0

Figure 6—Data-line Timing when RFA=1

If RFA=0, No ACK signal feedback. After all 24

bits data is transferred, data line keeps low for

EOS

(min. 2us) delay, and then it is pulled to static

high. Shown as Figure 5.

If RFA=1, ACK signal feedback to master. After

all 24 bits data is transferred, the data line keeps

low for t

ACKval (max. 2us) time ,then data line

should be released to output high impedance and

master is ready to detect the ACK signal from

slave . After t

ACKval, if ACK “false” (1-wire data is

not received successfully), the data line will be

pulled to high directly. After t

ACKval, if ACK “ture”

(1-wire data is received successfully), data line

will be continuously pulled to low V

ACKL (max.

0.4V) by slave for t

ACK (max. 512us) time. The

master reads this low logic, it means chip

received 1-wire data successfully. Then the data

line is pulled to static high. Shown as Figure 6.

MP3312 has a 9-bit DAC for digital dimming

control and the dimming resolution is 1/511. The

default code value of D0 (LSB)-D8(MSB) is

“111111111” when the device is first enabled.

The LED current is dependent on the internal

full

code

ILED ILED

511

=×

ILED

full

is the full scale output current set by R

ISET

to ISET pin. Code is the DEC value of resolution

bit (D0-D8).

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Cycle-by-Cycle Current Limit Protection

MP3312 provides cycle-by-cycle current limit

protection to avoid any damage due to too large

current rating. During startup, the current limit is

clamped to 1A for around 6ms to avoid output

overshoot and inrush current. After that, the

current limit returns back to normal 1.8A.

Open String Protection

Open string protection is achieved by detecting

the VOUT pin. If the LED string is open, the

feedback voltage is lower than the reference

voltage, thus the COMP rises up and keeps

charge the output capacitor until VOUT pin hits

the protection point VOVP. Then the IC stops

switching and shuts down till VIN and EN is reset

for enable again.

Unused LED Channel

In some cases, if one LED current channel is not

used, connect the corresponding LEDx to GND

to remove it from the control loop.

Short String Protection

The MP3312 monitors the LEDX pin voltage to

judge if the short string occurs. If one string is

short, the respective LEDX pin will be pulled up

to the boost output and tolerate high voltage

stress. If the LEDX pin voltage is higher than 5 V

and LED current is larger than 8% full-scale

setting current, the short string condition is

detected and if such condition lasts longer than

8ms, the fault string current source is disabled till

VIN and EN is reset for enable again.

Thermal Shutdown Protection

To prevent the IC operate at exceedingly high

temperature, thermal shutdown is implemented in

this chip by detecting the silicon die temperature.

When the die temperature exceeds the upper

threshold 150℃, the IC shutdowns and recovers

to normal operation when die temperature drops

below lower threshold. Typically, the hysteresis

value is 25°C.

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15

MP3312GC-Z

Mfr. #:

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Manufacturer:

Monolithic Power Systems (MPS)

Description:

LED Lighting Drivers 2.7V-5.5Vin, 38Vo, 2-Channel WLEDDriver

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MP3312GC-Z

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