Confidential

Datasheet Version 1.0

December

2012

Page 9

Application Information

Current Mode Boost switching regulator

operation

MAP3301B is being used Current mode control scheme for

boost regulation so its response is fast and output voltage is

stable.

Supply voltage and Oscillator

MAP3301B has wide input voltage ranged from 8.5V to 33V.

1uF decoupling capacitor is used to stabilize the internal

regulator and minimize noise on VCC pin. This decoupling

capacitor should be placed next to VCC pin. Ceramic

capacitor is recommended and incorrect placement of this

decoupling capacitor may cause the oscillation in the

switching waveform

MAP3301B is being operated at fixed 200Khz Switching

frequency and max duty is 90%.

LED Current Input setting (ADIM Input)

MAP3301B’s LED current is set by the voltage on ADIM pin

and LED sense resistor value as below.

Fig 1. Schematic for LED current set

R

_

Sense

_

Current

_

LED

V

=

I

ADIM

LED

The voltage range on ADIM pin is 0.1V ~ 3.0V. But it is

recommended that ADIM Input voltage is higher than 0.4V.

below 0.4V, LED current tolerance is increases.

Dimming PWM Input

MAP3301B’s PWMI signal is used for both Enable and PWM

dimming input. MAP3301B is enabled when PWMI voltage is

higher than 2.0V and disabled when PWMI

voltage is lower than 0.8V. This pin has internal 100Kohm

pull down resistance

PWM Input

Condition

High (2.0V)

Enable

Low (0.8V)

Disable

Enable Input

MAP3301B’s offers an Enable Function. MAP3301B is

enabled when EN voltage is higher than 2.0V and disabled

when EN voltage is lower than 0.8V. This pin has internal

125Kohm pull down resistance

EN Input

Condition

High (2.0V)

Enable

Low (0.8V)

Disable

Protection

MAP3301B has Under Voltage Lock Out (UVLO), Boost

switch current limit, Output Over Voltage Protection (OVP),

Line Under Voltage Protection(LUVP), LED Short Current

Protection(SCP).

When OVP and LED SCP are happened, MAP3301B

monitors if the failure condition is released or not every

1mS at Fs 200Khz.

This is MAP3301B’s Auto restart function.

1.

Under Voltage Lock Out (UVLO)

When VCC is higher than 8.0V, MAP3301B’s internal 5V

regulator and internal circuitry like oscillator, protections,

Gate drivers and PDIMO drivers are enabled, and the

MAP3301B starts to operate when PWMI voltage and EN

signal are higher than 2.0V.

If VCC is lower than 7.0V, MAP3301B is disable due to its

under voltage lock out.

2.

Boost current limit and Current Sense (CS)

MAP3301B has the Boost current limit function. If the

voltage on CS pin is higher than 0.49V (Typ.), the gate

pulse is limited every pulse. MAP3301B has 100nS

(Min.) leading edge blank.

3.

Output Over Voltage Protection (OVP)

When

MAP3301B’s

output

voltage

is

increased

abnormally, MAP3301B stops the switching to protect

external components.

MAP3301B has 200nS (Typ.) low pass filter on OVP pin,

but

using

external

Capacitor

is

recommended

to

need to be lower than 1Mohm.