Confidential

Datasheet Version 1.0

March 2011.

Page 10

Application Information

MAP3222 has an independent dual channel Boost type LED

driver. So, it can be controlled independently.

Current Mode Boost switching regulator

operation

MAP3222 is being used Current mode control scheme for

boost regulation so its response is fast and output voltage is

stable.

MAP3222 is designed to be operated in DCM so MAP3222

can be unstable when it operates in CCM and duty cycle is

50% or higher.

Supply voltage and Oscillator

MAP3222 has wide input voltage ranged from 8.5V to 20V.

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

MAP3222 is being operated at fixed 200KHz and max duty is

90%.

LED Current Input setting (ADIM Input)

MAP3222’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.

Dimming PWM Input

MAP3222’s PDIMI signal is used for both Enable and PWM

dimming input. MAP3222 is enabled when PDIMI voltage is

higher than 2.0V and disabled when PDIMI voltage is lower

than 0.8V. This pin has internal 100Kohm pull down

resistance

PWM Input

Condition

High

Enable

Low

Disable

Protection

MAP3222 has Under Voltage Lock Out (UVLO), Boost

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

LED Short Current Protection(SCP).

When OVP and LED SCP are happened, MAP3222

monitors if the failure condition is released or not every 1mS.

This is MAP3222’s Auto restart function.

1.

Under Voltage Lock Out (UVLO)

When VCC is higher than 8.2V, MAP3222’s internal 5V

regulator and internal circuitry like oscillator, protections,

Gate drivers and PDIMO drivers are enabled, and the

MAP3222 starts to operate when PDIMI voltage is higher

than 2.0V.

If VCC is lower than 7.2V, MAP3222 is disable due to its

Under voltage lock out.

Fig 2. Schematic for Under voltage Lock out

2.

Boost current limit and Current Sense (CS)

MAP3222 has the Boost current limit function. If the

voltage on CS pin is higher than 0.4V (Typ.), the gate pulse

is limited every pulse. MAP3222 has 100nS (Min.) leading

edge blank.