MIC3202YMEEV Просмотр технического описания (PDF) - Micrel

Номер в каталоге

Компоненты Описание

производитель

MIC3202YMEEV

MIC3202/MIC3202-1 Evaluation Board High-Brightness LED Driver with Integrated MOSFET and High-Side Current Sense

Micrel 

Micrel, Inc.

MIC3202/MIC3202-1 Evaluation Board

Other Features

EN Input

The EN pin provides a logic level control of the output

and the voltage has to be 2.0V or higher to enable the

current regulator. The output stage is gated by the DIM

pin. When the EN pin is pulled low, the regulator goes to

off-state and the supply current of the device is reduced

to below 1µA. Do not drive the EN pin above the supply

voltage.

DIM Input

The DIM pin provides a logic level control for brightness

of the LED. A PWM input can be used to control the

brightness of LED. DIM high enables the output and its

voltage has to be 2.0V or higher. DIM low disables the

output, regardless of EN high-state.

Current-Sense Input

The CS pin provides the high-side current sense to set

the LED current with an external sense resistor.

A sense resistor RCS is placed between VIN and LED+

terminals.

The current through LED is sensed by the sense resistor

(RCS). The sensed voltage is fed back to the MIC3202 to

regulate the LED current

RCS is given by:

RCS

=

1

2

x( VCS(MAX) + VCS(MIN)

ILED

)

Bookmark not defined.

Error!

ILED is LED current required to set.

Frequency of Operation

To calculate the frequency spread across input supply:

FSW

=

(VD

+ILED×RCS + VLED)×(VIN -ILED×RCS

L×ΔIL ×(VD + VIN)

-

VLED)

ΔIL

=

VCS(MAX) - VCS(MIN)

RCS

where:

VD is Schottky diode forward drop

VLED is total LEDs voltage drop

VIN is input voltage

ILED is average LED current

According to the above equation, choose the inductor to

make the operating frequency no higher than 1MHz.

Refer to the datasheet Application Information for more

information on components selection guidelines.

Frequency Dithering

The MIC3202 is designed to modulate the VCS(MAX) with

amplitude ±6mV by a pseudo random generator to

generate the ±12% of the switching frequency dithering.

This spreads the frequency spectrum over a wider range

and reduce the EMI noise peaks.

The MIC3202-1 is non-dithering version of the MIC3202.

RCS (Ω)

1.33

0.56

0.4

0.28

0.2

ILED (A)

0.15

0.35

0.5

0.7

1.0

I2R (W)

0.03

0.07

0.1

0.137

0.2

Size (SMD)

0603

0805

0805

0805

1206

For VCS(MAX) and VCS(MIN) refers to the Electrical

Characteristics table.

October 2010

2

M9999-102810

Share Link: