Datasheet > CAT3644

CAT3644

更新时间： 2022-04-23 23:00:11

品牌	Logo	应用领域
CATALYST		驱动器
页数	文件大小	规格书
14页	294K
描述
4-Channel Ultra High Efficiency Quad-Mode TM LED Driver

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CAT3644 数据手册

CAT3644

Unused LED Channels

External Components

For applications not requiring all the channels, it is

recommended the unused LED pins be tied directly to

V_OUT(see Figure 4).

The driver requires four external 1μF ceramic capa-

citors for decoupling input, output, and for the charge

pump. Both capacitors type X5R and X7R are

recommended for the LED driver application. In all

charge pump modes, the input current ripple is kept

very low by design and an input bypass capacitor of

1μF is sufficient.

1µF

C1+

C1- C2+

C2-

OUT

In 1x mode, the device operates in linear mode and

does not introduce switching noise back onto the

supply.

OUT

1µF

CAT3644

1µF

LED1

LED2

LED3

LED4

ENABLE

DIMMING

EN/DIM

RSET

Recommended Layout

In charge pump mode, the driver switches internally at

a high frequency. It is recommended to minimize trace

length to all four capacitors. A ground plane should

cover the area under the driver IC as well as the

bypass capacitors. Short connection to ground on

capacitors C_INand C_OUTcan be implemented with the

use of multiple via. A copper area matching the TQFN

exposed pad (TAB) must be connected to the ground

plane underneath. The use of multiple via improves

the package heat dissipation.

GND

SET

Figure 4. Application with 3 LEDs

Protection Mode

If an LED is disconnected, the driver senses that and

automatically ignores that channel. When all LEDs are

disconnected, the driver goes to 1x mode where the

output is equal to the input voltage.

GND

As soon as the output exceeds about 6V, the driver

resets itself and reevaluate the mode.

Pin1

If the die temperature exceeds +150°C, the driver will

enter a thermal protection shutdown mode. When the

device temperature drops by about 20°C, the device

will resume normal operation.

LED Selection

LEDs with forward voltages (V_F) ranging from 1.3V to

4.3V may be used. Selecting LEDs with lower V_Fis

recommended in order to improve the efficiency by

keeping the driver in 1x mode longer as the battery

voltage decreases.

EN/DIM

RSET

VIN

COUT

CIN

GND

For example, if a white LED with a V_Fof 3.3V is

selected over one with V_Fof 3.5V, the driver will stay

in 1x mode for lower supply voltage of 0.2V. This

helps improve the efficiency and extends battery life.

GND

Figure 5. Recommended Layout

Characteristics subject to change without notice

Doc. No. 5023, Rev. B

1...8 9 101112 13 14

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