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CAT3643
Unused LED Channels
For applications not requiring all the channels, it is
recommended the unused LED pins be tied directly to V OUT
(see Figure 30).
LED Selection
LEDs with forward voltages (V F ) ranging from 1.3 V to
4.3 V may be used. Selecting LEDs with lower V F is
recommended in order to improve the efficiency by keeping
the driver in 1x mode longer as the battery voltage decreases.
V IN
C IN
1 m F
ENABLE
DIMMING
R SET
1 m F
C1+ C1 ? C2+
V IN
CAT3643
EN/DIM
RSET
GND
1 m F
C2 ?
V OUT
LED1
LED2
LED3
C OUT
1 m F
For example, if a white LED with a V F of 3.3 V is selected
over one with V F of 3.5 V, the driver will stay in 1x mode for
lower supply voltage of 0.2 V. This helps improve the
efficiency and extends battery life.
External Components
The driver requires four external 1 m F ceramic capacitors
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 1 m F is sufficient.
In 1x mode, the device operates in linear mode and does
not introduce switching noise back onto the supply.
Figure 30. Application with 2 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.
As soon as the output exceeds about 6 V, the driver resets
itself and reevaluate the mode.
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.
Pin1
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 IN and C OUT can 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.
C2
RSET
EN/DIM
C1
GND
C OUT
C IN
VIN
GND
VOUT
Figure 31. TDFN ? 12 Recommended Layout
http://onsemi.com
12
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相关代理商/技术参数
CAT3643HV3 制造商:ON Semiconductor 功能描述:IC 3-LED DRIVER QUAD HI EFFICIENCY
CAT3643HV3-GT2 功能描述:LED照明驱动器 LED Driver,Quad mode,3 ch RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N
CAT3643HV3-T2 功能描述:LED照明驱动器 3-Channel Quad-Mode RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N
CAT3644 制造商:CATALYST 制造商全称:Catalyst Semiconductor 功能描述:4-Channel Ultra High Efficiency Quad-Mode⑩ LED Driver
CAT3644_0710 制造商:CATALYST 制造商全称:Catalyst Semiconductor 功能描述:4-Channel Ultra High Efficiency Quad-Mode⑩ LED Driver
CAT3644HV3 制造商:ON Semiconductor 功能描述:IC 4-LED DRIVER QUAD HI EFFICIENCY
CAT3644HV3G 制造商:Rochester Electronics LLC 功能描述: 制造商:Catalyst Semiconductor 功能描述:
CAT3644HV3-GT2 功能描述:LED照明驱动器 LED Driver,Quad mode,4 ch RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N