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参数资料
| 型号： | MIC3232YMM |
| 厂商： | Micrel Inc |
| 文件页数： | 9/19页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR HP CONS CURR 10-MSOP |
| 标准包装： | 100 |
| 恒定电流： | 是 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 1 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 通用 |
| 频率： | 400kHz |
| 电源电压： | 6 V ~ 45 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 供应商设备封装： | 10-MSOP |
| 包装： | 管件 |
| 工作温度： | -40°C ~ 125°C |
| 产品目录页面： | 1082 (CN2011-ZH PDF) |
| 其它名称： | 576-3405-5 |
Micrel, Inc.
Power Topology
Constant Output Current Controller
The MIC323x family is peak current mode boost
controllers designed to drive high power LEDs. Unlike a
standard constant output voltage controller, the MIC323x
family has been designed to provide a constant output
current. The MIC323x family is designed for a wide input
MIC3230/1/2
Output Over Voltage Protection (OVP)
The MIC323x provides an OVP circuitry in order to help
protect the system from an overvoltage fault condition.
This OVP point can be programmed through the use of
external resistors (R8 and R9 in Figure 1). A reference
value of 1.245V is used for the OVP. Equation 3 can be
used to calculate the resistor value for R9 to set the OVP
point.
voltage range, from 6V to 45V. In the boost configuration,
the output can be set from V IN up to 100V.
As a peak current mode controller, the MIC323x family
Eq. (3)
R 9 =
R 8
( V OVP / 1 . 245 ) ? 1
I LED =
R ADJ
?
?
R FS ( k Ω ) = ? ?
?
F SW ( kHz ) ? ?
provides the benefits of superior line transient response as
well as an easier to design compensation.
This family of LED drivers features a built-in soft-start
circuitry in order to prevent start-up surges. Other
protection features include:
? Current Limit (I LIMIT ) - Current sensing for over current
and overload protection
? Over Voltage Protection (OVP) - Output over voltage
protection to prevent operation above a safe upper
limit
? Under Voltage Lockout (UVLO) – UVLO designed to
prevent operation at very low input voltages
Setting the LED Current
The current through the LED string is set via the value
chosen for the current sense resistor, R ADJ . This value can
be calculated using Equation 1:
0 .25 V
Eq. (1)
Another important parameter to be aware of in the boost
controller design is the ripple current. The amount of ripple
current through the LED string is equal to the output ripple
voltage divided by the LED AC resistance (R LED – provided
by the LED manufacturer) plus the current sense resistor
(R ADJ ). The amount of allowable ripple through the LED
string is dependent upon the application and is left to the
designer’s discretion. This equation is shown in Equation
2:
LED Dimming
The MIC323x family of LED drivers can control the
brightness of the LED string via the use of pulse width
modulated (PWM) dimming. A PWM input signal of up to
500Hz can be applied to the PWM DIM pin (see Figure 1)
to pulse the LED string ON and OFF. It is recommended to
use PWM dimming signals above 120Hz to avoid any
recognizable flicker by the human eye. PWM dimming is
the preferred way to dim a LED in order to prevent
color/wavelength shifting, as occurs with analog dimming.
The output current level remains constant during each
PWMD pulse.
Oscillator and Switching Frequency Selection
The MIC323x family features an internal oscillator that
synchronizes all of the switching circuits internal to the IC.
This frequency is adjustable on the MIC3230 and MIC3231
and fixed at 400kHz in the MIC3232.
In the MIC3230/1, the switching frequency can be set by
choosing the appropriate value for the resistor, R 1
according to Equation 4:
1 . 035
7526
Eq. (4)
?
SYNC (MIC3230 Only)
Multiple MIC3230 ICs can be synchronized by connecting
their SYNC pins together. When synchronized, the
MIC3230 with the highest frequency (master) will override
Eq. (2)
Δ I LED ≈
V OUT RIPPLE
( R LED + R ADJ )
the other MIC3230s (slaves). The internal oscillator of the
master IC will override the oscillator of the slave part(s)
and all MIC3230 will be synchronized to the same master
Where
V OUT RIPPLE =
I LED × D × T
C OUT
switching frequency.
The SYNC pin is designed to be used only by other
MIC3230s and is available on the MIC3230 only. If the
SYNC pin is being unused, it is to be left floating (open). In
Reference Voltage
The voltage feedback loop of the MIC323x uses an
internal reference voltage of 0.25V with an accuracy of
±3%. The feedback voltage is the voltage drop across the
current setting resistor (R ADJ ) as shown in Figure 1. When
in regulation the voltage at I ADJ will equal 0.25V.
the MIC3231, the SYNC pin is to be left floating (open).
March 2011
9
M9999-030311-D
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC3232YMM EV | 功能描述:LED 照明开发工具 400kHz Fixed Frequency Boost Driver Controller for High Power LEDs - Evaluation Board RoHS:否 制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装: |
| MIC3232YMM TR | 功能描述:LED照明驱动器 400kHz Fixed Frequency Boost Driver Controller for High Power LEDs 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 |
| MIC3263 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Six-Channel WLED Driver for Backlighting Applications with Flicker-Free Dimming |
| MIC3263YML | 制造商:Micrel 功能描述:6 Channel WLED Driver for Backlighting |
| MIC3263YML EV | 制造商:Micrel Inc 功能描述: |
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