- 您现在的位置：买卖IC网 > Datasheet目录343 > MIC3231YTSE (Micrel Inc)IC LED DRVR HP CONS CURR 16TSSOP Datasheet资料下载
参数资料
| 型号： | MIC3231YTSE |
| 厂商： | Micrel Inc |
| 文件页数： | 16/19页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR HP CONS CURR 16TSSOP |
| 标准包装： | 94 |
| 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： | 100kHz ~ 1MHz |
| 电源电压： | 6 V ~ 45 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 供应商设备封装： | 16-EPAD TSSOP |
| 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： | 576-3404-5 |
Eq. (26) t transition _ max ≈
Micrel, Inc.
Qg
Igatedrv
where Qg is the total gate charge of the external
MOSFET provided by the MOSFET manufacturer and
MIC3230/1/2
voltage stress on the diode is the max V OUT and therefore a
diode with a higher rating than max V OUT should be used. An
80% de-rating is recommended here as well.
Eq (28) P diode ≈V SCHOTTKY ×I OUT_ max
the Qg should chosen at a V GS ≈ 10V. This is not an
exact value, but is more of an estimate of t transition _ max .
The FET manufacturers’ provide a gate charge at a
specified V GS voltage:
Eq. (29)
P diode ≈ V SCHOTTKY × I LED _ max
P diode ≈ 0 . 25 W
C In _ FET =
Q G
@ V GS
MIC3230 Power Losses
The power losses in the MIC3230are:
This is the FET’s input capacitance. Select a FET with
Eq.(30)
P MIC 3230 = Q gate × V gate × F + I Q × Vin
the R DS ( on ) ( 25 C ) for R DS ( on ) ( 125 C ) .
R DS(on) and Q G such that the external power is below
about 0.7W for a SO-8 or about 1W for a PowerPak
(FET package). The Vishay Siliconix Si7148DP in a
PowerPak SO-8 package is one good choice. The
internal gate driver in the MIC3230/1/2 is 2A. From the
Si7148DP data sheet:
R DS(on)_25°C =0.0145 ?
Total gate Charge=68nC (typical)
The R DS ( on ) ( temp ) is a function of temperature. As the
temperature in the FET increases so does the R DS(on) .
To find R DS ( on ) ( temp ) use Equation 27, or simply double
o o
where Q gate is the total gate charge of the external
MOSFET. V gate is the gate drive voltage of the MIC3230.
F is the switching frequency. I Q is the quiescent current of
the MIC3230 found in the electrical characterization table.
I Q = 3 . 2 mA . V IN is the voltage at the V IN pin of the MIC3230 .
From Eq.(30)
P MIC 3230 = 68 nF × 12 × 500 kHz + 3 . 2 mA × 14 = 0 . 45 W
OVP - Over voltage protection
Set OVP higher than the maximum output voltage by at least
one volt. To find the resistor divider values for OVP use
Equation 3 and set the OVP=30V and R8=100k ? :
Eq. (27) R DS ( on ) ( temp ) = R DS ( on ) ( 25 o C ) × ( 1 . 007 ( Temp ? 25 ) )
The R DS ( on ) ( temp ) at 125°C is:
o
R 9 =
100 k Ω × 1 . 245
30 ? 1 . 245
= 4 . 33 k Ω
? 25 o )
R DSon ( 125 o C ) = 0 . 0145 × ( 1 . 007 ( 125
) ≈ 30 m Ω
From Equation 26: t transition ≈
=
= 34 ns
?
From Equation 23: P FET _ COND = 1 . 64 2 × 30 m Ω = 62 mW
Qg 68 nC
Igatedrv 2 A
I FET _ AVE _ max = 1 . 64 A
V OUT _ max = 28 V
From Equation 25:
P FET _ SWITCH _ max = 1 . 64 A × 28 V × 34 ns × 500 kHz = 0 . 78 Watts
From Equation 22
P FET = 62 mW + 0 . 78 W = 0 . 84 W
This is about the limit for a part on a circuit board without
having to use any additional heat sinks.
Rectifier Diode
A Schottky Diode is best used here because of the lower
forward voltage and the low reverse recovery time. The
PCB Layout
1. All typologies of DC-to-DC converters have a reverse
recovery current (RRC) of the flyback or (freewheeling)
diode. Even a Schottky diode, which is advertised as having
zero RRC, it really is not zero. The RRC of the freewheeling
diode in a boost converter is even greater than in the Buck
converter. This is because the output voltage is higher than
the input voltage and the diode has to charge up to –V OUT
during each on-time pulse and then discharge to V F during
the off-time.
2. Even though the RRC is very short (tens of nanoseconds)
the peak currents are high (multiple amperes). The high
RRC causes a voltage drop on the ground trace of the PCB
and if the converter control IC is referenced to this voltage
drop, the output regulation will suffer.
3. It is important to connect the IC’s reference to the same
point as the output capacitors to avoid the voltage drop
caused by RRC. This is also called a star connection or
single point grounding.
4. Feedback trace: The high impedance traces of the FB
should be short.
March 2011
16
M9999-030311-D
相关PDF资料 |
PDF描述 |
|---|---|
| MIC3263YML TR | IC LED DRIVER 6CH BKLT 24-MLF |
| MIC3287-24YD6 TR | IC LED DRIVR WHITE BCKLGT TSOT-6 |
| MIC3289-16YD6 TR | IC LED DRIVR WHITE BCKLGT TSOT-6 |
| MIC3291-18YML TR | IC PWM WLED DVR 1.8V 1.2MHZ 8MLF |
| MIC4100YM | IC DRIVER MOSFET 100V CMOS 8SOIC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC3231YTSE TR | 功能描述:LED照明驱动器 Boost Driver Controller with Dither 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 |
| MIC3232YMM | 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 |
| 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 |
发布紧急采购，3分钟左右您将得到回复。