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| 型号： | MIC3263YML TR |
| 厂商： | Micrel Inc |
| 文件页数： | 12/32页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVER 6CH BKLT 24-MLF |
| 特色产品： | MIC3263 Boost Switching Regulator |
| 标准包装： | 1 |
| 恒定电流： | 是 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 6 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 400kHz ~ 1.8MHz |
| 电源电压： | 6 V ~ 40 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-VFQFN 裸露焊盘，24-MLF? |
| 供应商设备封装： | 24-MLF?（4x4） |
| 包装： | 标准包装 |
| 工作温度： | -40°C ~ 125°C |
| 其它名称： | 576-3663-6 MIC3263YML TRDKR MIC3263YML TRDKR-ND |
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Micrel, Inc.
V(IO) Too High
If the collector voltage V(IO1–IO6) is greate r than 1.2V,
then the CRV loop will slowly discharge (lower th e vo ltage)
the CRV capacitor. Since the CRV capacitor is u sed as the
The boost regulated output voltage is:
Equation 1
MIC3263
reference voltage for the boost error amp the b oost voltage
(V OUT ) will decrease. With lower V OUT , V(IO) als o
decreases. Discharging of CRV continues unt il V(IO) is
1.2V.
V OUT = CRV ×
(R1+ R2)
R2
V(IO) Too Low
If the collector voltage V(IO1-IO6) is less th an 1.2V the
CRV loop will slowly charge (increa se the vo ltage) the
CRV. Since CRV is used as the reference vol tage for the
boost converter’s error amp the boost voltag e (V OUT ) will
increase. With higher V OUT , V(IO) also increase s. C hargin g
of CRV continues until V(IO) is about 1.2V.
The MIC3263 is designed for a wide input voltage range,
from 6V to 40V. As a peak cu rrent-mode controller, the
MIC3263 provides the benefits of superior line transient
response as well as an easier to design compensation.
MIC3263 provides several protec tion features, including:
? Current Limit (I LIMIT ) ─ Current sensing for
over current and ov erload protection
These control loops operate as described a bo ve during
DR high pulses. When DR is low the booster is off and the
last state of the CRV charge or discharge w ill con tinue
until the next DR pulse. If the external PWM Dimming
pulse (DRC) is removed, the intern al dimming pulse (DR)
will continue dimming at the same dimming le vel before
the signal at DRC was removed and the CR V loop will
?
?
Over- Voltage Protection (OVP) ─ output
o ver-voltage protection to prevent
operation above a safe upper limit
The boost stage is on (switching) during a
high DR pulse and is off (not switching)
when the DR pulse is low.
keep operating normally. If external PWM DIM is 0% then
charge/discharge states will discontinue and C RV will n o
longer be charged or discharged. CRV will slowly
discharge through the circuitry connected to it
Boost Controller Operation
The MIC3263 uses a peak current-mode boo s t controller
in its boost stage. The boost converter is a p ulse width
modulation (PWM) controller and operates thu s . A flip-flop
Application Information
At Start Up
At star t up, a switch connects 1.8V to the CRV. The
feedback resi stor divider (R1 and R2) is calculated to
achieve the approximate b oost output voltage with a V CRV
of 1.8V.
(FF) is set on the leading edge of the clock cy cle. Whe n
the FF is set a gate driver drives the power b ip olar switch
on. Current flows from V IN through the induc t or (L) and
through the internal power switch and cu rr ent sense
resistor-to-PGND. The voltage acro ss the cur rent sense
resistor is added to a slope compensation ra m p (needed
for stability). The sum of the current-sense volta ge and the
Example:
?
?
?
?
8 LEDs at 3.5V each = 28V
VIO = 1.2V
V OUT = 29.3V estimate
Set R divider to: R1 =1 50k R2 = 9.88k
slope compensation voltages (V CS ) is fed into the positive
terminal of the PWM comparator. The other input to the
PWM comparator is the error amp output (called V EA ). The
error amp’s negative input is the feedback voltage (V OVP ).
The OVP pin is used as the voltage feedback to the error
amplifier. In this way the output voltage is regulated. If
V OVP drops, V EA increases and therefore the power switch
remains on longer so that V CS can increase to the level of
V EA . The reverse occurs when V OVP increases.
The output voltage is always higher than the input voltage.
The external CRV (see C7 in Typical Application
illustration) is used as the reference voltage to the boost
error amp.
The CRV control loop will charge/discharge CRV until the
correct boost voltage appears at the output.
Case 1
If 29.3V is too high to properly forward bias the LED
channel at the ISET current level, then the current amp
loop will decrease the drive to the bipolar transistor and
V(IO) will increase and the CRV control loop will decrease
CRV and the boost output voltage (V OUT ) will decrease.
January 2010
12
M9999-012110
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC3287 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:1.2MHz PWM White LED Driver with OVP in Thin SOT-23 and 2mm x 2mm MFL |
| MIC3287_10 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:1.2MHz PWM White LED Driver with OVP in Thin SOT-23 and 2mm x 2mm MFL |
| MIC3287-24YD6 | 制造商:Rochester Electronics LLC 功能描述: 制造商:RF Micro Devices Inc 功能描述: |
| MIC3287-24YD6 TR | 功能描述:LED照明驱动器 2x2mm White LED Driver w/ 24V OVP (Lead Free) 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 |
| MIC3287-24YD6TR | 制造商:RF Micro Devices Inc 功能描述: |
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