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參數(shù)資料
| 型號(hào)： | SC617ULTRT |
| 廠商： | Semtech Corporation |
| 英文描述： | Charge Pump Flash LED Driver with Safety Timer |
| 中文描述： | 充電泵閃光LED驅(qū)動(dòng)器的安全定時(shí)器 |
| 文件頁數(shù)： | 10/13頁 |
| 文件大小： | 219K |
| 代理商： | SC617ULTRT |
SC617
10
Applications Information (continued)
that the voltage on the ISET pin can no longer be main-
tained. After a 32ms delay (included to prevent false
transitions) the charge pump will convert to 2x mode.
After the charge pump switches from 1x mode to 2x
mode, the device remains in 2x mode until the part is
turned off. If the part is re-enabled in spotlight mode, it
will begin operation in 1x mode and determine the
appropriate mode of operation as previously described.
Protection Circuitry
The SC617 provides several protection features to safe-
guard the device from catastrophic failures. These features
include:
Input Over-Voltage Protection (IOVP)
Output Over-Voltage Protection (OVP)
Over-Temperature Protection (OTP)
Over-Current Protection (OCP)
Short-Circuit Current Protection (SCCP)
Input Over-Voltage Protection
IOVP is included to prevent operation at high input volt-
ages that could damage the device. The IOVP circuit
senses the input voltage and determines when the supply
exceeds 6V. Hysteresis is included in this circuit to avoid
chattering between states. When the voltage rises above
this threshold, the device is disabled until the input
voltage drops to a level within the specified range.
Output Over-Voltage Protection
Output OVP prevents the SC617 from generating an
output voltage that could damage other devices con-
nected to it such as load LEDs and bypass capacitors.
When the output voltage exceeds 5.5V, the OVP circuit
disables the charge pump until the voltage decreases to
a level within the acceptable range. This circuit allows the
device to drive LEDs with high forward voltages at a
reduced level without exceeding the output voltage
limits specified for the device.
Over-Temperature Protection
The OTP circuit prevents the device from overheating and
experiencing a catastrophic failure. When the junction
temperature exceeds 150°C the device is disabled. It
remains disabled until the junction temperature drops
below this threshold. Hysteresis is included to prevent
toggling between modes.
Over-Current Protection
When the SC617 is in 2x mode, the input current will be
approximately double the required output. When the
steady-state load requires the maximum current avail-
able in 2x mode, the OCP circuit prevents the device from
overheating from excessive power dissipation. This
feature protects the device when in 1x mode. The current
limit is set lower in the 1x mode due to lower current
requirements.
Short-Circuit Current Protection
SSCP is provided to limit the current that can be sourced
when the output is shorted to ground. When a short
circuit forces V
to drop below 2V, the SCCP detects the
condition and limits the output current.
Resistor Selection
The ISET resistor selection is critical in generating the
correct current. The value can be chosen to set the spot-
light mode current or the flash mode current, and the
two current settings are dependent on the same resistor.
It is recommended that the resistor be selected to match
the desired LED current for flash mode. This allows the
designer to set the SC617’s maximum current and select
the resistor package size necessary for the power dissi-
pation required in flash mode. The typical application
uses a 0.5Ω resistor to set a flash mode current of 500mA
and spotlight mode current of 150mA. A high precision
resistor should be used to ensure the specified accuracy
for LED current.
To avoid malfunction of the charge pump, it is recom-
mended that the resistance seen at the ISET pin remain
constant while the device is active (flash or spotlight
mode). Changing the resistance value or the load current
while the device is active could cause instability.
Capacitor Selection
The SC617 is designed to use low-ESR ceramic capacitors
for the input and output bypass capacitors as well as the
charge pump bucket capacitors. Ideal performance is
achieved when C1 is exactly equal to C2. It is recom-
mended that X5R or X7R ceramic capacitors be used for
best performance.
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相關(guān)代理商/技術(shù)參數(shù) |
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| SC618 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Charge Pump Flash LED Driver with Safety Timer |
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| SC618EVB | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Charge Pump Flash LED Driver with Safety Timer |
| SC618ULTRT | 功能描述:IC LED DRIVER PHOTO FLASH 10-MLP RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動(dòng)器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 恒定電流:- 恒定電壓:- 拓?fù)?升壓（升壓），切換式電容器（充電泵） 輸出數(shù):1 內(nèi)部驅(qū)動(dòng)器:是 類型 - 主要:背光 類型 - 次要:白色 LED 頻率:625kHz ~ 875kHz 電源電壓:2.7 V ~ 5.3 V 輸出電壓:5V 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-µMAX 包裝:帶卷 (TR) 工作溫度:-40°C ~ 85°C |
| SC619 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Charge Pump Flash LED Driver with Safety Timer |
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