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參數(shù)資料
| 型號(hào)： | SC605 |
| 廠商： | Semtech Corporation |
| 英文描述： | Charge Pump Flash LED Driver |
| 中文描述： | 電荷泵閃光LED驅(qū)動(dòng)器 |
| 文件頁(yè)數(shù)： | 5/12頁(yè) |
| 文件大小： | 356K |
| 代理商： | SC605 |
5
2005 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
Applications Information
GeneralOperation
The SC605 is a powerful 2x charge pump designed to drive
a high-intensity white LED with a constant current (Spotlight
mode) or with a pulsed current of higher intensity (Flash
mode) used for camera flash.
SC605
In Flash mode the SC605 output can drive 500mA at 4.25V
into an LED for up to 500ms. The FLASH pin is used to
trigger Flash mode. In spotlight mode the SC605 regulates
the output current to the value selected by the CTRL0 and
CTRL1 inputs. Note that Flash mode has priority over
Spotlight mode, i.e., the FLASH pin triggers Flash mode
regardless of the state of the CTRL0 and CTRL1 pins.
Output current is regulated by attaching the ISET pin to the
cathode(s) of the LED package and a load sense resistor
(typically 0.5
W
). The ISET pin monitors the voltage at the
cathode and signals the charge pump to increase or de-
crease the output current until the ISET voltage reaches
the programmed setting. Programmed settings are shown
in Table 1:
CTRL1
CTRL0
FLASH
V
ISET
Mode
0
0
0
0mV
Disabled
0
1
0
50mV
Spotlight
1
0
0
75mV
Spotlight
1
1
0
100mV
Spotlight
x
x
1
250mV
Flash
Table1-ControlStateTable
The resistor value is chosen to set the current through the
LED based on this reference voltage. The resistor should
not be less than 0.35
W
due to the output current limitations
of the device. Note that the resistor sets both the Flash
mode current and the Spotlight mode current.
In Flash mode, I
= V
/ R
ISET
= 250mV / R
ISET
.
In Spotlight mode, I
OUT
= V
ISET
ISET
.
SpotlightMode
Spotlight mode is enabled by setting the CTRL0 and CTRL1
pins as shown in Table . When in Spotlight mode, the
SC605 can maintain a constant current indefinitely to drive
an LED or bank of LEDs. The ISET pin voltage is the refer
-
ence V
and has three different settings - 50mV, 75mV,
and 100mV. These settings allow the designer the flexibility
to select the output level needed to suit the application.
FlashMode
Flash mode is enabled whenever the FLASH pin is pulled
high and remains active until the FLASH pin is released.
While in Flash mode the reference voltage on the ISET pin
is set to 250mV. During Flash mode the charge pump de-
velops enough output current to drive an LED with 500mA
for a duration up to 500ms. The duration of the pulse is
limited by the amount of power that can be dissipated in
the SC605 before it exceeds the maximum operating tem
-
perature. Note that if an output current less than the rated
500mA is desired the duration of the pulse can increase
proportionally. However, great care should be taken to in
-
sure the FLASH pin is not held high for an extended amount
of time so that overheating does not occur. Extending flash
mode beyond the 500ms pulse limit could adversely affect
the long-term reliability of the SC605. Flash duration must
be derated at higher currents, for example, 700mA derates
to a maximum of 350ms. The plot below shows maximum
Flash mode current for extended duration times.
MaximumFlashDuration
ProtectionCircuitry
The SC605 also provides protection circuitry that prevents
the device from operating in an unspecified state. These
include Input Over-Voltage Protection (IOVP), Output Over-
Voltage Protection (OVP), Over-Temperature Protection
(OTP), Over-Current Protection (OCP), and Short-Circuit
Current Protection (SCCP).
Input Over-Voltage Protection
Input over-voltage protection is included to prevent opera
-
tion at high input voltages that could damage the device.
The IOVP circuit senses the input voltage and determines
when the supply exceeds 6V. When the voltage rises
above this threshold, the device is disabled until the input
voltage drops to a level within the specified input range.
Hysteresis is included in this circuit to avoid chattering
between states.
0
100
200
300
400
500
600
700
800
0
500
1000
1500
2000
Flash Duration [ms]
F
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SC605EVB | Charge Pump Flash LED Driver |
| SC605MLTRT | Charge Pump Flash LED Driver |
| SC606 | Low Noise Smart LED Driver with Serial Interface |
| SC606AEVB | Low Noise Smart LED Driver with Serial Interface |
| SC606AIMLTRT | Low Noise Smart LED Driver with Serial Interface |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SC605EVB | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Charge Pump Flash LED Driver |
| SC605MLTRT | 制造商:Semtech Corporation 功能描述:LED DRVR 1Segment 3.3V/5V 12-Pin MLPD T/R |
| SC605-R | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Speech And Music Processor |
| SC605-RL1 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Speech And Music Processor |
| SC606 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Low Noise Smart LED Driver with Serial Interface |
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