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參數(shù)資料
| 型號(hào)： | SP7683 |
| 元件分類(lèi)： | LED驅(qū)動(dòng)器 |
| 英文描述： | Four Channel Charge Pump Regulator LED Driver |
| 中文描述： | 四通道電荷泵穩(wěn)壓器LED驅(qū)動(dòng)器 |
| 文件頁(yè)數(shù)： | 5/8頁(yè) |
| 文件大?。?/td> | 137K |
| 代理商： | SP7683 |
5
Date: 12/21/04
SP7683 Four Channel Charge Pump LED Driver Copyright 2004 Sipex Corporation
The SP7683 is comprised of two stages. First is a regulated change pump to convert the input
voltage V
into a stable output voltage
or current depending on the mode used. The second stage
is a low dropout current matching regulator that provides stable identical currents in all four
channels to drive LED1 - LED4. The first stage can drive an additional four LEDs that are
connected in parallel to the V
pin. It is recommended to use resistors in series with these
additional diodes for current matching.
The SP7683 provides dimming control for the LEDs, with a constant ratio of brightness between
them. It can also be used to turn off the LEDs completely.
The Charge Pump
The regulated charge pump can operate in two modes 1X V
and 1.5X V
to optimize efficiency
over the entire battery voltage range. The input voltage trip point at which the charge pump will
automatically switch from a 1X mode to 1.5X mode is defined by an external voltage divider
connected to V
pin. Cycle-by-cycle regulation ensures that no mode change occurs during
a switching cycle. To achieve better efficiency it is recommended that the V
is set at
V
=
V
+ 0.31 + MI
LED
*R
where
V
is the LED forward voltage and (M) is the number of LEDs
connected to V
OUT
. R
OUT
is the output resistance. I
LED
is the current per LED.
The charge pump may be configured in voltage mode or as a current source. When used as a
voltage source the output voltage is determined by an external resistive divider connected to FB
pin as: V
OUT
= (1+R10/R5)*V
FB
(see Figure 2) where V
FB
= 0.31V.
When used as a current source the current in one single LED (D5 - D8) may be set by series
resistor R
as I
= V
/ R
The current in the remaining LEDs will track based on the ballast
resistors. Three-wire LED modules with internal series resistors can also be driven in this way.
The flying capacitors C1 an C2 of the charge pump control the tade-off between the output voltage
ripple and the output current capability. Decreasing the flying capacitors will reduce the output
voltage ripple because less charge will be delivered to the output capacitor. However, smaller
flying capacitors lead to larger output resistance, thus decreasing the output current handling
capability and circuit efficiency. We recommend using ceramic capacitors in the range of 1
μ
F -
4.7
μ
F with low ESR, which helps reduce peak-to-peak output ripple and reduce high frequency
noise spikes.
Dimming control can be achieved by applying a PWM control signal to the EN/PWM pin. The
brightness of the LEDs is controlled by varying the duty cycle of the PWM signal. PWM repetition
rate from 60Hz - 700Hz. A repetition rate of at least 60Hz is required to prevent visible flickering.
Applying a logic low signal to EN/PWM control input turns of the device resulting in supply current
below 1
μ
A and high impedance state of the V
OUT
pin.
CIRCUIT DESCRIPTION
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP7683ER | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:Four Channel Charge Pump Regulator LED Driver |
| SP7683ER-L | 制造商:Exar Corporation 功能描述:CHARGE PUMP 4CH SMD 7683 QFN16 |
| SP7683TR | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:Four Channel Charge Pump Regulator LED Driver |
| SP7685 | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:1.2A Buck/Boost Charge Pump LED Driver |
| SP7685EB | 功能描述:電源管理IC開(kāi)發(fā)工具 Eval Board for SP7685 Series RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類(lèi)型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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