收藏本站
S P 7 6 0 0
2 A 2 9 V N o n - S y n c . B u c k H i g h P o w e r L E D D r i v e r
THEORY OF OPERATION
The SP7600 is a fixed frequency, Voltage-
mode, non-synchronous buck PWM regulator
optimized for driving LEDs. Constant LED
current is achieved using resistor RFB as
shown in the page 1 schematic. A low 0.2V
reference voltage minimizes power dissipation
in RFB. A tight reference voltage tolerance of
±3%, over full operating conditions, helps
accurately program the LED current. High
switching frequency of 1.2MHz (nominal)
reduces the size of passive components.
Dimming and power sequencing is achieved
using a logic-level PWM signal applied to FB
pin via a diode. Overcurrent protection (OCP)
is based on high-side MOSFET’s Rds(on) and is
programmable via a resistor placed at LX
node.
P ROGRAMMING THE LED CURRENT
Use the following equation to program the LED
current:
DIM = L. The DIM signal needs to be greater
than 600mV minimum to turn-off the SP7600
and less than 200mV to fully turn-on the
SP7600. It is recommended to use a signal
with DIM = 1V or more for OFF and 0V for ON.
The user should note that the logic is reversed
relative to many other PWM controlled LED
drivers. In other words a logic level high at
20% duty cycle will result in approximately an
80% duty cycle for the LED. Recommended
modulation frequencies are from 100Hz to
200Hz with 10 – 90% duty cycle, 500Hz with
10 – 80% duty cycle, and 1000Hz with 10 -
70% duty cycle. Figures 15 & 16 show the
output response at the maximum PWM DIM
signal of 1000Hz. See figure 17 for 100Hz to
1000Hz duty cycle response for two Luxeon K2
LEDs in parallel at 2A total current.
Equ.1: RFB =
0.2 V
I LED
The output voltage will adjust as needed to
ensure average I LED is supplied. For example if
the output current has to be set at 0.35A then
RFB=0.57 Ohm. If the output LED has a
corresponding Vf of 3.5V then SP7600 will step
down the V IN to 3.5V. If two of these LEDs are
placed in series then SP7600 will step down
the voltage to 7V. Superimposed on I LED there
is a current ripple that is equal in magnitude
to inductor current ripple. Current ripple will
be nominally set to 10% of I LED by proper
sizing of inductor. Note that throughout this
Ch1: DIM Signal
Ch2: VFB - 2A I OUT /div
Fig. 15: 1.1KHz, 10% Duty Cycle Dimming Signal
Dimming Signal is ~70% LED Duty Cycle
datasheet I LED
interchangeably.
D IMMING SIGNAL
and I O
will be used
Ch1: DIM Signal
Ch2: VFB - 2A I OUT /div
A logic-level PWM signal applied through a
small-signal diode to the feed-back (FB) pin
can be used for dimming control of the LED.
This external signal we call DIM turns the
MOSFET gate drive on/off, thereby modulating
the average current delivered to the LED. The
DIM signal connects to the VFB pin through a
1N4148 diode and will shutdown the SP7600
when DIM = H and turn-on the SP7600 when
Fig. 16: 1KHz, 70% Duty Cycle
Dimming Signal is ~10% LED Duty Cycle
? 2009 Exar Corporation
8/13
Rev. 2.0.0
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
SPB2 PANEL SWING KIT
SPIKECUBE SURGE SUPPRESSR 1OUT DIRECT PLUG
SPIKESTIK SURGE SUPPRESSOR SPIKE STIK 6OUT
SPS-615-HG SURGE SUPP 6OUT 15'CORD HOSP GRD
SR202 SHELF FIXED 4-POST HEAVY DUTY
SR204 SHELF FIXED 2U CANTILEVER
SR205 SHELF SLIDING 4-POST 1U
SR206 SHELF SLIDING 4-POST 2U
相关代理商/技术参数
SP7600EN2-L/TR 功能描述:LED照明驱动器 2A 29V NON-SYNC BUCK HIGH PWR 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
SP7601 制造商:EXAR 制造商全称:EXAR 功能描述:29V High Voltage LED Driver
SP7601_EB 制造商:EXAR 制造商全称:EXAR 功能描述:29V High Voltage LED Driver
SP7601EB 功能描述:LED 照明开发工具 Eval Board for SP7601 Series 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:
SP7601EK1-L 功能描述:LED照明驱动器 High Curr DC-to-DC Buck LED Drvr 1.2MHz 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
SP7601EK1-L/TR 功能描述:LED照明驱动器 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
SP7606 制造商:EXAR 制造商全称:EXAR 功能描述:Wide Input Voltage Boost Controller
SP7606ER-L 制造商:EXAR 制造商全称:EXAR 功能描述:Wide Input Voltage Boost Controller