- 您现在的位置：买卖IC网 > Sheet目录1009 > SP7601EB (Exar Corporation)EVAL BOARD FOR SP7601
GENERAL OVERVIEW
Overcurrent Programming
Calculate the ripple current requirement from:
Resistor Rs can be used to program
Overcurrent Protection (OCP). Use equation 2
for calculating the Rs value:
Irip = Io ×
D ( 1 ? D ) ………..………. (4)
D =
Rs =
0.35 V ? ( 1.5 × 1.05 × Iocp × Rds ( on ) )
33 uA
.… (2)
Where D is converter duty cycle:
Vo
Vin
Vo × ( Vin ? Vo )
Rds ( ON ) ≤ ?
? ……….. (5)
Where I ocp is the programmed overcurrent and
is generally set 50% above nominal output
current. The maximum value of Rs that can be
used for programming OCP is 3k ? .
Inductor Selection
Select the inductor L1 for inductance, I RMS and
I SAT . Calculate inductance from
L = ………………………. (3)
Vin × f × Δ I L
Where:
V IN is converter input voltage
Vo is converter output voltage. Since voltage
across R SET is small, Vo approximately equals
V F (for a string of series connected LEDs Vo
equals total V F )
Δ I L is inductor current ripple (nominally set to
10% of I o)
Inductor I SAT and I RMS must allow sufficient
safeguard over output current I o. As a rule of
thumb these parameters should be 50% higher
than I o. Where high efficiency is required, a low
DCR inductor should be used.
Input capacitor selection
Select the input capacitor for capacitance and
ripple current rating. Use the capacitances
listed in table 1 as a starting point and, if
needed, increase C IN .
Ceramic capacitors are recommended for input
filtering due to their low Equivalent Series
Resistance (ESR), Equivalent Series
Inductance (ESL) and small form factor.
MOSFET selection
Select the MOSFET M1 for ON resistance
R DS ( ON ), voltage rating (B VDSS ) and gate-to-
drain charge (Q GD ). The recommended
MOSFET voltage rating for 12V and 24V
applications is 30V and 40V respectively. As a
rule of thumb Q GD should be less than 10nC.
R DS ( ON ) must be selected such that, when
operating at peak current and junction
temperature, the Overcurrent threshold of the
SP7601 is not exceeded. Allowing 50% margin
for temperature coefficient of R DS ( ON ), 5%
margin for inductor current ripple and 50%
margin for OCP, the following expression can
be used:
? 350 mV ?
? 1 . 5 × 1 . 5 × 1 . 05 × Io ?
Within this constraint, selecting MOSFETs with
lower R DS ( ON ) will reduce conduction losses at
the expense of increased switching losses. If a
choice of several MOSFETs is available, select
the highest R DS ( ON ) MOSFET that meets the
above criteria.
Schottky Rectifier selection
Select the Schottky D1 for Voltage rating V R
and current rating I f . Voltage rating should be
selected using the same guidelines outlined for
? × Io ……………………… (6)
If ≥ ? 1 ?
Io (A)
< 0.7
0.71 to 1.2
> 1.2
Cin (uF)
2.2
4.7
2 x 4.7
MOSFET voltage selection. Current rating can
be calculated from:
? Vo ?
? Vin ?
Table1- C IN selection
Sept25-07 Rev D
SP7601 29V High Voltage LED Driver
Page 6
? 2007 Exar Corporation
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
SP7616EB
EVAL BOARD FOR SP7616
SP7648EB
EVAL BOARD FOR SP7648
SP7685EB
EVAL BOARD FOR SP7665
SP7686EB
EVAL BOARD FOR SP7666
SPA6191
RELAY SSR 1A 240VAC SIP ZERO-X
SPFE480D25R
RELAY SSR DC 480VAC 25A PCB
SR-7601
RELAY GEN PURPOSE 4PDT 2A 26.5V
SR-7602
RELAY GEN PURPOSE 4PDT 2A 26.5V
相关代理商/技术参数
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
SP7606ER-L/TR
制造商:EXAR 制造商全称:EXAR 功能描述:Wide Input Voltage Boost Controller
SP7611A
制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:2-4 Channel Low Dropout Linear LED Driver
SP7611A_07
制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:2-4 Channel Low Dropout Linear LED Driver
SP7611AEC6
制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:2-4 Channel Low Dropout Linear LED Driver