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| 型号： | SP7661ER-L |
| 厂商： | Exar Corporation |
| 文件页数： | 7/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 3A 26DFN |
| 产品变化通告： | SP76(55,61)ER-L/(TR) Obsolescence 29/Jul/2011 |
| 标准包装： | 500 |
| 系列： | Power Blox™ |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 20.2 V |
| 输入电压： | 4.75 V ~ 22 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 600kHz |
| 电流 - 输出： | 3A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 26-VFDFN 裸露焊盘 |
| 包装： | 散装 |
| 供应商设备封装： | 26-DFN（7x4） |
THEORY OF OPERATION
V OUT
Therefore without external biasing the V IN
start threshold is 9.5V. A small capacitor may
be required between UVIN and GND to filter
out noise. For applications with V IN of 5V
or 3.3V, connect UVIN directly to V IN . To
program the V IN start threshold, use a pair
of external resistors as shown. If external
resistors are an order of magnitude smaller
than internal resistors, then the V IN start
threshold is given by:
across the inductor. Over-current is de -
tected by monitoring a differential voltage
across the output inductor as shown in the
next figure.
SP7661
L = 2.7uH, DCR = 4.1m?
SWN
V IN (start) = 2.5 ? (R6+R7)/R7
R3
5.11K?
R4
5.11K?
For example, if it is required to have a V IN
start threshold of 7V, then let R7 = 5K? and
using the V IN start threshold equation we get
R6 = 9.09K?.
ISP
ISN
CSP
6.8nF
CS
0.1uF
Thermal and Short-Circuit Protection
R9
{R3 + R4 + R9}
Because the SP7661 is designed to drive
large output current, there is a chance that
the power converter will become too hot.
Therefore, an internal thermal shutdown
(145°C) has been included to prevent the
IC from malfunctioning at extreme tem -
peratures.
A short-circuit detection comparator has
also been included in the SP7661 to protect
against an accidental short at the output of
the power converter. This comparator con -
stantly monitors the positive and negative
terminals of the error amplifier, and if the V FB
pin falls more than 250mV (typical) below
the positive reference, a short-circuit fault
is set. Because the SS pin overrides the
internal 0.8V reference during soft start, the
SP7661 is capable of detecting short-circuit
faults throughout the duration of soft start as
well as in regular operation.
Over-Current Protection
The Over-current protection feature can
only be used on output voltages ≤ 3.3 volts.
It is limited by the common mode rating
of the op-amp used to sense the voltage
Over-current detection circuit
Inputs to an over-current detection com -
parator, set to trigger at 60 mV nominal, are
connected to the inductor as shown. Since
the average voltage sensed by the com -
parator is equal to the product of inductor
current and inductor DC resistance (DCR),
then I MAX = 60mV / DCR. Solving this equa -
tion for the specific inductor in circuit 1, I MAX
= 14.6A. When I MAX is reached, a 220 ms
time-out is initiated, during which top and
bottom drivers are turned off. Following the
time-out, a restart is attempted. If the fault
condition persists, then the time-out is re -
peated (referred to as hiccup).
Increasing the Current Limit
If it is desired to set I MAX > {60mV / DCR} (in
this case larger than 14.6A), then a resistor
R9 should be added as shown in the next
figure. R9 forms a resistor divider and re -
duces the voltage seen by the comparator.
Since: 60mV ( I MAX ? DCR)
=
Mar -07 Rev N
SP766 Wide Input Voltage Range 3A, 600kHz Buck Regulator
7
? 2007 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7661ERL/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 3A, 600kHz, Buck Regulator |
| SP7661ER-L/TR | 功能描述:开关变换器、稳压器与控制器 WIDE INPUT VOLTAGE Range A600KHz RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| SP7662 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7662_07 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 12A, 300kHz, Buck Regulator |
| SP7662_1 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
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