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参数资料
| 型号： | SP7662EB |
| 厂商： | Exar Corporation |
| 文件页数： | 10/19页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP7662 |
| 标准包装： | 1 |
| 系列： | * |
S P 7 6 6 2
P o w e r b l o x T M
1 2 A 3 0 0 K H z S y n c h r o n o u s S t e p D o w n R e g u l a t o r
resistors as shown. If external resistors are an
order of magnitude smaller than internal
resistors, then the V IN start threshold is given
by:
For example, if it is required to have a V IN
start threshold of 7V, then let R 7 = 5k Ω and
using the V IN start threshold equation we get
R 6 = 9.09k Ω.
T HERMAL AND S HORT -C IRCUIT P ROTECTION
Because the SP7662 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 temperatures.
A short-circuit detection comparator has also
been included in the SP7662 to protect against
an accidental short at the output of the power
converter. This comparator constantly
monitors the positive and negative terminals
of the error amplifier, and if the VFB 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 SP7662 is
capable of detecting short-circuit faults
throughout the duration of soft start as well as
in regular operation.
O VER -C URRENT P ROTECTION
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 across the
Fig. 19: Over Current Detection Circuit
Inputs to an over-current detection
comparator, set to trigger at 60mV nominal,
are connected to the inductor as shown. Since
the average voltage sensed by the comparator
is equal to the product of inductor current and
inductor DC resistance (DCR), then:
Solving this equation for the specific inductor
in circuit 1, I MAX =14.6A. When I MAX is reached,
a 220ms 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
repeated (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 R 9
should be added as shown in Figure 18. R 9
forms a resistor divider and reduces the
voltage seen by the comparator.
Since
inductor. Over-current
is detected by
monitoring a differential voltage across the
output inductor as shown in the Figure 16.
Solving for R 9 we get:
As an example: if desired I MAX is 17A, then
R 9 = 63.4k Ω.
? 2012 Exar Corporation
10/19
Rev. 2.1.0
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7662ER | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7662ER/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 12A, 300kHz, Buck Regulator |
| SP7662ER-L | 功能描述:开关变换器、稳压器与控制器 Buck Regulator 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 |
| SP7662ERL/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 12A, 300kHz, Buck Regulator |
| SP7662ER-L/TR | 功能描述:开关变换器、稳压器与控制器 WIDE INPUT VOLTAGE Range12A300KHz 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 |
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