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参数资料
| 型号： | SP7651EB |
| 厂商： | Exar Corporation |
| 文件页数： | 6/15页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP7651 |
| 标准包装： | 1 |
| 系列： | * |
current- limited (+/- 50μA) transconduc-
tance, there are many ways to compensate
the voltage loop or to control the COMP pin
externally. If a simple, single pole, single zero
response is desired, then compensation can
be as simple as an RC circuit to Ground. If
a more complex compensation is required,
then the amplifier has enough bandwidth
(45° at 4 MHz) and enough gain (60dB) to
run Type III compensation schemes with ad-
equate gain and phase margins at crossover
frequencies greater than 50kHz.
V BST
GH
V oltage
V SWN
V(V CC)
GL
V oltage
0V
V(V IN )
SWN
V oltage
THEORY OF OPERATION
R2=
The common mode output of the error am-
plifier is 0.9V to 2.2V. Therefore, the PWM
voltage ramp has been set between . V and
2.2V to ensure proper 0% to 100% duty cycle
capability. The voltage loop also includes
two other very important features. One is
asynchronous startup mode. Basically, the
synchronous rectifier cannot turn on unless
the high side NFET has attempted to turn
on or the SS pin has exceeded .7V. This
feature prevents the controller from “dragging
down” the output voltage during startup or in
fault modes. The second feature is a 100%
duty cycle timeout that ensures synchronized
refreshing of the BST capacitor at very high
duty ratios. In the event that the high side
NFET is on for 20 continuous clock cycles,
a reset is given to the PWM flip-flop half
way through the 21st cycle. This forces GL
to rise for the cycle, in turn refreshing the
BST capacitor.
Power MOSFETs
The SP765 contains a pair of integrated low
resistance N MOSFETs designed to drive
up to 3A of output current. Maximum output
current could be limited by thermal limitations
of a particular application. The SP765
incorporates a built-in over-temperature
protection to prevent internal overheating.
-0V
-V(Diode) V
V(V IN )+V(V CC )
BST
V oltage
V(V CC )
TIME
Setting Output Voltages
The SP765 can be set to different output
voltages. The relationship in the following
formula is based on a voltage divider from
the output to the feedback pin V FB , which is
set to an internal reference voltage of 0.80V.
Standard 1% metal film resistors of surface
mount size 0603 are recommended.
Vout = 0.80V ( R / R2 + ) =>
R
[(V OUT /0.80V) - ]
Where R1 = 68.1K? and for Vout = 0.80V
setting, simply remove R2 from the board.
Furthermore, one could select the value
of the R and R2 combination to meet the
exact output voltage setting by restricting
R1 resistance range such that 50K? < R1 <
100K? for overall system loop stability.
Rev J: 3/ 4/07
SP765 Wide Input Voltage Range 3A, 900kHz, Buck Regulator
6
? Copyright 2007 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7651ER | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7651ER/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 3A, 900kHz, Buck Regulator |
| SP7651ER-L | 功能描述:DC/DC 开关控制器 Buck Regulator RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| SP7651ER-L/TR | 功能描述:开关变换器、稳压器与控制器 WIDE INPUT VOLTAGE RANGE, 3A 900k 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 |
| SP7652 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 6A, 600kHz, Buck Regulator |
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