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参数资料
| 型号： | SP7661ER-L |
| 厂商： | Exar Corporation |
| 文件页数： | 6/20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
+
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General Overview
The SP7661 is a fixed frequency, volt -
age mode, synchronous PWM regulator
optimized for high efficiency. The part has
been specifically designed for single supply
operation from a 5V to 22V input.
The heart of the SP7661 is a wide bandwidth
transconductance amplifier designed to ac -
commodate Type II and Type III compensa -
tion schemes. A precision 0.8V reference,
present on the positive terminal of the error
amplifier, permits the programming of the
output voltage down to 0.8V via the VFB
pin. The output of the error amplifier, COMP,
is compared to a 1.1V peak-to-peak ramp,
which is responsible for trailing edge PWM
control. This voltage ramp and PWM control
logic are governed by the internal oscillator
that accurately sets the PWM frequency to
600kHz.
The SP7661 contains two unique control
features that are very powerful in distributed
applications. First, nonsynchronous driver
control is enabled during startup, to prohibit
the low side switch from pulling down the
output until the high side switch has at -
tempted to turn on. Second, a 100% duty
cycle timeout ensures that the low side switch
is periodically enhanced during extended
periods at 100% duty cycle. This guaran -
tees the synchronized refreshing of the
BST capacitor during very large duty ratios.
The SP7661 also contains a number of valu -
able protection features. Programmable V IN
UVLO allows the user to set the exact value
at which the conversion voltage can safely
begin down-conversion, and an internal V CC
UVLO which ensures that the controller itself
has enough voltage to properly operate.
Other protection features include thermal
shutdown and short-circuit detection. In the
event that either a thermal, short-circuit, or
UVLO fault is detected, the SP7661 is forced
into an idle state where the output drivers
are held off for a finite period before a restart
is attempted.
Soft Start
“Soft Start” is achieved when a power con -
verter ramps up the output voltage while
controlling the magnitude of the input sup -
ply source current. In a modern step down
converter, ramping up the positive terminal
of the error amplifier controls soft start. As a
result, excess source current can be defined
as the current required to charge the output
capacitor.
I VIN = C OUT ? (?V OUT / ?T SOFT - START )
The SP7661 provides the user with the op -
tion to program the soft start rate by tying
a capacitor from the SS pin to GND. The
selection of this capacitor is based on the
10μA pull up current present at the SS pin
and the 0.8V reference voltage. Therefore,
the excess source can be redefined as:
I VIN = C OUT ? [ ?V OUT ?10μA / (C SS ? 0.8V) ]
Under Voltage Lock Out (UVLO)
The SP7661 has two separate UVLO com -
parators to monitor the bias (Vcc) and Input
(V IN ) voltages independently. The Vcc UVLO
is internally set to 4.25V. The V IN UVLO is
programmable through UV IN pin. When
UVIN pin is greater than 2.5V the SP7661
is permitted to start up pending the removal
of all other faults. A pair of internal resistors
is connected to UVIN as shown in the figure
below.
SP7661
VIN
R6 140K?
UVIN
2.5V ON
2.2V OFF
R7
50K?
GND
Internal and external bias of UVIN
Mar -07 Rev N
SP766 Wide Input Voltage Range 3A, 600kHz Buck Regulator
6
? 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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