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参数资料
| 型号： | SP6650UEB |
| 厂商： | Exar Corporation |
| 文件页数： | 9/17页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP6650 |
| 标准包装： | 1 |
| 系列： | * |
S P 6 6 5 0
H i g h E f f i c i e n c y 6 0 0 m A S y n c h r o n o u s B u c k R e g u l a t o r
enough, the output voltage will follow, causing
the output ripple of the SP6650 regulator is
independent of the input and output voltages.
For battery powered applications, where the
battery voltage changes significantly, the
SP6650 provides constant output voltage
ripple throughout the battery lifetime. This
greatly simplifies the LC filter design.
O N -T IME C ONTROL : CONTINUED
The maximum loop frequency in CCM is
defined by the equation:
where:
F LP = CCM loop frequency
Rdc = NMOS on resistance, 0.3Ωtyp.
Ignoring conduction losses simplifies the loop
frequency to
OR'ing the loop comparator and the on-time
one shot reduces the switching frequency for
load currents below half the inductor ripple
current. This increases light load efficiency.
The minimum on-time insures that the
inductor current ripple is a minimum of K ON /L,
more than the load current demands. The
converter goes in to a standard pulse
frequency modulation (PFM) mode where the
switching frequency is proportional to the load
current.
L OW D ROPOUT AND L OAD T RANSIENT
O PERATION
OR'ing the loop comparator also increases the
duty ratio past the ideal D=V OUT /V IN up to and
including 100%. Under a light to heavy load
transient, the loop comparator will hold the
main switch on past the on-time one shot
pulse until the output is brought back into
regulation. Also, as the input voltage supply
drops down close to the output voltage, the
main MOSFET resistance loss will dictate a
much higher duty ratio to regulate the output.
Eventually as the input voltage drops low
the loop comparator to hold the converter at
100% duty cycle. This mode is critical in
extending battery life when the output voltage
is at or above the minimum usable input
voltage. The dropout voltage is the minimum
(V IN - V OUT ) below which the output regulation
cannot be maintained. The dropout voltage of
SP6650 is equal to I L (0.4Ω + R L ) where 0.4Ω
is the typical R DS(ON) of the P-Channel MOSFET
and R L is the DC resistance of the inductor.
The on-time control circuit seamlessly
operates the converter between CCM, DCM,
and low dropout modes without the need for
compensation. The converter's transient
response is quick since there is no
compensated error amplifier in the loop.
I NDUCTOR O VER -C URRENT P ROTECTION
The inductor over-current protection circuitry
is programmed to limit the peak inductor
current to 950mA (pin 4 tied to V IN ) or 500mA
(pin 4 to ground). This is done during the on-
time by comparing the source to drain voltage
drop of the PMOS passing the inductor current
with a second voltage drop representing the
maximum allowable inductor current. As the
two voltages become equal, the over-current
comparator triggers a minimum off-time one
shot. The off-time one shot forces the loop
into the discharge phase for a minimum time
causing the inductor current to decrease.
At the end of the off-time loop, control is
handed back to the OR'd on-time signal. If the
output voltage is still low, charging begins
until the output is in regulation or the current
limit has been reached again. During startup
and overload conditions, the converter
behaves like a current source at the
programmed limit minus half the current
ripple. The minimum T OFF is 6μs (typ.) at V OUT
= 0V and 2μs (typ.) for V OUT greater than
1.5V.
U NDER -V OLTAGE L OCKOUT
The SP6650 is equipped with under-voltage
lockout to protect the input battery source
from excessive currents when substantially
discharged. When the input supply is below
the UVLO threshold both power switches are
? 2012 Exar Corporation
9/17
Rev. 2.0.0
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| SP6651A | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High Efficiency 800mA Synchronous Buck Regulator Ideal for portable designs powered with Li Ion battery |
| SP6651AEB | 功能描述:DC/DC 开关控制器 Hi Efficiency 800mA Sync 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 |
| SP6651AER | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High Efficiency 800mA Synchronous Buck Regulator Ideal for portable designs powered with Li Ion battery |
| SP6651AER/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High Efficiency 800mA Synchronous Buck Regulator Ideal for portable designs powered with Li Ion battery |
| SP6651AER-L | 功能描述:DC/DC 开关控制器 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 |
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