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參數(shù)資料
| 型號： | SC2434SWTRT |
| 廠商： | Semtech Corporation |
| 英文描述： | TriPhase Current Mode Controller with Power Good |
| 中文描述： | 三相電流模式控制器與電源良好 |
| 文件頁數(shù)： | 7/19頁 |
| 文件大?。?/td> | 302K |
| 代理商： | SC2434SWTRT |
7
2005 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
Applications Information (Cont.)
SC2434
Phase Current Balance
One of the fundamental challenges for multi-phase solu-
tions is to balance the phase currents to achieve the best
possible electrical and thermal performance. It is quite
easy to use the SC2434 control topology to achieve very
good phase current balance. Since the current of all the
phases passes through the same current sensing compo-
nent and the same current current of all the phases are
well balanced on pulse by pulse basis. This control results
in small and even output voltage ripple and evenly distrib-
uted thermal load. Additional advantages of using input
current mode are less sensing circuitry, less IC pins, and
less power loss on the sensing resistor comparing sensing
inductor current on the output side. Fig. 2 shows the wave-
form of inductor currents under heavy load conditions,
which clearly demonstrates the excellent performance of
SC2434 on balancing the phase current.
voltage. Fig. 3 shows the measured waveforms of power
up and power down.
Fig. 3 - Shows the measured waveforms of power up and power
down.
Over Current Protection (OCP)
When sensed current signal across the differential input
of the current amplifier exceeds 120mV typical value, OCP
circuitry will pull down the error amplifier output voltage
and also discharge the soft start capacitor. The pull down
of the error amplifier will not be released until the soft
capacitor is discharged bellow 0.3V. At this point, the
PWM outputs are reactivated and the soft start capacitor
begins to charge up again through the internal 6 Kohm
resistor. The VR will try to bring up the output voltage until
the over load or short circuit condition is removed. The
hiccup mode OCP can significantly reduce the average out-
put current under overload conditions. The hiccup timing
is controlled by the soft start time constant. Please also
notice that the OCP threshold has less than 10% toler-
ance, hence, the onset of the OCP is quite accurate. The
advantage is that the VR designer does not need to re-
serve big thermal headroom to deal with the worst-case
operation when load is over 100% but the OCP has yet not
been triggered. An RC filter is needed to filter out the
leading edge voltage spike across the current sensing re-
sistor to prevent false triggering of the OCP. The time con-
stant should be around 200nS (please see application
schematic).
Power Good
SC2434 features a power good input and an open collec-
tor power good output. The VR output voltage is scaled
down through a resistive divider and this signal is fed into
PGIN (power good input) pin. The scaled VR output volt-
age has to be bigger than 0.8V otherwise the power good
output pin is pulled down. A 5 Kohm pull-up resistor and
a 0.1uF capacitor to ground are recommended to prevent
false trigger during logic transition.
Fig. 2 - Measured inductor currents of SC2434 3-phase VR
under heavy load condition.
Under Voltage Lockout (UVLO)
During power up, when UVLO circuitry detects the chip
supply (Vcc) be bigger than 7.5V (typical value with proper
hysteresis), the bandgap voltage reference starts to charge
the external soft start capacitor through a 6 Kohm inter-
nal resistor. When soft start capacitor voltage reaches
0.5V, the output voltage starts to build up which follows
the exponential voltage profile of the soft start capacitor.
The soft start process ensures that the output voltage will
have no over shoot. During power down, UVLO will dis-
charge the soft start capacitor to shut of the PWM. The
load will absorb the energy in the output filter and no reso-
nance will occur. Hence, the CPU will not see any negative
Output
voltage
Output
voltage
Input
voltage
Input
voltage
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| SC2434TSTR | TriPhase Current Mode Controller with Power Good |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SC2434TSTR | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:TriPhase Current Mode Controller with Power Good |
| SC2434TSTRT | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:TriPhase Current Mode Controller with Power Good |
| SC24-391-R | 功能描述:INDUCTOR SHIELD 390UH 60MA SMD RoHS:是 類別:電感器，線圈，扼流圈 >> 固定式 系列:SC24 標準包裝:500 系列:1331 電感:1.2µH 電流:247mA 電流 - 飽和:247mA 電流 - 溫升:- 類型:鐵芯體 容差:±10% 屏蔽:屏蔽 DC 電阻(DCR):最大 730 毫歐 Q因子@頻率:40 @ 7.9MHz 頻率 - 自諧振:130MHz 材料 - 芯體:鐵 封裝/外殼:0.312" L x 0.115" W x 0.135" H（7.94mm x 2.92mm x 3.43mm） 安裝類型:表面貼裝 包裝:帶卷 (TR) 工作溫度:-55°C ~ 105°C 頻率 - 測試:7.9MHz |
| SC2440 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:2.5 MHz Dual Switching Regulator with Integrated 2A Switches |
| SC2440EVB | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:2.5 MHz Dual Switching Regulator with Integrated 2A Switches |
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