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參數(shù)資料
| 型號(hào)： | SC473EVB |
| 廠商： | Semtech Corporation |
| 英文描述： | Single-Phase Single Chip Graphics Core Power Supply |
| 中文描述： | 單相單芯片圖形核心供電 |
| 文件頁(yè)數(shù)： | 10/18頁(yè) |
| 文件大?。?/td> | 486K |
| 代理商： | SC473EVB |
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10
2006 Semtech Corp.
www.semtech.com
SC473
POWER MANAGEMENT
Applications Information
Introduction
The SC473 is a new generation of hysteretic converters
which combines the best features of Semtech’s hysteretic
converter technology with the bene
fi
t of an error ampli
fi
er.
The SC473 provides a complete solution to high perfor-
mance graphics core requirements.
In the SC473, the ripple for the hysteretic switching control
is provided by DCR sensing. This provides several advan-
tages over plain voltage-mode hysteretic converters, which
switch on voltage ripple.
No current sense resistors are required resulting
in higher converter ef
fi
ciency
Full differential feedback of the output voltage
from the CPU die is enabled
Stable with all-ceramic output
Because the basic control is hysteretic, the SC473 provides
the fastest possible transient response without switching
at very high frequencies. This results in higher ef
fi
ciency
with less expensive parts because switching losses are
reduced.
The SC473 also provides a full range of features:
Graphics functions are implemented on-chip:
EN
PWRGD
VID programmable Output
Slew Rate Control
Power Monitor
A 2.00V voltage reference is provided
Separate hysteresis and current limit settings
A full suite of protection features is provided:
Over-current protection (OCP)
Fixed and DAC-referenced over-voltage
protection (OVP)
Over-temperature protection (OTP)
Under-voltage detection via PWRGD
All protection features are latching, and are reset either by
recycling power or toggling the EN signal.
Theory of Operation
Voltage Regulation:
Referring to the block diagram on the preceding page, the
hysteretic comparator is the heart of the converter. The
"FB+" input corresponds roughly to the CMPREF node of
our older generations of IC; the "FB-" input is similar to
CMP.
To regulate, the comparator needs this information:
DAC (reference) voltage
Feedback voltage
Hysteresis voltage
CMPREF receives the reference, voltage feedback and
current information via current sense ampli
fi
er. The refer-
ence source is the DAC. The feedback voltage is received
by the differential ampli
fi
er. A third ampli
fi
er, labeled the
"Error Ampli
fi
er", multiplies the difference between the
"ideal" voltage (DAC) and the actual voltage (FB+ minus
FB-) for faster response. This signal is the reference for
the hysteretic comparator.
CMP has the ripple signal derived from the current sense
inputs plus the hysteresis signal. The DC is stripped from
the ripple signals by the combination of low-pass
fi
lter and
summing ampli
fi
er.
Current Limit Regulation:
In Current Limit, the voltage hysteretic converter is overrid-
den by the current limit hysteretic comparator, and the TG
pulse is terminated when the output of the current sense
ampli
fi
er reaches the CL_hi threshold and BG is terminated
at the CL_lo threshold. These thresholds are set from the
CLSET resistor divider:
CL_hi = 0.33 * V(clset)
CL_lo = 0.20 * V(clset)
Current limit pulses continue until 32 pulses after the volt-
age droops to the PWRGD low threshold; then the controller
latches off. This current limit algorithm is used in several
generations of V
CORE
controllers and is extremely robust.
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PDF描述 |
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| SC473MLTRT | Single-Phase Single Chip Graphics Core Power Supply |
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| SC475AEVB | Synchronous Buck Controller with Dual-Level VOUT Transition Support |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SC473MLTRT | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Single-Phase Single Chip Graphics Core Power Supply |
| SC47-51-SUF | 制造商:Mikalor 功能描述:WIDE BOLT CLIP,47-51MM |
| SC475A | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Synchronous Buck Controller with Dual-Level VOUT Transition Support |
| SC475AEVB | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Synchronous Buck Controller with Dual-Level VOUT Transition Support |
| SC475AMLTRT | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Synchronous Buck Controller with Dual-Level VOUT Transition Support |
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