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參數(shù)資料
| 型號： | SP7651 |
| 英文描述： | Wide Input Voltage Range 3A, 900kHz, Buck Regulator |
| 中文描述： | 寬輸入電壓范圍第3A，900kHz的，降壓穩(wěn)壓器 |
| 文件頁數(shù)： | 5/12頁 |
| 文件大?。?/td> | 117K |
| 代理商： | SP7651 |
5
Date: 08/25/04
SP7651 Wide Input Voltage Range 3A, 900kHz, Buck Regulator Copyright 2004 Sipex Corporation
clude thermal shutdown and short-circuit detec-
tion. In the event that either a thermal, short-
circuit, or UVLO fault is detected, the SP7651 is
forced into an idle state where the output drivers
are held off for a finite period before a re-start is
attempted.
Soft Start
“Soft Start” is achieved when a power converter
ramps up the output voltage while controlling
the magnitude of the input supply source cur-
rent. 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
* (DV
OUT
/ DT
SOFT-START
)
The SP7651 provides the user with the option 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 10uA 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
* (DV
OUT
*10
μ
A / (C
SS
* 0.8V)
Under Voltage Lock Out (UVLO)
The SP7651 contains two separate UVLO com-
parators to monitor the internal bias (V
CC
) and
conversion (V
IN
) voltages independently. The
V
CC
UVLO threshold is internally set to 4.25V,
whereas the V
IN
UVLO threshold is program-
mable through the UVIN pin. When the UVIN
pin is greater than 2.5V, the SP7651 is permitted
to start up pending the removal of all other
faults. Both the V
CC
and V
IN
UVLO compara-
tors have been designed with hysteresis to pre-
vent noise from resetting a fault.
Thermal and Short-Circuit
Protection
Because the SP7651 is designed to drive large
output current, there is a chance that the power
converter will become too hot. Therefore, an
internal thermal shutdown (145
°
C) has been
included to prevent the IC from malfunctioning
at extreme temperatures.
A short-circuit detection comparator has also
been included in the SP7651 to protect against
an accidental short at the output of the power
converter. This comparator constantly monitors
the positive and negative terminals of the error
amplifier, and if the V
FB
pin falls more than
250mV (typical) below the positive reference, a
short-circuit fault is set. Because the SS pin
overrides the internal 0.8V reference during soft
start, the SP7651 is capable of detecting short-
circuit faults throughout the duration of soft
start as well as in regular operation.
Handling of Faults:
Upon the detection of power (UVLO), thermal,
or short-circuit faults, the SP7651 is forced into
an idle state where the SS and COMP pins are
pulled low and the NFETS are held off. In the
event of UVLO fault, the SP7651 remains in this
idle state until the UVLO fault is removed.
Upon the detection of a thermal or short-circuit
fault, an internal 200ms timer is activated. In the
event of a short-circuit fault, a re-start is at-
tempted immediately after the 200ms timeout
expires. Whereas, when a thermal fault is de-
tected the 200ms delay continuously recycles
and a re-start cannot be attempted until the
thermal fault is removed and the timer expires.
Error Amplifier and Voltage Loop
Since the heart of the SP7651 voltage error loop
is a high performance, wide bandwidth
transconductance amplifier great care should be
taken to select the optimal compensation net-
work. Because of the amplifier’s current lim-
ited (+/-150
μ
A) transconductance, there are
many ways to compensate the voltage loop or to
THEORY OF OPERATION
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP7652 | Wide Input Voltage Range 6A, 600kHz, Buck Regulator |
| SP7652EB | Evaluation Board Manual |
| SP7652EU | Evaluation Board Manual |
| SP7653 | Wide Input Voltage Range, 1.3MHz,Buck Regulator |
| SP7653ER | Wide Input Voltage Range, 1.3MHz,Buck Regulator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP7651_06 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7651_07 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input Voltage Range 3Amp 900kHz Buck Regulator |
| SP7651EB | 功能描述:電源管理IC開發(fā)工具 Wide In Volt Range 3A 900kHz Buck Reg RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| SP7651ER | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7651ER/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input Voltage Range 3A, 900kHz, Buck Regulator |
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