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參數(shù)資料
| 型號： | SP6120BCY |
| 英文描述： | Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| 中文描述： | 低電壓，AnyFETTM，同步，降壓控制器適合2A至10A條，高性能，DC - DC電源轉(zhuǎn)換器 |
| 文件頁數(shù)： | 9/22頁 |
| 文件大?。?/td> | 304K |
| 代理商： | SP6120BCY |
9
Date: 5/25/04
SP6120B Low Voltage, AnyFET
TM
, Synchronous, Buck Controller Copyright 2004 Sipex Corporation
if the conduction current reaches zero and the
Driver Logic has made an attempt to turn the
lower driver on and the Programming Logic is
set for discontinuous mode. Lastly, the 4
driv-
ers have internal gate non-overlap circuitry and
are designed to drive MOSFETs associated with
converter designs in the 5A to 10A range. Typi-
cally the high side driver is referenced to the
SWN pin; further improving the efficiency and
performance of the converter.
ENABLE
Low quiescent mode or “Sleep Mode” is initi-
ated by pulling the ENABLE pin below 650mV.
The ENABLE pin has an internal 4
μ
A pull-up
current and does not require any external inter-
face for normal operation. If the ENABLE pin is
driven from a voltage source, the voltage must
be above 1.45V in order to guarantee proper
“awake” operation. Assuming that V
CC
is above
2.85V, the SP6120B transitions from “Sleep
Mode” to “Awake Mode” in about 20
μ
s to 30
μ
s
and from “Awake Mode” to “Sleep Mode” in a
few microseconds. SP6120B quiescent current
in sleep mode is 20
μ
A maximum. During Sleep
Mode, the high side and low side MOSFETs are
turned off and the COMP and SS pins are held
low.
Bootstrap Circuit
When SP6120B is programmed to drive a high
side N channel MOSFET, a bootstrap circuit is
required to generate a voltage higher than V
IN
to
fully enhance the top MOSFET. A typical boot-
strap only requires a capacitor and diode shown
as C
BST
and D
BST
in the application circuit on the
front page. When the bottom MOSFET Q
B
is
turned on, D
BST
is forward biased and charges
the C
BST
close to V
IN
. When the top MOSFET
turn on, the switch node swings to the V
IN
voltage. Now the voltage at the BST pin is 2*V
IN
and D
BST
is reverse biased. The BST pin voltage
powers the high side MOSFET driver, and thus
the GH output goes up to 2*V
IN
to provide a V
DS
equal to V
IN
.
Under certain conditions, the bottom MOSFET
may not turn on long enough to replenish C
BST
voltage. Therefore, when the top MOSFET turns
on, the BST pin may not be high enough to fully
enhance the switch. To prevent this operation,
SP6120B monitors the BST pin voltage in refer-
ence to the V
CC
voltage. When the BST pin
voltage is less than V
BST
OK threshold, the
controller forces the GL to turn on for MINI-
MUM GL ON at the end of the switching cycle.
This provides enough time to recharge the C
BST
and ensures the proper operation of the boot-
strap circuit.
UVLO
Assuming that the ENABLE pin is either pulled
high or floating, the voltage on the V
CC
pin then
determines operation of the SP6120B. As V
CC
rises, the UVLO block monitors V
CC
and keeps
the high side and low side MOSFETs off and the
COMP and SS pins low until V
CC
reaches 2.85V.
If no faults are present, the SP6120B will initiate
a soft start when V
CC
exceeds 2.85V. Hysteresis
(about 100mV) in the UVLO comparator pro-
vides noise immunity at start-up.
Soft Start
(see figures on next page)
Soft start is required on step-down controllers to
prevent excess inrush current through the power
train during start-up. Typically this is managed
by sourcing a controlled current into a program-
ming capacitor (on the SS pin) and then using the
voltage across this capacitor to slowly ramp up
either the error amp reference or the error amp
output (COMP). The control loop creates nar-
row width driver pulses while the output voltage
is low and allows these pulses to increase to their
steady-state duty cycle as the output voltage
increases to its regulated value. As a result of
controlling the inductor volt*second product
during start-up, inrush current is also controlled.
The presence of the output capacitor creates
extra current draw during start-up. Simply stated,
dV
OUT
/dt requires an average sustained current
in the output capacitor and this current must be
considered while calculating peak inrush current
and over current thresholds. Since the SP6120B
ramps up the error amp reference voltage, an
expression for the output capacitor current can
be written as:
IC
OUT
= (C
OUT
/C
SS
) * (V
OUT
/1.25) * 50
μ
A
General Overview: continued
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP6120BEY | Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| SP6120CY | Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| SP6120HVEY | High Voltage, Synchronous ,Buck Controller Ideal for 2A to 20A, High Performance, DC-DC Power Converters |
| SP6120HVCY | CAPACITOR, F/TERM 6800PF 50V X8R 0805CAPACITOR, F/TERM 6800PF 50V X8R 0805; CAPACITANCE:6.8NF; VOLTAGE RATING, DC:50V; CAPACITOR DIELECTRIC TYPE:CERAMIC MULTI-LAYER; SERIES:08055F; TOLERANCE, :10%; TOLERANCE, -:10%; TEMP, OP. RoHS Compliant: Yes |
| SP6120EY | Low Voltage, AnyFETTM, Synchronous,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6120BCY/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| SP6120BCY-L | 功能描述:DC/DC 開關(guān)控制器 Low Voltage, AnyFET Synchronous, Cntrllr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| SP6120BCY-L/TR | 功能描述:DC/DC 開關(guān)控制器 Low Voltage, AnyFET Synchronous, Cntrllr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| SP6120BEY | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| SP6120BEY/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
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