- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄374721 > SC2440 (Semtech Corporation) 2.5 MHz Dual Switching Regulator with Integrated 2A Switches PDF資料下載
參數(shù)資料
| 型號： | SC2440 |
| 廠商： | Semtech Corporation |
| 英文描述： | 2.5 MHz Dual Switching Regulator with Integrated 2A Switches |
| 中文描述： | 2.5 MHz雙開關(guān)穩(wěn)壓器集成甲開關(guān) |
| 文件頁數(shù)： | 13/26頁 |
| 文件大小： | 643K |
| 代理商： | SC2440 |
13
2005 Semtech Corp.
www.semtech.com
SC2440
POWER MANAGEMENT
Applications Information
results from the ESR of the output capacitor while the
second term is due to the charging and discharging of
C
by the inductor ripple current. Substituting
I
= 0.6A,
f = 1MHz and C
OUT
= 10
μ
F ceramic with ESR = 3m
in
(7),
+
=
mV
3
mV
5
+
mV
8
=
)
m
5
=
12
m
3
A
6
V
OUT
Depending on operating frequency and the type of
capacitor, ripple voltage resulting from charging and
discharging of C
may be higer than that due to ESR. A
10
μ
F or 22
μ
F X5R ceramic capacitor is found adequate
for output filtering in most applications.
Ripple current
in the output capacitor is not a concern because the
inductor current of a buck converter directly feeds C
,
resulting in very low ripple current. Avoid using Z5U and
Y5V ceramic capacitors for output filtering because these
types of capacitors have high temperature and high
voltage coefficients.
Freewheeling Diode
Use of Schottky barrier diodes as freewheeling rectifiers
reduces diode reverse recovery input current spikes,
easing high-side current sensing in the SC2440. These
diodes should have a RMS current rating between 1A
and 2A and a reverse blocking voltage of at least 5V
higher than the input voltage. For switching regulators
operating at low duty cycles (i.e. low output voltage to
input voltage conversion ratios), it is beneficial to use
freewheeling diodes with somewhat higher RMS current
ratings (thus lower forward voltages). This is because the
diode conduction interval is much longer than that of
the transistor. Converter efficiency will be improved if
the voltage drop across the diode is lower.
The freewheeling diodes should be placed close to the
SW pins of the SC2440 to minimize ringing due to trace
inductance. Surface-mount equivalents of 1N5817 and
1N5819, MBRM120LT3 (ON Semi), UPS120 and
UPS140 (Micro-Semi) are all suitable.
Bootstrapping the Power Transistors
To maximize efficiency, the turn-on voltage across the
internal power NPN transistors should be minimized. If
these transistors are to be driven into saturation, then
their bases will have to be driven from a power supply
higher in voltage than V
IN
. The required driver supply
voltage (at least 2.5V higher than the SW voltage over
the industrial temperature range) is generated with a
bootstrap circuit (the diode D
BST
and the capacitor C
BST
in
Figure 8). The bootstrapped output (the common node
between D
BST
and C
BST
) is connected to the BOOST pin of
the SC2440. The power transistor in the SC2440 is first
switched on to build up current in the inductor. When
the transistor is switched off, the inductor current pulls
the SW node low, allowing C
BST
to be charged through
D
BST
. When the power switch is again turned on, the SW
voltage goes high. This brings the BOOST voltage to
V
V
+
, thus back-biasing D
BST
. C
BST
voltage increases
with each subsequent switching cycle, as does the
bootstrapped voltage at the BOOST pin. After a number
of switching cycles, C
BST
will be fully charged to a voltage
approximately equal to that applied to the anode of D
BST
.
Figure 7 shows the typical minimum BOOST to SW voltage
required to fully saturate the power transistor. This
differential voltage (
BST
room temperature. This is also specified in the “Electrical
Characteristics” as “Minimum Bootstrap Voltage”. The
minimum required V
increases as temperature
decreases. The bootstrap circuit reaches equilibrium
when the base charge drawn from C
during transistor
on time is equal to the charge replenished during the off
interval.
BST
C
SW
C
V
=
) must be at least 1.8V at
Figure 7. Typical Minimum Bootstrap Voltage Re-
quired to Maintain Saturation at I
SW
= 2A.
Minimum Bootstrap Voltage
vs Temperature
1.4
1.6
1.8
2.0
2.2
2.4
-50
-25
0
25
50
75
100
Temperature (°C)
V
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SC2440EVB | 2.5 MHz Dual Switching Regulator with Integrated 2A Switches |
| SC2440TETRT | 2.5 MHz Dual Switching Regulator with Integrated 2A Switches |
| SC2441A | 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441AEVB | 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441ATETRT | 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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 |
| SC2440STDEVB | 制造商:Semtech Corporation 功能描述:Evaluation Board For 2.5 MHz Dual Switching Regulator With Integrated 2A Switches |
| SC2440TE.TRTCUT | 制造商:Semtech Corporation 功能描述: |
| SC2440TETRT | 功能描述:IC REG BUCK 2A DL 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標準包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| SC2441 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。