参数资料
| 型号： | SC4524SETRT |
| 厂商： | Semtech |
| 文件页数： | 16/21页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 2A 8SOIC |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出数： | 1 |
| 输入电压： | 2.8 V ~ 30 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 1.4MHz |
| 电流 - 输出： | 2A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 标准包装 |
| 供应商设备封装： | 8-SOIC-EP |
| 产品目录页面： | 1358 (CN2011-ZH PDF) |
| 其它名称： | SC4524SEDKR |
SC4524
POWER MANAGEMENT
Applications Information
Y
Y
w
? -
= -
9
&
5
&
ü ?
= ì ì
( )
5 + 5 ü Y D + V 5 ?? 5 &
Y
Y * 5 ( + V& 5 )
?
( + V& 5 ) ? ( + V& 5
)
Y
longer blanked. If V FB is still below 0.7V, then the regulator
will undergo shutdown and restart. The soft-start process
should allow the output voltage to reach 70% of its final
value before C SS is charged above 2V. Figures 9(a) and
9(b) show the timing diagrams of successful and failed
start-up waveforms respectively. The soft-start interval
should also be made sufficiently long so that the output
voltage rises monotonically and it does not overshoot
its final voltage by more than 5%.
During normal soft-start, both the COMP voltage and the
switch current limit gradually increase until the converter
becomes regulated. If the regulator output is shorted to
ground, then the COMP voltage will continue to rise to
its 2.4V upper limit. The SC4524 will reach its cycle-by-
cycle current limit sometime during the soft-start charging
phase. As described previously, the switches in the
SC4524 either do not turn on at all or for at least 105ns.
With the output shorted, the error amplifier will command
the regulator to operate at full duty cycle. The current
limit comparator will turn off the switch if the switch
current exceeds 3.2A. However, this happens only after
the switch is turned on for 105ns. During switch off time,
the inductor current ramps down at a slow rate
determined by the forward voltage of the freewheeling
diode and the resistance of the short. If the resulting
reverse volt-second is insufficient to reset the inductor
before the start of the next cycle, then the inductor
current will keep increasing until the diode forward
voltage becomes high enough to achieve volt-second
balance. This makes the current limit comparator
ineffective. Setting the switching frequency below
500kHz at high V IN (> 20V) will make the off time
sufficiently long to keep the inductor current within
bounds under short circuit condition.Shortening the soft-
start interval from the onset of switching to hiccup enable
also makes short circuit operation more robust. A 22-
47nF soft-start capacitor is found adequate for most
applications.
Loop Compensation
proportional to its controlling input V COMP . Its
transconductance G MP is 8 W -1 . With the current loop
closed, the control-to-output transfer function has
a dominant-pole p 2 located at a frequency slightly higher
than that of the output filter pole.
Q, Q
(8)
where C 1 is the output capacitor, R OUT is the equivalent
load resistance and n (depending on duty ratio, slope
compensation, frequency and passive components) is
usually between 1 and 2.
If C 1 is ceramic, then its ESR zero can be neglected as it
situates well beyond half the switching frequency. The
low frequency gain of the control-to-output transfer
function is simply the product of power stage
transconductance and the equivalent load resistance
(Figure 11).
The transfer functions of the feedback network and the
error amplifier are:
Y ? 5 ? ? + V& 5 T
? (9)
í à
and
(10)
provided that & >> & and 5 >> 5 .
In Equation (10), C 5 forms a low frequency pole p 1 with
the output resistance R O of the error amplifier and C 6
forms a high frequency pole p 3 with R 5 :
5 =
w
= -
Figure 10 shows a simplified equivalent circuit of a step-
down converter. The power stage, which consists of the
current-mode PWM comparator, the power switch, the
freewheeling diode and the inductor, feeds the output
network. The power stage can be modeled as a voltage-
controlled current source, producing an output current
$PSOLILHU 2SHQ /RRS *DLQ
7UDQVFRQGX F WDQ FH
5 &
=
G%
m W
= 0 W
? 2006 Semtech Corp.
16
www.semtech.com
相关PDF资料 |
PDF描述 |
|---|---|
| SC4525ASETRT | IC REG BUCK 3A 8SOIC |
| SC4525CSETRT | IC REG BUCK ADJ 3A 8SOIC |
| SC4525DSETRT | IC REG BUCK ADJ 3A 8SOIC |
| SC458IMLTRT | IC REG CTRLR PWM 44-MLP |
| SC4620MLTRT | IC REG BUCK ADJ 2.5A 20MLPQ |
相关代理商/技术参数 |
参数描述 |
|---|---|
| SC4525A | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:28V 3A Step-Down Switching Regulator |
| SC4525AEVB | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:28V 3A Step-Down Switching Regulator |
| SC4525ASETRT | 功能描述:IC REG BUCK 3A 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:20 系列:SIMPLE SWITCHER® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:12V 输入电压:4 V ~ 60 V PWM 型:电压模式 频率 - 开关:52kHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 包装:管件 供应商设备封装:16-DIP 其它名称:*LM2575HVN-12LM2575HVN-12 |
| SC4525C | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:28V 3A Step-Down Switching Regulator Thermal Shutdown |
| SC4525CSETRT | 功能描述:IC REG BUCK ADJ 3A 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
发布紧急采购，3分钟左右您将得到回复。