参数资料
| 型号： | SC4524SETRT |
| 厂商： | Semtech |
| 文件页数： | 10/21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
shows that the minimum on time is about 105ns at room
temperature (Figure 5). The power switch in the SC4524
is either not turned on at all or for at least T ON(MIN) . If the
' =
+
+ -
= .
) is shorter than the minimum
required switch on time (=
= .+] .
converter is therefore
' =
=
D , =
=
= .+] .
the maximum operating frequency is
'
I
on time, the regulator will either skip cycles or it will jitter.
Example: Determine the maximum operating frequency
of a 24V to 1.2V switching regulator using the SC4524.
Assuming that V D = 0.45V, V CESAT = 0.25V and V IN = 26.4V
(10% high line), the duty ratio can be calculated using
(2).
+
+ -
To allow for transient headroom, the minimum operating
switch on time should be at least 30% higher than the
worst-case minimum on time exhibited in Figure 5.
Designing for a switch on time of 150ns at 9 = 9 ,
'
QV
Minimum Off Time Limitation
The PWM latch in Figure 2 is reset every period by the
clock. The clock also turns off the power transistor to
refresh the bootstrap capacitor. This minimum off time
limits the attainable duty cycle of the regulator at a given
switching frequency. The measured minimum off time is
120ns. For a step-down converter, D increases with
The maximum operating channel frequency of the
- '
QV
Transient headroom requires that channel frequency be
lower than 410kHz.
Inductor Selection
The inductor ripple current D I L for a non-synchronous
step-down converter in continuous-conduction mode is
9 + 9 - ' 9 + 9 9 - 9 - 9
I/ 9 + 9 - 9 I/
(3)
where f is the switching frequency and L is the
inductance.
In current-mode control, the slope of the modulating
(sensed switch current) ramp should be steep enough
to lessen jittery tendency but not so steep that large
flux swing decreases efficiency. Inductor ripple current
D I L between 25-40% of the peak inductor current limit is
a good compromise. Inductors so chosen are optimized
in size and DCR. Setting D , = = $ ,
9 = 9 and 9 = 9 in (3),
increasing
9
9
ratio. If the required duty cycle is higher
/ =
9
+ 9 - 9 -
9 + I
(4)
than the attainable maximum, then the output voltage
will not be able to reach its set value in continuous-
where L is in m H and f is in MHz.
conduction mode.
Equation (3) shows that for a given 9
D , increases
Example : Determine the maximum operating frequency
of a 5V to 4V switching regulator using the SC4524.
Assuming that V D = 0.45V, V CESAT = 0.25V and V IN = 4.5V
(10% low line), the duty ratio can be calculated using (2).
as D decreases. If 9 varies over a wide range, then
choose L based on the nominal input voltage. Always
verify converter operation at the input voltage extremes.
The peak current limits of both SC4524 power transistors
are internally set at 3.2A. The peak current limits are
? 2006 Semtech Corp.
10
www.semtech.com
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相关代理商/技术参数 |
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| 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 |
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