参数资料
| 型号： | SC4524BSETRT |
| 厂商： | Semtech |
| 文件页数： | 10/18页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 2A 8SOIC |
| 产品培训模块： | Power Supplies 101 |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出数： | 1 |
| 输入电压： | 3 V ~ 18 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 300kHz ~ 1.3MHz |
| 电流 - 输出： | 2A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm Width）裸露焊盘 |
| 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： | SC4524BSEDKR |
SC4524B
R 4 = R 6 ?
? ?
V O + V D
( V O + V D ) ? ( ? D )
F SW ? L
This current V ramp D is ( absent unless the switch is turned
on. The intersection I ? O of F SW this ramp with the output of the
L =
ApplicationsInformation(Cont.)
As the load draws more current from the regulator, the
current-limit comparator ILIM (Figure 2) will eventually
limit the switch current on a cycle-by-cycle basis. The
over-current signal OC goes high, setting the latch B 3 . The
soft-start capacitor is discharged with (I D - I C ) (Figure 3). If
the inductor current falls below the current limit and the
PWM comparator instead turns off the switch, then latch
B 3 will be reset and I C will recharge the soft-start capacitor.
If over-current condition persists or OC becomes asserted
more often than PWM over a period of time, then the
soft-start capacitor will be discharged below .9V. At this
juncture, comparator B 4 sets the overload latch B 2 . The
soft-start capacitor will be continuously discharged with
? V O ?
? . ?
down switching 0 V regulator in continuous-conduction
mode (CCM) is given by
D = (2)
V IN + V D ? V CESAT
where V CESAT is the switch saturation voltage and V D is
voltage drop across the rectifying diode.
D I L =
In peak current-mode control, the PWM modulating
ramp is the sensed current ramp of the power switch.
20 % ?
voltage feedback error amplifier determines the switch
A C =
A C =
R 7 =
C 5 =
C 8 =
(I D - I C ). The COMP pin is immediately pulled to ground. The
switching regulator is shut off until the soft-start capacitor
is discharged below .0V. At this moment, the overload
latch is reset. The soft-start capacitor is recharged and
pulse width. The propagation delay time required to
CIN = I O D ( ? ? ? D ) I RMS _
immediately turn off the switch after it is turned on is the
minimum controllable switch on time (T ON(MIN) ).
V o
V c
=
Fig.4
minimum on D time ? ? ESR about 35ns at ? ? room temperature
D V O = I L ? ? is +
the converter again undergoes soft-start. The regulator
will go through soft-start, overload shutdown and restart
until it is no longer overloaded.
If the FB voltage falls below 0.8V because of output
Closed-loop measurement shows that the SC4524B
? F SW ? C ? ? O
(Figure 4). If the required 8 switch on ? time is shorter than
the minimum on time, the regulator will either skip cycles
or it will jitter.
G PWM
R 7 =
C IN >
overload, then the switching frequency will be reduced.
Frequency foldback helps to limit the inductor current
when the output is hard shorted to ground.
SS270 REV 6-7
I O
D V IN ? F SW
4 ? Minimum On Time vs Temperature
200
C 5 =
During normal operation, the soft-start capacitor is
charged to 2.4V.
Setting the Output Voltage
190
180
170
160
150
V O =1.5V
1MHz
C 8 =
R 4 = R 6 ? ?
? ? ?
V O
? . 0 V
?
Setting D the Switching Frequency
V O + V D
A C = ? 20 ? log ? ?
? FB ? ?
?
? G CA R S 2 π F C C O
V O ?
A C = ? 20 ? log ? ?
Temperature ( O C) . 0 ?
? ? ? = 5
? 28 ? 6 . ? 0
2 π ? 80 ? 0 ? 22 ? 0
3 . 3 ?
R 7 =
= 22 . 3 k
To allow 28 for ? 0
0 .
transient headroom, the minimum operating
The regulator output voltage is set with an external
resistive divider (Figure ) with its center tap tied to the
FB pin. For a given R 6 value, R 4 can be found by
( )
=
V IN + V D ? V CESAT
The switching frequency of the SC4524B is set with an
external resistor from the ROSC pin to ground.
140
130
?
120 V ?
110
100
-50 -25 0 25 50 75 100 125
? 3 3 ? 6
Figure 4. Variation of Minimum On Time
5 . 9 with Ambient Temperature
0 20
? 3
Minimum L I = On Time Consideration
( V O + V D ) ? ( ? D )
C 5 =
= 0 . 45 nF
the worst-case minimum on 3 time.
D
F SW ? L
switch on time should be at least 20% to 30% higher than
3
( V O + V D ) ? ( ? D )
20 % ? I O ? F SW
The operating duty cycle of a non-synchronous step-
L =
C 8 =
2 π ? 600 ? 0 3 ? 22 . ? 0 3
= 2 pF
0
相关PDF资料 |
PDF描述 |
|---|---|
| SC4524CSETRT | IC REG BUCK ADJ 2A 8SOIC |
| SC4524DSETRT | IC REG BUCK ADJ 2A 8SOIC |
| SC4524SETRT | IC REG BUCK 2A 8SOIC |
| SC4525ASETRT | IC REG BUCK 3A 8SOIC |
| SC4525CSETRT | IC REG BUCK ADJ 3A 8SOIC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| SC4524C | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:28V 2A Step-Down Switching Regulator Wide input range: 3V to 28V |
| SC4524CSETRT | 功能描述:IC REG BUCK ADJ 2A 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 |
| SC4524CSETRT-CUT TAPE | 制造商:SEMTECH 功能描述:SC4524 Series 28 V 2 A 2 MHz Step-Down Switching Regulator - SOIC-8 |
| SC4524D | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:18V 2A Step-Down Switching Regulator 2A Output Current |
| SC4524DSETRT | 功能描述:IC REG BUCK ADJ 2A 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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