参数资料
| 型号： | SC4524SETRT |
| 厂商： | Semtech |
| 文件页数： | 12/21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
The switch base current =
?
, where I SW and b
Charge
is drawn from C BST during the switch on
time, resulting in a voltage droop of . If I SW = 2A,
at the end of conduction. This
9 - 9
+ 9
-
the input power supply will be (the base charge
output voltage to input voltage conversion ratios), it is
beneficial to use freewheeling diodes with somewhat
higher average 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 SC4524 to minimize ringing due to trace
inductance. 10BQ015, 20BQ030 (International Rectifier),
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 transistor should be minimized. If
the transistor is to be driven into saturation, then its
base 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 7). The
bootstrapped output (the common node between D BST
and C BST ) is connected to the BST pin of the SC4524.
The power transistor in the SC4524 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
during the off interval.
, ,
+
are the switch emitter current and current gain
respectively, is drawn from the bootstrap capacitor C BST .
, 7
, 7
&
T ON = 1 m s, b = 35 and C BST = 0.1 m F, then the 9 droop
will be 0.57V. C BST is refreshed to 9 - 9 + 9 every
cycle, where 9 is the applied D BST anode voltage. Switch
base current discharges the bootstrap capacitor to
, 7
b &
voltage must be higher than the minimum shown in Figure
6 to ensure full switch enhancement. D BST can be tied
either to the input or to the output of the DC/DC
converter.
If D BST is tied to the input, then the charge drawn from
, 7
b
of the switch). The energy loss due to base charge per
high. This brings the BST voltage to 9
+ 9
, thus back-
biasing D BST . C BST voltage increases with each subsequent
switching cycle, as does the bootstrapped voltage at the
BST 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 6 shows the typical
minimum BST to SW voltage required to fully saturate
the power transistor. This differential voltage ( = 9
)
must be at least 1.8V at room temperature. This is also
specified in the ?Electrical Characteristics? as ?Minimum
Bootstrap Voltage?. The minimum required V CBST increases
as temperature decreases. The bootstrap circuit reaches
equilibrium when the base charge drawn from C BST during
transistor on time is equal to the charge replenished
Figure 6. Typical Minimum Bootstrap Voltage Re-
quired to Maintain Saturation at I SW = 2A.
? 2006 Semtech Corp.
12
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。