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| 型号： | SC4626FSKTRT |
| 厂商： | Semtech |
| 文件页数： | 15/22页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC 1.3V 1A SOT23-5 |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 1.3V |
| 输入电压： | 2.9 V ~ 5.5 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 2.5MHz |
| 电流 - 输出： | 1A |
| 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： | SC-74A，SOT-753 |
| 包装： | 标准包装 |
| 供应商设备封装： | SOT-23-5 |
| 其它名称： | SC4626FSKDKR |
SC4626
Applications Information
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Detailed Description
The SC4626 is a synchronous step-down pulse width
modulated (PWM) voltage mode DC-DC regulator
operating at 2.5MHz fixed-frequency. The switching
frequency is chosen to minimize the size of the external
inductor and capacitors while maintaining high
efficiency.
Operation
During normal operation, the internal high-
side PMOS device is activated on each ris-
ing edge of the internal oscillator. The voltage
feedback loop uses an internal feedback resistor divider.
The period is set by the on board oscillator when in PWM
mode at average to high loads. The device has an internal
low-side synchronous NMOS device and does not require a
Schottky diode on the LX pin. The device operates as a buck
converter in PWM mode with a fixed frequency of 2.5MHz.
Output Voltage Selection
The SC4626 is designed for fixed output voltage. There
are some options for preset output voltage shown in
Table 1. If the voltage desired is not shown in the Table
1, it can be programmed via an external resistor di-
vider. There will be typical 1uA current flowing into the
VOUT pin. The typical schematic of adjustable output
voltage option from the part with standard 1.0V, the
SC4626A, is shown in Figure 1. The C FF is needed for
maintain the performance of the transient response. The
proper value of C FF can be calculated by the equation
adjusted to meet the equation shown above.
Protection Features
The SC4626 provides the following protection features:
Thermal Shutdown
Current Limit
Over-Voltage Protection
Soft-Start Operation
Thermal Shutdown
The device has a thermal shutdown feature to protect
the SC4626 if the junction temperature exceeds 160°C.
During thermal shutdown, the on-chip power devices
are disabled with the LX output floating. When the die
temperature drops by 10°C, the part will initiate a soft
start recovery to normal operation.
Current Limit
The internal PMOS power device in the switching stage is
protected by current limit feature. If the output is loaded
above the PMOS current limit for 32 consecutive cycles,
the SC4626 enters foldback current limit mode and the
output current is limited to the current limit holding
current (I CL_HOLD ) of a few hundred milliampere. Under
these conditions the output voltage will be the product
of I CL_HOLD and the load resistance. The current limit
holding current (I CL_HOLD ) will be decreased when output
voltage is increased. The load presented must fall below
the current limit holding current for the SC4626 to exit
foldback current limit mode. Figure 2 shows the typical
current limit holding current decreasing rate over differ-
a indefinite short circuit without damage and will resume
R FB 1 [ k ? ] ? ( V OUT ? V OSTD )
,where the V OSTD is the standard voltage shown in Table 1.
To simplify the design, it is recommended to program the
soft-start.
desired output voltage from standard 1.0V as shown in
Figure 1 with a proper C FF calculated from the equation
shown above. For programming the output voltage from
Schematic of Adjustable V OUT from SC4626A (Std V OUT =1.0V)
other standard voltage, the R FB1 , R FB2 and C FF need to be
( V OUT ? 0 . 5 ) 2 V OSTD ent output voltage. The SC4626 is capable of sustaining
C FF [ nF ] = 10 × × ( )
V OSTD ? 0 . 5
normal operation when the fault is removed. The fold-
back current limit mode will be disabled during the
Current Limit Holding Current over Vout
150
T A = 25°C
120
V IN = 5.0V
90
L
V IN
VIN
LX
V OUT
60
R EN
C IN
GND
R FB1
C FF
C OUT
30
V IN = 3.6V
Enable
EN
VOUT
SC4626A
R FB2
10k ?
R FB 1 = ( V OUT ? 1 ) × R FB 2
0
1.0
1.5
2.0
2.5
3.0
3.5
Output Voltage (V)
Figure 1 — Typical schematic for adjustable output
voltage option from standard 1.0V of SC4626A
Figure 2 — Current limit holding current decreasing
rate vs. output voltage
? 2009 Semtech =10k ? and C
Corp.
(2) R =10nF for standard design.
Note: (1) R EN is optional.
FB2 FF
15
www.semtech.com
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| SC4626HSK.TRT | 制造商:SEMTECH 功能描述:I.C. |
| SC4626HSKTRT | 功能描述:IC REG BUCK SYNC 1.5V 1A SOT23-5 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 |
| SC4626SK-1.8TRT | 制造商:Semtech Corporation 功能描述: |
| SC4626SK-3.3TRT | 制造商:Semtech Corporation 功能描述: |
| SC4626XEVB | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:2.5MHz, 1A Synchronous Step Down Regulator in SOT23-5 |
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