参数资料
型号: L5986ATR
厂商: STMICROELECTRONICS
元件分类: 稳压器
英文描述: 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
封装: ROHS COMPLIANT, HSOP-8
文件页数: 2/38页
文件大小: 1067K
代理商: L5986ATR
Functional description
L5986
10/38
Doc ID 14971 Rev 3
5.2
Soft-start
The soft-start is essential to assure correct and safe start up of the step-down converter. It
avoids inrush current surge and makes the output voltage increases monothonically.
The soft-start is performed by a staircase ramp on the non-inverting input (VREF) of the error
amplifier. So the output voltage slew rate is:
Equation 1
where SRVREF is the slew rate of the non-inverting input, while R1 and R2 is the resistor
divider to regulate the output voltage (see Figure 7). The soft-start stair case consists of 64
steps of 9.5 mV each one, from 0 V to 0.6 V. The time base of one step is of 32 clock cycles.
So the soft-start time and then the output voltage slew rate depend on the switching
frequency.
Figure 7.
Soft-start scheme
Soft-start time results:
Equation 2
For example with a switching frequency of 250 kHz the SSTIME is 8 ms.
SR
OUT
SR
VREF
1
R1
R2
--------
+
=
SS
TIME
32 64
Fsw
-----------------
=
相关PDF资料
PDF描述
L5986TR 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5986 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5987ATR 4.4 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5991D 1.5 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16
L5991AD13TR 1.5 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16
相关代理商/技术参数
参数描述
L5986TR 功能描述:直流/直流开关调节器 2.5 A Step-down Switch Regulator RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
L5987 功能描述:直流/直流开关调节器 3 A buck switching regulator RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
L5987A 功能描述:直流/直流开关调节器 3 A STEP-DOWN SWITCH REG RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
L5987ATR 功能描述:直流/直流开关调节器 Step-down switch regulator, 3A RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
L5987TR 功能描述:直流/直流开关调节器 3 A Step-down Switch Regulator RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5