参数资料
型号: L5988D
厂商: STMICROELECTRONICS
元件分类: 稳压器
英文描述: 5.6 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16
封装: LEAD FREE, HTSSOP-16
文件页数: 7/52页
文件大小: 1858K
代理商: L5988D
L5988D
Functional description
Doc ID 15324 Rev 3
15/52
5.2
Oscillator and synchronization
The generation of the internal saw-tooth waveform is based on the constant current charge /
discharge of an internal capacitor. The current generator is designed to get a switching
frequency of 400 kHz ± 10% in case the FSW pin is left floating.
The current mirror connected to FSW (see Figure 5.) pin acts increasing / decreasing the
value of the internal charging current to adjust the oscillator frequency. Since the internal
circuitry forces the FSW voltage bias at 1.235 V, the user can easily source / sink current in
this pin connecting a pull up resistor to VREF or a pull down to GND respectively.
Figure 5.
Oscillator circuit block diagram
The value of the pull up resistor versus VREF to decrease the oscillator frequency follows
the formula:
In the same way to increase the switching frequency the pull down resistor is selected using
the formula:
Table 10 shows some resistor values to adjust the oscillator frequency
Clock
Generator
Ramp
Generator
Sawtooth
Clock
Synchronization
SYNCH
VREF
Clock
Generator
Ramp
Generator
Sawtooth
Clock
Synchronization
SYNCH
VREF
R
1
()
8.5 10
3
400
F
SW KHz
()
---------------------------------------------
0.95
+
=
R
2
()
18 10
3
F
SW KHz
() 400
---------------------------------------------
2.1
=
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相关代理商/技术参数
参数描述
L5988DTR 功能描述:直流/直流开关调节器 4A Step Down Reg 2.9V to 18V 200ns 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
L5989D 功能描述:直流/直流开关调节器 4A cont 5A pulsed step-down sw 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
L5989DTR 功能描述:直流/直流开关调节器 4A cont 5A pulsed step-down sw 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
L5991 功能描述:电流型 PWM 控制器 Prog Current Mode RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14
L5991_01 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:PRIMARY CONTROLLER WITH STANDBY