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参数资料
| 型号： | L5973ADTR |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 稳压器 |
| 英文描述： | 2.3 A SWITCHING REGULATOR, PDSO8 |
| 封装： | EXPOSED PAD, HSOP-8 |
| 文件页数： | 22/22页 |
| 文件大小： | 486K |
| 代理商： | L5973ADTR |
L5973AD
Functional description
Doc ID 9552 Rev 9
9/22
In particular, connecting together two devices, the one with the lower switching frequency
works as Slave and the other one works as Master.
To synchronize the device, the SYNC pin has to pass from a low level to a level higher than
the synchronization threshold with a duty cycle that can vary approximately from 10% to
90%, depending also on the signal frequency and amplitude.
The frequency of the synchronization signal must be at least higher than the internal
switching frequency of the device (500 kHz).
Figure 5.
Oscillator circuit
4.4
Current protection
The L5973AD has two current limit protections, pulse by pulse and frequency fold back.
The schematic of the current limitation circuitry for the pulse by pulse protection is shown in
The output power PDMOS transistor is split in two parallel PDMOS. The smallest one has a
resistor in series, RSENSE. The current is sensed through Rsense and if reaches the
threshold, the mirror is unbalanced and the PDMOS is switched off until the next falling edge
of the internal clock pulse.
Due to this reduction of the ON time, the output voltage decreases.
Since the minimum switch ON time (necessary to avoid false overcurrent signal) is not
enough to obtain a sufficiently low duty cycle at 500 kHz, the output current, in strong
overcurrent or short circuit conditions, could increase again. For this reason the switching
frequency is also reduced, so keeping the inductor current under its maximum threshold.
The Frequency Shifter (see Figure 5) depends on the feedback voltage. As the feedback
voltage decreases (due to the reduced duty cycle), the switching frequency decreases too.
FREQUENCY
SHIFTER
CLOCK
GENERATOR
RAMP
GENERATOR
SYNCHRONIZATOR
CLOCK
RAMP
Ibias_osc
SYNC
t
D00IN1131
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| L5973D | 功能描述:开关变换器、稳压器与控制器 1.235 to 35V Step-Dn RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| L5973D_08 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:2.5 A switch step down switching regulator?癎 |
| L5973D013TR | 功能描述:直流/直流开关调节器 2.5 A Step-DN Switching 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 |
| L5974AD | 功能描述:直流/直流开关调节器 2A SD switch reg BCD5 220nF 5V 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 |
| L5974ADTR | 功能描述:直流/直流开关调节器 2A SD switch reg BCD5 220nF 5V 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 |
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