参数资料
| 型号： | LA5774MP-DL-E |
| 厂商： | ON Semiconductor |
| 文件页数： | 4/5页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ SMP5 |
| 标准包装： | 1,000 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 可调至 1.26V |
| 输入电压： | 4.5 V ~ 28 V |
| 频率 - 开关： | 160kHz |
| 同步整流器： | 无 |
| 工作温度： | -30°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | TO-252-6，DPak（5 引线 + 接片） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | SMP5 |
LA5774MP
Description of Functional Settings
1. Calculation equation to set the output voltage
This IC controls the switching output so that the VOS pin voltage becomes 1.26V (typ).
The equation to set the output voltage is as follows:
VO = 1+
R2
R1
× 1.26V(typ)
The VOS pin has the inrush current of 1 μ A (typ). Therefore, the error becomes larger when R1 and R2 resistance
values are large.
2. Start delay function
The SS pin has the internally-connected 22 μ A (typ) constant-current supply. When the voltage of SS pin exceeds the
threshold voltage, the regulator starts operation. As the threshold voltage is 0.62V (typ), the start delay time can be
calculated as follows:
ex. For setting at 1 μ F
1 μ F × 0.62
22 μ A
Td =
C × V
i
= = 28.2 ms
3. Soft start function
The internal PWM waveform has the voltage value as shown in the right.
If down-conversion from the voltage of VIN = 15 V to VIN = 3.3V is to be
made, for example, the PWM-ON duty has the value as shown below.
1.5V
0.62V
PWM wave
PWMduty = V IN
VOUT
? Vsat + VF = 23 %
(Note that calculation is made with Vsat = 1V and VF = 0.2V)
The output voltage of error amplifier, which is 3.3 V, is the value with PWM = 23%, as calculated in the above
equation, so that this voltage is determined as follows:
Ver = ( Δ VPWM) × PWMduty + VPWML = 0.88V × 0.23 + 0.62V = 0.82V
( Δ VPWM is the PWM amplitude value or 0.88V(typ) while VPWML is the lower limit voltage of PWM
waveform or 0.62V(typ))
SS pin and error amplifier output voltages are designed to prefer the lower voltages, so that VOUT will reach the
designed regulation voltage in timing when the SS pin voltage exceeds the error amplifier output.
Therefore, the soft start time is calculated as follows:
Tss =
C × Δ VPWM × PWMduty
i
=
C × 0.88 × PWMduty
22 μ A
For the set conditions of C = 1 μ F and PWMduty = 23%:
Tss =
1 μ F × 0.88V × 0.23
22 μ A
= 9.2ms
No.A0490-4/5
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相关代理商/技术参数 |
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| LA5774MP-E | 功能描述:直流/直流开关调节器 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 |
| LA5777 | 制造商:SANYO 制造商全称:Sanyo Semicon Device 功能描述:Monolithic Linear IC Separately-excited Step-down Switching Regulator (5V) |
| LA5777MP | 制造商:SANYO 制造商全称:Sanyo Semicon Device 功能描述:Monolithic Linear IC Separately-excited Step-down Switching Regulator (5V) |
| LA5779 | 制造商:SANYO 制造商全称:Sanyo Semicon Device 功能描述:Monolithic Linear IC Separately-excited Step-down Switching Regulator (Variable Type) |
| LA5779-E | 功能描述:直流/直流开关调节器 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 |
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