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参数资料
| 型号： | LM2830ZQMFE |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, 3750 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封装： | SOT-23, 5 PIN |
| 文件页数： | 2/24页 |
| 文件大小： | 508K |
| 代理商： | LM2830ZQMFE |
Applications Information
THEORY OF OPERATION
The LM2830 is a constant frequency PWM buck regulator IC
that delivers a 1.0A load current. The regulator has a preset
switching frequency of 1.6MHz or 3.0MHz. This high frequen-
cy allows the LM2830 to operate with small surface mount
capacitors and inductors, resulting in a DC/DC converter that
requires a minimum amount of board space. The LM2830 is
internally compensated, so it is simple to use and requires few
external components. The LM2830 uses current-mode con-
trol to regulate the output voltage. The following operating
description of the LM2830 will refer to the Simplified Block
Diagram (Figure 1) and to the waveforms in Figure 2. The
LM2830 supplies a regulated output voltage by switching the
internal PMOS control switch at constant frequency and vari-
able duty cycle. A switching cycle begins at the falling edge
of the reset pulse generated by the internal oscillator. When
this pulse goes low, the output control logic turns on the in-
ternal PMOS control switch. During this on-time, the SW pin
voltage (V
SW) swings up to approximately VIN, and the induc-
tor current (I
L) increases with a linear slope. IL is measured
by the current sense amplifier, which generates an output
proportional to the switch current. The sense signal is
summed with the regulator’s corrective ramp and compared
to the error amplifier’s output, which is proportional to the dif-
ference between the feedback voltage and V
REF. When the
PWM comparator output goes high, the output switch turns
off until the next switching cycle begins. During the switch off-
time, inductor current discharges through the Schottky catch
diode, which forces the SW pin to swing below ground by the
forward voltage (V
D) of the Schottky catch diode. The regu-
lator loop adjusts the duty cycle (D) to maintain a constant
output voltage.
20197466
FIGURE 2. Typical Waveforms
SOFT-START
This function forces V
OUT to increase at a controlled rate dur-
ing start up. During soft-start, the error amplifier’s reference
voltage ramps from 0V to its nominal value of 0.6V in approx-
imately 600 s. This forces the regulator output to ramp up in
a controlled fashion, which helps reduce inrush current.
OUTPUT OVERVOLTAGE PROTECTION
The over-voltage comparator compares the FB pin voltage to
a voltage that is 15% higher than the internal reference
V
REF. Once the FB pin voltage goes 15% above the internal
reference, the internal PMOS control switch is turned off,
which allows the output voltage to decrease toward regula-
tion.
UNDERVOLTAGE LOCKOUT
Under-voltage lockout (UVLO) prevents the LM2830 from op-
erating until the input voltage exceeds 2.73V (typ). The UVLO
threshold has approximately 430 mV of hysteresis, so the part
will operate until V
IN drops below 2.3V (typ). Hysteresis pre-
vents the part from turning off during power up if V
IN is non-
monotonic.
CURRENT LIMIT
The LM2830 uses cycle-by-cycle current limiting to protect
the output switch. During each switching cycle, a current limit
comparator detects if the output switch current exceeds 1.75A
(typ), and turns off the switch until the next switching cycle
begins.
THERMAL SHUTDOWN
Thermal shutdown limits total power dissipation by turning off
the output switch when the IC junction temperature exceeds
165°C. After thermal shutdown occurs, the output switch
doesn’t turn on until the junction temperature drops to ap-
proximately 150°C.
www.national.com
10
LM2830
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2830ZQMFE/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM2830ZQMFX/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM2830ZSD | 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 |
| LM2830ZSD/NOPB | 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 |
| LM2830ZSDX | 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 |
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