参数资料
型号: LM22674MRX-ADJ/NOPB
厂商: National Semiconductor
文件页数: 6/22页
文件大小: 0K
描述: IC REG BUCK ADJ 0.5A 8PSOP
产品培训模块: SIMPLE SWITCHER® Regulators
LM315x & LM2267x SIMPLE SWITCHER® and WEBENCH
标准包装: 2,500
系列: SIMPLE SWITCHER®
类型: 降压(降压)
输出类型: 可调式
输出数: 1
输出电压: 可调至 1.285V
输入电压: 4.5 V ~ 42 V
PWM 型: 电压模式
频率 - 开关: 500kHz
电流 - 输出: 500mA
同步整流器:
工作温度: -40°C ~ 125°C
安装类型: 表面贴装
封装/外壳: 8-SOIC(0.154",3.90mm Width)裸露焊盘
包装: 带卷 (TR)
供应商设备封装: 8-PSOP-EP
配用: 551600236-001-ND - WEBENCH BUILD IT LM2267X 8-PSOP
其它名称: LM22674MRX-ADJ
LM22674MRX-ADJ-ND
LM22674MRX-ADJ/NOPBTR

SNVS590L – SEPTEMBER 2008 – REVISED APRIL 2013
SIMPLIFIED BLOCK DIAGRAM
VIN
VIN
V cc
BOOT
EN
INT REG, EN,UVLO
PWM Cmp.
ILimit
-
FB
TYPE III
+ COMP
Error Amp.
+
-
LOGIC
VOUT
OSC
SW
1.285V
&
Soft-start
GND
Figure 11. Simplified Block Diagram
Detailed Operating Description
The LM22674 incorporates a voltage mode constant frequency PWM architecture. In addition, input voltage feed-
forward is used to stabilize the loop gain against variations in input voltage. This allows the loop compensation to
be optimized for transient performance. The power MOSFET, in conjunction with the diode, produce a
rectangular waveform at the switch pin, that swings from about zero volts to VIN. The inductor and output
capacitor average this waveform to become the regulator output voltage. By adjusting the duty cycle of this
waveform, the output voltage can be controlled. The error amplifier compares the output voltage with the internal
reference and adjusts the duty cycle to regulate the output at the desired value.
The internal loop compensation of the -ADJ option is optimized for outputs of 5V and below. If an output voltage
of 5V or greater is required, the -5.0 option can be used with an external voltage divider. The minimum output
voltage is equal to the reference voltage; 1.285V (typ.).
The functional block diagram of the LM22674 is shown in Figure 11 .
Precision Enable and UVLO
The precision enable input (EN) is used to control the regulator. The precision feature allows simple sequencing
of multiple power supplies with a resistor divider from another supply. Connecting this pin to ground or to a
voltage less than 1.6V (typ.) will turn off the regulator. The current drain from the input supply, in this state, is 25
μA (typ.) at an input voltage of 12V. The EN input has an internal pull-up of about 6 μA. Therefore this pin can be
left floating or pulled to a voltage greater than 2.2V (typ.) to turn the regulator on. The hysteresis on this input is
about 0.6V (typ.) above the 1.6V (typ.) threshold. When driving the enable input, the voltage must never exceed
the 6V absolute maximum specification for this pin.
6
Product Folder Links: LM22674
Copyright ? 2008–2013, Texas Instruments Incorporated
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LM22674QMR-5.0/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
LM22674QMR-ADJ/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
LM22674QMRE-5.0/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
LM22674QMRE-ADJ/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
LM22674QMRX-5.0/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