- 您现在的位置：买卖IC网 > PDF目录1820 > LM3495MTCX/NOPB (National Semiconductor)IC REG BUCK SYNC ADJ 10A 16TSSOP PDF资料下载
参数资料
| 型号： | LM3495MTCX/NOPB |
| 厂商： | National Semiconductor |
| 文件页数： | 19/36页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 10A 16TSSOP |
| 标准包装： | 1 |
| 系列： | PowerWise® |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 5.5 V |
| 输入电压： | 2.9 V ~ 18 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 200kHz ~ 1.5MHz |
| 电流 - 输出： | 10A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm 宽） |
| 包装： | 标准包装 |
| 供应商设备封装： | 16-TSSOP |
| 产品目录页面： | 1300 (CN2011-ZH PDF) |
| 配用： | LM3495EVAL-ND - BOARD EVALUATION LM3495 |
| 其它名称： | LM3495MTCXDKR |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页当前第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页
SNVS410F – FEBRUARY 2006 – REVISED APRIL 2013
PARALLEL LOW-SIDE SCHOTTKY DIODE
Many synchronous buck regulators include a Schottky diode in parallel with the low-side power FET. The low
forward drop and short reverse recovery time of Schottky diodes can improve efficiency by preventing the FET's
body diode from turning on. This technique is most effective in circuits with output currents of 5A or less. The
parallel Schottky diode must be placed as close as possible to the power FET to prevent trace inductance from
negating the gains in efficiency.
ADAPTIVE DUTY CYCLE CLAMP
The adaptive duty cycle clamp is an extra layer of protection used during high current conditions or large load
transients. When a high-side pulse is skipped due to current limit, the output voltage tends to decrease rapidly.
The steady state control loop of the LM3495 responds by commanding a higher duty cycle at the next high-side
turn-on. The result is a combination of high voltage across the output inductor and long duty cycles that could
result in inductor saturation. The adaptive duty cycle clamp prevents inductor saturation by providing a dynamic
maximum duty cycle, D CLAMP . The clamp is based on the sensed input and output voltages. D CLAMP can be
predicted with the following equation:
D CLAMP = 3.2 x
V O
V IN
(8)
D CLAMP cannot exceed 100%
(9)
SHUTDOWN
The LM3495 can be put into a low power shutdown mode by bringing the voltage at the COMP/SD pin below
0.3V. A signal-level BJT or FET can be controlled by most CMOS or TTL logic signals to perform this function.
The collector-to-emitter or drain-to-source capacitance should be less than 20 pF to minimize the effect on the
control loop compensation. During shutdown, both the high-side and low-side FETs are disabled. The output
voltage is discharged through the SNS pin by an internal 500 ? FET.
THERMAL SHUTDOWN
The LM3495 will enter a thermal shutdown state if the die temperature exceeds 150°C. Both the high-side and
low-side power FETs are turned off, the output voltage is discharged through an internal 500 ? FET, and the IC
will remain in this condition until the die temperature has dropped to approximately 135°C. At this point the
LM3495 will perform a soft-start.
Design Considerations
The most common circuit controlled by the LM3495 is a non-isolated, synchronous buck regulator. The buck
regulator steps down the input voltage and has a duty cycle, D, of:
D=
V O
V IN
(10)
The following is a design procedure for selecting all the components in the Typical Application circuit on the front
page. This circuit delivers a 1.2V ± 1% output voltage at output currents up to 10A from an input voltage of 12V ±
10%. This circuit is typical of a point-of-load (POL) module. A BOM for this typical application is listed in Table 3
at the end of this datasheet.
SWITCHING FREQUENCY
The selection of switching frequency is based on the tradeoffs between size, cost, and efficiency. In general, a
lower frequency means larger, more expensive inductors and capacitors will be needed. A higher switching
frequency generally results in a smaller but less efficient solution, as the power FET gate capacitances must be
charged and discharged more often in a given amount of time. For this application, a frequency of 500 kHz was
selected because the space on a POL circuit board is limited. This frequency is a good compromise between the
size of the inductor and FETs, transient response, and efficiency. Following the equation given for R FRQ in the
Applications Information section, a 54.9 k ? 1% resistor should be used to switch at 500 kHz.
Copyright ? 2006–2013, Texas Instruments Incorporated
Product Folder Links: LM3495
19
相关PDF资料 |
PDF描述 |
|---|---|
| LM350T | IC REG LDO ADJ 3A TO220AB |
| LM350T | IC REG LDO ADJ 3A TO220-3 |
| LM3686TLE-AAED/NOPB | IC REG BUCK SYNC .9A TRPL 12USMD |
| LM399AH | IC VREF SHUNT PREC 6.95V TO-46-4 |
| LM4040A25IDBZT | IC VREF SHUNT PREC 2.5V SOT23-3 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM3497M/NOPB | 制造商:Texas Instruments 功能描述:IC LED DRIVER 制造商:Texas Instruments 功能描述:POWER REGULATOR/CONTROLLER IC |
| LM3497MM/NOPB | 功能描述:板上安装温度传感器 RoHS:否 制造商:Omron Electronics 输出类型:Digital 配置: 准确性:+/- 1.5 C, +/- 3 C 温度阈值: 数字输出 - 总线接口:2-Wire, I2C, SMBus 电源电压-最大:5.5 V 电源电压-最小:4.5 V 最大工作温度:+ 50 C 最小工作温度:0 C 关闭: 安装风格: 封装 / 箱体: 设备功能:Temperature and Humidity Sensor |
| LM3497MMX/NOPB | 功能描述:板上安装温度传感器 RoHS:否 制造商:Omron Electronics 输出类型:Digital 配置: 准确性:+/- 1.5 C, +/- 3 C 温度阈值: 数字输出 - 总线接口:2-Wire, I2C, SMBus 电源电压-最大:5.5 V 电源电压-最小:4.5 V 最大工作温度:+ 50 C 最小工作温度:0 C 关闭: 安装风格: 封装 / 箱体: 设备功能:Temperature and Humidity Sensor |
| LM3497MX/NOPB | 制造商:Texas Instruments 功能描述:IC LED DRIVER 制造商:Texas Instruments 功能描述:POWER REGULATOR/CONTROLLER IC |
| LM349J | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Voltage-Feedback Operational Amplifier |
发布紧急采购，3分钟左右您将得到回复。