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参数资料
| 型号： | LM5045MHX |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, 540 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封装： | ETSSOP-28 |
| 文件页数： | 18/28页 |
| 文件大小： | 610K |
| 代理商： | LM5045MHX |
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HICCUP MODE CURRENT LIMIT RESTART
The operation of the hiccup mode restart circuit is explained
in the Functional Description section. During a continuous
current limit condition, the RES pin is charged with 30A cur-
rent source. The restart delay time required to reach the 1.0V
threshold is given by:
This establishes the time allowed before the IC initiates a hic-
cup restart sequence. For example, if the C
RES=0.01F, the
time TCS as noted in Figure 20 below is 334s. Once the RES
pin reaches 1.0V, the 30A current source is turned-off and
a 10A current source is turned-on during the ramp up to 4V
and a 5A is turned on during the ramp down to 2V. The hic-
cup mode off-time is given by:
With a C
RES=0.01F, the hiccup time is 49ms. Once the hic-
cup time is finished, the RES pin is pulled-low and the SS pin
is released allowing a soft-start sequence to commence.
Once the SS pin reaches 1V, the PWM pulses will commence.
The hiccup mode provides a cool-down period for the power
converter in the event of a sustained overload condition there-
by lowering the average input current and temperature of the
power components during such an event.
PRINTED CIRCUIT BOARD LAYOUT
The LM5045 current sense and PWM comparators are very
fast and respond to short duration noise pulses. The compo-
nents at the CS, COMP, SLOPE, RAMP, SS, SSSR, RES,
UVLO, OVP, RD1, RD2, and RT pins should be physically
close as possible to the IC, thereby minimizing noise pickup
on the PC board trace inductance. Eliminating or minimizing
via’s in these critical connections are essential. Layout con-
sideration is critical for the current sense filter. If a current
sense transformer is used, both leads of the transformer sec-
ondary should be routed to the sense filter components and
to the IC pins. The ground side of the transformer should be
connected via a dedicated PC board trace to the AGND pin,
rather than through the ground plane. If the current sense cir-
cuit employs a sense resistor in the drive transistor source,
low inductance resistors should be used. In this case, all the
noise sensitive, low-current ground trace should be connect-
ed in common near the IC, and then a single connection made
to the power ground (sense resistor ground point).
The gate drive outputs of the LM5045 should have short, di-
rect paths to the power MOSFETs in order to minimize in-
ductance in the PC board. The boot-strap capacitors required
for the high side gate drivers should be located very close to
the IC and connected directly to the BST and HS pins. The
VCC and REF capacitors should also be placed close to their
respective pins with short trace inductance. Low ESR and
ESL ceramic capacitors are recommended for the boot-strap,
VCC and the REF capacitors. The two ground pins (AGND,
PGND) must be connected together directly underneath the
IC with a short, direct connection, to avoid jitter due to relative
ground bounce.
Application Circuit Example
The following schematic shows an example of a 100W full-
bridge converter controlled by LM5045. The operating input
voltage range is 36V to 75V, and the output voltage is 3.3V.
The output current capability is 30 Amps. The converter is
configured for current mode control with external slope com-
pensation. An auxiliary winding is used to raise the VCC
voltage to reduce the controller power dissipation.
30145416
FIGURE 20. Hiccup Mode Delay and Soft-Start Timing Diagram
25
www.national.com
LM5045
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM5045MHX/NOPB | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| LM5045SQ | 制造商:TI 制造商全称:Texas Instruments 功能描述:Full-Bridge PWM Controller with Integrated MOSFET Drivers |
| LM5045SQ/NOPB | 功能描述:电流型 PWM 控制器 Full-Bridge PWM Cntrlr RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| LM5045SQX | 制造商:TI 制造商全称:Texas Instruments 功能描述:Full-Bridge PWM Controller with Integrated MOSFET Drivers |
| LM5045SQX/NOPB | 功能描述:IC PWM CTRLR FULL BRIDG 28LLP RoHS:是 类别:集成电路 (IC) >> PMIC - AC-DC 转换器，离线开关 系列:PowerWise® 标准包装:1 系列:FPS™ 输出隔离:隔离 频率范围:61kHz ~ 73kHz 输入电压:8 V ~ 26 V 输出电压:650V 功率（瓦特）:12W 工作温度:-40°C ~ 115°C 封装/外壳:8-DIP（0.300"，7.62mm） 供应商设备封装:8-MDIP 包装:Digi-Reel® 其它名称:FSL206MRBNFSDKR |
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