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參數(shù)資料
| 型號(hào)： | LMZ14203EXTTZX/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PSSO7 |
| 封裝： | 10.16 X 13.77 MM, 4.57 MM HEIGHT, ROHS COMPLIANT, TO-PMOD, 7 PIN |
| 文件頁數(shù)： | 2/19頁 |
| 文件大?。?/td> | 4031K |
| 代理商： | LMZ14203EXTTZX/NOPB |
Application Block Diagram
30117808
General Description
The LMZ14203EXT SIMPLE SWITCHER power module is an
easy-to-use step-down DC-DC solution capable of driving up
to 3A load with exceptional power conversion efficiency, line
and
load
regulation,
and
output
accuracy.
The
LMZ14203EXT is available in an innovative package that en-
hances thermal performance and allows for hand or machine
soldering.
The LMZ14203EXT can accept an input voltage rail between
6V and 42V and deliver an adjustable and highly accurate
output voltage as low as 0.8V. The LMZ14203EXT only re-
quires three external resistors and four external capacitors to
complete the power solution. The LMZ14203EXT is a reliable
and robust design with the following protection features: ther-
mal shutdown, input under-voltage lockout, output over-volt-
age protection, short-circuit protection, output current limit,
and allows startup into a pre-biased output. A single resistor
adjusts the switching frequency up to 1 MHz.
COT Control Circuit Overview
Constant On Time control is based on a comparator and an
on-time one shot, with the output voltage feedback compared
with an internal 0.8V reference. If the feedback voltage is be-
low the reference, the main MOSFET is turned on for a fixed
on-time determined by a programming resistor R
ON. RON is
connected to V
IN such that on-time is reduced with increasing
input supply voltage. Following this on-time, the main MOS-
FET remains off for a minimum of 260 ns. If the voltage on the
feedback pin falls below the reference level again the on-time
cycle is repeated. Regulation is achieved in this manner.
Design Steps for the LMZ14203EXT
Application
The LMZ14203EXT is fully supported by Webench and of-
fers the following: Component selection, electrical and ther-
mal simulations as well as the build-it board for a reduction in
design time. The following list of steps can be used to manu-
ally design the LMZ14203EXT application.
Select minimum operating V
IN with enable divider resistors
Program V
O with divider resistor selection
Program turn-on time with soft-start capacitor selection
Select C
O
Select C
IN
Set operating frequency with R
ON
Determine module dissipation
Layout PCB for required thermal performance
ENABLE DIVIDER, R
ENT AND RENB SELECTION
The enable input provides a precise 1.18V band-gap rising
threshold to allow direct logic drive or connection to a voltage
divider from a higher enable voltage such as V
IN. The enable
input also incorporates 90 mV (typ) of hysteresis resulting in
a falling threshold of 1.09V. The maximum recommended
voltage into the EN pin is 6.5V. For applications where the
midpoint of the enable divider exceeds 6.5V, a small zener
can be added to limit this voltage.
The function of this resistive divider is to allow the designer to
choose an input voltage below which the circuit will be dis-
abled. This implements the feature of programmable under
voltage lockout. This is often used in battery powered systems
to prevent deep discharge of the system battery. It is also
useful in system designs for sequencing of output rails or to
prevent early turn-on of the supply as the main input voltage
rail rises at power-up. Applying the enable divider to the main
input rail is often done in the case of higher input voltage sys-
tems such as 24V AC/DC systems where a lower boundary
of operation should be established. In the case of sequencing
supplies, the divider is connected to a rail that becomes active
earlier in the power-up cycle than the LMZ14203EXT output
rail. The two resistors should be chosen based on the follow-
ing ratio:
R
ENT / RENB = (VIN UVLO/ 1.18V) – 1 (1)
The LMZ14203EXT demonstration and evaluation boards
use 11.8k
for R
ENB and 68.1k for RENT resulting in a rising
UVLO of 8V. This divider presents 6.25V to the EN input when
the divider input is raised to 42V.
www.national.com
10
LMZ14203EXT
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMZ14203H | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Evaluation Board modules for high output voltage are easy-to-use DC-DC |
| LMZ14203H_1106 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:3A SIMPLE SWITCHER? Power Module for High Output Voltage |
| LMZ14203HEVAL/NOPB | 功能描述:電源管理IC開發(fā)工具 LMZ14203H EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LMZ14203HTZ | 制造商:Texas Instruments 功能描述:POWER MODULE, 42V, 3A, 7TOPMOD 制造商:Texas Instruments 功能描述:POWER MODULE, 42V, 3A, 7TOPMOD; Primary Input Voltage:42V; No. of Outputs:1; Output Voltage:30V; Output Current:3A; Voltage Regulator Case Style:TO-PMOD; No. of Pins:7; Operating Temperature Min:-40C; Operating Temperature ;RoHS Compliant: Yes |
| LMZ14203HTZ/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 42V,3A PWR MODULE RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
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