NS 公司的LMZ14203H是3A SIMPLE SWITCHER電源模塊,最大輸入電壓42V,具有極好的電源轉換效率,線路和負載調以及輸出精度.輸入電壓6V-42V,輸出電壓低至5V,效率高達97%.主要用在包括工業系統、通信網絡基建設備及軍事設備等市場.本文介紹了LMZ14203H電指標,主要特性和優勢, 應用方框圖以及LMZ14203H/02H/01H評估板主要指標,詳細電路和材料清單.

LMZ14203H: 3A SIMPLE SWITCHER® Power Module with 42V Maximum Input 

The LMZ14203H 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 LMZ14203H is available in an innovative package that enhances thermal performance and allows for hand or machine soldering. 

The LMZ14203H can accept an input voltage rail between 6V and 42V and deliver an adjustable and highly accurate output voltage as low as 5V. The LMZ14203H only requires three external resistors and four external capacitors to complete the power solution. The LMZ14203H is a reliable and robust design with the following protection features: thermal shutdown, input under-voltage lockout, output over-voltage 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. 

LMZ14203H電指標:

■ Up to 3A output current

■ Input voltage range 6V to 42V

■ Output voltage as low as 5V

■ Efficiency up to 97%

LMZ14203H主要特性:

■ Integrated shielded inductor

■ Simple PCB layout

■ Flexible startup sequencing using external soft-start and precision enable

■ Protection against inrush currents

■ Input UVLO and output short circuit protection

■ –40℃ to 125℃ junction temperature range

■ Single exposed pad and standard pinout for easy mounting and manufacturing

■ Low output voltage ripple

■ Pin-to-pin compatible family:

LMZ14203H/2H/1H (42V max 3A, 2A, 1A)

LMZ14203/2/1 (42V max 3A, 2A, 1A)

LMZ12003/2/1 (20V max 3A, 2A, 1A)

Fully enabled for Webench Power Designer

LMZ14203H主要優勢: 

■ High efficiency reduces system heat generation

■ Low radiated EMI (EN 55022 Class B compliant)

■ No compensation required

■ Low package thermal resistance

LMZ14203H應用:

■ Intermediate bus conversions to 12V and 24V rail

■ Time critical projects

■ Space constrained / high thermal requirement applications

■ Negative output voltage applications

圖1.LMZ14203H應用方框圖

圖2.LMZ14203H連接框圖Connection Diagram

LMZ14203H/02H/01H評估板

LMZ14203H/02H/01H Evaluation Board

The LMZ14203H/02H/01H SIMPLE SWITCHER power modules for high output voltage are easy-to-use DC-DC solutions capable of driving up to a 3A load with exceptional power conversion efficiency, output voltage accuracy, line and load regulation. They are available in an innovative package that enhances thermal performance and allows for hand or machine soldering.

The LMZ14203H/02H/01H Evaluation Board is configured for 12V output voltage from 15V to 42V input. The precision enable input allows for programmable UVLO of the input supply.

The resistor voltage divider RENT and RENB set the input UVLO threshold. Connect the VIN turret terminal to the EN turret on the board to enable operation.

The external soft-start capacitor CSS facilitates controlled startup output rise time. The resistors RFBT and RFBB set the output voltage. An output feed-forward capacitor CFF across the upper feedback resistor trims for optimum transient response.

The control loop operates well with low ESR output capacitors such as ceramic and polymer electrolytic capacitors.

The resistor RON sets the operating frequency.The LMZ14203H/02H/01H PCB layout offers excellent thermal performance, achieving junction-to-ambient thermal resistance θJA of 14.9℃/W. The evaluation board with its default Bill of Materials offers great EMI performance, complying with the EN 55022 Class B radiated emissions standard.

The solution also complies with the CISPR22 conducted emissions standard with the addition of a small input filter

LMZ14203H/02H/01H評估板指標:

• VIN = 15V to 42V

• VOUT = 12V

• 3A max load at 24VIN and 65℃ TAMB

• Low radiated EMI (EN 55022 Class B compliant)

• 400kHz switching frequency

• Enable UVLO set at 13.5V

• θJA = 14.9℃/W

• 4 copper layers

• 2 oz copper on top and bottom layer

• 1 oz copper on internal layers

• 6.985 cm x 7.620 cm (2.75 in x 3 in) with 1.575 cm (.062 in) thickness of FR4 laminate material

圖3.LMZ14203H/02H/01H評估板電路圖

LMZ1420xH評估板材料清單: VIN = 15V to 42V, VOUT = 12V, IOUT (MAX) = 3A/2A/1A


圖4.LMZ14203H/02H/01H評估板詳細電路圖:DNS=元件沒安裝

圖5.EMI LC濾波器連接圖
詳情請見:
http://www.national.com/ds/LM/LMZ14203H.pdf
和
http://www.national.com/an/AN/AN-2089.pdf