关于同步降压转换器主要特性,框图,基本应用电路及其元件表

ST公司的l6983是静态电流仅为17 μA的 38 V 3 A同步降压转换器.输入电压VIN为3.5V到38V,输出电压为0.85V到VIM,具有固定输出3.3V和5V版本.3A DC输出电流,内部补偿网络. L6983是基于峰值电流模式架构,采用QFN16 3x3封装.可采用低消耗模式(LCM)和低噪音模式(LNM)版本.LCM模式在轻负载时可控制输出电压波纹,最大化效率. LNM模式开关频率固定,因此轻负载时最小化输出电压波纹.L6983的开关频率可在200 Hz - 2.2 MHz间选择,同时具有扩频技术以改善EMC.关断电流2 μA.器件具有热软起动,具有过压保护和热保护以及输出电压加序.设计用于24V总线工业电源系统,24V电池供电设备,分散智能节点,传感器和常开应用以及低噪音应用.本文介绍了L6983主要特性,框图,基本应用电路(可调整版本)及其元件表,以及评估板STEVAL-ISA208V1主要特性,电路图,材料清单和PCB设计图.

The L6983 is an easy to use synchronous monolithic step-down regulator capable of delivering up to 3 A DC to the load. The wide input voltage range makes the device suitable for a broad range of applications. The L6983 is based on a peak current mode architecture and is packaged in a QFN16 3x3 with internal compensation thus minimizing design complexity and size.

The L6983 is available both in low consumption mode (LCM) and low noise mode (LNM) versions. LCM maximizes the efficiency at light-load with controlled output voltage ripple so the device is suitable for battery-powered applications. LNM makes the switching frequency constant and minimizes the output voltage ripple for light load operations, meeting the specification for low noise sensitive applications. The L6983 allows the switching frequency to be selected in the 200 Hz - 2.2 MHz range
with optional spread spectrum for improved EMC.

The EN pin provides enable/disable function. The typical shutdown current is 2 μA when disabled. As soon as the EN pin is pulled up, the device is enabled and the internal 1.3 ms soft-start takes place. The L6983 features Power Good open collector that monitors the FB voltage. Pulse-by-pulse current sensing on both power elements implements an effective constant current protection and thermal shutdown prevents thermal run-away.

L6983主要特性:

• 3.5 V to 38 V operating input voltage
• Output voltage from 0.85 V to VIN
• 3.3 V and 5 V fixed output voltage versions
• 3 A DC output current
• 17 μA operating quiescent current
• Internal compensation network
• Two different versions: LCM for high efficiency at light loads and LNM for noise sensitive applications
• 2 μA shutdown current
• Internal soft-start
• Enable
• Overvoltage protection
• Output voltage sequencing
• Thermal protection
• 200 kHz to 2.2 MHz programmable switching frequency. Stable with low ESR capacitor
• Optional spread spectrum for improved EMC
• Power Good
• Synchronization to external clock for LNM devices
• QFN16 package

L6983应用:

• Designed for 24 V buses industrial power systems
• 24 V battery powered equipment
• Decentralized intelligent nodes
• Sensors and always-on applications
• Low noise applications

图1. L6983框图

图2. L6983基本应用电路(可调整版本)
图2应用电路的元件表:

评估板STEVAL-ISA208V1

38 V, 3 A synchronous step-down switching regulator evaluation board based on the L6983CQTR

The L6983 is an easy-to-use synchronous monolithic step-down regulator capable of delivering up to 3 ADC to the load. Its wide input voltage range makes the device suitable for a broad range of applications. The device implements peak current mode architecture in a QFN16 3x3 package with internal compensation to minimize design complexity and size.

The L6983 is available both in low consumption mode (LCM) and low noise mode (LNM) versions. LCM maximizes efficiency at light-load with controlled output voltage ripple, which is ideal for battery-powered applications. LNM makes the switching frequency constant and minimizes the output voltage ripple overload current range,meeting the specification for noise sensitive applications.

The L6983 allows switching frequency selection between 200 Hz and 2.2 MHz with optional spread spectrum for improved EMC. The EN pin provides enable/disable function. The typical shutdown current is 2 μA when disabled. When the EN pin is pulled up, the device is enabled and the internal 1.3 ms soft-start takes place. The device features power good open collector that monitors the FB voltage. Pulse-bypulse
current sensing on both power elements implements effective constant current protection and thermal shutdown prevents thermal runaway.

评估板STEVAL-ISA208V1主要特性:

• 3.5 V to 38 V operating input voltage
• Output voltage from 0.85 V to VIN
• 3.3 V and 5 V fixed output voltage versions
• 3 A DC output current
• 17 μA operating quiescent current
• Internal compensation network
• Two different versions:
– LCM for high efficiency at light loads
– LNM for noise sensitive applications
• 2 μA shutdown current
• Internal soft-start
• Enable
• Overvoltage protection
• Thermal protection
• Output voltage sequencing
• QFN16 package
• 200 kHz to 2.2 MHz programmable switching frequency; stable with low ESR capacitor
• Optional spread spectrum for improved EMC
• Power good
• Synchronization to external clock for LNM devices

图3. 评估板STEVAL-ISA208V1外形图

图4. 评估板STEVAL-ISA208V1电路图
评估板STEVAL-ISA208V1材料清单:

图5. 评估板STEVAL-ISA208V1 PCB设计图(顶层)

图6. 评估板STEVAL-ISA208V1 PCB设计图(底层)
编辑：lyn