IR 公司的IRS29751/2是自振蕩半橋驅動器,其頻率和死區時間能用兩個外接元件編程,微功耗起動和超低靜態電流,典型應用為LCD和PDP TV,通信和PC開關電源,家庭音響系統.本文介紹了IRS2795(1,2)主要特性,方框圖,應用電路圖以及D類音頻放大器+/-30V 120W電源參考設計主要指標,主板和控制板電路圖,材料清單,PCB布局圖.
The IRS2795(1,2) is a self oscillating half-bridge driver IC for DC-DC resonant converter applications, especially the LLC resonant half-bridge converter. The frequency and dead time can be programmed externally using two external components. The IC offers over current protection using the on state resistance of the low-side MOSFET. The IC can be disabled by externally pulling the voltage at the CT/SD pin below its enable voltage threshold.
IRS2795(1,2)主要特性:
· Simple primary-side control solution for fixed and variable frequency DC-DC resonant converters.
· Max 500kHz per channel output with 50% duty cycle
· Floating channel bootstrap operation up to +600Vdc
· Programmable minimum and maximum switching frequency
· Programmable soft start frequency and soft start time
· Programmable dead time
· Micropower start-up & ultra low quiescent current
· Over-current protection using low side MOSFET Rds(on)
· User initiated micropower “Sleep mode”
· Under-voltage Lockout
· Simple design with minimal component count.
· Lead-free
IRS2795(1,2)典型應用:
· LCD & PDP TV
· Telecom SMPS, PC SMPS
· Home Audio Systems
圖1.IRS2795(1,2)方框圖
圖2.IRS2795(1,2)典型應用電路圖
D類音頻放大器+/-30V電源參考設計
The evaluation board consists of a front-end AC-DC rectifier stage cascaded with a half-bridge resonant DC/DC converter with +/-30V output voltage rails.
The front end is a conventional pi type EMI filter, followed by bridge rectifier stage. Two 200V/680uF bulk capacitors are connected in series to provide stable DC bus voltage. The rectifier can be configured as full bridge rectifier for 220Vac input, or voltage doubler rectifier for 110Vac input.
The downstream converter is a multi-resonant half bridge LLC converter whose control is implemented with the IRS27952 controller HVIC (U101 on the control board). The controller drives the two half-bridge MOSFETs with a 50 percent fixed duty cycle with pre-defined dead-time. Output voltage regulation is achieved by changing the switching frequency according to the feedback signal.
圖3.+/-30V電源參考設計外形圖
+/-30V電源參考設計技術指標:
圖4.+/-30V電源參考設計主板電路圖
圖5.+/-30V電源參考設計控制板電路圖
主板材料清單:
控制板材料清單:
圖6.諧振變壓器繞組電路圖
諧振變壓器繞組特征表:
圖7.主板布局圖(單層PCB)
圖8.控制板布局圖(雙層PCB) |
