| 简介 |
Intersil公司的ISL6228是两路同步降压PWM控制器，它采用Intersil的Robust Ripple Regulator (R3)技术，能对输入电压和输出负载的瞬态变化提供极好的动态响应。广泛应用于通用开关电源降压稳压器，PCI Express图像处理单元，辅助电源，VRM以及网络适配器。本文介绍了ISL6228的主要性能，方框图，典型应用电路图以及评估板 ISL6228EVAL3Z评估板的电路途遥远以及所用的材料清单（BOM）。
概述：
High-Performance Dual-Output Buck Controller for Notebook Applications
The ISL6228 IC is a dual channel synchronous-buck PWM controller featuring Intersils Robust Ripple Regulator (R3) technology that delivers truly superior dynamic response to input voltage and output load transients. Integrated MOSFET drivers and bootstrap diodes result in fewer components and smaller implementation area.
Intersil’s R3 technology combines the best features of fixedfrequency and hysteretic PWMs while eliminating many of their shortcomings. R3 technology employs an innovative modulator that synthesizes an AC ripple voltage signal VR, analogous to the output inductor ripple current. The AC signal VR enters a window comparator where the lower threshold is the error amplifier output VCOMP, and the upper threshold is a programmable voltage reference VW, resulting in generation of the PWM signal. The voltage reference VW sets the steady-state PWM frequency. Both edges of the PWM can be
modulated in response to input voltage transients and output load transients, much faster than conventional fixedfrequency PWM controllers. Unlike a conventional hysteretic converter, each channel of the ISL6228 has an error amplifier that provides ±1% voltage regulation at the FB pin.
The ISL6228 has a 1.5ms digital soft-start and can be started into a pre-biased output voltage. A resistor divider is used to program the output voltage setpoint. The ISL6228 operates in continuous-conduction-mode (CCM) in heavy load, and in diode-emulation-mode (DEM) in light load to
improve light-load efficiency. In CCM, the controller always operates as a synchronous rectifier. In DEM, the low-side MOSFET is permitted to stay off, blocking negative current flow into the low-side MOSFET from the output inductor.
ISL6228
主要特性：
High performance R3 technology
Fast transient response
±1% regulation accuracy: -10°C to +100°C
Individual power stage input rail for each channel
Wide input voltage range: +3.3V to +25V
Output voltage range: +0.6V to +5V
Diode emulation mode for increased light load efficiency
Programmable PWM frequency: 200kHz to 600kHz
Pre-biased output start-up capability
Integrated MOSFET drivers and bootstrap diode
Internal digital soft-start
Power good monitor
Fault protection
- Undervoltage protection
- Soft crowbar overvoltage protection
- Inductor DCR overcurrent protection
- Over-temperature protection
- Fault identification by PGOOD pull-down resistance
Pb-free available (RoHS compliant)
应用：
General purpose switching buck regulators
PCI express graphical processing unit
Auxiliary power rail
VRM
Network adapter
图1。ISL6228方框图。
图2。ISL6228应用电路图。
详情请见ISL6228数据表：
http://www.intersil.com/data/fn/fn9095.pdf
下面是评估板 ISL6228EVAL3Z评估板的性能和电路图介绍。
The ISL6228EVAL3Z evaluation board demonstrates the performance of the ISL6228 dual-channel PWM controller.
The ISL6228 features Intersils Robust Ripple Regulator (R3) technology. Channel-1 output voltage is 1.5V or 1.8V, pending the state of switch S5. Channel-2 output voltage is 1.8V. Each channel has an on-board dynamic-load generator included for evaluating the transient-load response. It applies a 300μs pulse of 4.5A load across VO1 and GND, and it applies a 300μs pulse of 5A load across VO2 and GND.
Contents of this document include:
Recommended Test Equipment
Interface Connections
Switch Descriptions
Test Point Descriptions
Design Criteria
Typical Performance
- Efficiency
- Start-up
- Shut-down
- Steady State, CCM
- Steady State, DCM
- Load-transient response
Evaluation Board Documentation
- Bill of materials
- Schematic
- Silk-screen plots
- Board layer plots
图3。评估板 ISL6228EVAL3Z 电路图
下面是评估板 ISL6228EVAL3Z 材料清单（BOM）：
详情请见评估板应用手册：
>http://www.intersil.com/data/an/an1291.pdf
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来源：中电网 |
