公开(公告)号：US20150115813A1

公开(公告)日：2015-04-30

申请号：US14503037

申请日：2014-09-30

Applicant: Apple Inc.

Inventor： Asif HUSSAIN ,  Behzad MOHTASHEMI ,  Mohammad J. NAVABI-SHIRAZI ,  Jingdong CHEN ,  Manisha P. PANDYA

IPC: H05B33/08

CPC classification number: H05B33/0815 ,  G09G3/3406 ,  G09G3/342 ,  G09G2310/08 ,  G09G2320/0233 ,  G09G2320/064 ,  Y02B20/346

Abstract: The embodiments discussed herein relate to systems, methods, and apparatus for executing a pulse frequency modulation (PFM) mode of a boost converter in order to ensure that a switching frequency of the boost converter is a above an audible frequency threshold. In this way, a user operating a display device that is controlled by the boost converter will not be disturbed by audible noises generated at the display device. The PFM mode enforces an audible frequency threshold by using control circuitry designed to increase or decrease the frequency of a pulse signal depending on how the frequency of the pulse signal changes over time. The control circuitry can apply an additional load to the boost converter in order to increase the frequency of the pulse signal when the frequency is approaching the audible frequency threshold.

Abstract translation: 本文讨论的实施例涉及用于执行升压转换器的脉冲频率调制（PFM）模式的系统，方法和装置，以便确保升压转换器的开关频率高于可听频率阈值。 以这种方式，操作由升压转换器控制的显示装置的用户不会被在显示装置处产生的可听见的噪声所扰乱。 PFM模式通过使用控制电路来实施可听频率阈值，该控制电路旨在根据脉冲信号的频率如何随时间而变化来增加或减少脉冲信号的频率。 控制电路可以向升压转换器施加额外的负载，以便在频率接近可听频率阈值时增加脉冲信号的频率。

公开(公告)号：US20160345395A1

公开(公告)日：2016-11-24

申请号：US15069724

申请日：2016-03-14

Applicant: Apple Inc.

Inventor： Jingdong CHEN ,  Asif HUSSAIN ,  Behzad MOHTASHEMI ,  Manisha P. PANDYA ,  Mohammad J. NAVABI-SHIRAZI

IPC: H05B33/08

CPC classification number: H05B33/0815 ,  G09G3/3406 ,  G09G2330/06 ,  H05B33/086

Abstract: This application relates to systems, methods, and apparatus for controlling a switching frequency of a boost or flyback converter to be above an audible frequency range when operating the boost or flyback converter in a pulse frequency modulation (PFM) mode. The boost or flyback converter uses one or more switches for converting power for a display panel. In order to boost the switching frequency when operating in the PFM mode, the boost or flyback converter can selectively implement certain current and/or voltage limits for pulses that are generated as a result of the switching. The current and/or voltage limits can be set according to a load of the boost or flyback converter, and a correspondence between the current and/or voltage limits and the loads can be stored in a lookup table accessible to the boost or flyback converter.

Abstract translation: 本申请涉及用于在脉冲频率调制（PFM）模式下操作升压或反激转换器时控制升压或反激式转换器的开关频率高于可听频率范围的系统，方法和装置。 升压或反激转换器使用一个或多个开关来转换显示面板的功率。 为了在PFM模式下工作时提高开关频率，升压或反激式转换器可以选择性地为由于切换而产生的脉冲实现一定的电流和/或电压限制。 可以根据升压或反激式转换器的负载来设置电流和/或电压限制，并且可以将电流和/或电压极限与负载之间的对应关系存储在升压或反激转换器可访问的查找表中。