公开(公告)号：US20180336843A1

公开(公告)日：2018-11-22

申请号：US15683648

申请日：2017-08-22

Applicant: Apple Inc.

Inventor： Yanhui XIE ,  Asif HUSSAIN ,  Jingdong CHEN ,  Mohammad J. NAVABI-SHIRAZI

IPC: G09G3/34 ,  H05B33/08

CPC classification number: G09G3/342 ,  G09G3/3413 ,  G09G2310/024 ,  G09G2320/064 ,  G09G2330/021 ,  G09G2330/12 ,  H05B33/0809 ,  H05B33/0824 ,  H05B33/0827 ,  H05B33/0848

Abstract: Aspects of the subject technology relate to control circuitry for operating light-emitting diodes (LEDs). The control circuitry may include a pulse-width-modulation (PWM) driver for the LEDs and headroom voltage control circuitry. The PWM driver may adjust a rising edge or a trailing edge of the PWM cycles for various LEDs to ensure a headroom voltage detection window for the headroom voltage control circuitry to sample the headroom voltage of those LEDs without being affected by the rising edge of the PWM cycle for LED or the falling edge of the PWM cycle for another LED.

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。