Charge Pump Voltage Control for Display Power Reduction
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Solution Overview
Problem
Display devices face power wastage issues when the porch period is elongated due to reduced vertical synchronization signal frequency, as the charge pump continues to output the same high pump voltage during inactive periods, leading to increased power consumption.
Innovation Solution
A display driving device with a timing controller and charge pump that adjusts its operation modes based on an anti-tearing signal, reducing power consumption by modulating the frequency of the pumping clock signal and selectively controlling switches during active and porch periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charge pump outputs the same high pump voltage during both active and porch periods, then the source driver can be reliably driven during the active period, but power is wasted during the inactive porch period
Solution Approach 1:
The charge pump circuit dynamically adjusts its operation based on the signal period. During the active period, the charge pump operates at high frequency to generate the required high pump voltage for reliable source driver operation. During the porch period, the charge pump switches to a low-frequency mode that maintains sufficient voltage for the source driver while significantly reducing power consumption, as the source driver does not require data updates during this inactive period.
Solution Approach 2:
The invention changes the operating parameters of the charge pump circuit based on the signal period. Specifically, the charge pump control unit modifies the pumping frequency and output voltage levels according to whether the current period is active or porch. This parameter adaptation allows the system to maintain reliability during active periods while minimizing energy waste during porch periods when the source driver does not require data updates.
2Reliability
If the charge pump operates at high frequency to provide sufficient pump voltage, then the source driver can be driven reliably, but power consumption increases significantly
Solution Approach 1:
The charge pump circuit dynamically adjusts its operation based on the signal period. During the active period, the charge pump operates at high frequency to generate the required high pump voltage for reliable source driver operation. During the porch period, the charge pump switches to a low-frequency mode that maintains sufficient voltage for the source driver while significantly reducing power consumption, as the source driver does not require data updates during this inactive period.
Solution Approach 2:
The invention implements periodic action by alternating between high-frequency charge pump operation during active periods and low-frequency operation during porch periods. This periodic adaptation of the charge pump frequency to the display signal timing allows the system to maintain voltage reliability when needed while reducing overall power consumption during inactive periods when the source driver does not require data updates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces power consumption by minimizing static current during inactive porch periods through controlled switching operations of the charge pump, optimizing power usage based on the display's active and inactive phases.
Implementation Method 1
the source driver may include a charge pump circuit capable of outputting and providing a pump voltage corresponding to the driving voltage by pumping the power supply voltage supplied by the battery
Implementation Method 2
The charge pump includes a flying capacitor; a first switch disposed between one end of the flying capacitor and a first terminal connected to a first external voltage
Data Source
AI summary
A display driving device includes a timing controller and a charge pump configured to output a pump voltage for driving a source driver. The charge pump includes a flying capacitor; a first switch disposed between one end of the flying capacitor and a first terminal; a second switch disposed between the one end of the flying capacitor and a second terminal; a third switch disposed between another end of the flying capacitor and a third terminal; a fourth switch disposed between the another end of the flying capacitor and a fourth terminal; and a charge pump control unit configured to control turning on or off of the first to the fourth switches based on the anti-tearing signal, and control the first to the fourth switches based on the anti-tearing signal to operate in a first mode or a second mode configured to reduce power consumption than in the first mode.