PCB News - Portable smart driver makes PCB layout more regular

Small portable electronic systems have been constantly moving forward, such as mobile phones, PMP (Personal Media Player), DSC (Digital Camera), DVC (Digital Video Camera), PME (Portable Medical Equipment) and GPS (Global Positioning System), functions Features are more abundant from one generation to another. What follows is that the requirements of some peripheral PCB circuits tend to be the same, because their power supplies, ports, and MMI (Man-Machine Interface) all use similar technologies.

Three-level strategy for low-power full-featured products

With the increase in functions and performance of portable systems, the demand for power consumption management is also increasing. Therefore, the strategies used by OEMs to solve power consumption problems are also evolving.

The first-level strategy focuses on the efficiency of the energy management subsystem, including minimizing losses on the DC/DC converter, LDO, battery management, and battery protection PCB circuits.

This is a power subsystem-centric approach, which depends largely on the ability of semiconductor suppliers to produce components and integrated devices with lower power consumption than similar architecture devices on the market. This turns the main task of the OEM engineer into the choice of components, balancing energy efficiency, component cost, and package size.

Although this strategy has been very effective and the component market has realized this benefit, most analog and analog-based mixed-signal IC manufacturers have not benefited significantly from the continuous reduction in process size.

The focus of the second-level strategy has shifted from the power supply to some parts of the system, and even some parts of the large-scale ASIC that do not work at a specific time. This strategy is particularly effective when applied to high-energy users such as wireless link hardware and display backlights, and it can be turned off even if the power consumption is not high, such as audio subsystems, I/O ports, or non-volatile configurations. Memory) to extend the working time of each charge. For example, mobile phones currently produced have 20 or more power domains.

In addition to saving power consumption caused by idle current in high-power PCB circuits such as radio frequency components and display backlights, as long as the system can turn off a certain clock-driven PCB circuits part, this strategy can effectively reduce static power consumption. With the development of the IC manufacturing process to an unprecedentedly smaller size, this strategy can effectively replace the clock gating to achieve the purpose of reducing idle current.

This power consumption reduction strategy relies on the technical contributions of system architects, software and hardware implementation personnel, and ASIC vendors. Although this strategy is successful, it is also limited by the number of loads on the application processor. These additional features will force designers to consume more computing resources that consume more power. For example, mobile phones have switched from ARM7 to ARM9 and ARM11 processors, using them as optional baseband and auxiliary processing resources. Other portable electronic products have similar trends, albeit to a lesser extent.

The third-level strategy focuses on reducing the power consumption of various functions without sacrificing performance. A feasible technology is to use distributed intelligent management, which is characterized by not requiring the powerful processing power and speed of the baseband or application processor.

This strategy allows the processor to transfer all functions to the semi-automatic peripheral controller. The result is such a working mode: the processor can enter a sleep state during human activities instead of data processing or communication tasks. However, data processing or communication tasks need to exert the full capabilities of the processor. Smart display backlight drivers are a good example.

The backlight scheme under the third-level strategy

Users of portable electronic products need to have a clearly visible screen display under various ambient light conditions. At present, portable products often use photodiodes or phototransistors to estimate the brightness of ambient light and use this as an input for backlight driver control. Photosensitive sensors require signal conditioning PCB circuits: excitation in the form of DC bias, amplification and analog-to-digital conversion or at least one or two levels of threshold detection.

Either through external components, or through on-chip analog I/O pins, the main processor usually monitors the output of the photosensitive sensor by means of periodic data conversion. The speed of this conversion is on the order of 1 to several times per second. The controller then estimates the conversion result, and usually divides the result into three levels, corresponding to the whole day, brightly lit indoor environment, or dimly lit environment.

The processor completes the control process like this: it sends a control signal to the backlight driver, and the driver provides one of three possible current levels to the LED string. But this approach is not efficient. In fact, this is a way of microprocessor management: under the monitoring of powerful and expensive central resources, tasks are delegated to a certain part of the system with lower operating costs. This does not seem to help the offloading of processor tasks.

The above is the introduction of the portable smart driver to make the PCB layout more regular. Ipcb also provides PCB manufacturers and PCB manufacturing technology.