Ten Daily Electronic Common Sense-Section 72

Chip package：

• BGA ball grid array package
• CSP chip scaling package
• Chip mounting on COB board
• Chip Mounting on COC Porcelain Substrate
• MCM multi-chip model placement
• LCC leadless chip carrier
• CFP ceramic flat package
• PQFP plastic quad-lead package
• SOJ plastic J-shaped wire package
• SOP Small Outline Shell Package
• TQFP flat film square package
• TSOP miniature thin film package
• CBGA ceramic ball array package
• CPGA ceramic pin grid array package
• CQFP ceramic four-sided lead flat
• CERDIP ceramic sealing double row
• PBGA plastic ball array package
• SSOP Narrow Pitch Small Outline Plastic Encapsulation
• WLCSP Wafer Level Chip Scale Packaging
• Flip chip on FCOB board

Circuit board debugging should start from those aspects？

• As far as digital circuits are concerned, first determine three things in order:
  1. Make sure that all power supply values meet the design requirements. Some systems with multiple power supplies may require certain specifications for the order and speed of certain power supplies.
  2. Verify that all clock signal frequencies are working properly and that there are no non-monotonic problems on the signal edges.
  3. Confirm whether the reset signal meets the specification requirements. If these are normal, the chip should send out the first cycle (cycle) signal. Next, debug according to the operating principle of the system and the busprotocol.

What are the two major benefits of link aggregation compared to the separate links managed by STP?

1. Increased bandwidth and load sharing: Because multiple links in a logical group are active, more bandwidth is available in each communication session. No single communication session (eg, communication between a single client and a single server) can use more than one physical link. You can think of it as building a multi-lane highway: you can drive more vehicles on the highway, but each vehicle can only occupy one lane at a time.
2. Improve redundancy and availability: If one link in the group fails, other links continue to pass traffic, and the group will not go offline. There is no need to reconfigure the STP topology, or to have STP migrate a new link from blocked to active.

What types of contact IC card readers are divided into?

The first type is to use the serial communication interface circuit with the function of serial port power taking. The other type uses the USB interface to obtain power from the USB interface of the peripheral.

What are the two types of interrupt signal triggering methods?

• MODEK=0, falling edge trigger: The characteristic of this trigger method is that if there are already pins maintained at a low level, then the falling edges on other pins cannot be triggered again, so an interrupt cannot be requested. To avoid missing interrupts, system design should take into account any port pins that are low. Interrupt requests for which other pins of the port are simultaneously low should be disabled.
• MODEK=1, falling edge and low level trigger: as long as the interrupt is allowed at this time, an interrupt request will be issued if a low level occurs on any keyboard interrupt input pin, and there will be no loss of interrupt.

What is the design and calculation procedure for the capacitor?

1. The type of capacitor. Correct selection of input and output capacitors is very important to ensure the lowest switching noise performance at the input and output.
2. Input capacitance. It is important that the input capacitor has low ESR, which can effectively reduce the input current noise. There are two separate requirements for the input capacitance.
3. Output filter capacitor. Output capacitor selection, based on the capacitor’s ESR and total capacitance, must be able to store enough current for the load to use when the switch is off.

What are the main expansion methods of the MCS-51 MCU I/O port?

• Bus expansion method. The data is input and output through the P0 port of the single-chip microcomputer. In order to distinguish different peripherals, each I/O port should have its own address. The address of the I/O port occupies the address space of the external data memory. Therefore, when I/O expansion is performed, the address allocation of the I/O H and the external data memory should be fully considered to avoid address overlap.
• Serial expansion method. The I/O port is expanded by using the MCS-51 single-chip serial 1:3 synchronous shift register working mode. Since the data is transmitted through the serial port, the transmission speed is slow and serial-to-parallel data conversion must be performed.

What is the meaning of the main part of the transformer?

• The meanings of the main letters in the transformer model are as follows:
  1. DB represents the power transformer.
  2. CB represents the audio output transformer.
  3. RB represents the audio input transformer.
  4. GB stands for high voltage transformer.
  5. HB represents a filament transformer.
  6. SB or ZB means audio (constant resistance) transmission transformer.
  7. SB or EB means audio (constant voltage or auto-coupled) transmission transformer.

What are the difficulties of amorphous silicon TFTs in driving OLEDs?

1. With the development of OLED displays towards large capacity, high brightness and high definition, the pixel size is getting smaller and smaller, and the unit pixel charging time is getting shorter and shorter, which requires TFr to have a larger on-state current.
2. In order to prevent the current change caused by the change of the OLED turn-on voltage, the OLED is usually driven by a P-channel device operating in a saturated state.
3. Amorphous silicon technology has the problem of excessive light sensitivity.

What are the basic principles of wireless power transmission?

Electromagnetic induction – short-range transmission; electromagnetic coupling resonance – medium-range transmission; microwave/laser – long-range transmission.