Star vs bus power routing in PCB Design - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the power routing method where all components connect to a single central point.

PCB Design

power_routing = '[1]'

Drag options to blanks, or click blank then click option'

Amesh

Bbus

Cstar

Dring

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing star with bus routing

Choosing mesh or ring which are different topologies

The star routing method connects all components to a single central point, like spokes on a wheel.

2fill in blank

medium

Complete the code to describe the power routing method where components share a common line.

PCB Design

power_routing = '[1]'

Drag options to blanks, or click blank then click option'

Aring

Bmesh

Cstar

Dbus

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing bus with star routing

Selecting ring or mesh which are not typical power routing methods

Bus routing uses a common line shared by all components for power distribution.

3fill in blank

hard

Fix the error in the statement describing star routing: 'In star routing, all components connect along a {{BLANK_1}} line.'

PCB Design

description = 'In star routing, all components connect along a [1] line.'

Drag options to blanks, or click blank then click option'

Acentral

Bring

Cbus

Dmesh

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing bus which describes bus routing

Selecting ring or mesh which are unrelated here

Star routing connects components to a central point, not along a bus line.

4fill in blank

hard

Fill both blanks to complete the comparison: 'Star routing reduces {{BLANK_1}} but requires more {{BLANK_2}}.'

PCB Design

comparison = 'Star routing reduces [1] but requires more [2].'

Drag options to blanks, or click blank then click option'

Anoise

Bcomponents

Cwiring

Dcost

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up noise and cost

Confusing wiring with components

Star routing reduces noise by isolating branches but needs more wiring to connect each component to the center.

5fill in blank

hard

Fill all three blanks to complete the statement: 'Bus routing is {{BLANK_1}} to implement, but it can cause {{BLANK_2}} and {{BLANK_3}} issues.'

PCB Design

statement = 'Bus routing is [1] to implement, but it can cause [2] and [3] issues.'

Drag options to blanks, or click blank then click option'

Acomplex

Bnoise

Csimple

Dvoltage_drop

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing complex instead of simple

Mixing noise and cost or other unrelated issues

Bus routing is simple to implement but can cause noise and voltage drop problems due to shared lines.

Practice

1. What is the main advantage of star power routing in PCB design?

easy

A. It is cheaper to manufacture than bus routing

B. It simplifies the layout by sharing one power line

C. It reduces noise by connecting power separately to each component

D. It increases voltage drop across components

Solution

1. Step 1: Understand star routing concept

   Star routing connects power from a single point directly to each component separately.

2. Step 2: Identify the benefit of separate connections

   This reduces electrical noise and interference between components.

3. Final Answer:

   It reduces noise by connecting power separately to each component -> Option C

4. Quick Check:

   Star routing = noise reduction [OK]

Hint: Star routing means separate power lines to reduce noise [OK]

Common Mistakes:

• Confusing star routing with bus routing
• Thinking bus routing reduces noise
• Assuming star routing is simpler to layout

2. Which of the following correctly describes bus power routing?

easy

A. It is used only for sensitive circuits

B. Each component has its own separate power line

C. It eliminates voltage drops completely

D. Power is shared on a single line among components

Solution

1. Step 1: Recall bus routing definition

   Bus routing shares one power line among multiple components.

2. Step 2: Identify the correct description

   This means power is distributed along a single line to all components.

3. Final Answer:

   Power is shared on a single line among components -> Option D

4. Quick Check:

   Bus routing = shared power line [OK]

Hint: Bus routing shares one power line for all components [OK]

Common Mistakes:

• Thinking bus routing uses separate lines
• Assuming bus routing removes voltage drops
• Confusing bus routing with star routing

3. Consider a PCB with 4 components powered by a bus routing line. If the voltage at the source is 5V and each component causes a 0.1V drop, what is the voltage at the last component?

medium

A. 4.6V

B. 4.7V

C. 5.4V

D. 5.0V

Solution

1. Step 1: Calculate total voltage drop

   Each component causes 0.1V drop, so total drop for 4 components = 0.1V * 4 = 0.4V.

2. Step 2: Subtract total drop from source voltage

   Voltage at last component = 5V - 0.4V = 4.6V.

3. Final Answer:

   4.6V -> Option A

4. Quick Check:

   5V - (4 * 0.1V) = 4.6V [OK]

Hint: Subtract total drops from source voltage for last component [OK]

Common Mistakes:

• Adding voltage drops instead of subtracting
• Multiplying voltage drop by wrong number of components
• Ignoring voltage drop in bus routing

4. A PCB designer used star routing but noticed unexpected voltage drops at some components. What is the most likely cause?

medium

A. The central power point has high resistance

B. Power lines were connected in a bus instead of star

C. Components were connected with separate power lines

D. Noise was reduced by star routing

Solution

1. Step 1: Understand star routing setup

   Star routing connects each component separately from a central power point.

2. Step 2: Identify cause of voltage drop in star routing

   If the central power point has high resistance, voltage drops can occur despite separate lines.

3. Final Answer:

   The central power point has high resistance -> Option A

4. Quick Check:

   High resistance at center causes voltage drop [OK]

Hint: Check central point resistance if star routing shows voltage drop [OK]

Common Mistakes:

• Confusing bus and star routing wiring
• Assuming separate lines always prevent voltage drop
• Ignoring resistance at power source

5. You are designing a sensitive analog circuit and a simple LED indicator circuit on the same PCB. Which power routing strategy should you use for each and why?

hard

A. Use bus routing for analog circuit to reduce voltage drop; star routing for LED to reduce noise

B. Use star routing for analog circuit to reduce noise; bus routing for LED to simplify layout

C. Use bus routing for both circuits to simplify design

D. Use star routing for both circuits to eliminate voltage drops

Solution

1. Step 1: Analyze requirements for analog circuit

   Sensitive analog circuits need low noise, so star routing is best to reduce interference.

2. Step 2: Analyze requirements for LED circuit

   LEDs are less sensitive and simpler, so bus routing is acceptable to simplify layout.

3. Final Answer:

   Use star routing for analog circuit to reduce noise; bus routing for LED to simplify layout -> Option B

4. Quick Check:

   Star for sensitive, bus for simple circuits [OK]

Hint: Star for sensitive, bus for simple circuits [OK]

Common Mistakes:

• Using bus routing for sensitive analog circuits
• Using star routing unnecessarily for simple LEDs
• Ignoring noise and layout complexity trade-offs