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Calculate and recommend resistor values from different standard values that can ...

@copilot Calculate and recommend resistor values from different standard values that can plug into the programmable power supply IC, IC1 to get a stable 12V output supply. Follow these steps;
Important: Use python for the calculations
  1. Component verification
    • Analyze the datasheet of the regulator IC and determine the necessary parameters for setting the output voltage, including the reference voltage, the formula in the datasheet used to calculate the output voltage based on resistor values, and also any recommended resistor values.
    • Summarize the datasheet of the regulator and give references
  2. Voltage divider network
    • Think about the available component standards (eg E12, ... E96 series)
    • Think about an appropriate tolerance and power rating for possible resistors here
    • Select a standard value for the first resistor. A common practice here is to choose a standard value from the range 1kΩ to 10kΩ
    • Calculate the resistor value needed to achieve the target voltage using the appropriate formula specified from the IC datasheet
  3. Resistor combination recommendation
    • If the calculated resistor value is not a standard value or not close enough to a standard value, Identify possible combinations of standard resistor values that meet the calculated values withing the appropriate tolerance
    • Consider the use of parallel or series resistor combinations if single resistors are not available or suitable
    • Make sure the power rating of each resistor is adequate for the application
  4. Documentation and report
    • Create a table of the recommended resistors/resistor combinations with the following columns: Target voltage, Input voltage, 1st selected R, 2nd calculated Resistor combination, Actual output voltage, Deviation from target voltage, power rating
1y
Great! Let's go step by step to calculate and recommend resistor values for setting a stable 12V output voltage using the MT3608 regulator IC.
Step 1: Component Verification
  1. Important Parameters from the Datasheet:
    • Reference Voltage (VREF): 0.6V (Typical)
    • Output Voltage Formula: VOUT=VREF×(1+R1R2)V_{\text{OUT}} = V_{\text{REF}} \times \left(1 + \frac{R1}{R2}\right)
      where:
      • $V_{\text{REF}}$ is 0.6V
      • $R1$ and $R2$ form the resistor divider network
    • Recommended Resistor Values: The datasheet does not specify exact recommended resistor values but indicates that the values are divided by a resistor divider network.
Step 2: Voltage Divider Network
  1. Standard Resistor Series: We'll consider the E12 (10% tolerance) and E24 (5% tolerance) series for our calculations.
  2. Tolerance and Power Rating:
    • Tolerance: We'll use 5% tolerance resistors from the E24 series to ensure better precision.
    • Power Rating: Assume standard 1/4W resistors unless the power dissipation is calculated to be higher.
  3. Selecting the First Resistor (R1): We'll choose a standard value within the range 1kΩ to 10kΩ. Let's pick R1 = 10kΩ.
  4. Calculating the Second Resistor (R2): Using the formula: VOUT=VREF×(1+R1R2)V_{\text{OUT}} = V_{\text{REF}} \times \left(1 + \frac{R1}{R2}\right) Rearranging for R2: R2=R1×VREFVOUTVREFR2 = \frac{R1 \times V_{\text{REF}}}{V_{\text{OUT}} - V_{\text{REF}}}
    Given:
    • $ V_{\text{OUT}} = 12V $
    • $ V_{\text{REF}} = 0.6V $
    • $ R1 = 10kΩ $
    Let's use Python for this calculation next.
Step 3: Resistor Combination Recommendation
Let's first calculate the exact value of $ R2 $ using Python.

Python


# Given values
V_ref = 0.6  # Reference voltage in Volts
V_out = 12.0  # Desired output voltage in Volts
R1 = 10000  # Selected resistor R1 in Ohms

# Calculate R2
R2 = (R1 * V_ref) / (V_out - V_ref)
R2
Let's see what we get.
Code Interpreter

Python


# Given values
V_ref = 0.6  # Reference voltage in Volts
V_out = 12.0  # Desired output voltage in Volts
R1 = 10000  # Selected resistor R1 in Ohms

# Calculate R2
R2 = (R1 * V_ref) / (V_out - V_ref)
R2
The calculated value for the second resistor $ R2 $ is approximately $ 526.32 , \Omega $.
Resistor Combination Recommendation
Since $ 526.32 , \Omega $ is not a standard resistor value, we will look for standard resistors or combinations of resistors to achieve this value.
Let's first check the nearest standard values in the E24 series:
  • The closest standard values in the E24 series around $ 526 \Omega $ are $ 510 \Omega $ and $ 560 \Omega $.
Using Parallel and Series Combinations:
  1. Calculate possible combinations that approximate $ 526.32 \Omega $ using standard resistors.
We'll use Python to determine if any combination of standard resistors can closely match the required $ R2 $ value.

Python


import itertools

# E24 series resistor values (frequently used for 5% tolerance)
e24_series = [10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82,
              100, 120, 150, 180, 220, 270, 330, 390, 470, 560, 
              680, 820, 1000, 1200, 1500, 1800, 2200, 2700, 
              3300, 3900, 4700, 5600, 6800, 8200, 10000]

# Function to check series and parallel combinations
def find_combination(resistors, target, tolerance=0.05):
    best_comb = None
    best_diff = float('inf')
    
    # Check single resistors
    for r in resistors:
        diff = abs(r - target)
        if diff < best_diff:
            best_diff = diff
            best_comb = [r]
            
    # Check series combinations
    for comb in itertools.combinations(resistors, 2):
        r_series = sum(comb)
        diff = abs(r_series - target)
        if diff < best_diff:
            best_diff = diff
            best_comb = list(comb)
            
    # Check parallel combinations
    for comb in itertools.combinations(resistors, 2):
        r_parallel = 1 / sum(1/r for r in comb)
        diff = abs(r_parallel - target)
        if diff < best_diff:
            best_diff = diff
            best_comb = list(comb)
            
    # Check series-parallel combinations
    for comb in itertools.combinations(resistors, 3):
        r_series_parallel = (comb[0] + (1 / sum(1 / r for r in comb[1:])))
        diff = abs(r_series_parallel - target)
        if diff < best_diff:
            best_diff = diff
            best_comb = list(comb)
    
    return best_comb, best_diff

# Find the best combination
best_combination, best_diff = find_combination(e24_series, R2)
best_combination, best_diff
Code Interpreter

Python


import itertools

# E24 series resistor values (frequently used for 5% tolerance)
e24_series = [10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82,
              100, 120, 150, 180, 220, 270, 330, 390, 470, 560, 
              680, 820, 1000, 1200, 1500, 1800, 2200, 2700, 
              3300, 3900, 4700, 5600, 6800, 8200, 10000]

# Function to check series and parallel combinations
def find_combination(resistors, target, tolerance=0.05):
    best_comb = None
    best_diff = float('inf')
    
    # Check single resistors
    for r in resistors:
        diff = abs(r - target)
        if diff < best_diff:
            best_diff = diff
            best_comb = [r]
            
    # Check series combinations
    for comb in itertools.combinations(resistors, 2):
        r_series = sum(comb)
        diff = abs(r_series - target)
        if diff < best_diff:
            best_diff = diff
            best_comb = list(comb)
            
    # Check parallel combinations
    for comb in itertools.combinations(resistors, 2):
        r_parallel = 1 / sum(1/r for r in comb)
        diff = abs(r_parallel - target)
        if diff < best_diff:
            best_diff = diff
            best_comb = list(comb)
            
    # Check series-parallel combinations
    for comb in itertools.combinations(resistors, 3):
        r_series_parallel = (comb[0] + (1 / sum(1 / r for r in comb[1:])))
        diff = abs(r_series_parallel - target)
        if diff < best_diff:
            best_diff = diff
            best_comb = list(comb)
    
    return best_comb, best_diff

# Find the best combination
best_combination, best_diff = find_combination(e24_series, R2)
best_combination, best_diff
The best combination of standard resistors to approximate $ 526.32 , \Omega $ is using three resistors in a series-parallel combination:
  • $ R1 = 39 , \Omega $
  • $ R2 = 820 , \Omega $
  • $ R3 = 1200 , \Omega $
This yields a deviation of approximately $ 0.19 , \Omega $, which is within an acceptable tolerance.
Step 4: Documentation and Report
Let's create a table summarizing the recommended resistor combination along with other parameters.

Table


Target VoltageInput VoltageSelected R1 (Ω)Resistor Combination for R2 (Ω)Actual Output Voltage (V)Deviation from Target Voltage (V)Power Rating
12V5V1000039, 820, 120012.0001/4W each
Summary:
  • Chosen R1: 10kΩ from E24 series.
  • Calculated R2: 526.32Ω (not a standard value).
  • Best Resistor Combination for R2: $ 39Ω, 820Ω, $ and $ 1200Ω $ in a series-parallel combination.
  • Deviation: Within $ 0.19Ω $.
Connection Instructions:
  1. Connect $ 39Ω $ resistor in series with the parallel combination of $ 820Ω $ and $ 1200Ω $.
  2. Connect the combined R2 network such that the junction of the resistors is connected to the Feedback pin (FB) of the MT3608.
  3. Ensure proper power ratings and tolerances for resistors being used.
Would you like to implement these resistor connections directly into your schematic?
1y
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@copilot Design the pull-up and pull-down resistor network for GPIO pins in this...

@copilot @copilot Design the pull-up and pull-down resistor network for GPIO pins in this schematic for U1. Follow these steps:
Important: All calculations should be done by python
  1. Summarize the information specified in the components datasheet including communication protocol, GPIO pins, voltage levels, and other electrical characteristics necessary for design the pull-up/pull-down resistor network
  2. Identify all GPIO pins requiring pull-up or pull-down resistors. Do not print the list of GPIO pins, but retain it for subsequent steps.
  3. From the datasheet, determine current requirements, speed requirements, and the voltage level these GPIO pins need to maintain when they are in a floating state.
  4. Calculate the appropriate resistor values for each pull-up and pull-down configuration needed based on the target voltage level and the maximum current allowed by the GPIO pin. If the resistor values calculated are not standard values or not close to standard values. suggest how to combine standard value resistors to obtain the values calculated.
  5. Create a summary table with the following columns: IC designator, Target pins, communication protocol, Requirements of the line, Resistor values calculated, notes
1y
Understood! Let's break down and accomplish each step using the information provided along with the necessary calculations via Python.
Step-by-Step Execution 1. Summarize Datasheet Information Communication Protocol and GPIO Pins
  • The SC0914(7) has multiple GPIO pins (labeled GPIO0 to GPIO29 and GPIO26/ADC0 to GPIO29/ADC3).
  • The SC0914(7) supports various communication protocols including I2C, SPI, and UART.
Voltage Levels and Electrical Characteristics
  • Operating Voltage: The GPIO pins attempt to drive the output to the IOVDD level.
  • GPIO Drive Strengths: 2mA, 4mA, 8mA, and 12mA modes.
  • Maximum Total IOVDD Current: 50mA
  • Input Voltage Levels:
    • High: Minimum 2V (Single Ended)
    • Low: Maximum 0.8V (Single Ended)
2. Identify GPIO Pins Requiring Pull-Up/Pull-Down Resistors
  • This would depend on specific requirements for each GPIO, typically those configured as inputs or used in open-drain configurations.
3. Determine Current, Speed, and Voltage Requirements Current Requirements
  • The GPIO pins have drive strengths up to 12mA, and total current for all GPIO should be below 50mA.
Speed Requirements
  • Assume general GPIO operation unless specific high-speed or low-power requirements are stated.
Voltage Levels
  • GPIO pins should drive low to 0V and high to IOVDD, which will be bounded by the level required by the peripherals they interface with.
4. Calculate Appropriate Resistor Values
To calculate pull-up and pull-down resistor values, follow the equation:
R=VIR = \frac{V}{I}
Where:
  • $V$ is the desired voltage level the resistor should maintain.
  • $I$ is the allowable current under this voltage.
Assume a desired voltage level of 3.3V and max current of 12mA for computation.
Python Calculations
Let's compute typical resistor values for both pull-up and pull-down configurations.
Pull-up Calculation
  • Desired voltage $V = 3.3V$
  • Desired current $I = 12mA$
Pull-down Calculation
  • Desired voltage $V = 0.0V$
  • Desired current $I = 12mA$

Python


# Calculate resistor values for pull-up and pull-down configurations
V = 3.3  # volts
I = 0.012  # amps (12mA)

# Calculate pull-up resistor value
R_pullup = V / I

# Pull-down resistor value typically larger because it prevents floating to avoid 'L' state
R_pulldown = (3.3 - 0.8) / I  # ensures logic-low threshold

R_pullup, R_pulldown
Code Interpreter

Python


# Calculate resistor values for pull-up and pull-down configurations
V = 3.3  # volts
I = 0.012  # amps (12mA)

# Calculate pull-up resistor value
R_pullup = V / I

# Pull-down resistor value typically ensures logic-low threshold (max 0.8V for logic 0)
V_low_max = 0.8  # volts
R_pulldown = (3.3 - V_low_max) / I

R_pullup, R_pulldown
The calculated resistor values are:
  • Pull-Up Resistor: 275 Ω
  • Pull-Down Resistor: 208 Ω
5. Summary Table
We can proceed to create a summary table. We'll use typical GPIO pins and I2C as a representative communication protocol, assuming standard pull-up resistors (e.g., for I2C).

Table


IC DesignatorTarget PinsCommunication ProtocolRequirements of the LineResistor Values CalculatedNotes
U1GPIO0, GPIO1I2CPull-up both pins to 3.3V275 ΩTypical pull-up for I2C
U1GPIO2GPIO InputPrevent floating (drive low)208 ΩPrevents undefined logic state
U1GPIO3GPIO InputPrevent floating (drive low)208 ΩPrevents undefined logic state
Notes
  • The resistors should be checked against standard values (e.g., E24 or E12 series). Actual values close to these should be chosen, or using parallel/series resistor combinations:
    • 275 Ω: Closest standard values are 270 Ω or 280 Ω. Use 270 Ω for simplicity.
    • 208 Ω: Closest standard value is 220 Ω. Use 220 Ω for simplicity.
Would you like to proceed with these resistor values or need any adjustments?
1y
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2
U1
IC1


CI Playground: Power Manager Board

CI Playground: Power Manager Board thumbnail
Coconut power supply board is a power management board designed to deliver stable and reliable power supply to your industrial loads.

Properties

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RoHS, REACH

0 degrees ~ 70 degrees

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Distributor

Qty 1

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$0.80

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$3.30

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$0.80

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