Microcontroller to RS-485 circuit

RS-485 bus can carry up to 256 transceiver modules and
over long distances
This is a circuit for connect microcontroller with Rs-485 bus

Max485
Max485 are low-power transceivers for RS-485 and RS-
422 communication. Each part contains one driver and one
receiver.
Line Length vs. Data Rate
The RS-485/RS-422 standard covers line lengths up to
4000 feet. For line lengths greater than 4000 feet, see
Typical Applications
The MAX481, MAX483, MAX485, MAX487–MAX491, and
MAX1487 transceivers are designed for bidirectional data
communications on multipoint bus transmission lines.

Features
- In μMAX Package: Smallest 8-Pin SO
- Slew-Rate Limited for Error-Free Data Transmission
- 0.1μA Low-Current Shutdown Mode
- Low Quiescent Current
- -7V to +12V Common-Mode Input Voltage Range
- Three-State Outputs
- 30ns Propagation Delays, 5ns Skew
- Full-Duplex and Half-Duplex Versions Available
- Operate from a Single 5V Supply
- Allows up to 128 Transceivers on the Bus
- Current- Limiting and Thermal Shutdown for Driver Overload

Datasheet

Ic switching regulator 3A adjustable

The LM2576 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving 3A load with
excellent line and load regulation. These devices are available
in fixed output voltages of 3.3V, 5V, 12V, 15V, and an
adjustable output version.
Requiring a minimum number of external components, these
regulators are simple to use and include internal frequency
compensation and a fixed-frequency oscillator.
The LM2576 series offers a high-efficiency replacement for
popular three-terminal linear regulators. It substantially reduces
the size of the heat sink, and in some cases no heat
sink is required.
A standard series of inductors optimized for use with the
LM2576 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode
power supplies.
Other features include a guaranteed ±4% tolerance on output
voltage within specified input voltages and output load
conditions, and ±10% on the oscillator frequency. External
shutdown is included, featuring 50 μA (typical) standby current.
The output switch includes cycle-by-cycle current limiting,
as well as thermal shutdown for full protection under
fault conditions.

Features
- 3.3V, 5V, 12V, 15V, and adjustable output versions
- Adjustable version output voltage range,1.23V to 37V
- Guaranteed 3A output current
- Wide input voltage range, 40V up to 60V for HV version
- Requires only 4 external components
- 52 kHz fixed frequency internal oscillator
- TTL shutdown capability, low power standby mode
- High efficiency
- Uses readily available standard inductors
- Thermal shutdown and current limit protection
- P+ Product Enhancement tested

datasheet

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dc to dc converters

Switching regulator subsystems intended for use as
dc to dc converters.

The use of switching regulators is becoming more pronounced
over that of linear regulators because the size reductions in
new equipment designs require greater conversion efficiency.
Another major advantage of the switching regulator is that it
has increasednapplication flexibility of output voltage.
The output can be less than, greater than, or of opposite polarity
to that of the input voltage

The MC34063 series is a monolithic control circuit
containing all the active functions required for dc to dc
converters. This device contains an internal temperature
compensated reference, comparator, controlled duty cycle
oscillator with an active peak current limit circuit, driver,
and a high current output switch. This series was specifically
designed to be incorporated in step–up, step–down and
voltage–inverting converter applications. These functions
are contained in an 8–pin dual in–line package

FEATURES
· Wide Input Voltage Range 3 V to 40 V
· Precision Internal Reference 2%
· High Output Switch Current Up to 1.5 A
· Short-Circuit Current Limiting
· Adjustable Output Voltage
· Low Standby Current
· Oscillator Frequency Up to 100 kHz

Datasheet

Digital Potentiometers

Digital Potentiometers

Digital potentiometers is potentiometers that control with signal SPI
Thay can be used in place of standard mechanical pots. And control
with microcontroller

Example Application

Programmable, inverting gain amplifier

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MCP41XXX/42XXX

Features

• 256 taps for each potentiometer
• Potentiometer values for 10 kΩ, 50 kΩ and 100 kΩ
• Single and dual versions
• SPI™ serial interface (mode 0,0 and 1,1)
• ±1 LSB max INL & DNL
• Low power CMOS technology
• 1 μA maximum supply current in static operation
• Multiple devices can be daisy-chained together (MCP42XXX only)
• Shutdown feature open circuits of all resistors
• Hardware shutdown pin available on MCP42XXX only
• Single supply operation (2.7V - 5.5V)
• Industrial temperature range: -40°C to +85°C
• Extended temperature range: -40°C to +125°C

Datasheet

Type of capacitor

Electrolytic

- Made of electrolyte, Aluminum electrodes are used by using a

thin oxidation membrane

- Polarized capacitor

- Cheap, readily available, good for storage of charge (energy)

availablein very small or very large values in μF- Not very accurate,

marginal electrical properties, leakage, drifting, not suitable for use in

hf circuits

Tantalum

- Made of Tantalum Pentoxide. They are electrolytic capacitors butused

with a material called tantalum for the electrodes. Superior to electrolytic

capacitors

- Nonpolarized capacitor

- Excellent temperature and frequency characteristics,lack of

current-spike-noise. Small size fits anywhere, reliable, most common

values readily available.

- Expensive, easily damaged by spikes

Polyester Film

- This capacitor uses a thin polyester film as a dielectric.

- Nonpolarized capacitor

- Not as high a tolerance as polypropylene, cheap, temperature

stable,readily available, widely used. Tolerance is approx 5% to 10%.

- Can be quite large depending on capacity or rated voltage and so

may not be suitable for all applications.

Polypropylene

- This capacitor uses polypropylene film is the dielectric.

- Nonpolarized capacitor

- Very little change in capacitance when these capacitors are used in

applications within frequency range 100KHz. Tolerance is about 1%

- higher tolerance is needed then polyester caps can offer .

Very small values are available.

Metalized Polyester Film

- Dielectric made of Polyester or DuPont trade name "Mylar".

- Nonpolarized capacitor

- Good quality, low drift, temperature stable. Because the

electrodesare thin they can be made very very small. Good

all-round capacitor.

Epoxy

- Manufactured using an epoxy dipped polymers as a protective coating.

- Nonpolarized capacitor

- Widely available, stable, cheap.

- large depending on capacity or rated voltage and so may not be suitable

for all applications.

Ceramic

- Constructed with materials such as titanium acid barium for dielectric.

Internally these capacitors are not constructed as a coil

- Nonpolarized capacitor

- Well suited for use in high frequency applications. Typically used to by

-pass high frequency signals to ground. They are shaped like a disk,

available in very smallcapacitance values and very small sizes. ,very small

size and value, very cheap, reliable

- Together with the electrolytics the most widely available and used

capacitor around. Subject to drifting depending on ambient temperature.

Multilayer Ceramic

- Dielectric is made up of many layers.

- Nonpolarized capacitor

- Small in size, very good temperature stability, excellent frequency stable

characteristics. Multilayer caps suffer from high-Q internal (parallel)

resonances

- generally in the VHF range. The CK05 style 0.1μF/50V caps for example

resonate around 30MHz. The effectof this resonance is effectively no apparent

capacitance near the resonant frequency.As with all ceramic capacitors, be

careful bending the legs or spreading them apart to closeto the disc body or

they may get damaged.

What is capacitor

Capacitor is a device that stores electrical charges and can be used to

maintain voltage levels in power lines and improve electrical-system efficiency

Capacitor consisting in general of two metallic plates separated and

insulated from each other by a dielectric

two metallic plates

Resistor

What is resistor

Resistor is an electrical device that resists the flow of electrical

current A current flowing through a resistance willcreate a voltage

drop across that resistance and convertselectrical energy directly

to heat.There are two types of resistors-fixed and variable.

A fixed resistor has a fixed value of ohms while a variableresistor

is adjustable.

Fixed resistor

Variable resistor

Resister color code

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Black = 0 , Brown = 1 , Red =2 , Orange = 3 , Yellow =4

Green = 5 , Blue = 6 , Violet = 7 , Gray = 8 , White=9
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Tolerance band
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Brown = 1% , Red = 2% , Gold = 5% , Silver = 10% , None = 20%
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How to read the resister color code

Values

= 1st Digit , 2st Digit , multiplier with “0” , % Tolerance

Example >> Brown - Red - Orange - Gold <<

Values = 12000 = 12KOhms Tolerance 5%

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Resister surface mout code

Same above but change color with number last digit

is the multiplier

Example

104 = 100K Ohms , 472 = 4.7K Ohms

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Resister BS 1852 Coding
You will see in variable resistor
- The letter R is used for Ohms
- The letter K used for Kohms
- The letter M used for Megohms
and placed where the decimal point would go
.At the end is a letter that represents tolerance

Where M=20%, K=10%, J=5%,G=2%, and F=1%

Example
R33 = 0.33 ohms
4M7 = 4.7M ohms
47K3F = 47.3 K Ohms 1%
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Standard Series Values Resister

1.0 , 10 , 100 , 1.0K , 10K , 100K , 1.0M , 10M

1.1 , 11 , 110 , 1.1K , 11K , 110K , 1.1M , 11M

1.2 , 12 , 120 , 1.2K , 12K , 120K , 1.2M , 12M

1.3 , 13 , 130 , 1.3K , 13K , 130K , 1.3M , 13M

1.5 , 15 , 150 , 1.5K , 15K , 150K , 1.5M , 15M

1.6 , 16 , 160 , 1.6K , 16K , 160K , 1.6M , 16M

1.8 , 18 , 180 , 1.8K , 18K , 180K , 1.8M , 18M

2.0 , 20 , 200 , 2.0K , 20K , 200K , 2.0M , 20M

2.2 , 22 , 220 , 2.2K , 22K , 220K , 2.2M , 22M

2.4 , 24 , 240 , 2.4K , 24K , 240K , 2.4M

2.7 , 27 , 270 , 2.7K , 27K , 270K , 2.7M

3.0 , 30 , 300 , 3.0K , 30K , 300K , 3.0M

3.3 , 33 , 330 , 3.3K , 33K , 330K , 3.3M

3.6 , 36 , 360 , 3.6K , 36K , 360K , 3.6M

3.9 , 39 , 390 , 3.9K , 39K , 390K , 3.9M

4.3 , 43 , 430 , 4.3K , 43K , 430K , 4.3M

4.7 , 47 , 470 , 4.7K , 47K , 470K , 4.7M

5.1 , 51 , 510 , 5.1K , 51K , 510K , 5.1M

5.6 , 56 , 560 , 5.6K , 56K , 560K , 5.6M

6.2 , 62 , 620 , 6.2K , 62K , 620K , 6.2M

6.8 , 68 , 680 , 6.8K , 68K , 680K , 6.8M

7.5 , 75 , 750 , 7.5K , 75K , 750K , 7.5M

8.2 , 82 , 820 , 8.2K , 82K , 820K , 8.2M

9.1 , 91 , 910 , 9.1K , 91K , 910K , 9.1M
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