Monthly Archives: July 2017

MicroUSB Interface IC

The MC34825 device supports various types of external power supplies to charge the battery, such as a dedicated AC/DC adapter or a USB port. It is designed to support the Universal Charging Solution (UCS) recommended by the OMTP (Open Mobile Terminal Platform), as well as to use the same 5-pin micro or mini-USB connector for other wired accessories.  It has functions built-in to identify the type of the power supply, and sets low or high charging current, based on the current capability of the power supply. The MC34825 monitors the power supply, and offers an up to 28 V of overvoltage protection (OVP) to the cell phone against failed power supplies. The 34825 also contains analog switches to multiplex the five pins, to support UART and high speed USB data communication, mono or stereo audio headset with or without a microphone and a cord remote controller, manufacturing or researchand-development (R/D) test cables, and other accessories.

Block Diagram

Block Diagram

Why Used

  • Internal power switch to offer OVP against up to 28 V failed power supply input
  • Supports stereo/mono headset with or without microphone and remote controller with pure passive components
  • Supports USB or UART R/D test cables
  • Supports 32 ID resistance values with a high accuracy 5-bit ADC
  • Identifies various types of power supplies to set low or high battery-charging current levels

Where Used

  • Cell phones
  • USB universal charging solution (USC-OMTP)
  • Supports mini/micro – USB connector
  • UART and USB high speed communication
  • Remote control/accessories IDs

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22 I/O MSDI Programmable Current Analog Mux

Designed to operate 4.5 V ≤ VBATP ≤ 36 V, the NXP MC33978 is a multiple switch detection interface (MSDI) . The switch status, either open or closed, is transferred to the microprocessor through a SPI in automotive environments. This SMARTMOS device also features a 24-to-1 analog multiplexer for reading the input channels as analog inputs. The analog selected input signal is buffered and provided on the AMUX output pin for the MCU to read. Independent programmable wetting currents are available as needed for the application. A battery and temperature monitor are included in the IC and available via the AMUX pin.

The 33978 device has two modes of operation, Normal and Low-power mode(LPM). Normal mode allows programming of the device and supplies switch contacts with pull-up or pull-down current as it monitors the change of state on the switches. The LPM provides low quiescent current, which makes the 33978 ideal for automotive and industrial products requiring low sleep-state currents.

Simplified Application Diagram

Simplified Application Diagram

Why Used

  • Operating switch input voltage range from -1.0 V to 36 V
  • Eight programmable inputs (switches to battery or ground)
  • 14 switch-to-ground inputs
  • Selectable wetting current (2, 6, 8, 10, 12, 14, 16, or 20 mA)
  • Interfaces directly to an MCU using 3.3 V / 5.0 V SPI protocol

Where Used

  • Automotive
    • Heating ventilation and air conditioning (HVAC)
    • Lighting
    • Central gateway/in-vehicle networking
    • Gasoline engine management
  • Industrial
    • Programmable logic control (PLC)
    • Process control, temperature control
    • Input-output control (I/O Control)
    • Single board comp

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Fm+ Parallel Bus to I2C-bus Controller

PCA9665/PCA9665A can operates as a master or a slave and can be a transmitter or receiver. It serves as an interface between most standard parallel-bus microcontrollers/microprocessors and the serial I²C-bus and allows the parallel bus system to communicate bidirectionally with the I²C-bus. Communication with the I²C-bus is carried out on a Byte or Buffered mode using interrupt or polled handshake. The PCA9665/PCA9665A controls all the I²C-bus specific sequences, protocol, arbitration and timing with no external timing element required.

Block Diagram

Block Diagram

Why Used

  • Operating supply voltage: 2.3 V to 3.6 V
  • Multi-master capability
  • Internal oscillator trimmed to 15 % accuracy reduces external components
  • 1 Mbit/s and up to 25 mA SCL/SDA IOL (Fast-mode Plus (Fm+)) capability
  • I 2C-bus General Call capability  Software reset on par

Where Used

  • Add I²C-bus port to controllers/processors that do not have one
  • Add additional I²C-bus ports to controllers/processors that need multiple I²C-bus ports
  • Converts 8 bits of parallel data to serial data stream to prevent having to run a large number of traces across the entire printed-circuit board

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Tiny Real-Time Clock/calendar with alarm function and I²C-bus

With clock operating voltage of 0.9V to 5.5V, the PCF85063A is a CMOS1 Real-Time Clock (RTC) and calendar optimized for low power consumption. An offset register allows fine-tuning of the clock. All addresses and data are transferred serially via the two-line bidirectional I2C-bus. Maximum data rate is 400 kbit/s. The register address is incremented automatically after each written or read data byte.

Tiny Real-Time Clock:calendar with alarm function and I²C-bus

Block Diagram

Why Used

  • Programmable clock output for peripheral devices (32.768 kHz, 16.384 kHz, 8.192 kHz, 4.096 kHz, 2.048 kHz, 1.024 kHz, and 1 Hz)
  • Provides year, month, day, weekday, hours, minutes, and seconds based on a 32.768 kHz quartz crystal
  • 400 kHz two-line I²C-bus interface (at VDD = 1.8 V to 5.5 V)
  • Low current; typical 0.27 μA at VDD = 3.0 V and Tamb= 25 °C
  • Selectable integrated oscillator load capacitors for CL= 7 pF or CL = 12.5 pF

Where Used

  • Battery powered devices
  • Digital video camera
  • Digital still camera
  • Printers
  • Mobile equipment

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