Tag Archives: Maxim

Isolated 24V to 12V 10W Flyback Power Supply

maximintegrated.com power supply experts have a reference design of a 24V to 12V flyback converter.

Maxim’s power supply experts have designed and built a series of isolated, industrial power-supply reference designs. Each of these power supplies efficiently converts 24V into useful voltage rails at a variety of power levels. Every power rail is isolated with a readily available transformer from multiple, global vendors, providing for quick, convenient transformer selection. Each design has been tested for load and line regulation, as well as efficiency and transient performance. As with all Maxim reference designs, the BOM, schematics, layout files, and Gerber files are all available. In addition, boards are available for purchase; most boards feature through-hole pins for immediate board placement and accelerated prototyping.

Isolated 24V to 12V 10W Flyback Power Supply – [Link]

MAX17055 – a 7μA operating current fuel gauge

by Graham Prophet @ eedesignnewseurope.com

Maxim Integrated has posted details of a battery charge monitor IC for which it claims the lowest quiescent current available, at 7µA. The 1-cell Fuel Gauge with Maxim’s ModelGauge m5 EZ algorithm can eliminate battery characterization issues.

MAX17055 – a 7μA operating current fuel gauge – [Link]

DS28EC20, A Serial 1-Wire 20Kb EEPROM

The American manufacturer of analog and mixed-signal integrated circuits, Maxim Integrated, has developed a new serial EEPROM memory that operates from single-contact 1-wire interface.

The DS28EC20 is a 20480-bit, 1-Wire® EEPROM organized as 80 memory pages of 256 bits each. An additional page is set aside for control functions. Data is written to a 32-byte scratchpad, verified, and then copied to the EEPROM memory.

The 1-Wire is a device communications bus system that provides low-speed data, signaling, and power over a single conductor. This technology uses only two wires; data and ground. It is similar in concept to I²C, but with lower data rates and longer range. It is typically used to communicate with small inexpensive devices such as digital thermometers and weather instruments.

DS28EC20 features:
  • 20480 Bits of Nonvolatile (NV) EEPROM Partitioned into Eighty 256-Bit Pages
  • Individual 8-Page Groups of Memory Pages (Blocks) can be Permanently Write Protected or Put in OTP EPROM-Emulation Mode (“Write to 0”)
  • Read and Write Access Highly Backward-Compatible to Legacy Devices (e.g., DS2433)
  • 256-Bit Scratchpad with Strict Read/Write Protocols Ensures Integrity of Data Transfer
  • 200k Write/Erase Cycle Endurance at +25°C
  • Unique Factory-Programmed 64-Bit Registration Number Ensures Error-Free Device Selection and Absolute Part Identity
  • Switchpoint Hysteresis and Filtering to Optimize Performance in the Presence of Noise
  • Communicates to Host at 15.4kbps or 90kbps Using 1-Wire Protocol
  • Low-Cost TO-92 Package
  • Operating Range: 5V ±5%, -40°C to +85°C
  • IEC 1000-4-2 Level 4 ESD Protection (8kV Contact, 15kV Air, Typical) for I/O Pin

Blocks of eight memory pages can be write-protected or put in EPROM-Emulation mode, where bits can only be changed from a 1 to a 0 state. The life-expectancy of the DS28EC20 is specified at more that 200 k erase/write cycles at 25 °C. The I/O pin has IEC 1000-4-2 Level 4 ESD protections (8 kV contact, 15 kV air).

Applications that can use the DS28EC20:
  • Card/Module Identification in Rack-Based Systems
  • Device Authentication
  • IEEE 1451.4 Sensors
  • Ink and Toner Cartridge ID
  • Medical and Industrial Sensor Identification/Calibration
  • PCB Identification
  • Smart Cable

Ordering DS28EC20 is available for about $1.7 per chip through Maxim website. You can also get design resources and technical documents of the chip.

A $20 Heart Rate Module For Health-Tech Projects

Heart rate monitoring is a common procedure for most of health related projects. Therefore, producing sensors modules and circuit boards for such tasks will facilitate and push forward the development of new health-tech projects.

Maxim Integrated, an analog and mixed-signal integrated circuits manufacturer, has developed a new module for measuring heart rate and pulse oximetry. It’s called “MAXREFDES117#”, derived from Maxim Reference Design, and it is a small board which is compatible with Arduino and Mbed boards, enabling a wide range of possibilities for developers.


MAXREFDES117# can be powered by 2 to 5.5 volts. It is a photoplethysmography (PPG)-based system that uses optical method for detecting heart rate and SpO2. It consists of three main parts:

1. MAX30102, a high sensitivity heart rate and pulse oximetry sensor. It is used with integrated red and IR LEDs for heart rate and pulse oximetry monitoring.

2. MAX1921, a low-power step-down digital-to-digital converter. It generates 1.8 V from input to supply the sensor.

3. MAX14595, a high speed logic-level translator. It works as an interface between the sensor and the connected developing board.

MAXREFDES117 Block Diagram
MAXREFDES117 Block Diagram

The board size is only 0.5” x 0.5” (12.7mm x 12.7mm) and has low power consumption that make it suitable for wearable applications. Thus, it can be placed on a finger, an earlobe, or other fleshy extremity.

MAXREFDES117# uses open-source heart-rate and SpO2 algorithm in its firmware. It also can be used with any controller having I2C interface. But the available firmware had been tested only on 6 different development boards, three of them are Arduinos (Adafruit Flora, Lilypad USB, and Arduino UNO), and the others are mbed boards (Maxim Integrated MAX32600MBED#, Freescale FRDM-K64F, and Freescale FRDM-KL25Z).

The MAXREFDES117# Firmware Flowchart
The MAXREFDES117# Firmware Flowchart

Accuracy of data collected by MAXREFDES117# depends on the used platform. According to the results with tested boards, Arduino boards give less accuracy than mbed ones because of theirs smaller SRAM size.

MAXREFDES117# is available for $20, it can be ordered online through the website.
More detailed information and quick start guide are presented here. In addition, all of the source files including schematic, PCB, BOM, and firmware are open and can be reached at the official product page.

Driving 14-segment displays with the MAX6954


App note from Maxim on using the MAX6954 to drive 14-segment monocolor LEDs, (PDF):

This article is how-to guide, intended as a quick learning aid for engineers considering using the MAX6954 to drive 14-segment monocolor LEDs.

The MAX6954 is a versatile display driver, capable of controlling a mix of discrete, 7-segment, 14-segment, and 16-segment LED displays through a serial interface. This application note shows a typical application and configuration for driving eight mono-color, 14-segment LEDs.
See the MAX6954 data sheet for additional information about MAX6954 features.

Driving 14-segment displays with the MAX6954 – [Link]

ATmega8 Thermocouple Thermostat


morethanuser.blogspot.com has published a thermocouple thermostat based on ATmega8 and  MAX31855KASA Thermocouple to digital converter IC from Maxim.

Here is a circuit, I used popular thermocouple type K and MAX31855KASA+ to interface it. I could also put some op amp, and connect to Atmega8’s ADC, but 31855 is for lazy people and has everything inside, just connect thermocouple, and get data through SPI interface. It has also some nice features, like error detect (if therm. is damaged or shorted to VCC or GND), it’s not so cheap from the other side.

ATmega8 Thermocouple Thermostat – [Link]


MAX30102 – High-Sensitivity Pulse Oximeter and Heart-Rate Sensor


The MAX30102 pulse oximeter and heart rate integrated sensor module is claimed as the lowest power solution on the market today

The MAX30102 is an integrated pulse oximetry and heart-rate monitor module. It includes internal LEDs, photodetectors, optical elements, and low-noise electronics with ambient light rejection. The MAX30102 provides a complete system solution to ease the design-in process for mobile and wearable devices.

The MAX30102 operates on a single 1.8V power supply and a separate 5.0V power supply for the internal LEDs. Communication is through a standard I²C-compatible interface. The module can be shut down through software with zero standby current, allowing the power rails to remain powered at all times.

MAX30102 – High-Sensitivity Pulse Oximeter and Heart-Rate Sensor – [Link]