CPAP Machine

CPAP Machine Solutions from Texas Instruments

Block Diagram

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AC/DC Supply

Reference Designs


CPAP or Continuous Positive Airway Pressure is a method of respiratory ventilation used mainly for the treatments of sleep apnea at home. During sleep, the muscles tend to naturally relax causing the upper airway to become narrow. This reduces the amount of oxygen in the blood and causes arousal from sleep.

Pressure sensors play an important role for respiration equipment by converting physical values such as airway pressure and flow into a differential signal. The air and flow sensors generate signals to help the microprocessor regulate the motor to adjust/maintain the desired pressure as the person inhales or exhales. Often, the sensors are very cost-effective with large offset and offset drift causing the signals to be off scale, temperature variant and non-linear. Amplifiers with low offset voltage and drift over time and temperature are ideal for signal conditioning.

The actual controlling of the DC Motor can be done by monitoring at least two of the three current phases and the DC bus voltage feeding the motor drive bridge. For the phase currents, two approaches can be used: high-side or low-side. Direct phase measurement or high side, requires high speed difference amplifiers or current shunt monitors and is generally more accurate. The low-side approach measures near the half bridge ground connection and uses more simple amplifiers which can be less costly but also less precise. The DC Motor is driven by discrete FETs. TI's DRV family offers an integrated driver and bridge with thermal protection that is smaller, more precise and much more efficient that is highly recommended.

The microprocessor performs multiple operations including sampling the pressure signals and computing a desired airway pressure and flow level to communicate with the motor. To achieve these operations efficiently and in real-time, a high-speed, low-power, highly-integrated microprocessor should be used. A high-quality DSP can be used for such applications and will also provide the patient with an ultra quiet operation.

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Application Notes (5)

Title Abstract Type Size (KB) Date Views
HTM 8 KB 16 Apr 2015 10832
HTM 9 KB 28 Feb 2013 5244
HTM 8 KB 01 Jul 2009 309
HTM 8 KB 08 Jun 2009 311
HTM 8 KB 20 Jan 1999 409

User Guides (1)

Title Abstract Type Size (KB) Date Views
htm 8 KB 07 Jul 2010 373

Selection and Solution Guides

Selection Guides (2)

Title Abstract Type Size (KB) Date Views
PDF 9.09 MB 02 May 2013 2311
PDF 11.49 MB 05 Aug 2010 541

Solution Guides (2)

Title Abstract Type Size (KB) Date Views
PDF 2.13 MB 20 Nov 2015 19125
PDF 2.05 MB 31 Oct 2014 19125

Product Bulletin & White Papers

Product Bulletin (1)

Title Abstract Type Size (MB) Date Views
PDF 208 KB 25 Apr 2011 630

White Papers (2)

Title Abstract Type Size (MB) Date Views
PDF 98 KB 08 Apr 2013 790
PDF 1014 KB 17 May 2011 526

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