Medical Applications User Guide (pdf) - Freescale Semiconductor

Diagnostic and Therapy Devices
The preparation of an air and oxygen blender
generally consists of attaching a 50 PSI air
and oxygen source to the device. After the
source gases are attached, inlet pressures
may be checked on some blenders by
checking the pressure-attached pressure
gauge. After the inlet gases are attached and
the air and oxygen blender is well secured
to a stand or wall mount, it is ready for use.
The MCU uses a PWM to control the blender
electro valves through a motor control design.
Early ventilator designs relied on mechanical
blenders to provide premixed gas to a single
flow control valve. With the availability of
high-quality flow sensors and processing
capabilities, accurate mixing becomes
possible by using separate flow valves for
air and oxygen. Because air already contains
about 21 percent oxygen, the total flow
control command between the oxygen and air
valve is divided ratiometrically. For extreme
mix settings, the valve that supplies the minor
flow at low total flow requirements may fall
below the resolution limits that either flow
delivery or measurement can provide. An
accurate delivered mix depends on accurate
flow delivery, but if accurate and reliable
oxygen sensors are used, improved mix
accuracy may be possible by feeding back a
measured concentration for mix correction.
Then, if the patient needs more pressure, the
MCU activates the compressor.
For more information on how to build a
ventilator/respirator, download Ventilator/
Respirator Hardware and Software Design
Specification (document DRM127) from
freescale.com.
Kinetis K20 MCUs
The K20 MCU family is pin, peripheral and
software compatible with the K10 MCU family
and adds full-speed USB 2.0 On-The-Go
with device charge detect capability. Devices
start from 128 KB of flash in 80-pin LQFP
packages extending up to 512 KB in a 144pin
MAPBGA package with a rich suite of
analog, communication, timing and control
peripherals.
Figure Figure 11-9: 12-7: Kinetis Kinetis K20 K20 Block Block Diagram Diagram
Security
and Integrity
Cyclic
Redundancy
Check (CRC)
Core
ARM ® Cortex-M4
50/72/100/120 MHz
Debug
Interfaces
Interrupt
Controller
Standard Feature
Key Features
• ARM Cortex-M4 core with DSP, 100MHz
clock, single cycle MAC, and single
instruction multiple data (SIMD) extensions
• 128 KB - 512 KB flash. Fast access, high
reliability with four-level security protection
• Hardware touch-sensing interface with up
to 16 inputs. Operates in all low-power
modes (minimum current adder when
enabled). Hardware implementation avoids
software polling method. High sensitivity
level allows use of overlay surfaces up to
5 mm thick
System Memories
Internal and
External
Watchdogs
Memory
Protection Unit
(MPU)
Xtrinsic
Low-Power
Touch-Sensing
Interface
• Memory protection unit provides memory
protection for all masters on the cross bar
switch, increasing software reliability
• Cyclic redundancy check engine validates
memory contents and communication data,
increasing system reliability
68 Medical Applications User Guide
DSP
Floating Point
Unit (FPU)
Analog
16-bit
ADC
PGA
Analog
Comparator
6-bit
DAC
12-bit
DAC
Voltage
Reference
DMA
Low-Leakage
Wake-Up Unit
Timers
FlexTimer
Carrier
Modulator
Transmitter
Programmable
Delay Block
Periodic
Interrupt
Timers
Low-Power
Timer
Independent
Real-Time
Clock (RTC)
Optional Feature
Program Flash
(32 KB to 1 MB)
FlexMemory
(32 KB to 512 KB)
(2 to 16 KB EE)
Serial
Programming
Interface
(EzPort)
NAND Flash
Controller
SRAM
(8 KB to 128 KB)
External
Bus Interface
(FlexBus)
Cache
Clocks
Phase-Locked
Loop
Frequency-
Locked Loop
Low/High-
Frequency
Oscillators
Internal
Reference
Clocks
Communication Interfaces HMI
I 2 C
UART
(ISO 7816)
SPI
CAN
I 2 S
Secure
Digital Host
Controller
(SDHC)
USB On-the-Go
(LS/FS)
USB On-the-Go
(HS)
USB Device
Charger Detect
(DCD)
USB Voltage
Regulator
Table 12-1: MPXx2050 Packaging Information
Device Type Packing Options Case
MPX2050D Differential 344
MPC2050DP Differential, Dual Port 423 A
MPX2050GP Gauge 344B
MPX2050GSX Gauge Axial PC Mount 344F
GPIO