Texas Instruments – Experimental Engineering

Posted on January 1, 2018December 20, 2017 by The Engineer — 8 Comments

Contec CMS-50F Pulse Oximeter Teardown

The rear has the specifications, laser-marked into the plastic. The serial numbers are just sticky labels though, and will come off easily with use.

This is the Contec CMS-50F wrist-mounted pulse oximeter unit, which has the capability to record data continuously to onboard memory, to be read out at a later time via a USB-Serial link. There is software supplied with the unit for this purpose, although it suffers from the usual Chinese quality problems. The hardware of this unit is rather well made, the firmware has some niggles but is otherwise fully functional, however the PC software looks completely rushed, is of low quality & just has enough functionality to kind-of pass as usable.

A total of 4 screws hold the casing together, once these are removed the top comes off. The large colour OLED display covers nearly all of the board here. The single button below is the user interface. The connection to the probe is made via the Lemo-style connector on the lower right.

Power is provided by a relatively large lithium-ion cell, rated at 1.78Wh.

All the heavy lifting work of the LCD, serial comms, etc are handled by this large Texas Instruments microcontroller, a MSP430F247. The clock crystal is just to the left, with the programming pins. I’m not sure of the purpose of the small IC in the top left corner, I couldn’t find any reference to the markings.

The actual pulse oximetry sensor readings seem to be dealth with by a secondary microcontroller, a Texas Instruments M430F1232 Mixed-Signal micro. This has it’s own clock crystal just underneath. The connections to the probe socket are to the right of this µC, while the programming bus is broken out to vias just above. The final devices on this side of the board are 3 linear regulators, supplying the rails to run all the logic in this device.

The rear of the PCB has the SiLabs CL2102 USB-Serial interface IC, the large Winbond 25X40CLNIG 512KByte SPI flash for recording oximetry data, and some of the power support components. The RTC crystal is also located here at the top of the board. Up in the top left corner is a Texas Instruments TPS61041 Boost converter, with it’s associated components. This is probably supplying the main voltage for the OLED display module.

Posted on February 14, 2016 by The Engineer — Leave a comment

First Decapping! Unknown TI Part

I’ve been working on something new for the blog, as I have a massive collection of scrap ICs – that is to decap the silicon & get them under a microscope!
Here’s the first image, a Texas Instruments part. This has been stitched together from 140 separate images to create the final version.

Posted on August 25, 2015 by The Engineer — Leave a comment

Rigol DS1054Z 12v Conversion Project Update

While searching around for regulators to convert my new scope to 12v power, I remembered I had some DC-DC modules from Texas Instruments that I’d got a while ago. Luckily a couple of these are inverting controllers, that will go down to -15v DC at 15W/3A capacity.

I’ve had to order a new module from TI to do the -17v rail, but in the meantime I’ve been getting the other regulators set up & ready to go.

The DC-DC module I’ve got for the -7.5v rail is the PTN78060A type, and the +7.5v & +5v rails will be provided by the PTN78020W 6A buck regulators.

These regulators are rated well above what the scope actually draws, so I shouldn’t have any issues with power.

Here’s the regulators for the 5v, 7.5v & -7.5v rails, with multiturn potentiometers attached for setting the voltage output accurately. I’ve also attached a couple of electrolytics on the output for some more filtering. I’ll add on some more LC filters on the output to keep the noise down to an absolute minimum. These are set up ready with the exact same output voltage as the existing mains AC switching supply, when the final regulator arrives from TI I will put everything together & get some proper rail readings.

There won’t be a proper PCB for this, as I don’t have the parts in Eagle CAD, and I simply don’t have the energy to draw them out from the datasheets.

More to come when parts arrive!

73s for now 🙂

Posted on October 7, 2014 by The Engineer — Leave a comment

HPI Savage X 4.6 LiPo Receiver Battery

To provide more run time with the conversion to petrol & spark ignition, I have also upgraded the on-board electronics supply to compensate for the extra ~650mA draw of the ignition module.
This modification is centred around a 3S Lithium-Polymer battery pack, providing a nominal 11.1v to a voltage regulator, which steps down this higher voltage to the ~6v required by the receiver & servo electronics.

The regulator, shown above, is a Texas Instruments PTN78060WAZ wide-input voltage adjustable regulator. This module has an exceptionally high efficiency of ~96% at it’s full output current of 3A. The output voltage is set by a precision resistor, soldered to the back of the module, in this case 6.5v. Standard RC connectors are used on the regulator to allow connection between the power switch & the radio receiver.

Everything tucked away into place inside the receiver box. The 3S 1000mAh LiPo fits perfectly in the space where the original Ni-Mh hump pack was located.
The completely stable output voltage of the regulator over the discharge curve of the new battery gives a much more stable supply to the radio & ignition, so I should experience fewer dropouts. Plus the fact that the engine now relies on power from the receiver pack to run, it’s a built in fail safe – if the power dies to the receiver, the engine also cuts out.

Posted on October 4, 2011 by The Engineer — Leave a comment

LED Lighting Part 1

Here I will document progress in replacing standard halogen MR10 lights with LEDs.

These units are from TruOpto, available through Rapid Electronics in the UK. They are 3W total, from 3x 1W emitters on an aluminium back plate.

Here is the LED attached to a heatsink for testing purposes – these units dissipate nearly 2W in heat at full output.

As the lights are to be run from a 12v battery bank, for simplicity a master regulator is required to provide a stable 11.4v rail for LED supply.

I have used a Texas Instruments part – PTN78020WAH. This is a 6A capable adjustable regulator module.

The LED lights are to be fully dimmable – the low voltage PWM dimmers are in progress of being built.

Posted on January 20, 2011 by The Engineer — Leave a comment

Power Pack Regulator Update

To help make my system more efficient, a pair of switching regulators has been fitted, the one shown above is a Texas Instruments PTN78060 switchmode regulator module, which provides a 7.5v rail from the main 12v battery pack.

A Lot like the LM317 & similar linear regulators, these modules require a single program resistor to set the output voltage, but are much more efficient, around the 94% mark at the settings used here.

The 7.5v rail supplies the LM317 constant current circuit in the laser diode driver subsection. This increases efficiency by taking some voltage drop away from the LM317.

The 7.5v rail also provides power to this Texas Instruments PTH08000 switchmode regulator module, providing the 5v rail for the USB port power.

Posted on September 23, 2010 by The Engineer — Leave a comment

Belkin F5U021 4-Port USB Hub

This is an old USB 1.1 hub that was recently retired from service on some servers. Top of the unit visible here.

Bottom label shows that this is a model F5U021 hub, a rather old unit.

PCB is here removed from the casing, Indicator LEDs along the bottom edge of the board, power supply is on the left. Connectors on the top edge are external power, USB host, & the 4 USB outputs. Yellow devices are polyswitch fuses for the 500mA at 5v each port must supply.

This is the USB Hub Controller IC, which is a Texas Instruments TUSB2046B device. Power filter capacitors next to the USB ports are visible here also, along with 2 of the polyswitches.

The power supply section of the unit, which supplies regulated 5v to the ports, while supplying regulated 3.3v to the hub controller IC. Large TO-220 IC is the 5v regulator. Smaller IC just under the power selector switch is the 3.3v regulator for the hub IC. The switch selects between Host powered or external power for the hub.

Posted on September 22, 2010 by The Engineer — 2 Comments

Epson Ink Cartridge Resetter

This is a device designed to reset Epson brand ink cartridges that are reportedly out of ink, so they again report full to the printer Here is the front of the unit, with the guide for attaching to a cartridge.

Back of the device removed. 3 button cells provide power to the PCB. Indicator LED sticks out of the top of the device for reset confirmation.
Row of pads on far left edge of the PCB are presumably a programming header for the uC on the other side of the board.

Here is the front of the PCB, main feature being the grid of pogo pins to connect to the cartridge chip. IC on lower right of that is a MSP430F2131 uController, a Texas Instruments part.
The IC directly to the left of the pogo pin bed is a voltage regulator, to step down the ~4.5v of the batteries down to the ~3.3v that the uC requires.

Posted on August 5, 2010 by The Engineer — Leave a comment

HP Photosmart 375

This is a HP PhotoSmart 375 portable photo printer. With built in card reader, screen & PictBridge.
Top of the printer showing the UI Buttons & Screen.

Front of the unit, card reader slots at the top, Pictbridge USB connector at top left. Paper out slot at bottom. Cartridge door is on the right.

Here the cartridge door is open. Takes HP 95 Tri-Colour Inkjet Cartridge.

Battery compartment on the bottom of the unit. A Li-Ion battery pack can be installed here for mobile photo printing.

Specifications label.

Power adaptor & USB connection for PC use.

Rear door opened. Showing the paper feed tray.

Rear door has been removed in this shot. Paper feed roller & platen roller can be seen here.

Paper holder attached to rear door.

Bottom of the top cover, with connections for the buttons & LCD panel.

This is the main PCB of the unit. Controls all aspects of the printer. CPU in center, card reader sockets are along bottom edge. various support circuitry surrounds the CPU.