Category Archives: Circuits

How to prototype circuits cleanly (Manhattan style)

manhattan.jpg

For me, site speed of construction is the ultimate goal for prototyping circuits. This often involves perforated prototyping boards with components and wires flowing everywhere giving an impression of a clump of hair. It got the job done, however, it was increasingly difficult to troubleshoot with each additional kludge and even harder to have somebody else understand the board. Even if they had the schematics. Some time ago I was pointed to an excellent article by K7Q0 describing Manhattan Building Techniques. The style involves taking a copper clad board and gluing smaller pieces of copper clad board to it to mount components on. Techniques are discussed to make this mounts for single point connectors to more complicated dual in-line connectors. The overall result is that the circuit looks much cleaner and is easier to diagnose. A secondary benefit is that the circuit typically includes a ground plane and the possibility of power planes for reduced noise. The chief downside is that the prototype board takes longer to produce, however, this may well be justified.

( manart.pdf )

IC Friday: Intersil’s X9250

x9250ts-small.JPG

This week we have the X9250 from Intersil. This is a SPI-programmable quad potentiometer. The one imaged is 100kOhm total resistance. This unit is responsible for the gain and offset control in my digitally-programmable amplifiers and has done a fairly good job so far. It should be noted that the device can read out the wiper positions and has non-volatile storage. Finally, see the maximum current limit for the device is 15mA through the wiper which may be lower than a comparable mechanical potentiometer.

x9250ts-stitched.jpg

x9250ts-10x-01.jpg x9250ts-10x-02.jpg x9250ts-10x-03.jpg

x9250ts-20x-01.jpg x9250ts-20x-02.jpg x9250ts-20x-03.jpg

x9250ts-60x-01.jpg x9250ts-60x-02.jpg x9250ts-60x-03.jpg

x9250ts-60x-04.jpg x9250ts-60x-05.jpg x9250ts-60x-06.jpg

x9250ts-100x-01.jpg x9250ts-100x-02.jpg x9250ts-100x-03.jpg

( x9250ts.pdf )

IC Friday: Marvell W8686B13

w8686b13-small.JPG

This is the Wifi chip aimed at smartphones from Marvell. Not too much to see with so much metal on the top, however, there are some open areas. A small note of interest is that there are pads on the perimeter of this chip as well as on the bottom leading me to think that the layout was destined for flip-chip bonding, such as in the iPhone, or to be put in a standard package. There is also an orientation mark at the center of the chip. There is some speculation that this chip features an ARM core and given my past experience looking at CPUs, it is reasonable that it can be in there below all of that metal. Although I don’t do RF IC design, I would speculate that the open windows are the last stages of RF amplifier designs and are open to minimize parasitic capacitance. I am not sure if the coils on the surface are used for tuning purposes or in a DC/DC converter application to power the output stage of the RF generator. As always, if you have more insight on the chip, please share!

Thanks to a tip by “marius”, I have made a composite image of the 4x scans (see below) using hugin.

w8686b13-4x-stitched.jpg

w8686b13-10x-01.jpg w8686b13-10x-02.jpg w8686b13-10x-03.jpg

w8686b13-10x-04.jpg w8686b13-10x-05.jpg w8686b13-10x-06.jpg

w8686b13-20x-01.jpg w8686b13-20x-02.jpg w8686b13-20x-03.jpg

w8686b13-60x-01.jpg w8686b13-60x-02.jpg w8686b13-60x-03.jpg

w8686b13-60x-04.jpg w8686b13-60x-05.jpg w8686b13-60x-06.jpg

w8686b13-100x-01.jpg w8686b13-100x-02.jpg w8686b13-100x-03.jpg

w8686b13-100x-04.jpg w8686b13-100x-05.jpg w8686b13-100x-06.jpg

iPhone PCB scans

iphone-initial-small1.JPG

I apologize to those who are sick of seeing iPhone related news clogging the internet. As per request, order below are the scans of the two PCBs with and without the chips. It is likely that there will be a few more IC Fridays displaying iPhone chips with the hope of finding some easter eggs and then the grand finale will be my attempt at reading the 4GB flash chip. The 48 TSSOP adapter has been ordered already and with a lot of luck, sovaldi sale I may be able to use a method that involves interfacing the flash with a SD card reader. With even more luck, the chip will not be destroyed. Finally, if the planets align, it may be possible to read the contents of the chip in a meaningful way. After that, I will look for other gadgets to dissect. Files are about 3MB each.

iphone-nometal-front256.jpg

iphone-nometal-back256.jpg

iphone-bare-w-cpu-front256.jpg

iphone-bare-w-cpu-back256.jpg

IC Friday: Apple iPhone’s CPU

iphone-cpu-chips.jpg

iphone-arm.jpg iphone-ram1.jpg iphone-ram2.jpg

As promised, store thanks to the guys at Think Secret, I have started imaging the chips inside the Apple iPhone. I started out with the processor and can confirm that the chip contains both the ARM CPU and the RAM, three dies to be exact. Unfortunately, there was not much to look at under the microscope. The CPU had what looked to be a model number and the RAM chips had what looked to be part of a model number on the cut-away part of the die. No visible logos or slogans on these chips. It was also unfortunate that the chips had a layer of metal on top which prevented me from seeing most of the actual circuitry. The only marginally interesting part was that under 100x magnification, it seemed that some of the perforations in the metal on the CPU may have been letters instead of square holes. You can judge for yourself.

In any case, I removed all of the chips from the iPhone using a hot plate so feel free to suggest the next chip for imaging in the comments. The FLASH was removed separately using Chipquick and will be saved for potential reading. Below are scans (~4MB each) of the two logic boards to help you make the selection.

iphone-circuits-nometal-front-small.jpg iphone-circuits-nometal-back-small.jpg

CPU:

iphone-cpu-4x-01.jpg iphone-cpu-4x-02.jpg iphone-cpu-4x-03.jpg

iphone-cpu-10x-01.jpg iphone-cpu-10x-02.jpg iphone-cpu-10x-03.jpg

iphone-cpu-10x-04.jpg iphone-cpu-10x-05.jpg iphone-cpu-10x-06.jpg

iphone-cpu-20x-01.jpg iphone-cpu-20x-02.jpg iphone-cpu-20x-03.jpg

iphone-cpu-40x-01.jpg iphone-cpu-40x-02.jpg iphone-cpu-40x-03.jpg

iphone-cpu-60x-01.jpg iphone-cpu-60x-02.jpg iphone-cpu-60x-03.jpg

iphone-cpu-60x-04.jpg iphone-cpu-60x-05.jpg iphone-cpu-60x-06.jpg

iphone-cpu-100x-01.jpg iphone-cpu-100x-02.jpg iphone-cpu-100x-03.jpg

iphone-cpu-100x-04.jpg iphone-cpu-100x-05.jpg iphone-cpu-100x-06.jpg
RAM:

iphone-ram-4x-01.jpg iphone-ram-4x-02.jpg iphone-ram-4x-03.jpg

iphone-ram-10x-01.jpg iphone-ram-10x-02.jpg iphone-ram-10x-03.jpg

iphone-ram-20x-01.jpg iphone-ram-20x-02.jpg iphone-ram-20x-03.jpg

iphone-ram-60x-01.jpg iphone-ram-60x-02.jpg iphone-ram-60x-03.jpg

iphone-ram-100x-01.jpg iphone-ram-100x-02.jpg iphone-ram-100x-03.jpg

So I ended up getting an iPhone…

iphone-initial-small.JPG

Well, for sale sort of. The great guys at Think Secret have sent me the logic boards from their disassembled iPhone. The hope is that I apply my skills in opening up integrated circuits to get further images of the device. I will try to uncap and image the ICs, disassemble the circuit board layer by layer (tough order, might not happen) and finally read out the flash chip (even tougher order). Hopefully, more images will start coming up at Think Secret and/or here, and then there is another IC Friday coming up.

iphone-initial.jpg

Sony digital video player training manual

sony-manual.jpg

While looking up a datasheet for IC Friday, patient I happened to come across this gem, ask a manual which described the troubleshooting procedures and the circuitry inside a late 1990s Sony DVD player. The manual gives a pretty decent overview of all of the optical drive subsystems which can then sometimes be generically applied to other optical drives on the market today. Furthermore, communications are described including various error codes. Unfortunately, I did not make a note of the source website for this manual to give credit, so if you know the source, please let me know.

( sony_dvd_training_manual_118.pdf )