April 12, 2014

Phillips PCF8574 - 8-bit I2C port expander : weekend die-shot

Phillips PCF8574 is 8-bit I2C port expander, 3µm manufacturing technology.

April 8, 2014

Fake audiophile opamps: OPA627 (AD744?!)

Walking around ebay I noticed insanely cheap OPA627's. It's rather old, popular and high-quality opamp, often used in audiophile gear. Manufacturer (Texas Instruments / Burr Brown) sells them 16-80$ each (depending on package & options) while on ebay it's cost was 2.7$, shipping included.

Obviously, something fishy was going on. I ordered one, and for comparison - older one in metal can package, apparently desoldered from some equipment. Let's see if there is any difference.


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March 29, 2014

SiTime SiT8008 - MEMS oscillator : weekend die-shot

SiTime SiT8008 is a programmable MEMS oscillator reaching quartz precision but with higher reliability and lower g-sensitivity. Also SiTime is one of companies who received investments from Rosnano - Russian high-tech investment fund.

Photo of MEMS die puzzled us for quite some time. Is it some sort of integrated SAW/STW resonator?

The trick is that to reach maximum Q-factor (up to ~186'000 according to patents) MEMS resonator must operate in vacuum. So they package resonator _inside_ the die in hydrogen atmosphere, then anneal it in vacuum so that hydrogen escapes through silicon. So we see here only a cap with contacts to "buried" MEMS resonator. We were unable to reach the resonator itself without x-ray camera or ion mill.

MEMS die size - 457x454 µm.

Thankfully relevant patents were specified right on the die : US6936491 US7514283 US7075160 US7750758 :)



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March 22, 2014

TI TL431 adjustable shunt regulator : weekend die-shot

TI TL431 is an adjustable shunt regulator often used in linear supplies with external power transistor.
Die size 1011x1013 µm.


March 18, 2014

TI LM393 - dual comparator : weekend die-shot

TI LM393 - dual comparator, one of old workhorses of electronics.
Die size 704x748 µm.


March 16, 2014

Ti TS5A3159 - 1Ω analog switch : weekend die-shot

Ti TS5A3159 is an 1.65-5V 2:1 analog switch with ~1Ω matched channel resistance and "break-before-make" feature.
Die size 1017x631 µm, 1µm technology.


February 17, 2014

FTDI FT232RL: real vs fake

For quite some time when you buy FTDI FT232RL chips from shady suppliers you have a good chance of getting mysteriously buggy chip which only works with drivers 2.08.14 or earlier. We've got a pair of such FTDI FT232RL chips - one genuine and one fake and decided to check if there is an internal difference between them. On the following photo - left one is genuine, right one is fake. One can notice difference in marking - on genuine chip it's laser engraved while on buggy it is printed (although this is not a universal distinguishing factor for other chips).

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