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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January 17, 2014
ST 34C02 - 2048-bit EEPROM : weekend die-shot
STMicroelectronics 34C02 is an 2048-bit EEPROM with hardwire write-protect and I2C interface, typically used as SPD chip in DIMM memory modules.Die size 1542x1422 µm, 1.2µm half-pitch.
