TLV7011 Series Comparator from Texas Instruments
Digital is not everything: in real life, one sometimes needs a comparator. Texas Instruments recently-introduced TLV70x1 series provide a cheap and space-conscious solution for this problem.
The traditional knee-jerk reaction to a problem requiring a comparator is a great indicator of your age; some will grab an LM324, others will go for an LM741. Both of these are opamps, who require quite a bit of external “diddling” before they can act as a reliable comparator. This not only increases BOM size and cost, but also wastes space on the board.
TI’s TLV70x1 family is a set of four ICs, each of which contain one comparator. The most outstanding attribute is the small size; the Extra Small Outline No-Lead (aka X2SON) package, described here, is but 0.8×0.8mm small. For prototyping, a classic SOT23 case is also available, which can be soldered by hand with some practice.
Generally, the parts are optimized to limit BOM changes. First of all, a supply voltage range of 1.6V to 5.5V means that the chip is very likely to “blend into” your environment. Benefit number two is an internal hysteresis to the – temperature dependent – tune of 4mV, thereby eliminating the need for a feedback resistor. One ambivalent aspect of the TLV70xx family is their capability to drive and sink insane amounts of current. Short-circuit values are in the range of 50mA, which means that most LEDs and even longer PCB traces can be driven directly. Of course, this also means that a bypass capacitor is recommended – the knife cuts both ways.
Greetings from the Kelly family
Traditionally, small part number deviations meant a change in the amount of chips in the case. This is not the case for the TLV family: the TLV7011 and 7031 have push-pull outputs, while the other ones use the open-drain principle. Furthermore, TLV7011 and TLV7021 use 5 Microamps of current and offer a propagation delay of 260ns, while the TLV7031 and TLV7041 need 335 Nanoamps at 3 Microseconds of propagation. Be aware that the TLV70xx series, being quite young, shows a tremendous price spread: as of this writing, quantity one prices range from 17 to more than 50 cents. Furthermore, finding datasheets can be difficult.