Hello Sir/Madam,
Product PN: STWD100xY.
Problem: The problem is not with the actual product itself, but with the datasheet. The existing datasheet makes it very difficult to determine if the product is suitable for our application. For the value for the parameter [Watchdog timeout period, tDW] we are looking for a variation of less than +/-5% from nominal, for constant Vcc (3.3V) and constant temperature (25C).
The problem is that the datasheet seems to show that the initial value for the parameter [Watchdog timeout period] is very wide: 1.6s typ, but can be as low as 1.12s and as high as 2.24s, a variation of -0.48s (30%) / +0.64s (40%). (refer datasheet, Table 4 on page 13, refer image below with link). We can accommodate some level of manufacturing tolerance, but -30/+40% is just too wide, we need a tighter range.
Note 1 of that datasheet table seems to indicate that the wide variation is due the Test Conditions, which are:
a) temperature, -40 to +125C
b) supply voltage, Vcc: 2.7V to 5.5V.
The problem is that the datasheet does not clearly indicate the variation of this parameter under constant temperature and constant Vcc. That is to say: the datasheet does not clearly separate out the dependence of this parameter upon each separate cause of variation, which are (of course): (a) temperature, (b) Vcc, (c) manufacturing spread.
Ideally, the datasheet should show how the device parameters vary for each of the common causes of variation, as mentioned above (temperature, Vcc, and manufacturing spread). Even better if the datasheet could provide data for long-term variation, ie: variation of parameters due to ageing during the service life of the device.
Part of Table 4 of Datasheet
