User`s guide

2-10
are commonly used in switching power supply circuits. ESR generally decreases with
higher DC working voltage rating, so C2 will usually be a 50V or 63V capacitor to
achieve the required ESR specifications even though C2 is connected to Vcc = 5V.
Table 2.6 Example C2 Capacitor Selections (22µF, ≥10V, Low ESR)
Manufacturer
(Series)
Part Number Temperature
Range
Application
Panasonic (HFZ) ECA1JFZ220 -55°C to +105°C 20,000 hr. @ +85°C
Nichicon (PL) UPL1J220MEH -55°C to +105°C ESR limits use to ≥ 10°C
Alternative Inductor and Capacitor Selection for Low-
Current Applications
For applications which require no more than 25mA of sustained peak application
current, a set of smaller, surface-mount components for L1, C1 and C2 may be optionally
substituted for those described above. These components are suitable for -40 to +85°C
applications. Molded style capacitors, Sprague type 293, may be also be used for C1 and
C2; they are typically lower-cost but physically larger than those in table 2.7.
Table 2.7 Optional Component Selection for Low-Current Applications (up to 25mA)
Component Description Manufacturer Part Number
L1 1.0mH, 50mA, 25Ω Murata LQH4N102K04M00
C1 10µF, 50V tantalum Sprague 195D106C9050R2
C2 22µF, 10V tantalum Sprague 195D226X9010Y2
Wake-Up Timer
The LPT-10 transceiver includes a facility for awakening the Neuron Chip
periodically to sample inputs/outputs and communicate with the network. At all other
times the Neuron Chip can remain asleep, dramatically reducing node power
consumption. The wake-up timer triggers an output pulse (open-drain type) from the
WAKEUP_OUT pin to a Neuron Chip input (IO 4 through 7) at a rate that is adjustable
from once per second to once every 100 seconds. The pulse frequency is adjustable via
WAKEUP_CAP. The wake-up pulse is a low-going pulse with a duration from 0.5 to 50
milliseconds. Since the output pin is an open-drain type, multiple devices can be tied
together to wake-up a commonly shared Neuron Chip.
The wake-up frequency is set by a one-pin oscillator that is controlled by an external
capacitor connected to WAKEUP_CAP (Cwu in figure 2.1). The capacitor is connected
between WAKEUP_CAP and GND. With capacitors from 0.001µF to 0.1µF, the