Specifications

Page 75
WT1231H
ADVANCED COMMUNICATIONS & SENSING DATASHEET
7. Application Information
7.1. Crystal Resonator Specification
Table 31 shows the crystal resonator spec
ification for the crystal reference oscillator circuit of the WT1231H.
This specification covers the full range of operation of the WT1231H and is employed in the reference design.
Table 31 Crystal Specification
Symbol Description Conditions Min Typ Max Unit
FXOSC
XTAL Frequency 26 - 32 MHz
RS XTAL Serial Resistance - 30 140 ohms
C0 XTAL Shunt Capacitance - 2.8 7 pF
CLOAD External Foot Capacitance On each pin XTA and XTB 8 16 22 pF
Notes - the initial frequency tolerance, temperature stability and ageing performance should be chosen in accordance
with the target operating temperature range and the receiver bandwidth selected.
- the loading capacitance should be applied externally, and adapted to the actual Cload specification of the XTAL.
- A minimum XTAL frequency of 28 MHz is required to cover the 863-870 MHz band, 29 MHz for the 902-928 MHz
band
7.2. Reset of the Module
A power-on reset of the WT1231H is triggered at power up. Additionally, a manual reset can be issued by controlling pin
RESET.
7.2.1. POR
If the application requires the disconnection of VDD from the WT1231H, despite of the extremely low Sleep Mode
current, the user should wait for 10 ms from of the end of the POR cycle before commencing communications over the SPI
bus. Pin 6 (Reset) should be left floating during the POR sequence.
VDD
Pin
Reset
(output)
Undefined
Wait f or
10
ms
Module is ready
from this point on
Figure 39. POR Timing Diagram
Please note that any CLKOUT activity can also be used to detect that the module is ready.