User's Manual

FLC-WFM301 Datasheet
Flaircomm Microelectronics Confidential
-13-
4. Physical Interfaces
4.1 Power Supply
4.1.1 Linear Regulators
FLC-WFM301 contains four linear regulators:
 A low-voltage regulator to supply the 1.2V core digital supply
 Three low-voltage regulators for the 1.2V core auxiliary, radio and RF synthesizer analogue supplies
4.1.2 LDO for Digital Supply
VREG_IN_DIG is the input voltage to the internal LDO for digital supply and VDD_DIG is the
output of the LDO. A low ESR 2.2uF capacitor to ground should be connected to this pin.
4.1.3 RF Front End Power Supply
VDD_RF1 and VDD_RF2 are the external 3.3V input to power RF front end. Clean voltage should
be used for these two pins.
4.1.4 I/O Power Supply
 VDD_PADS is used to power PIO[0] to PIO[7]. The typical voltage is 1.8V for this rail.
 VDD_AIO_PIO is used to power PIO[8] to PIO[15], AIO[0] to AIO[3]
4.2 Reset
WFM301CL can be reset from several sources,
 Via the external RST# pin (pin 5)
 Via an internal core power supply supervisor
 Using software watchdog timers
 Via SDIO/CSPI host interface
RST# is an active-low reset input that is internally filtered using the internal low frequency clock
oscillator to avoid spurious resets. A reset occurs after the signal has been asserted for between 250
and 375 s. This pin may be tied to VDD_PADS is unused; otherwise it should be asserted for at
least 1 ms to force a reset.
The power supply monitors VDD_DIG to trigger a power-on-reset. This occurs when the supply
falls below 1.05V (typical) in normal operation or 0.785C (typical) in deep sleep, and ends when the
supply exceeds 1.10V (typical). Glitches of up to 30mV and 2.5s duration, which could be caused
by large load steps, will not trigger a reset.
Each of the internal processors has its own independent watchdog timer to detect and recover from
erroneous software operation. These are typically configured with a timeout of 1.5s, but this may be
increased up to maximum of 64s for reduced power consumption. The watchdogs are enabled at
power-on and continue operating while WFM301CL is in deep sleep.