8.19 Timing and Switching Characteristics
8.19.1 Power Management
8.19.1.1 Block Diagram – Internal DC-DCs
The device incorporates three internal DC-DCs (switched-mode power supplies) to provide efficient internal
supplies, derived from V
BAT
.
WL18xx Top Level
Main DC2DC
V
BAT
V
IO
FB
SW
PA
DC2DC
FB
SW
Digital DC2DC
FB
SW
1.8 V
2.2 – 2.7 V
V
BAT
VIO_IN
VBAT_IN_MAIN_DC2DC
VBAT_IN_PA_DC2DC
V
BAT
MAIN_DC2DC_OUT
DIG_DC2DC_OUT
VDD_DIG
LDO_IN_DIG
PA_DC2DC_OUT
FB_IN_PA_DC2DC
1 V
Figure 8-1. Internal DC-DCs
8.19.2 Power-Up and Shut-Down States
The correct power-up and shut-down sequences must be followed to avoid damage to the device.
While V
BAT
or V
IO
or both are deasserted, no signals should be driven to the device. The only exception is the
slow clock that is a fail-safe I/O.
While V
BAT
, V
IO
, and slow clock are fed to the device, but WL_EN is deasserted (low), the device is in
SHUTDOWN state. In SHUTDOWN state all functional blocks, internal DC-DCs, clocks, and LDOs are disabled.
To perform the correct power-up sequence, assert (high) WL_EN. The internal DC-DCs, LDOs, and clock start
to ramp and stabilize. Stable slow clock, V
IO
, and V
BAT
are prerequisites to the assertion of one of the enable
signals.
To perform the correct shut-down sequence, deassert (low) WL_EN while all the supplies to the device (V
BAT
,
V
IO
, and slow clock) are still stable and available. The supplies to the chip (V
BAT
and V
IO
) can be deasserted only
after both enable signals are deasserted (low).
shows the general power scheme for the module, including the power-down sequence.
>10 µs
1
2
3
>10 µs
4
5
5
> 60 µs
VBAT
VIO
EXT_32K
WLEN
NOTE: 1. Either VBAT or VIO can come up first.
NOTE:
2. VBAT and VIO supplies and slow clock (SCLK), must be stable prior to EN being asserted and at all times
NOTE:
when the EN is active.
NOTE:
3. At least 60 µs is required between two successive device enables. The device is assumed to be in
NOTE:
shutdown state during that period, meaning all enables to the device are LOW for that minimum duration.
WL1801MOD, WL1805MOD, WL1831MOD, WL1835MOD
SWRS152N – JUNE 2013 – REVISED APRIL 2021
18
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