Open drain
external wake
up circuit
3 V
Battery
GND
VBAT
Input
Voltage
Regulator
or Switch
XOSC1
XOSC0
VDD
HIB
WAKE
OUT
IN
GNDX
7LYDŒ 0LFURFRQWUROOHU
R
BAT
C
BAT
R
PU
Clock
Source
(f
EXT_OSC
)
N.C.x
Functional Description
480
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Hibernation Module
NOTE:
Some devices may not supply the GNDX signal. If GNDX is absent, the crystal load
capacitors can be tied to GND externally. See for pins specific to your device.
X
1
= Crystal frequency is f
XOSC_XTAL
.
C
1,2
= Capacitor value derived from crystal vendor load capacitance specifications.
R
PU
= Pullup resistor is 200 k
Ω
R
BAT
= 51
Ω
±5%
C
BAT
= 0.1 µF ±20%
See the HIB electrical specifications in the device-specific data sheet for specific parameter
values.
Figure 6-3. Using a Dedicated Oscillator as the Hibernation Clock Source with VDD3ON Mode
NOTE:
Some devices may not supply a GNDX signal. See for pins specific to your device.
R
PU
= Pullup resistor is 1 M
Ω
R
BAT
= 51
Ω
±5%
C
BAT
= 0.1 µF ±20%
6.3.2.1
Hibernate Clock Output RTCOSC
The clock source that is configured as the HIB clock has the option of becoming an internal output,
RTCOSC, and being selected as the clock source for the system clock. To enable RTCOSC as a system
clock source, the SYSCLKEN bit must be set in the Hibernate Clock Control (HIBCC) register.
6.3.3 System Implementation
Several different system configurations are possible when using the Hibernation module:
•
Using a single battery source, where the battery provides both V
DD
and V
BAT
, as shown in
•
Using the VDD3ON mode, where V
DD
continues to be powered in hibernation, allowing the GPIO pins to
retain their states, as shown in
. In this mode, V
DDC
is powered off internally. In VDD3ON
mode, the RETCLR bit in the HIBCTL register must be set so that after power is reapplied, GPIO
retention is held until software clears the bit. GPIO retention is released when software writes a 0 to
the RETCLR bit.